riscv: Add initial Xen guest support for RISC-V

Commit Message

Milan Djokic Jan. 14, 2025, 4:09 p.m. UTC

From: Slavisa Petrovic <[e-mail]>

This patch introduces initial support for running RISC-V as a Xen guest.
It provides the necessary infrastructure and stubs for Xen-specific
operations. Key changes include:

- Modifications to the RISC-V kernel to integrate Xen-specific hypercalls
  and interfaces, with function implementations stubbed for future work.
- Introduction of Xen-specific headers for RISC-V, including event
  handling, hypervisor interaction, and page management. Functions are
  defined but not yet implemented.
- Stub implementations for memory management, grant tables, and context
  switching in the Xen environment, allowing further development and
  integration.

Signed-off-by: Milan Djokic <[e-mail]>
Signed-off-by: Slavisa Petrovic <[e-mail]>
---
 arch/riscv/Kbuild                        |   1 +
 arch/riscv/Kconfig                       |  19 +++
 arch/riscv/include/asm/cpu.h             |   1 +
 arch/riscv/include/asm/hypervisor.h      |   9 ++
 arch/riscv/include/asm/irq.h             |   5 +
 arch/riscv/include/asm/sync_bitops.h     |  27 ++++
 arch/riscv/include/asm/xen/events.h      |  28 ++++
 arch/riscv/include/asm/xen/hypercall.h   |   2 +
 arch/riscv/include/asm/xen/hypervisor.h  |   2 +
 arch/riscv/include/asm/xen/interface.h   |   2 +
 arch/riscv/include/asm/xen/page.h        |   3 +
 arch/riscv/include/asm/xen/swiotlb-xen.h |   2 +
 arch/riscv/xen/Makefile                  |   2 +
 arch/riscv/xen/enlighten.c               | 164 +++++++++++++++++++++++
 arch/riscv/xen/grant-table.c             |  57 ++++++++
 arch/riscv/xen/hypercall.S               |  71 ++++++++++
 arch/riscv/xen/p2m.c                     |  76 +++++++++++
 include/xen/interface/io/protocols.h     |   3 +
 include/xen/riscv/hypercall.h            |  71 ++++++++++
 include/xen/riscv/hypervisor.h           |  26 ++++
 include/xen/riscv/interface.h            |  85 ++++++++++++
 include/xen/riscv/page.h                 | 106 +++++++++++++++
 include/xen/riscv/swiotlb-xen.h          |  13 ++
 test.txt                                 |  21 +++
 24 files changed, 796 insertions(+)
 create mode 100644 arch/riscv/include/asm/hypervisor.h
 create mode 100644 arch/riscv/include/asm/sync_bitops.h
 create mode 100644 arch/riscv/include/asm/xen/events.h
 create mode 100644 arch/riscv/include/asm/xen/hypercall.h
 create mode 100644 arch/riscv/include/asm/xen/hypervisor.h
 create mode 100644 arch/riscv/include/asm/xen/interface.h
 create mode 100644 arch/riscv/include/asm/xen/page.h
 create mode 100644 arch/riscv/include/asm/xen/swiotlb-xen.h
 create mode 100644 arch/riscv/xen/Makefile
 create mode 100644 arch/riscv/xen/enlighten.c
 create mode 100644 arch/riscv/xen/grant-table.c
 create mode 100644 arch/riscv/xen/hypercall.S
 create mode 100644 arch/riscv/xen/p2m.c
 create mode 100644 include/xen/riscv/hypercall.h
 create mode 100644 include/xen/riscv/hypervisor.h
 create mode 100644 include/xen/riscv/interface.h
 create mode 100644 include/xen/riscv/page.h
 create mode 100644 include/xen/riscv/swiotlb-xen.h
 create mode 100644 test.txt

--
2.43.0

Comments

Anup Patel Jan. 14, 2025, 4:40 p.m. UTC | #1

On Tue, Jan 14, 2025 at 9:41 PM Milan Djokic <[e-mail]> wrote:
>
> From: Slavisa Petrovic <[e-mail]>
>
> This patch introduces initial support for running RISC-V as a Xen guest.
> It provides the necessary infrastructure and stubs for Xen-specific
> operations. Key changes include:
>
> - Modifications to the RISC-V kernel to integrate Xen-specific hypercalls
>   and interfaces, with function implementations stubbed for future work.
> - Introduction of Xen-specific headers for RISC-V, including event
>   handling, hypervisor interaction, and page management. Functions are
>   defined but not yet implemented.
> - Stub implementations for memory management, grant tables, and context
>   switching in the Xen environment, allowing further development and
>   integration.
>
> Signed-off-by: Milan Djokic <[e-mail]>
> Signed-off-by: Slavisa Petrovic <[e-mail]>

A single patch with many changes is hard to review.

Please convert this patch into a series with smaller patches.
Also, include a cover letter in the series explaining how to
test Xen on RISC-V.

Regards,
Anup

> ---
>  arch/riscv/Kbuild                        |   1 +
>  arch/riscv/Kconfig                       |  19 +++
>  arch/riscv/include/asm/cpu.h             |   1 +
>  arch/riscv/include/asm/hypervisor.h      |   9 ++
>  arch/riscv/include/asm/irq.h             |   5 +
>  arch/riscv/include/asm/sync_bitops.h     |  27 ++++
>  arch/riscv/include/asm/xen/events.h      |  28 ++++
>  arch/riscv/include/asm/xen/hypercall.h   |   2 +
>  arch/riscv/include/asm/xen/hypervisor.h  |   2 +
>  arch/riscv/include/asm/xen/interface.h   |   2 +
>  arch/riscv/include/asm/xen/page.h        |   3 +
>  arch/riscv/include/asm/xen/swiotlb-xen.h |   2 +
>  arch/riscv/xen/Makefile                  |   2 +
>  arch/riscv/xen/enlighten.c               | 164 +++++++++++++++++++++++
>  arch/riscv/xen/grant-table.c             |  57 ++++++++
>  arch/riscv/xen/hypercall.S               |  71 ++++++++++
>  arch/riscv/xen/p2m.c                     |  76 +++++++++++
>  include/xen/interface/io/protocols.h     |   3 +
>  include/xen/riscv/hypercall.h            |  71 ++++++++++
>  include/xen/riscv/hypervisor.h           |  26 ++++
>  include/xen/riscv/interface.h            |  85 ++++++++++++
>  include/xen/riscv/page.h                 | 106 +++++++++++++++
>  include/xen/riscv/swiotlb-xen.h          |  13 ++
>  test.txt                                 |  21 +++
>  24 files changed, 796 insertions(+)
>  create mode 100644 arch/riscv/include/asm/hypervisor.h
>  create mode 100644 arch/riscv/include/asm/sync_bitops.h
>  create mode 100644 arch/riscv/include/asm/xen/events.h
>  create mode 100644 arch/riscv/include/asm/xen/hypercall.h
>  create mode 100644 arch/riscv/include/asm/xen/hypervisor.h
>  create mode 100644 arch/riscv/include/asm/xen/interface.h
>  create mode 100644 arch/riscv/include/asm/xen/page.h
>  create mode 100644 arch/riscv/include/asm/xen/swiotlb-xen.h
>  create mode 100644 arch/riscv/xen/Makefile
>  create mode 100644 arch/riscv/xen/enlighten.c
>  create mode 100644 arch/riscv/xen/grant-table.c
>  create mode 100644 arch/riscv/xen/hypercall.S
>  create mode 100644 arch/riscv/xen/p2m.c
>  create mode 100644 include/xen/riscv/hypercall.h
>  create mode 100644 include/xen/riscv/hypervisor.h
>  create mode 100644 include/xen/riscv/interface.h
>  create mode 100644 include/xen/riscv/page.h
>  create mode 100644 include/xen/riscv/swiotlb-xen.h
>  create mode 100644 test.txt
>
> diff --git a/arch/riscv/Kbuild b/arch/riscv/Kbuild
> index 2c585f7a0b6e..d9b71deed2cd 100644
> --- a/arch/riscv/Kbuild
> +++ b/arch/riscv/Kbuild
> @@ -5,6 +5,7 @@ obj-$(CONFIG_BUILTIN_DTB) += boot/dts/
>  obj-$(CONFIG_CRYPTO) += crypto/
>  obj-y += errata/
>  obj-$(CONFIG_KVM) += kvm/
> +obj-$(CONFIG_XEN) += xen/
>
>  obj-$(CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY) += purgatory/
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index d4a7ca0388c0..13ea75221524 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -1071,6 +1071,25 @@ config PARAVIRT_TIME_ACCOUNTING
>
>           If in doubt, say N here.
>
> +config XEN_DOM0
> +       def_bool y
> +       depends on XEN
> +
> +config XEN
> +       bool "Xen guest support on RISCV"
> +       depends on RISCV && OF
> +       select PARAVIRT
> +       help
> +         Enables support for running Linux as a Xen guest on RISC-V.
> +
> +         Xen is a type-1 hypervisor that allows multiple operating systems
> +         to run on the same hardware. Enabling this option allows the kernel
> +         to function as a guest under the Xen hypervisor on RISC-V platforms.
> +
> +         Say Y if you want to run this kernel as a guest under Xen on RISC-V.
> +
> +         If unsure, say N.
> +
>  config RELOCATABLE
>         bool "Build a relocatable kernel"
>         depends on MMU && 64BIT && !XIP_KERNEL
> diff --git a/arch/riscv/include/asm/cpu.h b/arch/riscv/include/asm/cpu.h
> index 28d45a6678ce..fb2aac6a068e 100644
> --- a/arch/riscv/include/asm/cpu.h
> +++ b/arch/riscv/include/asm/cpu.h
> @@ -4,5 +4,6 @@
>  #define _ASM_CPU_H
>
>  /* This header is required unconditionally by the ACPI core */
> +#include <linux/cpu.h>
>
>  #endif /* _ASM_CPU_H */
> diff --git a/arch/riscv/include/asm/hypervisor.h b/arch/riscv/include/asm/hypervisor.h
> new file mode 100644
> index 000000000000..3a117afe57f0
> --- /dev/null
> +++ b/arch/riscv/include/asm/hypervisor.h
> @@ -0,0 +1,9 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_RISCV_HYPERVISOR_H
> +#define _ASM_RISCV_HYPERVISOR_H
> +
> +#include <asm/xen/hypervisor.h>
> +
> +void kvm_init_hyp_services(void);
> +
> +#endif
> diff --git a/arch/riscv/include/asm/irq.h b/arch/riscv/include/asm/irq.h
> index 7b038f3b7cb0..b14621848eae 100644
> --- a/arch/riscv/include/asm/irq.h
> +++ b/arch/riscv/include/asm/irq.h
> @@ -23,6 +23,11 @@ void riscv_set_intc_hwnode_fn(struct fwnode_handle *(*fn)(void));
>
>  struct fwnode_handle *riscv_get_intc_hwnode(void);
>
> +static inline int nr_legacy_irqs(void)
> +{
> +       return 0;
> +}
> +
>  #ifdef CONFIG_ACPI
>
>  enum riscv_irqchip_type {
> diff --git a/arch/riscv/include/asm/sync_bitops.h b/arch/riscv/include/asm/sync_bitops.h
> new file mode 100644
> index 000000000000..28e3c64ba852
> --- /dev/null
> +++ b/arch/riscv/include/asm/sync_bitops.h
> @@ -0,0 +1,27 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __ASM_SYNC_BITOPS_H__
> +#define __ASM_SYNC_BITOPS_H__
> +
> +#include <asm/bitops.h>
> +#include <asm/cmpxchg.h>
> +
> +/* sync_bitops functions are equivalent to the SMP implementation of the
> + * original functions, independently from CONFIG_SMP being defined.
> + *
> + * We need them because _set_bit etc are not SMP safe if !CONFIG_SMP. But
> + * under Xen you might be communicating with a completely external entity
> + * who might be on another CPU (e.g. two uniprocessor guests communicating
> + * via event channels and grant tables). So we need a variant of the bit
> + * ops which are SMP safe even on a UP kernel.
> + */
> +
> +#define sync_set_bit(nr, p)             set_bit(nr, p)
> +#define sync_clear_bit(nr, p)           clear_bit(nr, p)
> +#define sync_change_bit(nr, p)          change_bit(nr, p)
> +#define sync_test_and_set_bit(nr, p)    test_and_set_bit(nr, p)
> +#define sync_test_and_clear_bit(nr, p)  test_and_clear_bit(nr, p)
> +#define sync_test_and_change_bit(nr, p) test_and_change_bit(nr, p)
> +#define sync_test_bit(nr, addr)         test_bit(nr, addr)
> +#define arch_sync_cmpxchg               arch_cmpxchg
> +
> +#endif
> diff --git a/arch/riscv/include/asm/xen/events.h b/arch/riscv/include/asm/xen/events.h
> new file mode 100644
> index 000000000000..a3d0332ca46c
> --- /dev/null
> +++ b/arch/riscv/include/asm/xen/events.h
> @@ -0,0 +1,28 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_RISCV_XEN_EVENTS_H
> +#define _ASM_RISCV_XEN_EVENTS_H
> +
> +#include <asm/ptrace.h>
> +#include <asm/atomic.h>
> +
> +enum ipi_vector {
> +       XEN_PLACEHOLDER_VECTOR,
> +
> +       /* Xen IPIs go here */
> +       XEN_NR_IPIS,
> +};
> +
> +static inline int xen_irqs_disabled(struct pt_regs *regs)
> +{
> +       return 0;
> +}
> +
> +#define xchg_xen_ulong(ptr, val) xchg((ptr), (val))
> +
> +/* Rebind event channel is supported by default */
> +static inline bool xen_support_evtchn_rebind(void)
> +{
> +       return true;
> +}
> +
> +#endif /* _ASM_RISCV_XEN_EVENTS_H */
> diff --git a/arch/riscv/include/asm/xen/hypercall.h b/arch/riscv/include/asm/xen/hypercall.h
> new file mode 100644
> index 000000000000..0841ba1f0835
> --- /dev/null
> +++ b/arch/riscv/include/asm/xen/hypercall.h
> @@ -0,0 +1,2 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#include <xen/riscv/hypercall.h>
> diff --git a/arch/riscv/include/asm/xen/hypervisor.h b/arch/riscv/include/asm/xen/hypervisor.h
> new file mode 100644
> index 000000000000..05b7c834d0a9
> --- /dev/null
> +++ b/arch/riscv/include/asm/xen/hypervisor.h
> @@ -0,0 +1,2 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#include <xen/riscv/hypervisor.h>
> diff --git a/arch/riscv/include/asm/xen/interface.h b/arch/riscv/include/asm/xen/interface.h
> new file mode 100644
> index 000000000000..9f30b1d7e77c
> --- /dev/null
> +++ b/arch/riscv/include/asm/xen/interface.h
> @@ -0,0 +1,2 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#include <xen/riscv/interface.h>
> diff --git a/arch/riscv/include/asm/xen/page.h b/arch/riscv/include/asm/xen/page.h
> new file mode 100644
> index 000000000000..c8f5b873445b
> --- /dev/null
> +++ b/arch/riscv/include/asm/xen/page.h
> @@ -0,0 +1,3 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#include <xen/riscv/page.h>
> +#include <asm/mmu.h>
> diff --git a/arch/riscv/include/asm/xen/swiotlb-xen.h b/arch/riscv/include/asm/xen/swiotlb-xen.h
> new file mode 100644
> index 000000000000..aa3bc339df03
> --- /dev/null
> +++ b/arch/riscv/include/asm/xen/swiotlb-xen.h
> @@ -0,0 +1,2 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#include <xen/riscv/swiotlb-xen.h>
> diff --git a/arch/riscv/xen/Makefile b/arch/riscv/xen/Makefile
> new file mode 100644
> index 000000000000..f6d3a357e4c7
> --- /dev/null
> +++ b/arch/riscv/xen/Makefile
> @@ -0,0 +1,2 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +obj-y := enlighten.o p2m.o grant-table.o hypercall.o
> diff --git a/arch/riscv/xen/enlighten.c b/arch/riscv/xen/enlighten.c
> new file mode 100644
> index 000000000000..28bd66c288f9
> --- /dev/null
> +++ b/arch/riscv/xen/enlighten.c
> @@ -0,0 +1,164 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +#include <xen/xen.h>
> +#include <xen/events.h>
> +#include <xen/grant_table.h>
> +#include <xen/hvm.h>
> +#include <xen/interface/vcpu.h>
> +#include <xen/interface/xen.h>
> +#include <xen/interface/memory.h>
> +#include <xen/interface/hvm/params.h>
> +#include <xen/features.h>
> +#include <xen/platform_pci.h>
> +#include <xen/xenbus.h>
> +#include <xen/page.h>
> +#include <xen/interface/sched.h>
> +#include <xen/xen-ops.h>
> +#include <asm/xen/hypervisor.h>
> +#include <asm/xen/hypercall.h>
> +#include <asm/efi.h>
> +#include <linux/interrupt.h>
> +#include <linux/irqreturn.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_fdt.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_address.h>
> +#include <linux/cpuidle.h>
> +#include <linux/cpufreq.h>
> +#include <linux/cpu.h>
> +#include <linux/console.h>
> +#include <linux/pvclock_gtod.h>
> +#include <linux/reboot.h>
> +#include <linux/time64.h>
> +#include <linux/timekeeping.h>
> +#include <linux/timekeeper_internal.h>
> +#include <linux/acpi.h>
> +#include <linux/virtio_anchor.h>
> +
> +#include <linux/mm.h>
> +
> +static struct start_info _xen_start_info;
> +struct start_info *xen_start_info = &_xen_start_info;
> +EXPORT_SYMBOL(xen_start_info);
> +
> +enum xen_domain_type xen_domain_type = XEN_NATIVE;
> +EXPORT_SYMBOL(xen_domain_type);
> +
> +struct shared_info xen_dummy_shared_info;
> +struct shared_info *HYPERVISOR_shared_info = (void *)&xen_dummy_shared_info;
> +
> +DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu);
> +static struct vcpu_info __percpu *xen_vcpu_info;
> +
> +/* Linux <-> Xen vCPU id mapping */
> +DEFINE_PER_CPU(uint32_t, xen_vcpu_id);
> +EXPORT_PER_CPU_SYMBOL(xen_vcpu_id);
> +
> +/* These are unused until we support booting "pre-ballooned" */
> +unsigned long xen_released_pages;
> +struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS] __initdata;
> +
> +static __read_mostly unsigned int xen_events_irq;
> +static __read_mostly phys_addr_t xen_grant_frames;
> +
> +#define GRANT_TABLE_INDEX   0
> +#define EXT_REGION_INDEX    1
> +
> +uint32_t xen_start_flags;
> +EXPORT_SYMBOL(xen_start_flags);
> +
> +int xen_unmap_domain_gfn_range(struct vm_area_struct *vma,
> +                                       int nr, struct page **pages)
> +{
> +       return 0;
> +}
> +EXPORT_SYMBOL_GPL(xen_unmap_domain_gfn_range);
> +
> +static void xen_read_wallclock(struct timespec64 *ts)
> +{
> +}
> +
> +static int xen_pvclock_gtod_notify(struct notifier_block *nb,
> +                                       unsigned long was_set, void *priv)
> +{
> +       return 0;
> +}
> +
> +static struct notifier_block xen_pvclock_gtod_notifier = {
> +       .notifier_call = xen_pvclock_gtod_notify,
> +};
> +
> +static int xen_starting_cpu(unsigned int cpu)
> +{
> +       return 0;
> +}
> +
> +static int xen_dying_cpu(unsigned int cpu)
> +{
> +       return 0;
> +}
> +
> +void xen_reboot(int reason)
> +{
> +}
> +
> +static int xen_restart(struct notifier_block *nb, unsigned long action,
> +                                       void *data)
> +{
> +       return 0;
> +}
> +
> +static struct notifier_block xen_restart_nb = {
> +       .notifier_call = xen_restart,
> +       .priority = 192,
> +};
> +
> +static void xen_power_off(void)
> +{
> +}
> +
> +static __initdata struct {
> +       const char *compat;
> +       const char *prefix;
> +       const char *version;
> +       bool found;
> +} hyper_node = {"xen,xen", "xen,xen-", NULL, false};
> +
> +static int __init fdt_find_hyper_node(unsigned long node, const char *uname,
> +                                       int depth, void *data)
> +{
> +       return 0;
> +}
> +
> +void __init xen_early_init(void)
> +{
> +}
> +
> +static void __init xen_dt_guest_init(void)
> +{
> +}
> +
> +static int __init xen_guest_init(void)
> +{
> +       return 0;
> +}
> +early_initcall(xen_guest_init);
> +
> +static int xen_starting_runstate_cpu(unsigned int cpu)
> +{
> +       return 0;
> +}
> +
> +static int __init xen_late_init(void)
> +{
> +       return 0;
> +}
> +late_initcall(xen_late_init);
> +
> +
> +/* empty stubs */
> +void xen_arch_pre_suspend(void) { }
> +void xen_arch_post_suspend(int suspend_cancelled) { }
> +void xen_timer_resume(void) { }
> +void xen_arch_resume(void) { }
> +void xen_arch_suspend(void) { }
> diff --git a/arch/riscv/xen/grant-table.c b/arch/riscv/xen/grant-table.c
> new file mode 100644
> index 000000000000..9dd0cea74360
> --- /dev/null
> +++ b/arch/riscv/xen/grant-table.c
> @@ -0,0 +1,57 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/******************************************************************************
> + * grant_table.c
> + *
> + * Granting foreign access to our memory reservation.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License version 2
> + * as published by the Free Software Foundation; or, when distributed
> + * separately from the Linux kernel or incorporated into other
> + * software packages, subject to the following license:
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a copy
> + * of this source file (the "Software"), to deal in the Software without
> + * restriction, including without limitation the rights to use, copy, modify,
> + * merge, publish, distribute, sublicense, and/or sell copies of the Software,
> + * and to permit persons to whom the Software is furnished to do so, subject to
> + * the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
> + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + */
> +
> +#include <xen/interface/xen.h>
> +#include <xen/page.h>
> +#include <xen/grant_table.h>
> +
> +int arch_gnttab_map_shared(xen_pfn_t *frames, unsigned long nr_gframes,
> +                                       unsigned long max_nr_gframes,
> +                                       void **__shared)
> +{
> +       return 0;
> +}
> +
> +void arch_gnttab_unmap(void *shared, unsigned long nr_gframes)
> +{
> +}
> +
> +int arch_gnttab_map_status(uint64_t *frames, unsigned long nr_gframes,
> +                                       unsigned long max_nr_gframes,
> +                                       grant_status_t **__shared)
> +{
> +       return 0;
> +}
> +
> +int arch_gnttab_init(unsigned long nr_shared, unsigned long nr_status)
> +{
> +       return 0;
> +}
> diff --git a/arch/riscv/xen/hypercall.S b/arch/riscv/xen/hypercall.S
> new file mode 100644
> index 000000000000..a81afd2a11c4
> --- /dev/null
> +++ b/arch/riscv/xen/hypercall.S
> @@ -0,0 +1,71 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#include <linux/linkage.h>
> +#include <asm/assembler.h>
> +#include <xen/interface/xen.h>
> +EXPORT_SYMBOL_GPL(HYPERVISOR_event_channel_op);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_grant_table_op);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_xen_version);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_console_io);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_sched_op);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_hvm_op);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_memory_op);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_physdev_op);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_vcpu_op);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_platform_op_raw);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_multicall);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_vm_assist);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_dm_op);
> +EXPORT_SYMBOL_GPL(privcmd_call);
> +#define SBI_ECALL 0xE
> +
> +    .data
> +
> +#define HYPERCALL_SIMPLE(hypercall) \
> +SYM_FUNC_START(HYPERVISOR_##hypercall) \
> +    li a6, __HYPERVISOR_##hypercall; \
> +    li a7, SBI_ECALL; \
> +    mv a5, a4; \
> +    mv a4, a3; \
> +    mv a3, a2; \
> +    mv a2, a1; \
> +    mv a1, a0; \
> +    li a0, 0; \
> +    ecall; \
> +    ret; \
> +SYM_FUNC_END(HYPERVISOR_##hypercall)
> +
> +#define HYPERCALL0 HYPERCALL_SIMPLE
> +#define HYPERCALL1 HYPERCALL_SIMPLE
> +#define HYPERCALL2 HYPERCALL_SIMPLE
> +#define HYPERCALL3 HYPERCALL_SIMPLE
> +#define HYPERCALL4 HYPERCALL_SIMPLE
> +#define HYPERCALL5 HYPERCALL_SIMPLE
> +
> +    .text
> +
> +HYPERCALL2(xen_version);
> +HYPERCALL3(console_io);
> +HYPERCALL3(grant_table_op);
> +HYPERCALL2(sched_op);
> +HYPERCALL2(event_channel_op);
> +HYPERCALL2(hvm_op);
> +HYPERCALL2(memory_op);
> +HYPERCALL2(physdev_op);
> +HYPERCALL3(vcpu_op);
> +HYPERCALL1(platform_op_raw);
> +HYPERCALL2(multicall);
> +HYPERCALL2(vm_assist);
> +HYPERCALL3(dm_op);
> +
> +SYM_FUNC_START(privcmd_call)
> +    mv a6, a0
> +    li a7, SBI_ECALL
> +    mv a5, a4;
> +    mv a4, a3;
> +    mv a3, a2;
> +    mv a2, a1;
> +    mv a1, a0;
> +    li a0, 0;
> +    ecall
> +    ret
> +SYM_FUNC_END(privcmd_call);
> diff --git a/arch/riscv/xen/p2m.c b/arch/riscv/xen/p2m.c
> new file mode 100644
> index 000000000000..7ce75e52d7c4
> --- /dev/null
> +++ b/arch/riscv/xen/p2m.c
> @@ -0,0 +1,76 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +#include <linux/memblock.h>
> +#include <linux/gfp.h>
> +#include <linux/export.h>
> +#include <linux/spinlock.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/vmalloc.h>
> +#include <linux/swiotlb.h>
> +
> +#include <xen/xen.h>
> +#include <xen/interface/memory.h>
> +#include <xen/grant_table.h>
> +#include <xen/page.h>
> +#include <xen/swiotlb-xen.h>
> +
> +#include <asm/cacheflush.h>
> +#include <asm/xen/hypercall.h>
> +#include <asm/xen/interface.h>
> +
> +struct xen_p2m_entry {
> +       unsigned long pfn;
> +       unsigned long mfn;
> +       unsigned long nr_pages;
> +       struct rb_node rbnode_phys;
> +};
> +
> +static rwlock_t p2m_lock;
> +struct rb_root phys_to_mach = RB_ROOT;
> +EXPORT_SYMBOL_GPL(phys_to_mach);
> +
> +static int xen_add_phys_to_mach_entry(struct xen_p2m_entry *new)
> +{
> +
> +       return 0;
> +}
> +
> +unsigned long __pfn_to_mfn(unsigned long pfn)
> +{
> +       return 0;
> +}
> +EXPORT_SYMBOL_GPL(__pfn_to_mfn);
> +
> +int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
> +                                       struct gnttab_map_grant_ref *kmap_ops,
> +                                       struct page **pages, unsigned int count)
> +{
> +       return 0;
> +}
> +
> +int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
> +                                       struct gnttab_unmap_grant_ref *kunmap_ops,
> +                                       struct page **pages, unsigned int count)
> +{
> +       return 0;
> +}
> +
> +bool __set_phys_to_machine_multi(unsigned long pfn,
> +                                       unsigned long mfn, unsigned long nr_pages)
> +{
> +       return true;
> +}
> +EXPORT_SYMBOL_GPL(__set_phys_to_machine_multi);
> +
> +bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
> +{
> +       return true;
> +}
> +EXPORT_SYMBOL_GPL(__set_phys_to_machine);
> +
> +static int p2m_init(void)
> +{
> +       return 0;
> +}
> +arch_initcall(p2m_init);
> diff --git a/include/xen/interface/io/protocols.h b/include/xen/interface/io/protocols.h
> index 22099bb4079f..6c6317462be0 100644
> --- a/include/xen/interface/io/protocols.h
> +++ b/include/xen/interface/io/protocols.h
> @@ -6,6 +6,7 @@
>  #define XEN_IO_PROTO_ABI_X86_64     "x86_64-abi"
>  #define XEN_IO_PROTO_ABI_POWERPC64  "powerpc64-abi"
>  #define XEN_IO_PROTO_ABI_ARM        "arm-abi"
> +#define XEN_IO_PROTO_ABI_RISCV      "riscv-abi"
>
>  #if defined(__i386__)
>  # define XEN_IO_PROTO_ABI_NATIVE XEN_IO_PROTO_ABI_X86_32
> @@ -15,6 +16,8 @@
>  # define XEN_IO_PROTO_ABI_NATIVE XEN_IO_PROTO_ABI_POWERPC64
>  #elif defined(__arm__) || defined(__aarch64__)
>  # define XEN_IO_PROTO_ABI_NATIVE XEN_IO_PROTO_ABI_ARM
> +#elif defined(__riscv)
> +# define XEN_IO_PROTO_ABI_NATIVE XEN_IO_PROTO_ABI_RISCV
>  #else
>  # error arch fixup needed here
>  #endif
> diff --git a/include/xen/riscv/hypercall.h b/include/xen/riscv/hypercall.h
> new file mode 100644
> index 000000000000..f76d8a018f26
> --- /dev/null
> +++ b/include/xen/riscv/hypercall.h
> @@ -0,0 +1,71 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/******************************************************************************
> + * hypercall.h
> + *
> + * Linux-specific hypervisor handling.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License version 2
> + * as published by the Free Software Foundation; or, when distributed
> + * separately from the Linux kernel or incorporated into other
> + * software packages, subject to the following license:
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a copy
> + * of this source file (the "Software"), to deal in the Software without
> + * restriction, including without limitation the rights to use, copy, modify,
> + * merge, publish, distribute, sublicense, and/or sell copies of the Software,
> + * and to permit persons to whom the Software is furnished to do so, subject to
> + * the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
> + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + */
> +
> +#ifndef _ASM_RISCV_XEN_HYPERCALL_H
> +#define _ASM_RISCV_XEN_HYPERCALL_H
> +
> +#include <linux/bug.h>
> +
> +#include <xen/interface/xen.h>
> +#include <xen/interface/sched.h>
> +#include <xen/interface/platform.h>
> +
> +struct xen_dm_op_buf;
> +
> +long privcmd_call(unsigned int call, unsigned long a1,
> +               unsigned long a2, unsigned long a3,
> +               unsigned long a4, unsigned long a5);
> +int HYPERVISOR_xen_version(int cmd, void *arg);
> +int HYPERVISOR_console_io(int cmd, int count, char *str);
> +int HYPERVISOR_grant_table_op(unsigned int cmd, void *uop, unsigned int count);
> +int HYPERVISOR_sched_op(int cmd, void *arg);
> +int HYPERVISOR_event_channel_op(int cmd, void *arg);
> +unsigned long HYPERVISOR_hvm_op(int op, void *arg);
> +int HYPERVISOR_memory_op(unsigned int cmd, void *arg);
> +int HYPERVISOR_physdev_op(int cmd, void *arg);
> +int HYPERVISOR_vcpu_op(int cmd, int vcpuid, void *extra_args);
> +int HYPERVISOR_vm_assist(unsigned int cmd, unsigned int type);
> +int HYPERVISOR_dm_op(domid_t domid, unsigned int nr_bufs,
> +                        struct xen_dm_op_buf *bufs);
> +int HYPERVISOR_platform_op_raw(void *arg);
> +static inline int HYPERVISOR_platform_op(struct xen_platform_op *op)
> +{
> +       return 0;
> +}
> +int HYPERVISOR_multicall(struct multicall_entry *calls, uint32_t nr);
> +
> +static inline int
> +HYPERVISOR_suspend(unsigned long start_info_mfn)
> +{
> +       return 0;
> +}
> +
> +#endif /* _ASM_RISCV_XEN_HYPERCALL_H */
> diff --git a/include/xen/riscv/hypervisor.h b/include/xen/riscv/hypervisor.h
> new file mode 100644
> index 000000000000..2c1f9625be80
> --- /dev/null
> +++ b/include/xen/riscv/hypervisor.h
> @@ -0,0 +1,26 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_RISCV_XEN_HYPERVISOR_H
> +#define _ASM_RISCV_XEN_HYPERVISOR_H
> +
> +#include <linux/init.h>
> +
> +extern struct shared_info *HYPERVISOR_shared_info;
> +extern struct start_info *xen_start_info;
> +
> +#ifdef CONFIG_XEN
> +void __init xen_early_init(void);
> +#else
> +static inline void xen_early_init(void) { return; }
> +#endif
> +
> +#ifdef CONFIG_HOTPLUG_CPU
> +static inline void xen_arch_register_cpu(int num)
> +{
> +}
> +
> +static inline void xen_arch_unregister_cpu(int num)
> +{
> +}
> +#endif
> +
> +#endif /* _ASM_RISCV_XEN_HYPERVISOR_H */
> diff --git a/include/xen/riscv/interface.h b/include/xen/riscv/interface.h
> new file mode 100644
> index 000000000000..6769b5b39cba
> --- /dev/null
> +++ b/include/xen/riscv/interface.h
> @@ -0,0 +1,85 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/******************************************************************************
> + * Guest OS interface to RISCV Xen.
> + *
> + */
> +
> +#ifndef _ASM_RISCV_XEN_INTERFACE_H
> +#define _ASM_RISCV_XEN_INTERFACE_H
> +
> +#include <linux/types.h>
> +
> +#define uint64_aligned_t uint64_t __aligned(8)
> +
> +#define __DEFINE_GUEST_HANDLE(name, type) \
> +       typedef struct { union { type * p; uint64_aligned_t q; }; }  \
> +               __guest_handle_ ## name
> +
> +#define DEFINE_GUEST_HANDLE_STRUCT(name) \
> +       __DEFINE_GUEST_HANDLE(name, struct name)
> +#define DEFINE_GUEST_HANDLE(name) __DEFINE_GUEST_HANDLE(name, name)
> +#define GUEST_HANDLE(name)        __guest_handle_ ## name
> +
> +#define set_xen_guest_handle(hnd, val)                 \
> +       do {                                            \
> +               if (sizeof(hnd) == 8)                   \
> +                       *(uint64_t *)&(hnd) = 0;        \
> +               (hnd).p = val;                          \
> +       } while (0)
> +
> +#define __HYPERVISOR_platform_op_raw __HYPERVISOR_platform_op
> +
> +#ifndef __ASSEMBLY__
> +/* Explicitly size integers that represent pfns in the interface with
> + * Xen so that we can have one ABI that works for 32 and 64 bit guests.
> + * Note that this means that the xen_pfn_t type may be capable of
> + * representing pfn's which the guest cannot represent in its own pfn
> + * type. However since pfn space is controlled by the guest this is
> + * fine since it simply wouldn't be able to create any sure pfns in
> + * the first place.
> + */
> +typedef uint64_t xen_pfn_t;
> +#define PRI_xen_pfn "llx"
> +typedef uint64_t xen_ulong_t;
> +#define PRI_xen_ulong "llx"
> +typedef int64_t xen_long_t;
> +#define PRI_xen_long "llx"
> +/* Guest handles for primitive C types. */
> +__DEFINE_GUEST_HANDLE(uchar, unsigned char);
> +__DEFINE_GUEST_HANDLE(uint,  unsigned int);
> +DEFINE_GUEST_HANDLE(char);
> +DEFINE_GUEST_HANDLE(int);
> +DEFINE_GUEST_HANDLE(void);
> +DEFINE_GUEST_HANDLE(uint64_t);
> +DEFINE_GUEST_HANDLE(uint32_t);
> +DEFINE_GUEST_HANDLE(xen_pfn_t);
> +DEFINE_GUEST_HANDLE(xen_ulong_t);
> +
> +/* Maximum number of virtual CPUs in multi-processor guests. */
> +#define MAX_VIRT_CPUS 1
> +
> +struct arch_vcpu_info { };
> +struct arch_shared_info { };
> +
> +/* TODO: Move pvclock definitions some place arch independent */
> +struct pvclock_vcpu_time_info {
> +       u32   version;
> +       u32   pad0;
> +       u64   tsc_timestamp;
> +       u64   system_time;
> +       u32   tsc_to_system_mul;
> +       s8    tsc_shift;
> +       u8    flags;
> +       u8    pad[2];
> +} __packed; /* 32 bytes */
> +
> +/* It is OK to have a 12 bytes struct with no padding because it is packed */
> +struct pvclock_wall_clock {
> +       u32   version;
> +       u32   sec;
> +       u32   nsec;
> +       u32   sec_hi;
> +} __packed;
> +#endif
> +
> +#endif /* _ASM_RISCV_XEN_INTERFACE_H */
> diff --git a/include/xen/riscv/page.h b/include/xen/riscv/page.h
> new file mode 100644
> index 000000000000..fe07a9bffa7e
> --- /dev/null
> +++ b/include/xen/riscv/page.h
> @@ -0,0 +1,106 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_RISCV_XEN_PAGE_H
> +#define _ASM_RISCV_XEN_PAGE_H
> +
> +#include <asm/page.h>
> +
> +#include <linux/pfn.h>
> +#include <linux/types.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/pgtable.h>
> +
> +#include <xen/xen.h>
> +#include <xen/interface/grant_table.h>
> +
> +/* Xen machine address */
> +struct xmaddr {
> +       phys_addr_t maddr;
> +};
> +
> +/* Xen pseudo-physical address */
> +struct xpaddr {
> +       phys_addr_t paddr;
> +};
> +
> +#define XMADDR(x)      ((struct xmaddr) { .maddr = (x) })
> +#define XPADDR(x)      ((struct xpaddr) { .paddr = (x) })
> +
> +#define INVALID_P2M_ENTRY      (~0UL)
> +
> +/*
> + * The pseudo-physical frame (pfn) used in all the helpers is always based
> + * on Xen page granularity (i.e 4KB).
> + *
> + * A Linux page may be split across multiple non-contiguous Xen page so we
> + * have to keep track with frame based on 4KB page granularity.
> + *
> + * PV drivers should never make a direct usage of those helpers (particularly
> + * pfn_to_gfn and gfn_to_pfn).
> + */
> +
> +unsigned long __pfn_to_mfn(unsigned long pfn);
> +extern struct rb_root phys_to_mach;
> +
> +/* Pseudo-physical <-> Guest conversion */
> +static inline unsigned long pfn_to_gfn(unsigned long pfn)
> +{
> +       return 0;
> +}
> +
> +static inline unsigned long gfn_to_pfn(unsigned long gfn)
> +{
> +       return 0;
> +}
> +
> +/* Pseudo-physical <-> BUS conversion */
> +static inline unsigned long pfn_to_bfn(unsigned long pfn)
> +{
> +       return 0;
> +}
> +
> +static inline unsigned long bfn_to_pfn(unsigned long bfn)
> +{
> +       return 0;
> +}
> +
> +#define bfn_to_local_pfn(bfn)  bfn_to_pfn(bfn)
> +
> +/* VIRT <-> GUEST conversion */
> +#define virt_to_gfn(v)                                                         \
> +       ({                                                                     \
> +               WARN_ON_ONCE(!virt_addr_valid(v));                              \
> +               pfn_to_gfn(virt_to_phys(v) >> XEN_PAGE_SHIFT);                 \
> +       })
> +#define gfn_to_virt(m)         (__va(gfn_to_pfn(m) << XEN_PAGE_SHIFT))
> +
> +#define percpu_to_gfn(v)       \
> +       (pfn_to_gfn(per_cpu_ptr_to_phys(v) >> XEN_PAGE_SHIFT))
> +
> +static inline struct xmaddr arbitrary_virt_to_machine(void *vaddr)
> +{
> +       WARN_ON_ONCE(1);
> +       return (struct xmaddr){0};
> +}
> +
> +extern int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
> +                                  struct gnttab_map_grant_ref *kmap_ops,
> +                                  struct page **pages, unsigned int count);
> +
> +extern int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
> +                                        struct gnttab_unmap_grant_ref *kunmap_ops,
> +                                        struct page **pages, unsigned int count);
> +
> +bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn);
> +bool __set_phys_to_machine_multi(unsigned long pfn, unsigned long mfn,
> +               unsigned long nr_pages);
> +
> +static inline bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
> +{
> +       return 0;
> +}
> +
> +bool xen_arch_need_swiotlb(struct device *dev,
> +                          phys_addr_t phys,
> +                          dma_addr_t dev_addr);
> +
> +#endif /* _ASM_RISCV_XEN_PAGE_H */
> diff --git a/include/xen/riscv/swiotlb-xen.h b/include/xen/riscv/swiotlb-xen.h
> new file mode 100644
> index 000000000000..97ecd8cbbc2d
> --- /dev/null
> +++ b/include/xen/riscv/swiotlb-xen.h
> @@ -0,0 +1,13 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_RISCV_SWIOTLB_XEN_H
> +#define _ASM_RISCV_SWIOTLB_XEN_H
> +
> +#include <xen/features.h>
> +#include <xen/xen.h>
> +
> +static inline int xen_swiotlb_detect(void)
> +{
> +       return 0;
> +}
> +
> +#endif /* _ASM_RISCV_SWIOTLB_XEN_H */
> diff --git a/test.txt b/test.txt
> new file mode 100644
> index 000000000000..e54267998982
> --- /dev/null
> +++ b/test.txt
> @@ -0,0 +1,21 @@
> +WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
> +#120:
> +new file mode 100644
> +
> +WARNING: do not add new typedefs
> +#808: FILE: include/xen/riscv/interface.h:15:
> ++      typedef struct { union { type * p; uint64_aligned_t q; }; }  \
> +
> +WARNING: please, no spaces at the start of a line
> +#1006: FILE: include/xen/riscv/swiotlb-xen.h:10:
> ++    return 0;$
> +
> +total: 0 errors, 3 warnings, 810 lines checked
> +
> +NOTE: For some of the reported defects, checkpatch may be able to
> +      mechanically convert to the typical style using --fix or --fix-inplace.
> +
> +0001-riscv-Add-initial-Xen-guest-support-for-RISC-V.patch has style problems, please review.
> +
> +NOTE: If any of the errors are false positives, please report
> +      them to the maintainer, see CHECKPATCH in MAINTAINERS.
> --
> 2.43.0
>
>

Teddy Astie Jan. 14, 2025, 5:51 p.m. UTC | #2

Le 14/01/2025 à 17:13, Milan Djokic a écrit :
> diff --git a/test.txt b/test.txt
> new file mode 100644
> index 000000000000..e54267998982
> --- /dev/null
> +++ b/test.txt
> @@ -0,0 +1,21 @@
> +WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
> +#120:
> +new file mode 100644
> +
> +WARNING: do not add new typedefs
> +#808: FILE: include/xen/riscv/interface.h:15:
> ++	typedef struct { union { type * p; uint64_aligned_t q; }; }  \
> +
> +WARNING: please, no spaces at the start of a line
> +#1006: FILE: include/xen/riscv/swiotlb-xen.h:10:
> ++    return 0;$
> +
> +total: 0 errors, 3 warnings, 810 lines checked
> +
> +NOTE: For some of the reported defects, checkpatch may be able to
> +      mechanically convert to the typical style using --fix or --fix-inplace.
> +
> +0001-riscv-Add-initial-Xen-guest-support-for-RISC-V.patch has style problems, please review.
> +
> +NOTE: If any of the errors are false positives, please report
> +      them to the maintainer, see CHECKPATCH in MAINTAINERS.

I am not sure you want this here.

 > diff --git a/arch/riscv/include/asm/hypervisor.h 
b/arch/riscv/include/> asm/hypervisor.h
 > new file mode 100644
 > index 000000000000..3a117afe57f0
 > --- /dev/null
 > +++ b/arch/riscv/include/asm/hypervisor.h
 > @@ -0,0 +1,9 @@
 > +/* SPDX-License-Identifier: GPL-2.0 */
 > +#ifndef _ASM_RISCV_HYPERVISOR_H
 > +#define _ASM_RISCV_HYPERVISOR_H
 > +
 > +#include <asm/xen/hypervisor.h>
 > +
 > +void kvm_init_hyp_services(void);
 > +
 > +#endif

kvm_init_hyp_services seems KVM-specific and doesn't seem to exist (yet) 
for RISC-V.

Teddy


Teddy Astie | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

web: https://vates.tech

Andrew Jones Jan. 14, 2025, 6:18 p.m. UTC | #3

On Tue, Jan 14, 2025 at 05:09:36PM +0100, Milan Djokic wrote:
> From: Slavisa Petrovic <[e-mail]>
> 
> This patch introduces initial support for running RISC-V as a Xen guest.
> It provides the necessary infrastructure and stubs for Xen-specific
> operations. Key changes include:
> 
> - Modifications to the RISC-V kernel to integrate Xen-specific hypercalls
>   and interfaces, with function implementations stubbed for future work.
> - Introduction of Xen-specific headers for RISC-V, including event
>   handling, hypervisor interaction, and page management. Functions are
>   defined but not yet implemented.
> - Stub implementations for memory management, grant tables, and context
>   switching in the Xen environment, allowing further development and
>   integration.
> 
> Signed-off-by: Milan Djokic <[e-mail]>
> Signed-off-by: Slavisa Petrovic <[e-mail]>
> ---
>  arch/riscv/Kbuild                        |   1 +
>  arch/riscv/Kconfig                       |  19 +++
>  arch/riscv/include/asm/cpu.h             |   1 +
>  arch/riscv/include/asm/hypervisor.h      |   9 ++
>  arch/riscv/include/asm/irq.h             |   5 +
>  arch/riscv/include/asm/sync_bitops.h     |  27 ++++
>  arch/riscv/include/asm/xen/events.h      |  28 ++++
>  arch/riscv/include/asm/xen/hypercall.h   |   2 +
>  arch/riscv/include/asm/xen/hypervisor.h  |   2 +
>  arch/riscv/include/asm/xen/interface.h   |   2 +
>  arch/riscv/include/asm/xen/page.h        |   3 +
>  arch/riscv/include/asm/xen/swiotlb-xen.h |   2 +
>  arch/riscv/xen/Makefile                  |   2 +
>  arch/riscv/xen/enlighten.c               | 164 +++++++++++++++++++++++
>  arch/riscv/xen/grant-table.c             |  57 ++++++++
>  arch/riscv/xen/hypercall.S               |  71 ++++++++++
>  arch/riscv/xen/p2m.c                     |  76 +++++++++++
>  include/xen/interface/io/protocols.h     |   3 +
>  include/xen/riscv/hypercall.h            |  71 ++++++++++
>  include/xen/riscv/hypervisor.h           |  26 ++++
>  include/xen/riscv/interface.h            |  85 ++++++++++++
>  include/xen/riscv/page.h                 | 106 +++++++++++++++
>  include/xen/riscv/swiotlb-xen.h          |  13 ++
>  test.txt                                 |  21 +++
>  24 files changed, 796 insertions(+)
>  create mode 100644 arch/riscv/include/asm/hypervisor.h
>  create mode 100644 arch/riscv/include/asm/sync_bitops.h
>  create mode 100644 arch/riscv/include/asm/xen/events.h
>  create mode 100644 arch/riscv/include/asm/xen/hypercall.h
>  create mode 100644 arch/riscv/include/asm/xen/hypervisor.h
>  create mode 100644 arch/riscv/include/asm/xen/interface.h
>  create mode 100644 arch/riscv/include/asm/xen/page.h
>  create mode 100644 arch/riscv/include/asm/xen/swiotlb-xen.h
>  create mode 100644 arch/riscv/xen/Makefile
>  create mode 100644 arch/riscv/xen/enlighten.c
>  create mode 100644 arch/riscv/xen/grant-table.c
>  create mode 100644 arch/riscv/xen/hypercall.S
>  create mode 100644 arch/riscv/xen/p2m.c
>  create mode 100644 include/xen/riscv/hypercall.h
>  create mode 100644 include/xen/riscv/hypervisor.h
>  create mode 100644 include/xen/riscv/interface.h
>  create mode 100644 include/xen/riscv/page.h
>  create mode 100644 include/xen/riscv/swiotlb-xen.h
>  create mode 100644 test.txt
> 
> diff --git a/arch/riscv/Kbuild b/arch/riscv/Kbuild
> index 2c585f7a0b6e..d9b71deed2cd 100644
> --- a/arch/riscv/Kbuild
> +++ b/arch/riscv/Kbuild
> @@ -5,6 +5,7 @@ obj-$(CONFIG_BUILTIN_DTB) += boot/dts/
>  obj-$(CONFIG_CRYPTO) += crypto/
>  obj-y += errata/
>  obj-$(CONFIG_KVM) += kvm/
> +obj-$(CONFIG_XEN) += xen/
> 
>  obj-$(CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY) += purgatory/
> 
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index d4a7ca0388c0..13ea75221524 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -1071,6 +1071,25 @@ config PARAVIRT_TIME_ACCOUNTING
> 
>  	  If in doubt, say N here.
> 
> +config XEN_DOM0
> +	def_bool y
> +	depends on XEN
> +
> +config XEN
> +	bool "Xen guest support on RISCV"
> +	depends on RISCV && OF
> +	select PARAVIRT
> +	help
> +	  Enables support for running Linux as a Xen guest on RISC-V.
> +
> +	  Xen is a type-1 hypervisor that allows multiple operating systems
> +	  to run on the same hardware. Enabling this option allows the kernel
> +	  to function as a guest under the Xen hypervisor on RISC-V platforms.
> +
> +	  Say Y if you want to run this kernel as a guest under Xen on RISC-V.
> +
> +	  If unsure, say N.
> +
>  config RELOCATABLE
>  	bool "Build a relocatable kernel"
>  	depends on MMU && 64BIT && !XIP_KERNEL
> diff --git a/arch/riscv/include/asm/cpu.h b/arch/riscv/include/asm/cpu.h
> index 28d45a6678ce..fb2aac6a068e 100644
> --- a/arch/riscv/include/asm/cpu.h
> +++ b/arch/riscv/include/asm/cpu.h
> @@ -4,5 +4,6 @@
>  #define _ASM_CPU_H
> 
>  /* This header is required unconditionally by the ACPI core */
> +#include <linux/cpu.h>
> 
>  #endif /* _ASM_CPU_H */
> diff --git a/arch/riscv/include/asm/hypervisor.h b/arch/riscv/include/asm/hypervisor.h
> new file mode 100644
> index 000000000000..3a117afe57f0
> --- /dev/null
> +++ b/arch/riscv/include/asm/hypervisor.h
> @@ -0,0 +1,9 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_RISCV_HYPERVISOR_H
> +#define _ASM_RISCV_HYPERVISOR_H
> +
> +#include <asm/xen/hypervisor.h>
> +
> +void kvm_init_hyp_services(void);

riscv doesn't have kvm_init_hyp_services(), which is why it didn't have
asm/hypervisor.h. I also didn't see where asm/hypervisor.h is getting
included in this patch, so this hunk should be dropped.

> +
> +#endif
> diff --git a/arch/riscv/include/asm/irq.h b/arch/riscv/include/asm/irq.h
> index 7b038f3b7cb0..b14621848eae 100644
> --- a/arch/riscv/include/asm/irq.h
> +++ b/arch/riscv/include/asm/irq.h
> @@ -23,6 +23,11 @@ void riscv_set_intc_hwnode_fn(struct fwnode_handle *(*fn)(void));
> 
>  struct fwnode_handle *riscv_get_intc_hwnode(void);
> 
> +static inline int nr_legacy_irqs(void)
> +{
> +	return 0;
> +}
> +
>  #ifdef CONFIG_ACPI
> 
>  enum riscv_irqchip_type {
> diff --git a/arch/riscv/include/asm/sync_bitops.h b/arch/riscv/include/asm/sync_bitops.h
> new file mode 100644
> index 000000000000..28e3c64ba852
> --- /dev/null
> +++ b/arch/riscv/include/asm/sync_bitops.h
> @@ -0,0 +1,27 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __ASM_SYNC_BITOPS_H__
> +#define __ASM_SYNC_BITOPS_H__
> +
> +#include <asm/bitops.h>
> +#include <asm/cmpxchg.h>
> +
> +/* sync_bitops functions are equivalent to the SMP implementation of the
> + * original functions, independently from CONFIG_SMP being defined.
> + *
> + * We need them because _set_bit etc are not SMP safe if !CONFIG_SMP. But
> + * under Xen you might be communicating with a completely external entity
> + * who might be on another CPU (e.g. two uniprocessor guests communicating
> + * via event channels and grant tables). So we need a variant of the bit
> + * ops which are SMP safe even on a UP kernel.
> + */
> +
> +#define sync_set_bit(nr, p)             set_bit(nr, p)
> +#define sync_clear_bit(nr, p)           clear_bit(nr, p)
> +#define sync_change_bit(nr, p)          change_bit(nr, p)
> +#define sync_test_and_set_bit(nr, p)    test_and_set_bit(nr, p)
> +#define sync_test_and_clear_bit(nr, p)  test_and_clear_bit(nr, p)
> +#define sync_test_and_change_bit(nr, p) test_and_change_bit(nr, p)
> +#define sync_test_bit(nr, addr)         test_bit(nr, addr)
> +#define arch_sync_cmpxchg               arch_cmpxchg
> +
> +#endif
> diff --git a/arch/riscv/include/asm/xen/events.h b/arch/riscv/include/asm/xen/events.h
> new file mode 100644
> index 000000000000..a3d0332ca46c
> --- /dev/null
> +++ b/arch/riscv/include/asm/xen/events.h
> @@ -0,0 +1,28 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_RISCV_XEN_EVENTS_H
> +#define _ASM_RISCV_XEN_EVENTS_H
> +
> +#include <asm/ptrace.h>
> +#include <asm/atomic.h>
> +
> +enum ipi_vector {
> +	XEN_PLACEHOLDER_VECTOR,
> +
> +	/* Xen IPIs go here */
> +	XEN_NR_IPIS,
> +};
> +
> +static inline int xen_irqs_disabled(struct pt_regs *regs)
> +{
> +	return 0;
> +}
> +
> +#define xchg_xen_ulong(ptr, val) xchg((ptr), (val))
> +
> +/* Rebind event channel is supported by default */
> +static inline bool xen_support_evtchn_rebind(void)
> +{
> +	return true;
> +}
> +
> +#endif /* _ASM_RISCV_XEN_EVENTS_H */
> diff --git a/arch/riscv/include/asm/xen/hypercall.h b/arch/riscv/include/asm/xen/hypercall.h
> new file mode 100644
> index 000000000000..0841ba1f0835
> --- /dev/null
> +++ b/arch/riscv/include/asm/xen/hypercall.h
> @@ -0,0 +1,2 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#include <xen/riscv/hypercall.h>
> diff --git a/arch/riscv/include/asm/xen/hypervisor.h b/arch/riscv/include/asm/xen/hypervisor.h
> new file mode 100644
> index 000000000000..05b7c834d0a9
> --- /dev/null
> +++ b/arch/riscv/include/asm/xen/hypervisor.h
> @@ -0,0 +1,2 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#include <xen/riscv/hypervisor.h>
> diff --git a/arch/riscv/include/asm/xen/interface.h b/arch/riscv/include/asm/xen/interface.h
> new file mode 100644
> index 000000000000..9f30b1d7e77c
> --- /dev/null
> +++ b/arch/riscv/include/asm/xen/interface.h
> @@ -0,0 +1,2 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#include <xen/riscv/interface.h>
> diff --git a/arch/riscv/include/asm/xen/page.h b/arch/riscv/include/asm/xen/page.h
> new file mode 100644
> index 000000000000..c8f5b873445b
> --- /dev/null
> +++ b/arch/riscv/include/asm/xen/page.h
> @@ -0,0 +1,3 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#include <xen/riscv/page.h>
> +#include <asm/mmu.h>
> diff --git a/arch/riscv/include/asm/xen/swiotlb-xen.h b/arch/riscv/include/asm/xen/swiotlb-xen.h
> new file mode 100644
> index 000000000000..aa3bc339df03
> --- /dev/null
> +++ b/arch/riscv/include/asm/xen/swiotlb-xen.h
> @@ -0,0 +1,2 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#include <xen/riscv/swiotlb-xen.h>
> diff --git a/arch/riscv/xen/Makefile b/arch/riscv/xen/Makefile
> new file mode 100644
> index 000000000000..f6d3a357e4c7
> --- /dev/null
> +++ b/arch/riscv/xen/Makefile
> @@ -0,0 +1,2 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +obj-y := enlighten.o p2m.o grant-table.o hypercall.o
> diff --git a/arch/riscv/xen/enlighten.c b/arch/riscv/xen/enlighten.c
> new file mode 100644
> index 000000000000..28bd66c288f9
> --- /dev/null
> +++ b/arch/riscv/xen/enlighten.c
> @@ -0,0 +1,164 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +#include <xen/xen.h>
> +#include <xen/events.h>
> +#include <xen/grant_table.h>
> +#include <xen/hvm.h>
> +#include <xen/interface/vcpu.h>
> +#include <xen/interface/xen.h>
> +#include <xen/interface/memory.h>
> +#include <xen/interface/hvm/params.h>
> +#include <xen/features.h>
> +#include <xen/platform_pci.h>
> +#include <xen/xenbus.h>
> +#include <xen/page.h>
> +#include <xen/interface/sched.h>
> +#include <xen/xen-ops.h>
> +#include <asm/xen/hypervisor.h>
> +#include <asm/xen/hypercall.h>
> +#include <asm/efi.h>
> +#include <linux/interrupt.h>
> +#include <linux/irqreturn.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_fdt.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_address.h>
> +#include <linux/cpuidle.h>
> +#include <linux/cpufreq.h>
> +#include <linux/cpu.h>
> +#include <linux/console.h>
> +#include <linux/pvclock_gtod.h>
> +#include <linux/reboot.h>
> +#include <linux/time64.h>
> +#include <linux/timekeeping.h>
> +#include <linux/timekeeper_internal.h>
> +#include <linux/acpi.h>
> +#include <linux/virtio_anchor.h>
> +
> +#include <linux/mm.h>
> +
> +static struct start_info _xen_start_info;
> +struct start_info *xen_start_info = &_xen_start_info;
> +EXPORT_SYMBOL(xen_start_info);
> +
> +enum xen_domain_type xen_domain_type = XEN_NATIVE;
> +EXPORT_SYMBOL(xen_domain_type);
> +
> +struct shared_info xen_dummy_shared_info;
> +struct shared_info *HYPERVISOR_shared_info = (void *)&xen_dummy_shared_info;
> +
> +DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu);
> +static struct vcpu_info __percpu *xen_vcpu_info;
> +
> +/* Linux <-> Xen vCPU id mapping */
> +DEFINE_PER_CPU(uint32_t, xen_vcpu_id);
> +EXPORT_PER_CPU_SYMBOL(xen_vcpu_id);
> +
> +/* These are unused until we support booting "pre-ballooned" */
> +unsigned long xen_released_pages;
> +struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS] __initdata;
> +
> +static __read_mostly unsigned int xen_events_irq;
> +static __read_mostly phys_addr_t xen_grant_frames;
> +
> +#define GRANT_TABLE_INDEX   0
> +#define EXT_REGION_INDEX    1
> +
> +uint32_t xen_start_flags;
> +EXPORT_SYMBOL(xen_start_flags);
> +
> +int xen_unmap_domain_gfn_range(struct vm_area_struct *vma,
> +					int nr, struct page **pages)
> +{
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(xen_unmap_domain_gfn_range);
> +
> +static void xen_read_wallclock(struct timespec64 *ts)
> +{
> +}
> +
> +static int xen_pvclock_gtod_notify(struct notifier_block *nb,
> +					unsigned long was_set, void *priv)
> +{
> +	return 0;
> +}
> +
> +static struct notifier_block xen_pvclock_gtod_notifier = {
> +	.notifier_call = xen_pvclock_gtod_notify,
> +};
> +
> +static int xen_starting_cpu(unsigned int cpu)
> +{
> +	return 0;
> +}
> +
> +static int xen_dying_cpu(unsigned int cpu)
> +{
> +	return 0;
> +}
> +
> +void xen_reboot(int reason)
> +{
> +}
> +
> +static int xen_restart(struct notifier_block *nb, unsigned long action,
> +					void *data)
> +{
> +	return 0;
> +}
> +
> +static struct notifier_block xen_restart_nb = {
> +	.notifier_call = xen_restart,
> +	.priority = 192,
> +};
> +
> +static void xen_power_off(void)
> +{
> +}
> +
> +static __initdata struct {
> +	const char *compat;
> +	const char *prefix;
> +	const char *version;
> +	bool found;
> +} hyper_node = {"xen,xen", "xen,xen-", NULL, false};
> +
> +static int __init fdt_find_hyper_node(unsigned long node, const char *uname,
> +					int depth, void *data)
> +{
> +	return 0;
> +}
> +
> +void __init xen_early_init(void)
> +{
> +}
> +
> +static void __init xen_dt_guest_init(void)
> +{
> +}
> +
> +static int __init xen_guest_init(void)
> +{
> +	return 0;
> +}
> +early_initcall(xen_guest_init);
> +
> +static int xen_starting_runstate_cpu(unsigned int cpu)
> +{
> +	return 0;
> +}
> +
> +static int __init xen_late_init(void)
> +{
> +	return 0;
> +}
> +late_initcall(xen_late_init);
> +
> +
> +/* empty stubs */
> +void xen_arch_pre_suspend(void) { }
> +void xen_arch_post_suspend(int suspend_cancelled) { }
> +void xen_timer_resume(void) { }
> +void xen_arch_resume(void) { }
> +void xen_arch_suspend(void) { }

I don't see the point of creating arch/riscv/xen/enlighten.c by what looks
like copying arm's version and then deleting all the function
implementations. Much of arm's implementations look generic, so why not
keep them?

> diff --git a/arch/riscv/xen/grant-table.c b/arch/riscv/xen/grant-table.c
> new file mode 100644
> index 000000000000..9dd0cea74360
> --- /dev/null
> +++ b/arch/riscv/xen/grant-table.c
> @@ -0,0 +1,57 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/******************************************************************************
> + * grant_table.c
> + *
> + * Granting foreign access to our memory reservation.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License version 2
> + * as published by the Free Software Foundation; or, when distributed
> + * separately from the Linux kernel or incorporated into other
> + * software packages, subject to the following license:
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a copy
> + * of this source file (the "Software"), to deal in the Software without
> + * restriction, including without limitation the rights to use, copy, modify,
> + * merge, publish, distribute, sublicense, and/or sell copies of the Software,
> + * and to permit persons to whom the Software is furnished to do so, subject to
> + * the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
> + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + */
> +
> +#include <xen/interface/xen.h>
> +#include <xen/page.h>
> +#include <xen/grant_table.h>
> +
> +int arch_gnttab_map_shared(xen_pfn_t *frames, unsigned long nr_gframes,
> +					unsigned long max_nr_gframes,
> +					void **__shared)
> +{
> +	return 0;

should return -ENOSYS. arm returns that even now.

> +}
> +
> +void arch_gnttab_unmap(void *shared, unsigned long nr_gframes)
> +{
> +}
> +
> +int arch_gnttab_map_status(uint64_t *frames, unsigned long nr_gframes,
> +					unsigned long max_nr_gframes,
> +					grant_status_t **__shared)
> +{
> +	return 0;

should return -ENOSYS. arm returns that even now.

> +}
> +
> +int arch_gnttab_init(unsigned long nr_shared, unsigned long nr_status)
> +{
> +	return 0;
> +}
> diff --git a/arch/riscv/xen/hypercall.S b/arch/riscv/xen/hypercall.S
> new file mode 100644
> index 000000000000..a81afd2a11c4
> --- /dev/null
> +++ b/arch/riscv/xen/hypercall.S
> @@ -0,0 +1,71 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#include <linux/linkage.h>
> +#include <asm/assembler.h>
> +#include <xen/interface/xen.h>
> +EXPORT_SYMBOL_GPL(HYPERVISOR_event_channel_op);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_grant_table_op);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_xen_version);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_console_io);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_sched_op);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_hvm_op);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_memory_op);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_physdev_op);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_vcpu_op);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_platform_op_raw);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_multicall);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_vm_assist);
> +EXPORT_SYMBOL_GPL(HYPERVISOR_dm_op);
> +EXPORT_SYMBOL_GPL(privcmd_call);
> +#define SBI_ECALL 0xE

Shouldn't this be 0xA000007, i.e. the SBI firmware specific extension
for Xen. Otherwise why refer to SBI? Note, '0xE' is an invalid, legacy
extension ID in SBI.

> +
> +    .data
> +
> +#define HYPERCALL_SIMPLE(hypercall) \
> +SYM_FUNC_START(HYPERVISOR_##hypercall) \
> +    li a6, __HYPERVISOR_##hypercall; \
> +    li a7, SBI_ECALL; \
> +    mv a5, a4; \
> +    mv a4, a3; \
> +    mv a3, a2; \
> +    mv a2, a1; \
> +    mv a1, a0; \
> +    li a0, 0; \

Assuming a0 has to be zero, then we should look for a solution to avoid
all the register shifting. Either some wrapper functions for the
hypercalls that convince the compiler to do the right thing or at
least use the HYPERCALL{0,1,2,...} defines to reduce the amount of
shifting to the minimum.

> +    ecall; \
> +    ret; \
> +SYM_FUNC_END(HYPERVISOR_##hypercall)
> +
> +#define HYPERCALL0 HYPERCALL_SIMPLE
> +#define HYPERCALL1 HYPERCALL_SIMPLE
> +#define HYPERCALL2 HYPERCALL_SIMPLE
> +#define HYPERCALL3 HYPERCALL_SIMPLE
> +#define HYPERCALL4 HYPERCALL_SIMPLE
> +#define HYPERCALL5 HYPERCALL_SIMPLE
> +
> +    .text
> +
> +HYPERCALL2(xen_version);
> +HYPERCALL3(console_io);
> +HYPERCALL3(grant_table_op);
> +HYPERCALL2(sched_op);
> +HYPERCALL2(event_channel_op);
> +HYPERCALL2(hvm_op);
> +HYPERCALL2(memory_op);
> +HYPERCALL2(physdev_op);
> +HYPERCALL3(vcpu_op);
> +HYPERCALL1(platform_op_raw);
> +HYPERCALL2(multicall);
> +HYPERCALL2(vm_assist);
> +HYPERCALL3(dm_op);
> +
> +SYM_FUNC_START(privcmd_call)
> +    mv a6, a0
> +    li a7, SBI_ECALL
> +    mv a5, a4;
> +    mv a4, a3;
> +    mv a3, a2;
> +    mv a2, a1;
> +    mv a1, a0;
> +    li a0, 0;

same comments as above

> +    ecall
> +    ret
> +SYM_FUNC_END(privcmd_call);
> diff --git a/arch/riscv/xen/p2m.c b/arch/riscv/xen/p2m.c
> new file mode 100644
> index 000000000000..7ce75e52d7c4
> --- /dev/null
> +++ b/arch/riscv/xen/p2m.c
> @@ -0,0 +1,76 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +#include <linux/memblock.h>
> +#include <linux/gfp.h>
> +#include <linux/export.h>
> +#include <linux/spinlock.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/vmalloc.h>
> +#include <linux/swiotlb.h>
> +
> +#include <xen/xen.h>
> +#include <xen/interface/memory.h>
> +#include <xen/grant_table.h>
> +#include <xen/page.h>
> +#include <xen/swiotlb-xen.h>
> +
> +#include <asm/cacheflush.h>
> +#include <asm/xen/hypercall.h>
> +#include <asm/xen/interface.h>
> +
> +struct xen_p2m_entry {
> +	unsigned long pfn;
> +	unsigned long mfn;
> +	unsigned long nr_pages;
> +	struct rb_node rbnode_phys;
> +};
> +
> +static rwlock_t p2m_lock;
> +struct rb_root phys_to_mach = RB_ROOT;
> +EXPORT_SYMBOL_GPL(phys_to_mach);
> +
> +static int xen_add_phys_to_mach_entry(struct xen_p2m_entry *new)
> +{
> +
> +	return 0;
> +}
> +
> +unsigned long __pfn_to_mfn(unsigned long pfn)
> +{
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(__pfn_to_mfn);
> +
> +int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
> +					struct gnttab_map_grant_ref *kmap_ops,
> +					struct page **pages, unsigned int count)
> +{
> +	return 0;
> +}
> +
> +int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
> +					struct gnttab_unmap_grant_ref *kunmap_ops,
> +					struct page **pages, unsigned int count)
> +{
> +	return 0;
> +}
> +
> +bool __set_phys_to_machine_multi(unsigned long pfn,
> +					unsigned long mfn, unsigned long nr_pages)
> +{
> +	return true;
> +}
> +EXPORT_SYMBOL_GPL(__set_phys_to_machine_multi);
> +
> +bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
> +{
> +	return true;
> +}
> +EXPORT_SYMBOL_GPL(__set_phys_to_machine);
> +
> +static int p2m_init(void)
> +{
> +	return 0;
> +}
> +arch_initcall(p2m_init);

Again, I'm not sure what the point of copying functions from arm without
their (what appear to be generic) implementations is.

> diff --git a/include/xen/interface/io/protocols.h b/include/xen/interface/io/protocols.h
> index 22099bb4079f..6c6317462be0 100644
> --- a/include/xen/interface/io/protocols.h
> +++ b/include/xen/interface/io/protocols.h
> @@ -6,6 +6,7 @@
>  #define XEN_IO_PROTO_ABI_X86_64     "x86_64-abi"
>  #define XEN_IO_PROTO_ABI_POWERPC64  "powerpc64-abi"
>  #define XEN_IO_PROTO_ABI_ARM        "arm-abi"
> +#define XEN_IO_PROTO_ABI_RISCV      "riscv-abi"
> 
>  #if defined(__i386__)
>  # define XEN_IO_PROTO_ABI_NATIVE XEN_IO_PROTO_ABI_X86_32
> @@ -15,6 +16,8 @@
>  # define XEN_IO_PROTO_ABI_NATIVE XEN_IO_PROTO_ABI_POWERPC64
>  #elif defined(__arm__) || defined(__aarch64__)
>  # define XEN_IO_PROTO_ABI_NATIVE XEN_IO_PROTO_ABI_ARM
> +#elif defined(__riscv)
> +# define XEN_IO_PROTO_ABI_NATIVE XEN_IO_PROTO_ABI_RISCV
>  #else
>  # error arch fixup needed here
>  #endif
> diff --git a/include/xen/riscv/hypercall.h b/include/xen/riscv/hypercall.h
> new file mode 100644
> index 000000000000..f76d8a018f26
> --- /dev/null
> +++ b/include/xen/riscv/hypercall.h
> @@ -0,0 +1,71 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/******************************************************************************
> + * hypercall.h
> + *
> + * Linux-specific hypervisor handling.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License version 2
> + * as published by the Free Software Foundation; or, when distributed
> + * separately from the Linux kernel or incorporated into other
> + * software packages, subject to the following license:
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a copy
> + * of this source file (the "Software"), to deal in the Software without
> + * restriction, including without limitation the rights to use, copy, modify,
> + * merge, publish, distribute, sublicense, and/or sell copies of the Software,
> + * and to permit persons to whom the Software is furnished to do so, subject to
> + * the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
> + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + */

Just the SPDX should be sufficient.

> +
> +#ifndef _ASM_RISCV_XEN_HYPERCALL_H
> +#define _ASM_RISCV_XEN_HYPERCALL_H
> +
> +#include <linux/bug.h>
> +
> +#include <xen/interface/xen.h>
> +#include <xen/interface/sched.h>
> +#include <xen/interface/platform.h>
> +
> +struct xen_dm_op_buf;
> +
> +long privcmd_call(unsigned int call, unsigned long a1,
> +		unsigned long a2, unsigned long a3,
> +		unsigned long a4, unsigned long a5);
> +int HYPERVISOR_xen_version(int cmd, void *arg);
> +int HYPERVISOR_console_io(int cmd, int count, char *str);
> +int HYPERVISOR_grant_table_op(unsigned int cmd, void *uop, unsigned int count);
> +int HYPERVISOR_sched_op(int cmd, void *arg);
> +int HYPERVISOR_event_channel_op(int cmd, void *arg);
> +unsigned long HYPERVISOR_hvm_op(int op, void *arg);
> +int HYPERVISOR_memory_op(unsigned int cmd, void *arg);
> +int HYPERVISOR_physdev_op(int cmd, void *arg);
> +int HYPERVISOR_vcpu_op(int cmd, int vcpuid, void *extra_args);
> +int HYPERVISOR_vm_assist(unsigned int cmd, unsigned int type);
> +int HYPERVISOR_dm_op(domid_t domid, unsigned int nr_bufs,
> +			 struct xen_dm_op_buf *bufs);
> +int HYPERVISOR_platform_op_raw(void *arg);
> +static inline int HYPERVISOR_platform_op(struct xen_platform_op *op)
> +{
> +	return 0;
> +}
> +int HYPERVISOR_multicall(struct multicall_entry *calls, uint32_t nr);
> +
> +static inline int
> +HYPERVISOR_suspend(unsigned long start_info_mfn)

Don't wrap this function definition

> +{
> +	return 0;
> +}
> +
> +#endif /* _ASM_RISCV_XEN_HYPERCALL_H */
> diff --git a/include/xen/riscv/hypervisor.h b/include/xen/riscv/hypervisor.h
> new file mode 100644
> index 000000000000..2c1f9625be80
> --- /dev/null
> +++ b/include/xen/riscv/hypervisor.h
> @@ -0,0 +1,26 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_RISCV_XEN_HYPERVISOR_H
> +#define _ASM_RISCV_XEN_HYPERVISOR_H
> +
> +#include <linux/init.h>
> +
> +extern struct shared_info *HYPERVISOR_shared_info;
> +extern struct start_info *xen_start_info;
> +
> +#ifdef CONFIG_XEN
> +void __init xen_early_init(void);
> +#else
> +static inline void xen_early_init(void) { return; }
> +#endif
> +
> +#ifdef CONFIG_HOTPLUG_CPU
> +static inline void xen_arch_register_cpu(int num)
> +{
> +}
> +
> +static inline void xen_arch_unregister_cpu(int num)
> +{
> +}
> +#endif
> +
> +#endif /* _ASM_RISCV_XEN_HYPERVISOR_H */
> diff --git a/include/xen/riscv/interface.h b/include/xen/riscv/interface.h
> new file mode 100644
> index 000000000000..6769b5b39cba
> --- /dev/null
> +++ b/include/xen/riscv/interface.h
> @@ -0,0 +1,85 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/******************************************************************************
> + * Guest OS interface to RISCV Xen.
> + *
> + */
> +
> +#ifndef _ASM_RISCV_XEN_INTERFACE_H
> +#define _ASM_RISCV_XEN_INTERFACE_H
> +
> +#include <linux/types.h>
> +
> +#define uint64_aligned_t uint64_t __aligned(8)
> +
> +#define __DEFINE_GUEST_HANDLE(name, type) \
> +	typedef struct { union { type * p; uint64_aligned_t q; }; }  \
> +		__guest_handle_ ## name
> +
> +#define DEFINE_GUEST_HANDLE_STRUCT(name) \
> +	__DEFINE_GUEST_HANDLE(name, struct name)
> +#define DEFINE_GUEST_HANDLE(name) __DEFINE_GUEST_HANDLE(name, name)
> +#define GUEST_HANDLE(name)        __guest_handle_ ## name
> +
> +#define set_xen_guest_handle(hnd, val)			\
> +	do {						\
> +		if (sizeof(hnd) == 8)			\
> +			*(uint64_t *)&(hnd) = 0;	\
> +		(hnd).p = val;				\
> +	} while (0)
> +
> +#define __HYPERVISOR_platform_op_raw __HYPERVISOR_platform_op
> +
> +#ifndef __ASSEMBLY__
> +/* Explicitly size integers that represent pfns in the interface with
> + * Xen so that we can have one ABI that works for 32 and 64 bit guests.
> + * Note that this means that the xen_pfn_t type may be capable of
> + * representing pfn's which the guest cannot represent in its own pfn
> + * type. However since pfn space is controlled by the guest this is
> + * fine since it simply wouldn't be able to create any sure pfns in
> + * the first place.
> + */
> +typedef uint64_t xen_pfn_t;
> +#define PRI_xen_pfn "llx"
> +typedef uint64_t xen_ulong_t;
> +#define PRI_xen_ulong "llx"
> +typedef int64_t xen_long_t;
> +#define PRI_xen_long "llx"
> +/* Guest handles for primitive C types. */
> +__DEFINE_GUEST_HANDLE(uchar, unsigned char);
> +__DEFINE_GUEST_HANDLE(uint,  unsigned int);
> +DEFINE_GUEST_HANDLE(char);
> +DEFINE_GUEST_HANDLE(int);
> +DEFINE_GUEST_HANDLE(void);
> +DEFINE_GUEST_HANDLE(uint64_t);
> +DEFINE_GUEST_HANDLE(uint32_t);
> +DEFINE_GUEST_HANDLE(xen_pfn_t);
> +DEFINE_GUEST_HANDLE(xen_ulong_t);
> +
> +/* Maximum number of virtual CPUs in multi-processor guests. */
> +#define MAX_VIRT_CPUS 1
> +
> +struct arch_vcpu_info { };
> +struct arch_shared_info { };
> +
> +/* TODO: Move pvclock definitions some place arch independent */
> +struct pvclock_vcpu_time_info {
> +	u32   version;
> +	u32   pad0;
> +	u64   tsc_timestamp;
> +	u64   system_time;
> +	u32   tsc_to_system_mul;
> +	s8    tsc_shift;
> +	u8    flags;
> +	u8    pad[2];
> +} __packed; /* 32 bytes */
> +
> +/* It is OK to have a 12 bytes struct with no padding because it is packed */
> +struct pvclock_wall_clock {
> +	u32   version;
> +	u32   sec;
> +	u32   nsec;
> +	u32   sec_hi;
> +} __packed;
> +#endif
> +
> +#endif /* _ASM_RISCV_XEN_INTERFACE_H */
> diff --git a/include/xen/riscv/page.h b/include/xen/riscv/page.h
> new file mode 100644
> index 000000000000..fe07a9bffa7e
> --- /dev/null
> +++ b/include/xen/riscv/page.h
> @@ -0,0 +1,106 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_RISCV_XEN_PAGE_H
> +#define _ASM_RISCV_XEN_PAGE_H
> +
> +#include <asm/page.h>
> +
> +#include <linux/pfn.h>
> +#include <linux/types.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/pgtable.h>
> +
> +#include <xen/xen.h>
> +#include <xen/interface/grant_table.h>
> +
> +/* Xen machine address */
> +struct xmaddr {
> +	phys_addr_t maddr;
> +};
> +
> +/* Xen pseudo-physical address */
> +struct xpaddr {
> +	phys_addr_t paddr;
> +};
> +
> +#define XMADDR(x)	((struct xmaddr) { .maddr = (x) })
> +#define XPADDR(x)	((struct xpaddr) { .paddr = (x) })
> +
> +#define INVALID_P2M_ENTRY      (~0UL)
> +
> +/*
> + * The pseudo-physical frame (pfn) used in all the helpers is always based
> + * on Xen page granularity (i.e 4KB).
> + *
> + * A Linux page may be split across multiple non-contiguous Xen page so we
> + * have to keep track with frame based on 4KB page granularity.
> + *
> + * PV drivers should never make a direct usage of those helpers (particularly
> + * pfn_to_gfn and gfn_to_pfn).
> + */
> +
> +unsigned long __pfn_to_mfn(unsigned long pfn);
> +extern struct rb_root phys_to_mach;
> +
> +/* Pseudo-physical <-> Guest conversion */
> +static inline unsigned long pfn_to_gfn(unsigned long pfn)
> +{
> +	return 0;
> +}
> +
> +static inline unsigned long gfn_to_pfn(unsigned long gfn)
> +{
> +	return 0;
> +}
> +
> +/* Pseudo-physical <-> BUS conversion */
> +static inline unsigned long pfn_to_bfn(unsigned long pfn)
> +{
> +	return 0;
> +}
> +
> +static inline unsigned long bfn_to_pfn(unsigned long bfn)
> +{
> +	return 0;
> +}
> +
> +#define bfn_to_local_pfn(bfn)	bfn_to_pfn(bfn)
> +
> +/* VIRT <-> GUEST conversion */
> +#define virt_to_gfn(v)                                                         \
> +	({                                                                     \
> +		WARN_ON_ONCE(!virt_addr_valid(v));                              \
> +		pfn_to_gfn(virt_to_phys(v) >> XEN_PAGE_SHIFT);                 \
> +	})
> +#define gfn_to_virt(m)		(__va(gfn_to_pfn(m) << XEN_PAGE_SHIFT))
> +
> +#define percpu_to_gfn(v)	\
> +	(pfn_to_gfn(per_cpu_ptr_to_phys(v) >> XEN_PAGE_SHIFT))
> +
> +static inline struct xmaddr arbitrary_virt_to_machine(void *vaddr)
> +{
> +	WARN_ON_ONCE(1);
> +	return (struct xmaddr){0};
> +}
> +
> +extern int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
> +				   struct gnttab_map_grant_ref *kmap_ops,
> +				   struct page **pages, unsigned int count);
> +
> +extern int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
> +					 struct gnttab_unmap_grant_ref *kunmap_ops,
> +					 struct page **pages, unsigned int count);
> +
> +bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn);
> +bool __set_phys_to_machine_multi(unsigned long pfn, unsigned long mfn,
> +		unsigned long nr_pages);
> +
> +static inline bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
> +{
> +	return 0;
> +}
> +
> +bool xen_arch_need_swiotlb(struct device *dev,
> +			   phys_addr_t phys,
> +			   dma_addr_t dev_addr);
> +
> +#endif /* _ASM_RISCV_XEN_PAGE_H */
> diff --git a/include/xen/riscv/swiotlb-xen.h b/include/xen/riscv/swiotlb-xen.h
> new file mode 100644
> index 000000000000..97ecd8cbbc2d
> --- /dev/null
> +++ b/include/xen/riscv/swiotlb-xen.h
> @@ -0,0 +1,13 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_RISCV_SWIOTLB_XEN_H
> +#define _ASM_RISCV_SWIOTLB_XEN_H
> +
> +#include <xen/features.h>
> +#include <xen/xen.h>
> +
> +static inline int xen_swiotlb_detect(void)
> +{
> +	return 0;
> +}
> +
> +#endif /* _ASM_RISCV_SWIOTLB_XEN_H */
> diff --git a/test.txt b/test.txt
> new file mode 100644
> index 000000000000..e54267998982
> --- /dev/null
> +++ b/test.txt
> @@ -0,0 +1,21 @@
> +WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
> +#120:
> +new file mode 100644
> +
> +WARNING: do not add new typedefs
> +#808: FILE: include/xen/riscv/interface.h:15:
> ++	typedef struct { union { type * p; uint64_aligned_t q; }; }  \
> +
> +WARNING: please, no spaces at the start of a line
> +#1006: FILE: include/xen/riscv/swiotlb-xen.h:10:
> ++    return 0;$
> +
> +total: 0 errors, 3 warnings, 810 lines checked
> +
> +NOTE: For some of the reported defects, checkpatch may be able to
> +      mechanically convert to the typical style using --fix or --fix-inplace.
> +
> +0001-riscv-Add-initial-Xen-guest-support-for-RISC-V.patch has style problems, please review.
> +
> +NOTE: If any of the errors are false positives, please report
> +      them to the maintainer, see CHECKPATCH in MAINTAINERS.

You obviously added this file by accident. Please proof read patches
before sending them.

I'm glad to see interest in getting Xen support upstream, but this isn't
the right approach. For starters, the patch is clearly missing the 'RFC'
it should have in its prefix, but it also doesn't make sense to post
(much less merge) a bunch of stubs, at least not without another patch
in the same series filling most or all those stubs in with tested code.
Also, anything that is generic should either be copied in the first go
(rather than deleting it just to add it back later) or, even better, it
should be factored out of the other architecture specific code into a
common place where it can be shared.

Thanks,
drew

Stefano Stabellini Jan. 15, 2025, 12:01 a.m. UTC | #4

+Oleksii

On Tue, 14 Jan 2025, Milan Djokic wrote:
> From: Slavisa Petrovic <[e-mail]>
> 
> This patch introduces initial support for running RISC-V as a Xen guest.
> It provides the necessary infrastructure and stubs for Xen-specific
> operations. Key changes include:
> 
> - Modifications to the RISC-V kernel to integrate Xen-specific hypercalls
>   and interfaces, with function implementations stubbed for future work.
> - Introduction of Xen-specific headers for RISC-V, including event
>   handling, hypervisor interaction, and page management. Functions are
>   defined but not yet implemented.
> - Stub implementations for memory management, grant tables, and context
>   switching in the Xen environment, allowing further development and
>   integration.
> 
> Signed-off-by: Milan Djokic <[e-mail]>
> Signed-off-by: Slavisa Petrovic <[e-mail]>

Hi Milan, Slavisa,

Thank you very much for your contribution! Which Xen tree are you using
for development? I am asking because RISC-V support in Xen is still in
the process of being upstreamed, and [1] is the tree that consolidates
all patches currently on the to-be-upstreamed list.  

While the specific Xen tree you are using is not particularly important
at this stage, and using [1] is not a requirement, I am asking because
it is essential to align on the hypervisor ABI, especially regarding any
details that have not yet been upstreamed. Specifically, is there
anything in this patch series that relies on features not yet upstream
in Xen?  

[1] https://gitlab.com/xen-project/people/olkur/xen/-/tree/latest?ref_type=heads

Patch

diff --git a/arch/riscv/Kbuild b/arch/riscv/Kbuild
index 2c585f7a0b6e..d9b71deed2cd 100644
--- a/arch/riscv/Kbuild
+++ b/arch/riscv/Kbuild
@@ -5,6 +5,7 @@  obj-$(CONFIG_BUILTIN_DTB) += boot/dts/
 obj-$(CONFIG_CRYPTO) += crypto/
 obj-y += errata/
 obj-$(CONFIG_KVM) += kvm/
+obj-$(CONFIG_XEN) += xen/

 obj-$(CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY) += purgatory/

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index d4a7ca0388c0..13ea75221524 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -1071,6 +1071,25 @@  config PARAVIRT_TIME_ACCOUNTING

 	  If in doubt, say N here.

+config XEN_DOM0
+	def_bool y
+	depends on XEN
+
+config XEN
+	bool "Xen guest support on RISCV"
+	depends on RISCV && OF
+	select PARAVIRT
+	help
+	  Enables support for running Linux as a Xen guest on RISC-V.
+
+	  Xen is a type-1 hypervisor that allows multiple operating systems
+	  to run on the same hardware. Enabling this option allows the kernel
+	  to function as a guest under the Xen hypervisor on RISC-V platforms.
+
+	  Say Y if you want to run this kernel as a guest under Xen on RISC-V.
+
+	  If unsure, say N.
+
 config RELOCATABLE
 	bool "Build a relocatable kernel"
 	depends on MMU && 64BIT && !XIP_KERNEL
diff --git a/arch/riscv/include/asm/cpu.h b/arch/riscv/include/asm/cpu.h
index 28d45a6678ce..fb2aac6a068e 100644
--- a/arch/riscv/include/asm/cpu.h
+++ b/arch/riscv/include/asm/cpu.h
@@ -4,5 +4,6 @@ 
 #define _ASM_CPU_H

 /* This header is required unconditionally by the ACPI core */
+#include <linux/cpu.h>

 #endif /* _ASM_CPU_H */
diff --git a/arch/riscv/include/asm/hypervisor.h b/arch/riscv/include/asm/hypervisor.h
new file mode 100644
index 000000000000..3a117afe57f0
--- /dev/null
+++ b/arch/riscv/include/asm/hypervisor.h
@@ -0,0 +1,9 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_RISCV_HYPERVISOR_H
+#define _ASM_RISCV_HYPERVISOR_H
+
+#include <asm/xen/hypervisor.h>
+
+void kvm_init_hyp_services(void);
+
+#endif
diff --git a/arch/riscv/include/asm/irq.h b/arch/riscv/include/asm/irq.h
index 7b038f3b7cb0..b14621848eae 100644
--- a/arch/riscv/include/asm/irq.h
+++ b/arch/riscv/include/asm/irq.h
@@ -23,6 +23,11 @@  void riscv_set_intc_hwnode_fn(struct fwnode_handle *(*fn)(void));

 struct fwnode_handle *riscv_get_intc_hwnode(void);

+static inline int nr_legacy_irqs(void)
+{
+	return 0;
+}
+
 #ifdef CONFIG_ACPI

 enum riscv_irqchip_type {
diff --git a/arch/riscv/include/asm/sync_bitops.h b/arch/riscv/include/asm/sync_bitops.h
new file mode 100644
index 000000000000..28e3c64ba852
--- /dev/null
+++ b/arch/riscv/include/asm/sync_bitops.h
@@ -0,0 +1,27 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_SYNC_BITOPS_H__
+#define __ASM_SYNC_BITOPS_H__
+
+#include <asm/bitops.h>
+#include <asm/cmpxchg.h>
+
+/* sync_bitops functions are equivalent to the SMP implementation of the
+ * original functions, independently from CONFIG_SMP being defined.
+ *
+ * We need them because _set_bit etc are not SMP safe if !CONFIG_SMP. But
+ * under Xen you might be communicating with a completely external entity
+ * who might be on another CPU (e.g. two uniprocessor guests communicating
+ * via event channels and grant tables). So we need a variant of the bit
+ * ops which are SMP safe even on a UP kernel.
+ */
+
+#define sync_set_bit(nr, p)             set_bit(nr, p)
+#define sync_clear_bit(nr, p)           clear_bit(nr, p)
+#define sync_change_bit(nr, p)          change_bit(nr, p)
+#define sync_test_and_set_bit(nr, p)    test_and_set_bit(nr, p)
+#define sync_test_and_clear_bit(nr, p)  test_and_clear_bit(nr, p)
+#define sync_test_and_change_bit(nr, p) test_and_change_bit(nr, p)
+#define sync_test_bit(nr, addr)         test_bit(nr, addr)
+#define arch_sync_cmpxchg               arch_cmpxchg
+
+#endif
diff --git a/arch/riscv/include/asm/xen/events.h b/arch/riscv/include/asm/xen/events.h
new file mode 100644
index 000000000000..a3d0332ca46c
--- /dev/null
+++ b/arch/riscv/include/asm/xen/events.h
@@ -0,0 +1,28 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_RISCV_XEN_EVENTS_H
+#define _ASM_RISCV_XEN_EVENTS_H
+
+#include <asm/ptrace.h>
+#include <asm/atomic.h>
+
+enum ipi_vector {
+	XEN_PLACEHOLDER_VECTOR,
+
+	/* Xen IPIs go here */
+	XEN_NR_IPIS,
+};
+
+static inline int xen_irqs_disabled(struct pt_regs *regs)
+{
+	return 0;
+}
+
+#define xchg_xen_ulong(ptr, val) xchg((ptr), (val))
+
+/* Rebind event channel is supported by default */
+static inline bool xen_support_evtchn_rebind(void)
+{
+	return true;
+}
+
+#endif /* _ASM_RISCV_XEN_EVENTS_H */
diff --git a/arch/riscv/include/asm/xen/hypercall.h b/arch/riscv/include/asm/xen/hypercall.h
new file mode 100644
index 000000000000..0841ba1f0835
--- /dev/null
+++ b/arch/riscv/include/asm/xen/hypercall.h
@@ -0,0 +1,2 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <xen/riscv/hypercall.h>
diff --git a/arch/riscv/include/asm/xen/hypervisor.h b/arch/riscv/include/asm/xen/hypervisor.h
new file mode 100644
index 000000000000..05b7c834d0a9
--- /dev/null
+++ b/arch/riscv/include/asm/xen/hypervisor.h
@@ -0,0 +1,2 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <xen/riscv/hypervisor.h>
diff --git a/arch/riscv/include/asm/xen/interface.h b/arch/riscv/include/asm/xen/interface.h
new file mode 100644
index 000000000000..9f30b1d7e77c
--- /dev/null
+++ b/arch/riscv/include/asm/xen/interface.h
@@ -0,0 +1,2 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <xen/riscv/interface.h>
diff --git a/arch/riscv/include/asm/xen/page.h b/arch/riscv/include/asm/xen/page.h
new file mode 100644
index 000000000000..c8f5b873445b
--- /dev/null
+++ b/arch/riscv/include/asm/xen/page.h
@@ -0,0 +1,3 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <xen/riscv/page.h>
+#include <asm/mmu.h>
diff --git a/arch/riscv/include/asm/xen/swiotlb-xen.h b/arch/riscv/include/asm/xen/swiotlb-xen.h
new file mode 100644
index 000000000000..aa3bc339df03
--- /dev/null
+++ b/arch/riscv/include/asm/xen/swiotlb-xen.h
@@ -0,0 +1,2 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <xen/riscv/swiotlb-xen.h>
diff --git a/arch/riscv/xen/Makefile b/arch/riscv/xen/Makefile
new file mode 100644
index 000000000000..f6d3a357e4c7
--- /dev/null
+++ b/arch/riscv/xen/Makefile
@@ -0,0 +1,2 @@ 
+# SPDX-License-Identifier: GPL-2.0-only
+obj-y := enlighten.o p2m.o grant-table.o hypercall.o
diff --git a/arch/riscv/xen/enlighten.c b/arch/riscv/xen/enlighten.c
new file mode 100644
index 000000000000..28bd66c288f9
--- /dev/null
+++ b/arch/riscv/xen/enlighten.c
@@ -0,0 +1,164 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+#include <xen/xen.h>
+#include <xen/events.h>
+#include <xen/grant_table.h>
+#include <xen/hvm.h>
+#include <xen/interface/vcpu.h>
+#include <xen/interface/xen.h>
+#include <xen/interface/memory.h>
+#include <xen/interface/hvm/params.h>
+#include <xen/features.h>
+#include <xen/platform_pci.h>
+#include <xen/xenbus.h>
+#include <xen/page.h>
+#include <xen/interface/sched.h>
+#include <xen/xen-ops.h>
+#include <asm/xen/hypervisor.h>
+#include <asm/xen/hypercall.h>
+#include <asm/efi.h>
+#include <linux/interrupt.h>
+#include <linux/irqreturn.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
+#include <linux/cpuidle.h>
+#include <linux/cpufreq.h>
+#include <linux/cpu.h>
+#include <linux/console.h>
+#include <linux/pvclock_gtod.h>
+#include <linux/reboot.h>
+#include <linux/time64.h>
+#include <linux/timekeeping.h>
+#include <linux/timekeeper_internal.h>
+#include <linux/acpi.h>
+#include <linux/virtio_anchor.h>
+
+#include <linux/mm.h>
+
+static struct start_info _xen_start_info;
+struct start_info *xen_start_info = &_xen_start_info;
+EXPORT_SYMBOL(xen_start_info);
+
+enum xen_domain_type xen_domain_type = XEN_NATIVE;
+EXPORT_SYMBOL(xen_domain_type);
+
+struct shared_info xen_dummy_shared_info;
+struct shared_info *HYPERVISOR_shared_info = (void *)&xen_dummy_shared_info;
+
+DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu);
+static struct vcpu_info __percpu *xen_vcpu_info;
+
+/* Linux <-> Xen vCPU id mapping */
+DEFINE_PER_CPU(uint32_t, xen_vcpu_id);
+EXPORT_PER_CPU_SYMBOL(xen_vcpu_id);
+
+/* These are unused until we support booting "pre-ballooned" */
+unsigned long xen_released_pages;
+struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS] __initdata;
+
+static __read_mostly unsigned int xen_events_irq;
+static __read_mostly phys_addr_t xen_grant_frames;
+
+#define GRANT_TABLE_INDEX   0
+#define EXT_REGION_INDEX    1
+
+uint32_t xen_start_flags;
+EXPORT_SYMBOL(xen_start_flags);
+
+int xen_unmap_domain_gfn_range(struct vm_area_struct *vma,
+					int nr, struct page **pages)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(xen_unmap_domain_gfn_range);
+
+static void xen_read_wallclock(struct timespec64 *ts)
+{
+}
+
+static int xen_pvclock_gtod_notify(struct notifier_block *nb,
+					unsigned long was_set, void *priv)
+{
+	return 0;
+}
+
+static struct notifier_block xen_pvclock_gtod_notifier = {
+	.notifier_call = xen_pvclock_gtod_notify,
+};
+
+static int xen_starting_cpu(unsigned int cpu)
+{
+	return 0;
+}
+
+static int xen_dying_cpu(unsigned int cpu)
+{
+	return 0;
+}
+
+void xen_reboot(int reason)
+{
+}
+
+static int xen_restart(struct notifier_block *nb, unsigned long action,
+					void *data)
+{
+	return 0;
+}
+
+static struct notifier_block xen_restart_nb = {
+	.notifier_call = xen_restart,
+	.priority = 192,
+};
+
+static void xen_power_off(void)
+{
+}
+
+static __initdata struct {
+	const char *compat;
+	const char *prefix;
+	const char *version;
+	bool found;
+} hyper_node = {"xen,xen", "xen,xen-", NULL, false};
+
+static int __init fdt_find_hyper_node(unsigned long node, const char *uname,
+					int depth, void *data)
+{
+	return 0;
+}
+
+void __init xen_early_init(void)
+{
+}
+
+static void __init xen_dt_guest_init(void)
+{
+}
+
+static int __init xen_guest_init(void)
+{
+	return 0;
+}
+early_initcall(xen_guest_init);
+
+static int xen_starting_runstate_cpu(unsigned int cpu)
+{
+	return 0;
+}
+
+static int __init xen_late_init(void)
+{
+	return 0;
+}
+late_initcall(xen_late_init);
+
+
+/* empty stubs */
+void xen_arch_pre_suspend(void) { }
+void xen_arch_post_suspend(int suspend_cancelled) { }
+void xen_timer_resume(void) { }
+void xen_arch_resume(void) { }
+void xen_arch_suspend(void) { }
diff --git a/arch/riscv/xen/grant-table.c b/arch/riscv/xen/grant-table.c
new file mode 100644
index 000000000000..9dd0cea74360
--- /dev/null
+++ b/arch/riscv/xen/grant-table.c
@@ -0,0 +1,57 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/******************************************************************************
+ * grant_table.c
+ *
+ * Granting foreign access to our memory reservation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include <xen/interface/xen.h>
+#include <xen/page.h>
+#include <xen/grant_table.h>
+
+int arch_gnttab_map_shared(xen_pfn_t *frames, unsigned long nr_gframes,
+					unsigned long max_nr_gframes,
+					void **__shared)
+{
+	return 0;
+}
+
+void arch_gnttab_unmap(void *shared, unsigned long nr_gframes)
+{
+}
+
+int arch_gnttab_map_status(uint64_t *frames, unsigned long nr_gframes,
+					unsigned long max_nr_gframes,
+					grant_status_t **__shared)
+{
+	return 0;
+}
+
+int arch_gnttab_init(unsigned long nr_shared, unsigned long nr_status)
+{
+	return 0;
+}
diff --git a/arch/riscv/xen/hypercall.S b/arch/riscv/xen/hypercall.S
new file mode 100644
index 000000000000..a81afd2a11c4
--- /dev/null
+++ b/arch/riscv/xen/hypercall.S
@@ -0,0 +1,71 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+#include <xen/interface/xen.h>
+EXPORT_SYMBOL_GPL(HYPERVISOR_event_channel_op);
+EXPORT_SYMBOL_GPL(HYPERVISOR_grant_table_op);
+EXPORT_SYMBOL_GPL(HYPERVISOR_xen_version);
+EXPORT_SYMBOL_GPL(HYPERVISOR_console_io);
+EXPORT_SYMBOL_GPL(HYPERVISOR_sched_op);
+EXPORT_SYMBOL_GPL(HYPERVISOR_hvm_op);
+EXPORT_SYMBOL_GPL(HYPERVISOR_memory_op);
+EXPORT_SYMBOL_GPL(HYPERVISOR_physdev_op);
+EXPORT_SYMBOL_GPL(HYPERVISOR_vcpu_op);
+EXPORT_SYMBOL_GPL(HYPERVISOR_platform_op_raw);
+EXPORT_SYMBOL_GPL(HYPERVISOR_multicall);
+EXPORT_SYMBOL_GPL(HYPERVISOR_vm_assist);
+EXPORT_SYMBOL_GPL(HYPERVISOR_dm_op);
+EXPORT_SYMBOL_GPL(privcmd_call);
+#define SBI_ECALL 0xE
+
+    .data
+
+#define HYPERCALL_SIMPLE(hypercall) \
+SYM_FUNC_START(HYPERVISOR_##hypercall) \
+    li a6, __HYPERVISOR_##hypercall; \
+    li a7, SBI_ECALL; \
+    mv a5, a4; \
+    mv a4, a3; \
+    mv a3, a2; \
+    mv a2, a1; \
+    mv a1, a0; \
+    li a0, 0; \
+    ecall; \
+    ret; \
+SYM_FUNC_END(HYPERVISOR_##hypercall)
+
+#define HYPERCALL0 HYPERCALL_SIMPLE
+#define HYPERCALL1 HYPERCALL_SIMPLE
+#define HYPERCALL2 HYPERCALL_SIMPLE
+#define HYPERCALL3 HYPERCALL_SIMPLE
+#define HYPERCALL4 HYPERCALL_SIMPLE
+#define HYPERCALL5 HYPERCALL_SIMPLE
+
+    .text
+
+HYPERCALL2(xen_version);
+HYPERCALL3(console_io);
+HYPERCALL3(grant_table_op);
+HYPERCALL2(sched_op);
+HYPERCALL2(event_channel_op);
+HYPERCALL2(hvm_op);
+HYPERCALL2(memory_op);
+HYPERCALL2(physdev_op);
+HYPERCALL3(vcpu_op);
+HYPERCALL1(platform_op_raw);
+HYPERCALL2(multicall);
+HYPERCALL2(vm_assist);
+HYPERCALL3(dm_op);
+
+SYM_FUNC_START(privcmd_call)
+    mv a6, a0
+    li a7, SBI_ECALL
+    mv a5, a4;
+    mv a4, a3;
+    mv a3, a2;
+    mv a2, a1;
+    mv a1, a0;
+    li a0, 0;
+    ecall
+    ret
+SYM_FUNC_END(privcmd_call);
diff --git a/arch/riscv/xen/p2m.c b/arch/riscv/xen/p2m.c
new file mode 100644
index 000000000000..7ce75e52d7c4
--- /dev/null
+++ b/arch/riscv/xen/p2m.c
@@ -0,0 +1,76 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/memblock.h>
+#include <linux/gfp.h>
+#include <linux/export.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/dma-mapping.h>
+#include <linux/vmalloc.h>
+#include <linux/swiotlb.h>
+
+#include <xen/xen.h>
+#include <xen/interface/memory.h>
+#include <xen/grant_table.h>
+#include <xen/page.h>
+#include <xen/swiotlb-xen.h>
+
+#include <asm/cacheflush.h>
+#include <asm/xen/hypercall.h>
+#include <asm/xen/interface.h>
+
+struct xen_p2m_entry {
+	unsigned long pfn;
+	unsigned long mfn;
+	unsigned long nr_pages;
+	struct rb_node rbnode_phys;
+};
+
+static rwlock_t p2m_lock;
+struct rb_root phys_to_mach = RB_ROOT;
+EXPORT_SYMBOL_GPL(phys_to_mach);
+
+static int xen_add_phys_to_mach_entry(struct xen_p2m_entry *new)
+{
+
+	return 0;
+}
+
+unsigned long __pfn_to_mfn(unsigned long pfn)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(__pfn_to_mfn);
+
+int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
+					struct gnttab_map_grant_ref *kmap_ops,
+					struct page **pages, unsigned int count)
+{
+	return 0;
+}
+
+int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
+					struct gnttab_unmap_grant_ref *kunmap_ops,
+					struct page **pages, unsigned int count)
+{
+	return 0;
+}
+
+bool __set_phys_to_machine_multi(unsigned long pfn,
+					unsigned long mfn, unsigned long nr_pages)
+{
+	return true;
+}
+EXPORT_SYMBOL_GPL(__set_phys_to_machine_multi);
+
+bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
+{
+	return true;
+}
+EXPORT_SYMBOL_GPL(__set_phys_to_machine);
+
+static int p2m_init(void)
+{
+	return 0;
+}
+arch_initcall(p2m_init);
diff --git a/include/xen/interface/io/protocols.h b/include/xen/interface/io/protocols.h
index 22099bb4079f..6c6317462be0 100644
--- a/include/xen/interface/io/protocols.h
+++ b/include/xen/interface/io/protocols.h
@@ -6,6 +6,7 @@ 
 #define XEN_IO_PROTO_ABI_X86_64     "x86_64-abi"
 #define XEN_IO_PROTO_ABI_POWERPC64  "powerpc64-abi"
 #define XEN_IO_PROTO_ABI_ARM        "arm-abi"
+#define XEN_IO_PROTO_ABI_RISCV      "riscv-abi"

 #if defined(__i386__)
 # define XEN_IO_PROTO_ABI_NATIVE XEN_IO_PROTO_ABI_X86_32
@@ -15,6 +16,8 @@ 
 # define XEN_IO_PROTO_ABI_NATIVE XEN_IO_PROTO_ABI_POWERPC64
 #elif defined(__arm__) || defined(__aarch64__)
 # define XEN_IO_PROTO_ABI_NATIVE XEN_IO_PROTO_ABI_ARM
+#elif defined(__riscv)
+# define XEN_IO_PROTO_ABI_NATIVE XEN_IO_PROTO_ABI_RISCV
 #else
 # error arch fixup needed here
 #endif
diff --git a/include/xen/riscv/hypercall.h b/include/xen/riscv/hypercall.h
new file mode 100644
index 000000000000..f76d8a018f26
--- /dev/null
+++ b/include/xen/riscv/hypercall.h
@@ -0,0 +1,71 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+/******************************************************************************
+ * hypercall.h
+ *
+ * Linux-specific hypervisor handling.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#ifndef _ASM_RISCV_XEN_HYPERCALL_H
+#define _ASM_RISCV_XEN_HYPERCALL_H
+
+#include <linux/bug.h>
+
+#include <xen/interface/xen.h>
+#include <xen/interface/sched.h>
+#include <xen/interface/platform.h>
+
+struct xen_dm_op_buf;
+
+long privcmd_call(unsigned int call, unsigned long a1,
+		unsigned long a2, unsigned long a3,
+		unsigned long a4, unsigned long a5);
+int HYPERVISOR_xen_version(int cmd, void *arg);
+int HYPERVISOR_console_io(int cmd, int count, char *str);
+int HYPERVISOR_grant_table_op(unsigned int cmd, void *uop, unsigned int count);
+int HYPERVISOR_sched_op(int cmd, void *arg);
+int HYPERVISOR_event_channel_op(int cmd, void *arg);
+unsigned long HYPERVISOR_hvm_op(int op, void *arg);
+int HYPERVISOR_memory_op(unsigned int cmd, void *arg);
+int HYPERVISOR_physdev_op(int cmd, void *arg);
+int HYPERVISOR_vcpu_op(int cmd, int vcpuid, void *extra_args);
+int HYPERVISOR_vm_assist(unsigned int cmd, unsigned int type);
+int HYPERVISOR_dm_op(domid_t domid, unsigned int nr_bufs,
+			 struct xen_dm_op_buf *bufs);
+int HYPERVISOR_platform_op_raw(void *arg);
+static inline int HYPERVISOR_platform_op(struct xen_platform_op *op)
+{
+	return 0;
+}
+int HYPERVISOR_multicall(struct multicall_entry *calls, uint32_t nr);
+
+static inline int
+HYPERVISOR_suspend(unsigned long start_info_mfn)
+{
+	return 0;
+}
+
+#endif /* _ASM_RISCV_XEN_HYPERCALL_H */
diff --git a/include/xen/riscv/hypervisor.h b/include/xen/riscv/hypervisor.h
new file mode 100644
index 000000000000..2c1f9625be80
--- /dev/null
+++ b/include/xen/riscv/hypervisor.h
@@ -0,0 +1,26 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_RISCV_XEN_HYPERVISOR_H
+#define _ASM_RISCV_XEN_HYPERVISOR_H
+
+#include <linux/init.h>
+
+extern struct shared_info *HYPERVISOR_shared_info;
+extern struct start_info *xen_start_info;
+
+#ifdef CONFIG_XEN
+void __init xen_early_init(void);
+#else
+static inline void xen_early_init(void) { return; }
+#endif
+
+#ifdef CONFIG_HOTPLUG_CPU
+static inline void xen_arch_register_cpu(int num)
+{
+}
+
+static inline void xen_arch_unregister_cpu(int num)
+{
+}
+#endif
+
+#endif /* _ASM_RISCV_XEN_HYPERVISOR_H */
diff --git a/include/xen/riscv/interface.h b/include/xen/riscv/interface.h
new file mode 100644
index 000000000000..6769b5b39cba
--- /dev/null
+++ b/include/xen/riscv/interface.h
@@ -0,0 +1,85 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+/******************************************************************************
+ * Guest OS interface to RISCV Xen.
+ *
+ */
+
+#ifndef _ASM_RISCV_XEN_INTERFACE_H
+#define _ASM_RISCV_XEN_INTERFACE_H
+
+#include <linux/types.h>
+
+#define uint64_aligned_t uint64_t __aligned(8)
+
+#define __DEFINE_GUEST_HANDLE(name, type) \
+	typedef struct { union { type * p; uint64_aligned_t q; }; }  \
+		__guest_handle_ ## name
+
+#define DEFINE_GUEST_HANDLE_STRUCT(name) \
+	__DEFINE_GUEST_HANDLE(name, struct name)
+#define DEFINE_GUEST_HANDLE(name) __DEFINE_GUEST_HANDLE(name, name)
+#define GUEST_HANDLE(name)        __guest_handle_ ## name
+
+#define set_xen_guest_handle(hnd, val)			\
+	do {						\
+		if (sizeof(hnd) == 8)			\
+			*(uint64_t *)&(hnd) = 0;	\
+		(hnd).p = val;				\
+	} while (0)
+
+#define __HYPERVISOR_platform_op_raw __HYPERVISOR_platform_op
+
+#ifndef __ASSEMBLY__
+/* Explicitly size integers that represent pfns in the interface with
+ * Xen so that we can have one ABI that works for 32 and 64 bit guests.
+ * Note that this means that the xen_pfn_t type may be capable of
+ * representing pfn's which the guest cannot represent in its own pfn
+ * type. However since pfn space is controlled by the guest this is
+ * fine since it simply wouldn't be able to create any sure pfns in
+ * the first place.
+ */
+typedef uint64_t xen_pfn_t;
+#define PRI_xen_pfn "llx"
+typedef uint64_t xen_ulong_t;
+#define PRI_xen_ulong "llx"
+typedef int64_t xen_long_t;
+#define PRI_xen_long "llx"
+/* Guest handles for primitive C types. */
+__DEFINE_GUEST_HANDLE(uchar, unsigned char);
+__DEFINE_GUEST_HANDLE(uint,  unsigned int);
+DEFINE_GUEST_HANDLE(char);
+DEFINE_GUEST_HANDLE(int);
+DEFINE_GUEST_HANDLE(void);
+DEFINE_GUEST_HANDLE(uint64_t);
+DEFINE_GUEST_HANDLE(uint32_t);
+DEFINE_GUEST_HANDLE(xen_pfn_t);
+DEFINE_GUEST_HANDLE(xen_ulong_t);
+
+/* Maximum number of virtual CPUs in multi-processor guests. */
+#define MAX_VIRT_CPUS 1
+
+struct arch_vcpu_info { };
+struct arch_shared_info { };
+
+/* TODO: Move pvclock definitions some place arch independent */
+struct pvclock_vcpu_time_info {
+	u32   version;
+	u32   pad0;
+	u64   tsc_timestamp;
+	u64   system_time;
+	u32   tsc_to_system_mul;
+	s8    tsc_shift;
+	u8    flags;
+	u8    pad[2];
+} __packed; /* 32 bytes */
+
+/* It is OK to have a 12 bytes struct with no padding because it is packed */
+struct pvclock_wall_clock {
+	u32   version;
+	u32   sec;
+	u32   nsec;
+	u32   sec_hi;
+} __packed;
+#endif
+
+#endif /* _ASM_RISCV_XEN_INTERFACE_H */
diff --git a/include/xen/riscv/page.h b/include/xen/riscv/page.h
new file mode 100644
index 000000000000..fe07a9bffa7e
--- /dev/null
+++ b/include/xen/riscv/page.h
@@ -0,0 +1,106 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_RISCV_XEN_PAGE_H
+#define _ASM_RISCV_XEN_PAGE_H
+
+#include <asm/page.h>
+
+#include <linux/pfn.h>
+#include <linux/types.h>
+#include <linux/dma-mapping.h>
+#include <linux/pgtable.h>
+
+#include <xen/xen.h>
+#include <xen/interface/grant_table.h>
+
+/* Xen machine address */
+struct xmaddr {
+	phys_addr_t maddr;
+};
+
+/* Xen pseudo-physical address */
+struct xpaddr {
+	phys_addr_t paddr;
+};
+
+#define XMADDR(x)	((struct xmaddr) { .maddr = (x) })
+#define XPADDR(x)	((struct xpaddr) { .paddr = (x) })
+
+#define INVALID_P2M_ENTRY      (~0UL)
+
+/*
+ * The pseudo-physical frame (pfn) used in all the helpers is always based
+ * on Xen page granularity (i.e 4KB).
+ *
+ * A Linux page may be split across multiple non-contiguous Xen page so we
+ * have to keep track with frame based on 4KB page granularity.
+ *
+ * PV drivers should never make a direct usage of those helpers (particularly
+ * pfn_to_gfn and gfn_to_pfn).
+ */
+
+unsigned long __pfn_to_mfn(unsigned long pfn);
+extern struct rb_root phys_to_mach;
+
+/* Pseudo-physical <-> Guest conversion */
+static inline unsigned long pfn_to_gfn(unsigned long pfn)
+{
+	return 0;
+}
+
+static inline unsigned long gfn_to_pfn(unsigned long gfn)
+{
+	return 0;
+}
+
+/* Pseudo-physical <-> BUS conversion */
+static inline unsigned long pfn_to_bfn(unsigned long pfn)
+{
+	return 0;
+}
+
+static inline unsigned long bfn_to_pfn(unsigned long bfn)
+{
+	return 0;
+}
+
+#define bfn_to_local_pfn(bfn)	bfn_to_pfn(bfn)
+
+/* VIRT <-> GUEST conversion */
+#define virt_to_gfn(v)                                                         \
+	({                                                                     \
+		WARN_ON_ONCE(!virt_addr_valid(v));                              \
+		pfn_to_gfn(virt_to_phys(v) >> XEN_PAGE_SHIFT);                 \
+	})
+#define gfn_to_virt(m)		(__va(gfn_to_pfn(m) << XEN_PAGE_SHIFT))
+
+#define percpu_to_gfn(v)	\
+	(pfn_to_gfn(per_cpu_ptr_to_phys(v) >> XEN_PAGE_SHIFT))
+
+static inline struct xmaddr arbitrary_virt_to_machine(void *vaddr)
+{
+	WARN_ON_ONCE(1);
+	return (struct xmaddr){0};
+}
+
+extern int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
+				   struct gnttab_map_grant_ref *kmap_ops,
+				   struct page **pages, unsigned int count);
+
+extern int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
+					 struct gnttab_unmap_grant_ref *kunmap_ops,
+					 struct page **pages, unsigned int count);
+
+bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn);
+bool __set_phys_to_machine_multi(unsigned long pfn, unsigned long mfn,
+		unsigned long nr_pages);
+
+static inline bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
+{
+	return 0;
+}
+
+bool xen_arch_need_swiotlb(struct device *dev,
+			   phys_addr_t phys,
+			   dma_addr_t dev_addr);
+
+#endif /* _ASM_RISCV_XEN_PAGE_H */
diff --git a/include/xen/riscv/swiotlb-xen.h b/include/xen/riscv/swiotlb-xen.h
new file mode 100644
index 000000000000..97ecd8cbbc2d
--- /dev/null
+++ b/include/xen/riscv/swiotlb-xen.h
@@ -0,0 +1,13 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_RISCV_SWIOTLB_XEN_H
+#define _ASM_RISCV_SWIOTLB_XEN_H
+
+#include <xen/features.h>
+#include <xen/xen.h>
+
+static inline int xen_swiotlb_detect(void)
+{
+	return 0;
+}
+
+#endif /* _ASM_RISCV_SWIOTLB_XEN_H */
diff --git a/test.txt b/test.txt
new file mode 100644
index 000000000000..e54267998982
--- /dev/null
+++ b/test.txt
@@ -0,0 +1,21 @@ 
+WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
+#120:
+new file mode 100644
+
+WARNING: do not add new typedefs
+#808: FILE: include/xen/riscv/interface.h:15:
++	typedef struct { union { type * p; uint64_aligned_t q; }; }  \
+
+WARNING: please, no spaces at the start of a line
+#1006: FILE: include/xen/riscv/swiotlb-xen.h:10:
++    return 0;$
+
+total: 0 errors, 3 warnings, 810 lines checked
+
+NOTE: For some of the reported defects, checkpatch may be able to
+      mechanically convert to the typical style using --fix or --fix-inplace.
+
+0001-riscv-Add-initial-Xen-guest-support-for-RISC-V.patch has style problems, please review.
+
+NOTE: If any of the errors are false positives, please report
+      them to the maintainer, see CHECKPATCH in MAINTAINERS.