| Message ID | 20210108121524.656872-14-qperret@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM/arm64: A stage 2 for the host | expand |
Hi Quentin, On 2021-01-08 12:15, Quentin Perret wrote: > Introduce the infrastructure in KVM enabling to copy CPU feature > registers into EL2-owned data-structures, to allow reading sanitised > values directly at EL2 in nVHE. > > Given that only a subset of these features are being read by the > hypervisor, the ones that need to be copied are to be listed under > <asm/kvm_cpufeature.h> together with the name of the nVHE variable that > will hold the copy. > > While at it, introduce the first user of this infrastructure by > implementing __flush_dcache_area at EL2, which needs > arm64_ftr_reg_ctrel0. > > Signed-off-by: Quentin Perret <qperret@google.com> > --- > arch/arm64/include/asm/cpufeature.h | 1 + > arch/arm64/include/asm/kvm_cpufeature.h | 17 ++++++++++++++ > arch/arm64/kernel/cpufeature.c | 12 ++++++++++ > arch/arm64/kvm/arm.c | 31 +++++++++++++++++++++++++ > arch/arm64/kvm/hyp/nvhe/Makefile | 3 ++- > arch/arm64/kvm/hyp/nvhe/cache.S | 13 +++++++++++ > arch/arm64/kvm/hyp/nvhe/cpufeature.c | 8 +++++++ > 7 files changed, 84 insertions(+), 1 deletion(-) > create mode 100644 arch/arm64/include/asm/kvm_cpufeature.h > create mode 100644 arch/arm64/kvm/hyp/nvhe/cache.S > create mode 100644 arch/arm64/kvm/hyp/nvhe/cpufeature.c > > diff --git a/arch/arm64/include/asm/cpufeature.h > b/arch/arm64/include/asm/cpufeature.h > index 16063c813dcd..742e9bcc051b 100644 > --- a/arch/arm64/include/asm/cpufeature.h > +++ b/arch/arm64/include/asm/cpufeature.h > @@ -600,6 +600,7 @@ void __init setup_cpu_features(void); > void check_local_cpu_capabilities(void); > > u64 read_sanitised_ftr_reg(u32 id); > +int copy_ftr_reg(u32 id, struct arm64_ftr_reg *dst); > > static inline bool cpu_supports_mixed_endian_el0(void) > { > diff --git a/arch/arm64/include/asm/kvm_cpufeature.h > b/arch/arm64/include/asm/kvm_cpufeature.h > new file mode 100644 > index 000000000000..d34f85cba358 > --- /dev/null > +++ b/arch/arm64/include/asm/kvm_cpufeature.h > @@ -0,0 +1,17 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > +/* > + * Copyright (C) 2020 - Google LLC > + * Author: Quentin Perret <qperret@google.com> > + */ > + > +#include <asm/cpufeature.h> > + > +#ifndef KVM_HYP_CPU_FTR_REG > +#if defined(__KVM_NVHE_HYPERVISOR__) > +#define KVM_HYP_CPU_FTR_REG(id, name) extern struct arm64_ftr_reg > name; > +#else > +#define KVM_HYP_CPU_FTR_REG(id, name) DECLARE_KVM_NVHE_SYM(name); > +#endif > +#endif > + > +KVM_HYP_CPU_FTR_REG(SYS_CTR_EL0, arm64_ftr_reg_ctrel0) > diff --git a/arch/arm64/kernel/cpufeature.c > b/arch/arm64/kernel/cpufeature.c > index bc3549663957..c2019aaaadc3 100644 > --- a/arch/arm64/kernel/cpufeature.c > +++ b/arch/arm64/kernel/cpufeature.c > @@ -1113,6 +1113,18 @@ u64 read_sanitised_ftr_reg(u32 id) > } > EXPORT_SYMBOL_GPL(read_sanitised_ftr_reg); > > +int copy_ftr_reg(u32 id, struct arm64_ftr_reg *dst) > +{ > + struct arm64_ftr_reg *regp = get_arm64_ftr_reg(id); > + > + if (!regp) > + return -EINVAL; > + > + memcpy(dst, regp, sizeof(*regp)); > + > + return 0; > +} > + > #define read_sysreg_case(r) \ > case r: return read_sysreg_s(r) > > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c > index 51b53ca36dc5..9fd769349e9e 100644 > --- a/arch/arm64/kvm/arm.c > +++ b/arch/arm64/kvm/arm.c > @@ -34,6 +34,7 @@ > #include <asm/virt.h> > #include <asm/kvm_arm.h> > #include <asm/kvm_asm.h> > +#include <asm/kvm_cpufeature.h> > #include <asm/kvm_mmu.h> > #include <asm/kvm_emulate.h> > #include <asm/sections.h> > @@ -1697,6 +1698,29 @@ static void teardown_hyp_mode(void) > } > } > > +#undef KVM_HYP_CPU_FTR_REG > +#define KVM_HYP_CPU_FTR_REG(id, name) \ > + { .sys_id = id, .dst = (struct arm64_ftr_reg *)&kvm_nvhe_sym(name) }, > +static const struct __ftr_reg_copy_entry { > + u32 sys_id; > + struct arm64_ftr_reg *dst; Why do we need the whole data structure? Can't we just live with sys_val? > +} hyp_ftr_regs[] = { > + #include <asm/kvm_cpufeature.h> > +}; Can't this be made __initdata? > + > +static int copy_cpu_ftr_regs(void) > +{ > + int i, ret; > + > + for (i = 0; i < ARRAY_SIZE(hyp_ftr_regs); i++) { > + ret = copy_ftr_reg(hyp_ftr_regs[i].sys_id, hyp_ftr_regs[i].dst); > + if (ret) > + return ret; > + } > + > + return 0; > +} > + > /** > * Inits Hyp-mode on all online CPUs > */ > @@ -1705,6 +1729,13 @@ static int init_hyp_mode(void) > int cpu; > int err = 0; > > + /* > + * Copy the required CPU feature register in their EL2 counterpart > + */ > + err = copy_cpu_ftr_regs(); > + if (err) > + return err; > + Just to keep things together, please move any sysreg manipulation into sys_regs.c, most probably into kvm_sys_reg_table_init(). Thanks, M.
Hey Marc, On Wednesday 13 Jan 2021 at 11:33:13 (+0000), Marc Zyngier wrote: > > +#undef KVM_HYP_CPU_FTR_REG > > +#define KVM_HYP_CPU_FTR_REG(id, name) \ > > + { .sys_id = id, .dst = (struct arm64_ftr_reg *)&kvm_nvhe_sym(name) }, > > +static const struct __ftr_reg_copy_entry { > > + u32 sys_id; > > + struct arm64_ftr_reg *dst; > > Why do we need the whole data structure? Can't we just live with sys_val? I don't have a use-case for anything else than sys_val, so yes I think I should be able to simplify. I'll try that for v3. > > > +} hyp_ftr_regs[] = { > > + #include <asm/kvm_cpufeature.h> > > +}; > > Can't this be made __initdata? Good point, that would be nice indeed. Can I use that from outside an __init function? If not, I'll need to rework the code a bit more, but that should be simple enough either way. > > + > > +static int copy_cpu_ftr_regs(void) > > +{ > > + int i, ret; > > + > > + for (i = 0; i < ARRAY_SIZE(hyp_ftr_regs); i++) { > > + ret = copy_ftr_reg(hyp_ftr_regs[i].sys_id, hyp_ftr_regs[i].dst); > > + if (ret) > > + return ret; > > + } > > + > > + return 0; > > +} > > + > > /** > > * Inits Hyp-mode on all online CPUs > > */ > > @@ -1705,6 +1729,13 @@ static int init_hyp_mode(void) > > int cpu; > > int err = 0; > > > > + /* > > + * Copy the required CPU feature register in their EL2 counterpart > > + */ > > + err = copy_cpu_ftr_regs(); > > + if (err) > > + return err; > > + > > Just to keep things together, please move any sysreg manipulation into > sys_regs.c, most probably into kvm_sys_reg_table_init(). Will do. Thanks, Quentin
On Wednesday 13 Jan 2021 at 14:23:03 (+0000), Quentin Perret wrote: > Good point, that would be nice indeed. Can I use that from outside an > __init function? Just gave it a go, and the answer to this appears to be yes, surprisingly -- I was expecting a compile-time warning similar to what we get when non-__init code calls into __init, but that doesn't seem to trigger here. Anyways, I'll add the annotation in v3. Thanks, Quentin
On 2021-01-13 14:35, Quentin Perret wrote: > On Wednesday 13 Jan 2021 at 14:23:03 (+0000), Quentin Perret wrote: >> Good point, that would be nice indeed. Can I use that from outside an >> __init function? > > Just gave it a go, and the answer to this appears to be yes, > surprisingly -- I was expecting a compile-time warning similar to what > we get when non-__init code calls into __init, but that doesn't seem to > trigger here. Anyways, I'll add the annotation in v3. That's surprising. I'd definitely expect something to explode... Do you have CONFIG_DEBUG_SECTION_MISMATCH=y? M.
On Wednesday 13 Jan 2021 at 17:27:49 (+0000), Marc Zyngier wrote: > On 2021-01-13 14:35, Quentin Perret wrote: > > On Wednesday 13 Jan 2021 at 14:23:03 (+0000), Quentin Perret wrote: > > > Good point, that would be nice indeed. Can I use that from outside an > > > __init function? > > > > Just gave it a go, and the answer to this appears to be yes, > > surprisingly -- I was expecting a compile-time warning similar to what > > we get when non-__init code calls into __init, but that doesn't seem to > > trigger here. Anyways, I'll add the annotation in v3. > > That's surprising. I'd definitely expect something to explode... > Do you have CONFIG_DEBUG_SECTION_MISMATCH=y? Yes I do, so, that doesn't seem to be it. Now, the plot thickens: I _do_ get a warning if I remove the 'const' qualifier. But interestingly, in both cases hyp_ftr_regs is placed in .init.data: $ objdump -t vmlinux | grep hyp_ftr_regs ffff8000116c17b0 g O .init.data 0000000000000030 hyp_ftr_regs The warning is silenced only if I mark hyp_ftr_regs as const. modpost bug? I'll double check my findings and follow up in a separate series. Thanks, Quentin
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index 16063c813dcd..742e9bcc051b 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -600,6 +600,7 @@ void __init setup_cpu_features(void); void check_local_cpu_capabilities(void); u64 read_sanitised_ftr_reg(u32 id); +int copy_ftr_reg(u32 id, struct arm64_ftr_reg *dst); static inline bool cpu_supports_mixed_endian_el0(void) { diff --git a/arch/arm64/include/asm/kvm_cpufeature.h b/arch/arm64/include/asm/kvm_cpufeature.h new file mode 100644 index 000000000000..d34f85cba358 --- /dev/null +++ b/arch/arm64/include/asm/kvm_cpufeature.h @@ -0,0 +1,17 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2020 - Google LLC + * Author: Quentin Perret <qperret@google.com> + */ + +#include <asm/cpufeature.h> + +#ifndef KVM_HYP_CPU_FTR_REG +#if defined(__KVM_NVHE_HYPERVISOR__) +#define KVM_HYP_CPU_FTR_REG(id, name) extern struct arm64_ftr_reg name; +#else +#define KVM_HYP_CPU_FTR_REG(id, name) DECLARE_KVM_NVHE_SYM(name); +#endif +#endif + +KVM_HYP_CPU_FTR_REG(SYS_CTR_EL0, arm64_ftr_reg_ctrel0) diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index bc3549663957..c2019aaaadc3 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1113,6 +1113,18 @@ u64 read_sanitised_ftr_reg(u32 id) } EXPORT_SYMBOL_GPL(read_sanitised_ftr_reg); +int copy_ftr_reg(u32 id, struct arm64_ftr_reg *dst) +{ + struct arm64_ftr_reg *regp = get_arm64_ftr_reg(id); + + if (!regp) + return -EINVAL; + + memcpy(dst, regp, sizeof(*regp)); + + return 0; +} + #define read_sysreg_case(r) \ case r: return read_sysreg_s(r) diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 51b53ca36dc5..9fd769349e9e 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -34,6 +34,7 @@ #include <asm/virt.h> #include <asm/kvm_arm.h> #include <asm/kvm_asm.h> +#include <asm/kvm_cpufeature.h> #include <asm/kvm_mmu.h> #include <asm/kvm_emulate.h> #include <asm/sections.h> @@ -1697,6 +1698,29 @@ static void teardown_hyp_mode(void) } } +#undef KVM_HYP_CPU_FTR_REG +#define KVM_HYP_CPU_FTR_REG(id, name) \ + { .sys_id = id, .dst = (struct arm64_ftr_reg *)&kvm_nvhe_sym(name) }, +static const struct __ftr_reg_copy_entry { + u32 sys_id; + struct arm64_ftr_reg *dst; +} hyp_ftr_regs[] = { + #include <asm/kvm_cpufeature.h> +}; + +static int copy_cpu_ftr_regs(void) +{ + int i, ret; + + for (i = 0; i < ARRAY_SIZE(hyp_ftr_regs); i++) { + ret = copy_ftr_reg(hyp_ftr_regs[i].sys_id, hyp_ftr_regs[i].dst); + if (ret) + return ret; + } + + return 0; +} + /** * Inits Hyp-mode on all online CPUs */ @@ -1705,6 +1729,13 @@ static int init_hyp_mode(void) int cpu; int err = 0; + /* + * Copy the required CPU feature register in their EL2 counterpart + */ + err = copy_cpu_ftr_regs(); + if (err) + return err; + /* * Allocate Hyp PGD and setup Hyp identity mapping */ diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile index 9e5eacfec6ec..72cfe53f106f 100644 --- a/arch/arm64/kvm/hyp/nvhe/Makefile +++ b/arch/arm64/kvm/hyp/nvhe/Makefile @@ -10,7 +10,8 @@ lib-objs := clear_page.o copy_page.o memcpy.o memset.o lib-objs := $(addprefix ../../../lib/, $(lib-objs)) obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \ - hyp-main.o hyp-smp.o psci-relay.o early_alloc.o stub.o page_alloc.o + hyp-main.o hyp-smp.o psci-relay.o early_alloc.o stub.o page_alloc.o \ + cache.o cpufeature.o obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \ ../fpsimd.o ../hyp-entry.o ../exception.o obj-y += $(lib-objs) diff --git a/arch/arm64/kvm/hyp/nvhe/cache.S b/arch/arm64/kvm/hyp/nvhe/cache.S new file mode 100644 index 000000000000..36cef6915428 --- /dev/null +++ b/arch/arm64/kvm/hyp/nvhe/cache.S @@ -0,0 +1,13 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Code copied from arch/arm64/mm/cache.S. + */ + +#include <linux/linkage.h> +#include <asm/assembler.h> +#include <asm/alternative.h> + +SYM_FUNC_START_PI(__flush_dcache_area) + dcache_by_line_op civac, sy, x0, x1, x2, x3 + ret +SYM_FUNC_END_PI(__flush_dcache_area) diff --git a/arch/arm64/kvm/hyp/nvhe/cpufeature.c b/arch/arm64/kvm/hyp/nvhe/cpufeature.c new file mode 100644 index 000000000000..a887508f996f --- /dev/null +++ b/arch/arm64/kvm/hyp/nvhe/cpufeature.c @@ -0,0 +1,8 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2020 - Google LLC + * Author: Quentin Perret <qperret@google.com> + */ + +#define KVM_HYP_CPU_FTR_REG(id, name) struct arm64_ftr_reg name; +#include <asm/kvm_cpufeature.h>
Introduce the infrastructure in KVM enabling to copy CPU feature registers into EL2-owned data-structures, to allow reading sanitised values directly at EL2 in nVHE. Given that only a subset of these features are being read by the hypervisor, the ones that need to be copied are to be listed under <asm/kvm_cpufeature.h> together with the name of the nVHE variable that will hold the copy. While at it, introduce the first user of this infrastructure by implementing __flush_dcache_area at EL2, which needs arm64_ftr_reg_ctrel0. Signed-off-by: Quentin Perret <qperret@google.com> --- arch/arm64/include/asm/cpufeature.h | 1 + arch/arm64/include/asm/kvm_cpufeature.h | 17 ++++++++++++++ arch/arm64/kernel/cpufeature.c | 12 ++++++++++ arch/arm64/kvm/arm.c | 31 +++++++++++++++++++++++++ arch/arm64/kvm/hyp/nvhe/Makefile | 3 ++- arch/arm64/kvm/hyp/nvhe/cache.S | 13 +++++++++++ arch/arm64/kvm/hyp/nvhe/cpufeature.c | 8 +++++++ 7 files changed, 84 insertions(+), 1 deletion(-) create mode 100644 arch/arm64/include/asm/kvm_cpufeature.h create mode 100644 arch/arm64/kvm/hyp/nvhe/cache.S create mode 100644 arch/arm64/kvm/hyp/nvhe/cpufeature.c