kvm_mmu_pte_prefetch is a per-VCPU structure that holds a PTE prefetch pages array, lock and the number of PTE to prefetch. This is needed to turn PTE_PREFETCH_NUM into a tunable VM parameter. Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx> --- arch/x86/include/asm/kvm_host.h | 12 +++++++ arch/x86/kvm/mmu.h | 4 +++ arch/x86/kvm/mmu/mmu.c | 57 ++++++++++++++++++++++++++++++--- arch/x86/kvm/x86.c | 9 +++++- 4 files changed, 77 insertions(+), 5 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 5271fce6cd65..11400bc3c70d 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -607,6 +607,16 @@ struct kvm_vcpu_xen { u64 runstate_times[4]; }; +struct kvm_mmu_pte_prefetch { + /* + * This will be cast either to array of pointers to struct page, + * or array of u64, or array of u32 + */ + void *ents; + unsigned int num_ents; + spinlock_t lock; +}; + struct kvm_vcpu_arch { /* * rip and regs accesses must go through @@ -682,6 +692,8 @@ struct kvm_vcpu_arch { struct kvm_mmu_memory_cache mmu_gfn_array_cache; struct kvm_mmu_memory_cache mmu_page_header_cache; + struct kvm_mmu_pte_prefetch mmu_pte_prefetch; + /* * QEMU userspace and the guest each have their own FPU state. * In vcpu_run, we switch between the user and guest FPU contexts. diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h index 75367af1a6d3..b953a3a4083a 100644 --- a/arch/x86/kvm/mmu.h +++ b/arch/x86/kvm/mmu.h @@ -68,6 +68,10 @@ static __always_inline u64 rsvd_bits(int s, int e) void kvm_mmu_set_mmio_spte_mask(u64 mmio_value, u64 mmio_mask, u64 access_mask); void kvm_mmu_set_ept_masks(bool has_ad_bits, bool has_exec_only); +int kvm_set_pte_prefetch(struct kvm_vcpu *vcpu, u64 num_ents); +int kvm_init_pte_prefetch(struct kvm_vcpu *vcpu); +void kvm_pte_prefetch_destroy(struct kvm_vcpu *vcpu); + void kvm_init_mmu(struct kvm_vcpu *vcpu); void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr0, unsigned long cr4, u64 efer, gpa_t nested_cr3); diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 24a9f4c3f5e7..fed3a498a729 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -115,6 +115,7 @@ module_param(dbg, bool, 0644); #endif #define PTE_PREFETCH_NUM 8 +#define MAX_PTE_PREFETCH_NUM 128 #define PT32_LEVEL_BITS 10 @@ -732,7 +733,7 @@ static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu, bool maybe_indirect) /* 1 rmap, 1 parent PTE per level, and the prefetched rmaps. */ r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache, - 1 + PT64_ROOT_MAX_LEVEL + PTE_PREFETCH_NUM); + 1 + PT64_ROOT_MAX_LEVEL + MAX_PTE_PREFETCH_NUM); if (r) return r; r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_shadow_page_cache, @@ -2753,12 +2754,13 @@ static int direct_pte_prefetch_many(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, u64 *start, u64 *end) { - struct page *pages[PTE_PREFETCH_NUM]; + struct page **pages; struct kvm_memory_slot *slot; unsigned int access = sp->role.access; int i, ret; gfn_t gfn; + pages = (struct page **)vcpu->arch.mmu_pte_prefetch.ents; gfn = kvm_mmu_page_get_gfn(sp, start - sp->spt); slot = gfn_to_memslot_dirty_bitmap(vcpu, gfn, access & ACC_WRITE_MASK); if (!slot) @@ -2781,14 +2783,17 @@ static void __direct_pte_prefetch(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, u64 *sptep) { u64 *spte, *start = NULL; + unsigned int pte_prefetch_num; int i; WARN_ON(!sp->role.direct); - i = (sptep - sp->spt) & ~(PTE_PREFETCH_NUM - 1); + spin_lock(&vcpu->arch.mmu_pte_prefetch.lock); + pte_prefetch_num = vcpu->arch.mmu_pte_prefetch.num_ents; + i = (sptep - sp->spt) & ~(pte_prefetch_num - 1); spte = sp->spt + i; - for (i = 0; i < PTE_PREFETCH_NUM; i++, spte++) { + for (i = 0; i < pte_prefetch_num; i++, spte++) { if (is_shadow_present_pte(*spte) || spte == sptep) { if (!start) continue; @@ -2800,6 +2805,7 @@ static void __direct_pte_prefetch(struct kvm_vcpu *vcpu, } if (start) direct_pte_prefetch_many(vcpu, sp, start, spte); + spin_unlock(&vcpu->arch.mmu_pte_prefetch.lock); } static void direct_pte_prefetch(struct kvm_vcpu *vcpu, u64 *sptep) @@ -4914,6 +4920,49 @@ void kvm_init_mmu(struct kvm_vcpu *vcpu) } EXPORT_SYMBOL_GPL(kvm_init_mmu); +int kvm_set_pte_prefetch(struct kvm_vcpu *vcpu, u64 num_ents) +{ + u64 *ents; + + if (!num_ents) + return -EINVAL; + + if (!is_power_of_2(num_ents)) + return -EINVAL; + + if (num_ents > MAX_PTE_PREFETCH_NUM) + return -EINVAL; + + ents = kmalloc_array(num_ents, sizeof(u64), GFP_KERNEL); + if (!ents) + return -ENOMEM; + + spin_lock(&vcpu->arch.mmu_pte_prefetch.lock); + kfree(vcpu->arch.mmu_pte_prefetch.ents); + vcpu->arch.mmu_pte_prefetch.ents = ents; + vcpu->arch.mmu_pte_prefetch.num_ents = num_ents; + spin_unlock(&vcpu->arch.mmu_pte_prefetch.lock); + + return 0; +} +EXPORT_SYMBOL_GPL(kvm_set_pte_prefetch); + +int kvm_init_pte_prefetch(struct kvm_vcpu *vcpu) +{ + spin_lock_init(&vcpu->arch.mmu_pte_prefetch.lock); + + return kvm_set_pte_prefetch(vcpu, PTE_PREFETCH_NUM); +} +EXPORT_SYMBOL_GPL(kvm_init_pte_prefetch); + +void kvm_pte_prefetch_destroy(struct kvm_vcpu *vcpu) +{ + vcpu->arch.mmu_pte_prefetch.num_ents = 0; + kfree(vcpu->arch.mmu_pte_prefetch.ents); + vcpu->arch.mmu_pte_prefetch.ents = NULL; +} +EXPORT_SYMBOL_GPL(kvm_pte_prefetch_destroy); + static union kvm_mmu_page_role kvm_mmu_calc_root_page_role(struct kvm_vcpu *vcpu) { diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b0f99132d7d1..4805960a89e6 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10707,10 +10707,14 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu) vcpu->arch.hv_root_tdp = INVALID_PAGE; #endif - r = static_call(kvm_x86_vcpu_create)(vcpu); + r = kvm_init_pte_prefetch(vcpu); if (r) goto free_guest_fpu; + r = static_call(kvm_x86_vcpu_create)(vcpu); + if (r) + goto free_pte_prefetch; + vcpu->arch.arch_capabilities = kvm_get_arch_capabilities(); vcpu->arch.msr_platform_info = MSR_PLATFORM_INFO_CPUID_FAULT; kvm_vcpu_mtrr_init(vcpu); @@ -10721,6 +10725,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu) vcpu_put(vcpu); return 0; +free_pte_prefetch: + kvm_pte_prefetch_destroy(vcpu); free_guest_fpu: kvm_free_guest_fpu(vcpu); free_user_fpu: @@ -10782,6 +10788,7 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu) kvm_free_lapic(vcpu); idx = srcu_read_lock(&vcpu->kvm->srcu); kvm_mmu_destroy(vcpu); + kvm_pte_prefetch_destroy(vcpu); srcu_read_unlock(&vcpu->kvm->srcu, idx); free_page((unsigned long)vcpu->arch.pio_data); kvfree(vcpu->arch.cpuid_entries); -- 2.33.0.1079.g6e70778dc9-goog