| Message ID | 20200214123430.4942-4-liuwe@microsoft.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Xen on Hyper-V: Implement L0 assisted TLB flush | expand |
On Fri, Feb 14, 2020 at 12:34:30PM +0000, Wei Liu wrote: > Implement L0 assisted TLB flush for Xen on Hyper-V. It takes advantage > of several hypercalls: > > * HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST > * HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX > * HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE > * HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX > > Pick the most efficient hypercalls available. > > Signed-off-by: Wei Liu <liuwe@microsoft.com> Thanks! LGTM, I've just got a couple of comments below. > --- > v2: > 1. Address Roger and Jan's comments re types etc. > 2. Fix pointer arithmetic. > 3. Misc improvement to code. > --- > xen/arch/x86/guest/hyperv/Makefile | 1 + > xen/arch/x86/guest/hyperv/private.h | 9 ++ > xen/arch/x86/guest/hyperv/tlb.c | 172 +++++++++++++++++++++++++++- > xen/arch/x86/guest/hyperv/util.c | 74 ++++++++++++ > 4 files changed, 255 insertions(+), 1 deletion(-) > create mode 100644 xen/arch/x86/guest/hyperv/util.c > > diff --git a/xen/arch/x86/guest/hyperv/Makefile b/xen/arch/x86/guest/hyperv/Makefile > index 18902c33e9..0e39410968 100644 > --- a/xen/arch/x86/guest/hyperv/Makefile > +++ b/xen/arch/x86/guest/hyperv/Makefile > @@ -1,2 +1,3 @@ > obj-y += hyperv.o > obj-y += tlb.o > +obj-y += util.o > diff --git a/xen/arch/x86/guest/hyperv/private.h b/xen/arch/x86/guest/hyperv/private.h > index 509bedaafa..79a77930a0 100644 > --- a/xen/arch/x86/guest/hyperv/private.h > +++ b/xen/arch/x86/guest/hyperv/private.h > @@ -24,12 +24,21 @@ > > #include <xen/cpumask.h> > #include <xen/percpu.h> > +#include <xen/types.h> > > DECLARE_PER_CPU(void *, hv_input_page); > DECLARE_PER_CPU(void *, hv_vp_assist); > DECLARE_PER_CPU(unsigned int, hv_vp_index); > > +static inline unsigned int hv_vp_index(unsigned int cpu) > +{ > + return per_cpu(hv_vp_index, cpu); > +} > + > int hyperv_flush_tlb(const cpumask_t *mask, const void *va, > unsigned int flags); > > +/* Returns number of banks, -ev if error */ > +int cpumask_to_vpset(struct hv_vpset *vpset, const cpumask_t *mask); > + > #endif /* __XEN_HYPERV_PRIVIATE_H__ */ > diff --git a/xen/arch/x86/guest/hyperv/tlb.c b/xen/arch/x86/guest/hyperv/tlb.c > index 48f527229e..f68e14f151 100644 > --- a/xen/arch/x86/guest/hyperv/tlb.c > +++ b/xen/arch/x86/guest/hyperv/tlb.c > @@ -19,15 +19,185 @@ > * Copyright (c) 2020 Microsoft. > */ > > +#include <xen/cpu.h> > #include <xen/cpumask.h> > #include <xen/errno.h> > > +#include <asm/guest/hyperv.h> > +#include <asm/guest/hyperv-hcall.h> > +#include <asm/guest/hyperv-tlfs.h> > + > #include "private.h" > > +/* > + * It is possible to encode up to 4096 pages using the lower 12 bits > + * in an element of gva_list > + */ > +#define HV_TLB_FLUSH_UNIT (4096 * PAGE_SIZE) > + > +static unsigned int fill_gva_list(uint64_t *gva_list, const void *va, > + unsigned int order) > +{ > + unsigned long start = (unsigned long)va; > + unsigned long end = start + (PAGE_SIZE << order) - 1; > + unsigned int n = 0; > + > + do { > + unsigned long remain = end - start; > + > + gva_list[n] = start & PAGE_MASK; > + > + /* > + * Use lower 12 bits to encode the number of additional pages > + * to flush > + */ > + if ( remain >= HV_TLB_FLUSH_UNIT ) > + { > + gva_list[n] |= ~PAGE_MASK; > + start += HV_TLB_FLUSH_UNIT; > + } > + else if ( remain ) remain is always going to be > 0, since the loop condition is end > start, and hence this can be a plain else. > + { > + gva_list[n] |= (remain - 1) >> PAGE_SHIFT; > + start = end; > + } > + > + n++; > + } while ( start < end ); > + > + return n; > +} > + > +static uint64_t flush_tlb_ex(const cpumask_t *mask, const void *va, > + unsigned int flags) > +{ > + struct hv_tlb_flush_ex *flush = this_cpu(hv_input_page); > + int nr_banks; > + unsigned int max_gvas, order = flags & FLUSH_ORDER_MASK; > + uint64_t ret; > + > + if ( !flush || local_irq_is_enabled() ) > + { > + ASSERT_UNREACHABLE(); > + return ~0ULL; > + } > + > + if ( !(ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED) ) > + return ~0ULL; > + > + flush->address_space = 0; > + flush->flags = HV_FLUSH_ALL_VIRTUAL_ADDRESS_SPACES; > + if ( !(flags & FLUSH_TLB_GLOBAL) ) > + flush->flags |= HV_FLUSH_NON_GLOBAL_MAPPINGS_ONLY; > + > + nr_banks = cpumask_to_vpset(&flush->hv_vp_set, mask); > + if ( nr_banks < 0 ) > + return ~0ULL; It would be nice to propagate the error code from cpumask_to_vpset, but since the function can also return HyperV error codes this doesn't make much sense. > + > + max_gvas = > + (PAGE_SIZE - sizeof(*flush) - nr_banks * > + sizeof(flush->hv_vp_set.bank_contents[0])) / > + sizeof(uint64_t); /* gva is represented as uint64_t */ > + > + /* > + * Flush the entire address space if va is NULL or if there is not > + * enough space for gva_list. > + */ > + if ( !va || (PAGE_SIZE << order) / HV_TLB_FLUSH_UNIT > max_gvas ) > + ret = hv_do_rep_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX, 0, > + nr_banks, virt_to_maddr(flush), 0); You could just return hv_do_rep_hypercall(...); here, which will avoid the else branch below and the indentation. > + else > + { > + uint64_t *gva_list = > + (uint64_t *)flush + sizeof(*flush) / sizeof(uint64_t) + nr_banks; > + unsigned int gvas = fill_gva_list(gva_list, va, order); > + > + BUILD_BUG_ON(sizeof(*flush) % sizeof(uint64_t)); > + > + ret = hv_do_rep_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX, > + gvas, nr_banks, virt_to_maddr(flush), 0); > + } > + > + return ret; > +} > + > int hyperv_flush_tlb(const cpumask_t *mask, const void *va, > unsigned int flags) > { > - return -EOPNOTSUPP; > + unsigned long irq_flags; > + struct hv_tlb_flush *flush = this_cpu(hv_input_page); > + unsigned int max_gvas, order = flags & FLUSH_ORDER_MASK; > + uint64_t ret; > + > + ASSERT(flush); > + ASSERT(!cpumask_empty(mask)); I would also turn this into an if ( ... ) { ASSERT; return -EFOO; } > + > + local_irq_save(irq_flags); > + > + flush->address_space = 0; > + flush->flags = HV_FLUSH_ALL_VIRTUAL_ADDRESS_SPACES; > + flush->processor_mask = 0; > + if ( !(flags & FLUSH_TLB_GLOBAL) ) > + flush->flags |= HV_FLUSH_NON_GLOBAL_MAPPINGS_ONLY; > + > + if ( cpumask_equal(mask, &cpu_online_map) ) > + flush->flags |= HV_FLUSH_ALL_PROCESSORS; > + else > + { > + unsigned int cpu; > + > + /* > + * Normally VP indices are in ascending order and match Xen's > + * idea of CPU ids. Check the last index to see if VP index is > + * >= 64. If so, we can skip setting up parameters for > + * non-applicable hypercalls without looking further. > + */ > + if ( hv_vp_index(cpumask_last(mask)) >= 64 ) > + goto do_ex_hypercall; > + > + for_each_cpu ( cpu, mask ) > + { > + uint32_t vpid = hv_vp_index(cpu); This should be unsigned int now. > + > + if ( vpid > ms_hyperv.max_vp_index ) > + { > + local_irq_restore(irq_flags); > + return -ENXIO; > + } > + > + if ( vpid >= 64 ) > + goto do_ex_hypercall; > + > + __set_bit(vpid, &flush->processor_mask); > + } Would it make sense to abstract this as cpumask_to_processor_mask, since you are adding cpumask_to_vpset below. > + } > + > + max_gvas = (PAGE_SIZE - sizeof(*flush)) / sizeof(flush->gva_list[0]); You could init this at declaration, and make it const static since the value can be calculated at compile time AFAICT. Or create a define with it (HV_TLB_FLUSH_MAX_GVAS?). There's no need to store it on the stack. > + > + /* > + * Flush the entire address space if va is NULL or if there is not > + * enough space for gva_list. > + */ > + if ( !va || (PAGE_SIZE << order) / HV_TLB_FLUSH_UNIT > max_gvas ) > + ret = hv_do_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE, > + virt_to_maddr(flush), 0); > + else > + { > + unsigned int gvas = fill_gva_list(flush->gva_list, va, order); No need for the gvas variable, you can just call fill_gva_list at hv_do_rep_hypercall. > + > + ret = hv_do_rep_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST, gvas, 0, > + virt_to_maddr(flush), 0); > + } > + > + goto done; > + > + do_ex_hypercall: > + ret = flush_tlb_ex(mask, va, flags); > + > + done: > + local_irq_restore(irq_flags); > + > + return ret & HV_HYPERCALL_RESULT_MASK ? -ENXIO : 0; > } > > /* > diff --git a/xen/arch/x86/guest/hyperv/util.c b/xen/arch/x86/guest/hyperv/util.c > new file mode 100644 > index 0000000000..e092593746 > --- /dev/null > +++ b/xen/arch/x86/guest/hyperv/util.c > @@ -0,0 +1,74 @@ > +/****************************************************************************** > + * arch/x86/guest/hyperv/util.c > + * > + * Hyper-V utility functions > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License as published by > + * the Free Software Foundation; either version 2 of the License, or > + * (at your option) any later version. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + * > + * You should have received a copy of the GNU General Public License > + * along with this program; If not, see <http://www.gnu.org/licenses/>. > + * > + * Copyright (c) 2020 Microsoft. > + */ > + > +#include <xen/cpu.h> > +#include <xen/cpumask.h> > +#include <xen/errno.h> > + > +#include <asm/guest/hyperv.h> > +#include <asm/guest/hyperv-tlfs.h> > + > +#include "private.h" > + > +int cpumask_to_vpset(struct hv_vpset *vpset, > + const cpumask_t *mask) > +{ > + int nr = 1; > + unsigned int cpu, vcpu_bank, vcpu_offset; > + unsigned int max_banks = ms_hyperv.max_vp_index / 64; > + > + /* Up to 64 banks can be represented by valid_bank_mask */ > + if ( max_banks >= 64 ) > + return -E2BIG; > + > + /* Clear all banks to avoid flushing unwanted CPUs */ > + for ( vcpu_bank = 0; vcpu_bank <= max_banks; vcpu_bank++ ) I think this is off by one and should be vcpu_bank < max_banks? Or else you are clearing one extra bank. Thanks, Roger.
On Fri, Feb 14, 2020 at 03:42:17PM +0100, Roger Pau Monné wrote: [...] > > #endif /* __XEN_HYPERV_PRIVIATE_H__ */ > > diff --git a/xen/arch/x86/guest/hyperv/tlb.c b/xen/arch/x86/guest/hyperv/tlb.c > > index 48f527229e..f68e14f151 100644 > > --- a/xen/arch/x86/guest/hyperv/tlb.c > > +++ b/xen/arch/x86/guest/hyperv/tlb.c > > @@ -19,15 +19,185 @@ > > * Copyright (c) 2020 Microsoft. > > */ > > > > +#include <xen/cpu.h> > > #include <xen/cpumask.h> > > #include <xen/errno.h> > > > > +#include <asm/guest/hyperv.h> > > +#include <asm/guest/hyperv-hcall.h> > > +#include <asm/guest/hyperv-tlfs.h> > > + > > #include "private.h" > > > > +/* > > + * It is possible to encode up to 4096 pages using the lower 12 bits > > + * in an element of gva_list > > + */ > > +#define HV_TLB_FLUSH_UNIT (4096 * PAGE_SIZE) > > + > > +static unsigned int fill_gva_list(uint64_t *gva_list, const void *va, > > + unsigned int order) > > +{ > > + unsigned long start = (unsigned long)va; > > + unsigned long end = start + (PAGE_SIZE << order) - 1; > > + unsigned int n = 0; > > + > > + do { > > + unsigned long remain = end - start; > > + > > + gva_list[n] = start & PAGE_MASK; > > + > > + /* > > + * Use lower 12 bits to encode the number of additional pages > > + * to flush > > + */ > > + if ( remain >= HV_TLB_FLUSH_UNIT ) > > + { > > + gva_list[n] |= ~PAGE_MASK; > > + start += HV_TLB_FLUSH_UNIT; > > + } > > + else if ( remain ) > > remain is always going to be > 0, since the loop condition is end > > start, and hence this can be a plain else. Ack. > > > + { > > + gva_list[n] |= (remain - 1) >> PAGE_SHIFT; > > + start = end; > > + } > > + > > + n++; > > + } while ( start < end ); > > + > > + return n; > > +} > > + > > +static uint64_t flush_tlb_ex(const cpumask_t *mask, const void *va, > > + unsigned int flags) > > +{ > > + struct hv_tlb_flush_ex *flush = this_cpu(hv_input_page); > > + int nr_banks; > > + unsigned int max_gvas, order = flags & FLUSH_ORDER_MASK; > > + uint64_t ret; > > + > > + if ( !flush || local_irq_is_enabled() ) > > + { > > + ASSERT_UNREACHABLE(); > > + return ~0ULL; > > + } > > + > > + if ( !(ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED) ) > > + return ~0ULL; > > + > > + flush->address_space = 0; > > + flush->flags = HV_FLUSH_ALL_VIRTUAL_ADDRESS_SPACES; > > + if ( !(flags & FLUSH_TLB_GLOBAL) ) > > + flush->flags |= HV_FLUSH_NON_GLOBAL_MAPPINGS_ONLY; > > + > > + nr_banks = cpumask_to_vpset(&flush->hv_vp_set, mask); > > + if ( nr_banks < 0 ) > > + return ~0ULL; > > It would be nice to propagate the error code from cpumask_to_vpset, > but since the function can also return HyperV error codes this doesn't > make much sense. > > > + > > + max_gvas = > > + (PAGE_SIZE - sizeof(*flush) - nr_banks * > > + sizeof(flush->hv_vp_set.bank_contents[0])) / > > + sizeof(uint64_t); /* gva is represented as uint64_t */ > > + > > + /* > > + * Flush the entire address space if va is NULL or if there is not > > + * enough space for gva_list. > > + */ > > + if ( !va || (PAGE_SIZE << order) / HV_TLB_FLUSH_UNIT > max_gvas ) > > + ret = hv_do_rep_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX, 0, > > + nr_banks, virt_to_maddr(flush), 0); > > You could just return hv_do_rep_hypercall(...); here, which will avoid > the else branch below and the indentation. Ack. > > > + else > > + { > > + uint64_t *gva_list = > > + (uint64_t *)flush + sizeof(*flush) / sizeof(uint64_t) + nr_banks; > > + unsigned int gvas = fill_gva_list(gva_list, va, order); > > + > > + BUILD_BUG_ON(sizeof(*flush) % sizeof(uint64_t)); > > + > > + ret = hv_do_rep_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX, > > + gvas, nr_banks, virt_to_maddr(flush), 0); > > + } > > + > > + return ret; > > +} > > + > > int hyperv_flush_tlb(const cpumask_t *mask, const void *va, > > unsigned int flags) > > { > > - return -EOPNOTSUPP; > > + unsigned long irq_flags; > > + struct hv_tlb_flush *flush = this_cpu(hv_input_page); > > + unsigned int max_gvas, order = flags & FLUSH_ORDER_MASK; > > + uint64_t ret; > > + > > + ASSERT(flush); > > + ASSERT(!cpumask_empty(mask)); > > I would also turn this into an if ( ... ) { ASSERT; return -EFOO; } Ack. > > > + > > + local_irq_save(irq_flags); > > + > > + flush->address_space = 0; > > + flush->flags = HV_FLUSH_ALL_VIRTUAL_ADDRESS_SPACES; > > + flush->processor_mask = 0; > > + if ( !(flags & FLUSH_TLB_GLOBAL) ) > > + flush->flags |= HV_FLUSH_NON_GLOBAL_MAPPINGS_ONLY; > > + > > + if ( cpumask_equal(mask, &cpu_online_map) ) > > + flush->flags |= HV_FLUSH_ALL_PROCESSORS; > > + else > > + { > > + unsigned int cpu; > > + > > + /* > > + * Normally VP indices are in ascending order and match Xen's > > + * idea of CPU ids. Check the last index to see if VP index is > > + * >= 64. If so, we can skip setting up parameters for > > + * non-applicable hypercalls without looking further. > > + */ > > + if ( hv_vp_index(cpumask_last(mask)) >= 64 ) > > + goto do_ex_hypercall; > > + > > + for_each_cpu ( cpu, mask ) > > + { > > + uint32_t vpid = hv_vp_index(cpu); > > This should be unsigned int now. Good catch. > > > + > > + if ( vpid > ms_hyperv.max_vp_index ) > > + { > > + local_irq_restore(irq_flags); > > + return -ENXIO; > > + } > > + > > + if ( vpid >= 64 ) > > + goto do_ex_hypercall; > > + > > + __set_bit(vpid, &flush->processor_mask); > > + } > > Would it make sense to abstract this as cpumask_to_processor_mask, > since you are adding cpumask_to_vpset below. > There is only one usage so far, so I don't think it is necessary. > > + } > > + > > + max_gvas = (PAGE_SIZE - sizeof(*flush)) / sizeof(flush->gva_list[0]); > > You could init this at declaration, and make it const static since the > value can be calculated at compile time AFAICT. Or create a define > with it (HV_TLB_FLUSH_MAX_GVAS?). There's no need to store it on the > stack. I can introduce a define, but the name you suggested is too generic. If there is variable sized header, the calculation is going to be different. > > > + > > + /* > > + * Flush the entire address space if va is NULL or if there is not > > + * enough space for gva_list. > > + */ > > + if ( !va || (PAGE_SIZE << order) / HV_TLB_FLUSH_UNIT > max_gvas ) > > + ret = hv_do_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE, > > + virt_to_maddr(flush), 0); > > + else > > + { > > + unsigned int gvas = fill_gva_list(flush->gva_list, va, order); > > No need for the gvas variable, you can just call fill_gva_list at > hv_do_rep_hypercall. > Sure. > > + > > + ret = hv_do_rep_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST, gvas, 0, > > + virt_to_maddr(flush), 0); > > + } > > + > > + goto done; > > + > > + do_ex_hypercall: > > + ret = flush_tlb_ex(mask, va, flags); > > + > > + done: > > + local_irq_restore(irq_flags); > > + > > + return ret & HV_HYPERCALL_RESULT_MASK ? -ENXIO : 0; > > } > > > > /* > > diff --git a/xen/arch/x86/guest/hyperv/util.c b/xen/arch/x86/guest/hyperv/util.c > > new file mode 100644 > > index 0000000000..e092593746 > > --- /dev/null > > +++ b/xen/arch/x86/guest/hyperv/util.c > > @@ -0,0 +1,74 @@ > > +/****************************************************************************** > > + * arch/x86/guest/hyperv/util.c > > + * > > + * Hyper-V utility functions > > + * > > + * This program is free software; you can redistribute it and/or modify > > + * it under the terms of the GNU General Public License as published by > > + * the Free Software Foundation; either version 2 of the License, or > > + * (at your option) any later version. > > + * > > + * This program is distributed in the hope that it will be useful, > > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > > + * GNU General Public License for more details. > > + * > > + * You should have received a copy of the GNU General Public License > > + * along with this program; If not, see <http://www.gnu.org/licenses/>. > > + * > > + * Copyright (c) 2020 Microsoft. > > + */ > > + > > +#include <xen/cpu.h> > > +#include <xen/cpumask.h> > > +#include <xen/errno.h> > > + > > +#include <asm/guest/hyperv.h> > > +#include <asm/guest/hyperv-tlfs.h> > > + > > +#include "private.h" > > + > > +int cpumask_to_vpset(struct hv_vpset *vpset, > > + const cpumask_t *mask) > > +{ > > + int nr = 1; > > + unsigned int cpu, vcpu_bank, vcpu_offset; > > + unsigned int max_banks = ms_hyperv.max_vp_index / 64; > > + > > + /* Up to 64 banks can be represented by valid_bank_mask */ > > + if ( max_banks >= 64 ) > > + return -E2BIG; > > + > > + /* Clear all banks to avoid flushing unwanted CPUs */ > > + for ( vcpu_bank = 0; vcpu_bank <= max_banks; vcpu_bank++ ) > > I think this is off by one and should be vcpu_bank < max_banks? Or > else you are clearing one extra bank. If max_vp_index were the maximum vp index, max_banks would be inclusive (for example, max_vp_index is 63, 63/64=0). The code should be correct in that case. However, when I did another round of self-review, I discovered that the value stored in max_vp_index was actually "the maximum number of virtual processors supported", so it wasn't really the maximum index. This means I will need to adjust places where max_vp_index is used. Here, max_banks is not inclusive anymore. And an earlier place + if ( vpid > ms_hyperv.max_vp_index ) + { also requires fixing. I will also see about changing max_{l,v}p_index to more sensible names or add some comments to their definitions. Wei. > > Thanks, Roger.
From: Wei Liu <wei.liu.xen@gmail.com> On Behalf Of Wei Liu Sent: Friday, February 14, 2020 4:35 AM > > Implement L0 assisted TLB flush for Xen on Hyper-V. It takes advantage > of several hypercalls: > > * HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST > * HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX > * HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE > * HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX > > Pick the most efficient hypercalls available. > > Signed-off-by: Wei Liu <liuwe@microsoft.com> > --- > v2: > 1. Address Roger and Jan's comments re types etc. > 2. Fix pointer arithmetic. > 3. Misc improvement to code. > --- > xen/arch/x86/guest/hyperv/Makefile | 1 + > xen/arch/x86/guest/hyperv/private.h | 9 ++ > xen/arch/x86/guest/hyperv/tlb.c | 172 +++++++++++++++++++++++++++- > xen/arch/x86/guest/hyperv/util.c | 74 ++++++++++++ > 4 files changed, 255 insertions(+), 1 deletion(-) > create mode 100644 xen/arch/x86/guest/hyperv/util.c > > diff --git a/xen/arch/x86/guest/hyperv/Makefile b/xen/arch/x86/guest/hyperv/Makefile > index 18902c33e9..0e39410968 100644 > --- a/xen/arch/x86/guest/hyperv/Makefile > +++ b/xen/arch/x86/guest/hyperv/Makefile > @@ -1,2 +1,3 @@ > obj-y += hyperv.o > obj-y += tlb.o > +obj-y += util.o > diff --git a/xen/arch/x86/guest/hyperv/private.h b/xen/arch/x86/guest/hyperv/private.h > index 509bedaafa..79a77930a0 100644 > --- a/xen/arch/x86/guest/hyperv/private.h > +++ b/xen/arch/x86/guest/hyperv/private.h > @@ -24,12 +24,21 @@ > > #include <xen/cpumask.h> > #include <xen/percpu.h> > +#include <xen/types.h> > > DECLARE_PER_CPU(void *, hv_input_page); > DECLARE_PER_CPU(void *, hv_vp_assist); > DECLARE_PER_CPU(unsigned int, hv_vp_index); > > +static inline unsigned int hv_vp_index(unsigned int cpu) > +{ > + return per_cpu(hv_vp_index, cpu); > +} > + > int hyperv_flush_tlb(const cpumask_t *mask, const void *va, > unsigned int flags); > > +/* Returns number of banks, -ev if error */ > +int cpumask_to_vpset(struct hv_vpset *vpset, const cpumask_t *mask); > + > #endif /* __XEN_HYPERV_PRIVIATE_H__ */ > diff --git a/xen/arch/x86/guest/hyperv/tlb.c b/xen/arch/x86/guest/hyperv/tlb.c > index 48f527229e..f68e14f151 100644 > --- a/xen/arch/x86/guest/hyperv/tlb.c > +++ b/xen/arch/x86/guest/hyperv/tlb.c > @@ -19,15 +19,185 @@ > * Copyright (c) 2020 Microsoft. > */ > > +#include <xen/cpu.h> > #include <xen/cpumask.h> > #include <xen/errno.h> > > +#include <asm/guest/hyperv.h> > +#include <asm/guest/hyperv-hcall.h> > +#include <asm/guest/hyperv-tlfs.h> > + > #include "private.h" > > +/* > + * It is possible to encode up to 4096 pages using the lower 12 bits > + * in an element of gva_list > + */ > +#define HV_TLB_FLUSH_UNIT (4096 * PAGE_SIZE) > + > +static unsigned int fill_gva_list(uint64_t *gva_list, const void *va, > + unsigned int order) > +{ > + unsigned long start = (unsigned long)va; > + unsigned long end = start + (PAGE_SIZE << order) - 1; > + unsigned int n = 0; > + > + do { > + unsigned long remain = end - start; The calculated value here isn't actually the remaining bytes in the range to flush -- it's one less than the remaining bytes in the range to flush because of the -1 in the calculation of 'end'. That difference will mess up the comparison below against HV_TLB_FLUSH_UNIT in the case that there are exactly 4096 page remaining to be flushed. It should take the "=" case, but won't. Also, the '-1' in 'remain - 1' in the else clause becomes unneeded, and the 'start = end' assignment then propagates the error. In the parallel code in Linux, if you follow the call sequence to get to fill_gav_list(), the 'end' argument is really the address of the first byte of the first page that isn't in the flush range (i.e., one beyond the true 'end') and so is a bit misnamed. I think the calculation of 'end' should drop the -1, and perhaps 'end' should be renamed. Michael > + > + gva_list[n] = start & PAGE_MASK; > + > + /* > + * Use lower 12 bits to encode the number of additional pages > + * to flush > + */ > + if ( remain >= HV_TLB_FLUSH_UNIT ) > + { > + gva_list[n] |= ~PAGE_MASK; > + start += HV_TLB_FLUSH_UNIT; > + } > + else if ( remain ) > + { > + gva_list[n] |= (remain - 1) >> PAGE_SHIFT; > + start = end; > + } > + > + n++; > + } while ( start < end ); > + > + return n; > +} > +
On Fri, Feb 14, 2020 at 04:42:47PM +0000, Michael Kelley wrote: > From: Wei Liu <wei.liu.xen@gmail.com> On Behalf Of Wei Liu Sent: Friday, February 14, 2020 4:35 AM > > > > Implement L0 assisted TLB flush for Xen on Hyper-V. It takes advantage > > of several hypercalls: > > > > * HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST > > * HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX > > * HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE > > * HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX > > > > Pick the most efficient hypercalls available. > > > > Signed-off-by: Wei Liu <liuwe@microsoft.com> > > --- > > v2: > > 1. Address Roger and Jan's comments re types etc. > > 2. Fix pointer arithmetic. > > 3. Misc improvement to code. > > --- > > xen/arch/x86/guest/hyperv/Makefile | 1 + > > xen/arch/x86/guest/hyperv/private.h | 9 ++ > > xen/arch/x86/guest/hyperv/tlb.c | 172 +++++++++++++++++++++++++++- > > xen/arch/x86/guest/hyperv/util.c | 74 ++++++++++++ > > 4 files changed, 255 insertions(+), 1 deletion(-) > > create mode 100644 xen/arch/x86/guest/hyperv/util.c > > > > diff --git a/xen/arch/x86/guest/hyperv/Makefile b/xen/arch/x86/guest/hyperv/Makefile > > index 18902c33e9..0e39410968 100644 > > --- a/xen/arch/x86/guest/hyperv/Makefile > > +++ b/xen/arch/x86/guest/hyperv/Makefile > > @@ -1,2 +1,3 @@ > > obj-y += hyperv.o > > obj-y += tlb.o > > +obj-y += util.o > > diff --git a/xen/arch/x86/guest/hyperv/private.h b/xen/arch/x86/guest/hyperv/private.h > > index 509bedaafa..79a77930a0 100644 > > --- a/xen/arch/x86/guest/hyperv/private.h > > +++ b/xen/arch/x86/guest/hyperv/private.h > > @@ -24,12 +24,21 @@ > > > > #include <xen/cpumask.h> > > #include <xen/percpu.h> > > +#include <xen/types.h> > > > > DECLARE_PER_CPU(void *, hv_input_page); > > DECLARE_PER_CPU(void *, hv_vp_assist); > > DECLARE_PER_CPU(unsigned int, hv_vp_index); > > > > +static inline unsigned int hv_vp_index(unsigned int cpu) > > +{ > > + return per_cpu(hv_vp_index, cpu); > > +} > > + > > int hyperv_flush_tlb(const cpumask_t *mask, const void *va, > > unsigned int flags); > > > > +/* Returns number of banks, -ev if error */ > > +int cpumask_to_vpset(struct hv_vpset *vpset, const cpumask_t *mask); > > + > > #endif /* __XEN_HYPERV_PRIVIATE_H__ */ > > diff --git a/xen/arch/x86/guest/hyperv/tlb.c b/xen/arch/x86/guest/hyperv/tlb.c > > index 48f527229e..f68e14f151 100644 > > --- a/xen/arch/x86/guest/hyperv/tlb.c > > +++ b/xen/arch/x86/guest/hyperv/tlb.c > > @@ -19,15 +19,185 @@ > > * Copyright (c) 2020 Microsoft. > > */ > > > > +#include <xen/cpu.h> > > #include <xen/cpumask.h> > > #include <xen/errno.h> > > > > +#include <asm/guest/hyperv.h> > > +#include <asm/guest/hyperv-hcall.h> > > +#include <asm/guest/hyperv-tlfs.h> > > + > > #include "private.h" > > > > +/* > > + * It is possible to encode up to 4096 pages using the lower 12 bits > > + * in an element of gva_list > > + */ > > +#define HV_TLB_FLUSH_UNIT (4096 * PAGE_SIZE) > > + > > +static unsigned int fill_gva_list(uint64_t *gva_list, const void *va, > > + unsigned int order) > > +{ > > + unsigned long start = (unsigned long)va; > > + unsigned long end = start + (PAGE_SIZE << order) - 1; > > + unsigned int n = 0; > > + > > + do { > > + unsigned long remain = end - start; > > The calculated value here isn't actually the remaining bytes in the > range to flush -- it's one less than the remaining bytes in the range > to flush because of the -1 in the calculation of 'end'. That difference > will mess up the comparison below against HV_TLB_FLUSH_UNIT > in the case that there are exactly 4096 page remaining to be > flushed. It should take the "=" case, but won't. Also, the > '-1' in 'remain - 1' in the else clause becomes unneeded, and > the 'start = end' assignment then propagates the error. > > In the parallel code in Linux, if you follow the call sequence to get to > fill_gav_list(), the 'end' argument is really the address of the first byte > of the first page that isn't in the flush range (i.e., one beyond the true > 'end') and so is a bit misnamed. > > I think the calculation of 'end' should drop the -1, and perhaps 'end' > should be renamed. Thanks for the detailed review. Let me fix this. Wei. > > Michael >
diff --git a/xen/arch/x86/guest/hyperv/Makefile b/xen/arch/x86/guest/hyperv/Makefile index 18902c33e9..0e39410968 100644 --- a/xen/arch/x86/guest/hyperv/Makefile +++ b/xen/arch/x86/guest/hyperv/Makefile @@ -1,2 +1,3 @@ obj-y += hyperv.o obj-y += tlb.o +obj-y += util.o diff --git a/xen/arch/x86/guest/hyperv/private.h b/xen/arch/x86/guest/hyperv/private.h index 509bedaafa..79a77930a0 100644 --- a/xen/arch/x86/guest/hyperv/private.h +++ b/xen/arch/x86/guest/hyperv/private.h @@ -24,12 +24,21 @@ #include <xen/cpumask.h> #include <xen/percpu.h> +#include <xen/types.h> DECLARE_PER_CPU(void *, hv_input_page); DECLARE_PER_CPU(void *, hv_vp_assist); DECLARE_PER_CPU(unsigned int, hv_vp_index); +static inline unsigned int hv_vp_index(unsigned int cpu) +{ + return per_cpu(hv_vp_index, cpu); +} + int hyperv_flush_tlb(const cpumask_t *mask, const void *va, unsigned int flags); +/* Returns number of banks, -ev if error */ +int cpumask_to_vpset(struct hv_vpset *vpset, const cpumask_t *mask); + #endif /* __XEN_HYPERV_PRIVIATE_H__ */ diff --git a/xen/arch/x86/guest/hyperv/tlb.c b/xen/arch/x86/guest/hyperv/tlb.c index 48f527229e..f68e14f151 100644 --- a/xen/arch/x86/guest/hyperv/tlb.c +++ b/xen/arch/x86/guest/hyperv/tlb.c @@ -19,15 +19,185 @@ * Copyright (c) 2020 Microsoft. */ +#include <xen/cpu.h> #include <xen/cpumask.h> #include <xen/errno.h> +#include <asm/guest/hyperv.h> +#include <asm/guest/hyperv-hcall.h> +#include <asm/guest/hyperv-tlfs.h> + #include "private.h" +/* + * It is possible to encode up to 4096 pages using the lower 12 bits + * in an element of gva_list + */ +#define HV_TLB_FLUSH_UNIT (4096 * PAGE_SIZE) + +static unsigned int fill_gva_list(uint64_t *gva_list, const void *va, + unsigned int order) +{ + unsigned long start = (unsigned long)va; + unsigned long end = start + (PAGE_SIZE << order) - 1; + unsigned int n = 0; + + do { + unsigned long remain = end - start; + + gva_list[n] = start & PAGE_MASK; + + /* + * Use lower 12 bits to encode the number of additional pages + * to flush + */ + if ( remain >= HV_TLB_FLUSH_UNIT ) + { + gva_list[n] |= ~PAGE_MASK; + start += HV_TLB_FLUSH_UNIT; + } + else if ( remain ) + { + gva_list[n] |= (remain - 1) >> PAGE_SHIFT; + start = end; + } + + n++; + } while ( start < end ); + + return n; +} + +static uint64_t flush_tlb_ex(const cpumask_t *mask, const void *va, + unsigned int flags) +{ + struct hv_tlb_flush_ex *flush = this_cpu(hv_input_page); + int nr_banks; + unsigned int max_gvas, order = flags & FLUSH_ORDER_MASK; + uint64_t ret; + + if ( !flush || local_irq_is_enabled() ) + { + ASSERT_UNREACHABLE(); + return ~0ULL; + } + + if ( !(ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED) ) + return ~0ULL; + + flush->address_space = 0; + flush->flags = HV_FLUSH_ALL_VIRTUAL_ADDRESS_SPACES; + if ( !(flags & FLUSH_TLB_GLOBAL) ) + flush->flags |= HV_FLUSH_NON_GLOBAL_MAPPINGS_ONLY; + + nr_banks = cpumask_to_vpset(&flush->hv_vp_set, mask); + if ( nr_banks < 0 ) + return ~0ULL; + + max_gvas = + (PAGE_SIZE - sizeof(*flush) - nr_banks * + sizeof(flush->hv_vp_set.bank_contents[0])) / + sizeof(uint64_t); /* gva is represented as uint64_t */ + + /* + * Flush the entire address space if va is NULL or if there is not + * enough space for gva_list. + */ + if ( !va || (PAGE_SIZE << order) / HV_TLB_FLUSH_UNIT > max_gvas ) + ret = hv_do_rep_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX, 0, + nr_banks, virt_to_maddr(flush), 0); + else + { + uint64_t *gva_list = + (uint64_t *)flush + sizeof(*flush) / sizeof(uint64_t) + nr_banks; + unsigned int gvas = fill_gva_list(gva_list, va, order); + + BUILD_BUG_ON(sizeof(*flush) % sizeof(uint64_t)); + + ret = hv_do_rep_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX, + gvas, nr_banks, virt_to_maddr(flush), 0); + } + + return ret; +} + int hyperv_flush_tlb(const cpumask_t *mask, const void *va, unsigned int flags) { - return -EOPNOTSUPP; + unsigned long irq_flags; + struct hv_tlb_flush *flush = this_cpu(hv_input_page); + unsigned int max_gvas, order = flags & FLUSH_ORDER_MASK; + uint64_t ret; + + ASSERT(flush); + ASSERT(!cpumask_empty(mask)); + + local_irq_save(irq_flags); + + flush->address_space = 0; + flush->flags = HV_FLUSH_ALL_VIRTUAL_ADDRESS_SPACES; + flush->processor_mask = 0; + if ( !(flags & FLUSH_TLB_GLOBAL) ) + flush->flags |= HV_FLUSH_NON_GLOBAL_MAPPINGS_ONLY; + + if ( cpumask_equal(mask, &cpu_online_map) ) + flush->flags |= HV_FLUSH_ALL_PROCESSORS; + else + { + unsigned int cpu; + + /* + * Normally VP indices are in ascending order and match Xen's + * idea of CPU ids. Check the last index to see if VP index is + * >= 64. If so, we can skip setting up parameters for + * non-applicable hypercalls without looking further. + */ + if ( hv_vp_index(cpumask_last(mask)) >= 64 ) + goto do_ex_hypercall; + + for_each_cpu ( cpu, mask ) + { + uint32_t vpid = hv_vp_index(cpu); + + if ( vpid > ms_hyperv.max_vp_index ) + { + local_irq_restore(irq_flags); + return -ENXIO; + } + + if ( vpid >= 64 ) + goto do_ex_hypercall; + + __set_bit(vpid, &flush->processor_mask); + } + } + + max_gvas = (PAGE_SIZE - sizeof(*flush)) / sizeof(flush->gva_list[0]); + + /* + * Flush the entire address space if va is NULL or if there is not + * enough space for gva_list. + */ + if ( !va || (PAGE_SIZE << order) / HV_TLB_FLUSH_UNIT > max_gvas ) + ret = hv_do_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE, + virt_to_maddr(flush), 0); + else + { + unsigned int gvas = fill_gva_list(flush->gva_list, va, order); + + ret = hv_do_rep_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST, gvas, 0, + virt_to_maddr(flush), 0); + } + + goto done; + + do_ex_hypercall: + ret = flush_tlb_ex(mask, va, flags); + + done: + local_irq_restore(irq_flags); + + return ret & HV_HYPERCALL_RESULT_MASK ? -ENXIO : 0; } /* diff --git a/xen/arch/x86/guest/hyperv/util.c b/xen/arch/x86/guest/hyperv/util.c new file mode 100644 index 0000000000..e092593746 --- /dev/null +++ b/xen/arch/x86/guest/hyperv/util.c @@ -0,0 +1,74 @@ +/****************************************************************************** + * arch/x86/guest/hyperv/util.c + * + * Hyper-V utility functions + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; If not, see <http://www.gnu.org/licenses/>. + * + * Copyright (c) 2020 Microsoft. + */ + +#include <xen/cpu.h> +#include <xen/cpumask.h> +#include <xen/errno.h> + +#include <asm/guest/hyperv.h> +#include <asm/guest/hyperv-tlfs.h> + +#include "private.h" + +int cpumask_to_vpset(struct hv_vpset *vpset, + const cpumask_t *mask) +{ + int nr = 1; + unsigned int cpu, vcpu_bank, vcpu_offset; + unsigned int max_banks = ms_hyperv.max_vp_index / 64; + + /* Up to 64 banks can be represented by valid_bank_mask */ + if ( max_banks >= 64 ) + return -E2BIG; + + /* Clear all banks to avoid flushing unwanted CPUs */ + for ( vcpu_bank = 0; vcpu_bank <= max_banks; vcpu_bank++ ) + vpset->bank_contents[vcpu_bank] = 0; + + vpset->valid_bank_mask = 0; + vpset->format = HV_GENERIC_SET_SPARSE_4K; + + for_each_cpu ( cpu, mask ) + { + unsigned int vcpu = hv_vp_index(cpu); + + vcpu_bank = vcpu / 64; + vcpu_offset = vcpu % 64; + + __set_bit(vcpu_offset, &vpset->bank_contents[vcpu_bank]); + __set_bit(vcpu_bank, &vpset->valid_bank_mask); + + if ( vcpu_bank >= nr ) + nr = vcpu_bank + 1; + } + + return nr; +} + +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * tab-width: 4 + * indent-tabs-mode: nil + * End: + */
Implement L0 assisted TLB flush for Xen on Hyper-V. It takes advantage of several hypercalls: * HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST * HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX * HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE * HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX Pick the most efficient hypercalls available. Signed-off-by: Wei Liu <liuwe@microsoft.com> --- v2: 1. Address Roger and Jan's comments re types etc. 2. Fix pointer arithmetic. 3. Misc improvement to code. --- xen/arch/x86/guest/hyperv/Makefile | 1 + xen/arch/x86/guest/hyperv/private.h | 9 ++ xen/arch/x86/guest/hyperv/tlb.c | 172 +++++++++++++++++++++++++++- xen/arch/x86/guest/hyperv/util.c | 74 ++++++++++++ 4 files changed, 255 insertions(+), 1 deletion(-) create mode 100644 xen/arch/x86/guest/hyperv/util.c