From f57f2ef58f6703e6df70ed52a198920cb3e8edba Mon Sep 17 00:00:00 2001 From: Xiao Guangrong Date: Thu, 22 Sep 2011 16:56:39 +0800 Subject: [PATCH] KVM: MMU: fast prefetch spte on invlpg path Fast prefetch spte for the unsync shadow page on invlpg path Signed-off-by: Xiao Guangrong Signed-off-by: Avi Kivity --- arch/x86/include/asm/kvm_host.h | 4 +--- arch/x86/kvm/mmu.c | 38 +++++++++++++-------------------- arch/x86/kvm/paging_tmpl.h | 30 +++++++++++++++----------- arch/x86/kvm/x86.c | 4 ++-- 4 files changed, 36 insertions(+), 40 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index f8ab0d760231..3c9ea26c7aea 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -461,7 +461,6 @@ struct kvm_arch { unsigned int n_requested_mmu_pages; unsigned int n_max_mmu_pages; unsigned int indirect_shadow_pages; - atomic_t invlpg_counter; struct hlist_head mmu_page_hash[KVM_NUM_MMU_PAGES]; /* * Hash table of struct kvm_mmu_page. @@ -757,8 +756,7 @@ int fx_init(struct kvm_vcpu *vcpu); void kvm_mmu_flush_tlb(struct kvm_vcpu *vcpu); void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, - const u8 *new, int bytes, - bool guest_initiated); + const u8 *new, int bytes); int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn); int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva); void __kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu); diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index d15f908649e7..c01137f10c6b 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -3531,8 +3531,7 @@ static bool last_updated_pte_accessed(struct kvm_vcpu *vcpu) } void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, - const u8 *new, int bytes, - bool guest_initiated) + const u8 *new, int bytes) { gfn_t gfn = gpa >> PAGE_SHIFT; union kvm_mmu_page_role mask = { .word = 0 }; @@ -3541,7 +3540,7 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, LIST_HEAD(invalid_list); u64 entry, gentry, *spte; unsigned pte_size, page_offset, misaligned, quadrant, offset; - int level, npte, invlpg_counter, r, flooded = 0; + int level, npte, r, flooded = 0; bool remote_flush, local_flush, zap_page; /* @@ -3556,19 +3555,16 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, pgprintk("%s: gpa %llx bytes %d\n", __func__, gpa, bytes); - invlpg_counter = atomic_read(&vcpu->kvm->arch.invlpg_counter); - /* * Assume that the pte write on a page table of the same type * as the current vcpu paging mode since we update the sptes only * when they have the same mode. */ - if ((is_pae(vcpu) && bytes == 4) || !new) { + if (is_pae(vcpu) && bytes == 4) { /* Handle a 32-bit guest writing two halves of a 64-bit gpte */ - if (is_pae(vcpu)) { - gpa &= ~(gpa_t)7; - bytes = 8; - } + gpa &= ~(gpa_t)7; + bytes = 8; + r = kvm_read_guest(vcpu->kvm, gpa, &gentry, min(bytes, 8)); if (r) gentry = 0; @@ -3594,22 +3590,18 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, */ mmu_topup_memory_caches(vcpu); spin_lock(&vcpu->kvm->mmu_lock); - if (atomic_read(&vcpu->kvm->arch.invlpg_counter) != invlpg_counter) - gentry = 0; kvm_mmu_free_some_pages(vcpu); ++vcpu->kvm->stat.mmu_pte_write; trace_kvm_mmu_audit(vcpu, AUDIT_PRE_PTE_WRITE); - if (guest_initiated) { - if (gfn == vcpu->arch.last_pt_write_gfn - && !last_updated_pte_accessed(vcpu)) { - ++vcpu->arch.last_pt_write_count; - if (vcpu->arch.last_pt_write_count >= 3) - flooded = 1; - } else { - vcpu->arch.last_pt_write_gfn = gfn; - vcpu->arch.last_pt_write_count = 1; - vcpu->arch.last_pte_updated = NULL; - } + if (gfn == vcpu->arch.last_pt_write_gfn + && !last_updated_pte_accessed(vcpu)) { + ++vcpu->arch.last_pt_write_count; + if (vcpu->arch.last_pt_write_count >= 3) + flooded = 1; + } else { + vcpu->arch.last_pt_write_gfn = gfn; + vcpu->arch.last_pt_write_count = 1; + vcpu->arch.last_pte_updated = NULL; } mask.cr0_wp = mask.cr4_pae = mask.nxe = 1; diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index d8d3906649da..9efb86035774 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -672,20 +672,27 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva) { struct kvm_shadow_walk_iterator iterator; struct kvm_mmu_page *sp; - gpa_t pte_gpa = -1; int level; u64 *sptep; vcpu_clear_mmio_info(vcpu, gva); - spin_lock(&vcpu->kvm->mmu_lock); + /* + * No need to check return value here, rmap_can_add() can + * help us to skip pte prefetch later. + */ + mmu_topup_memory_caches(vcpu); + spin_lock(&vcpu->kvm->mmu_lock); for_each_shadow_entry(vcpu, gva, iterator) { level = iterator.level; sptep = iterator.sptep; sp = page_header(__pa(sptep)); if (is_last_spte(*sptep, level)) { + pt_element_t gpte; + gpa_t pte_gpa; + if (!sp->unsync) break; @@ -694,22 +701,21 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva) if (mmu_page_zap_pte(vcpu->kvm, sp, sptep)) kvm_flush_remote_tlbs(vcpu->kvm); + + if (!rmap_can_add(vcpu)) + break; + + if (kvm_read_guest_atomic(vcpu->kvm, pte_gpa, &gpte, + sizeof(pt_element_t))) + break; + + FNAME(update_pte)(vcpu, sp, sptep, &gpte); } if (!is_shadow_present_pte(*sptep) || !sp->unsync_children) break; } - - atomic_inc(&vcpu->kvm->arch.invlpg_counter); - spin_unlock(&vcpu->kvm->mmu_lock); - - if (pte_gpa == -1) - return; - - if (mmu_topup_memory_caches(vcpu)) - return; - kvm_mmu_pte_write(vcpu, pte_gpa, NULL, sizeof(pt_element_t), 0); } static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr, u32 access, diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a2154487917d..9c980ce26e61 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4087,7 +4087,7 @@ int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa, ret = kvm_write_guest(vcpu->kvm, gpa, val, bytes); if (ret < 0) return 0; - kvm_mmu_pte_write(vcpu, gpa, val, bytes, 1); + kvm_mmu_pte_write(vcpu, gpa, val, bytes); return 1; } @@ -4324,7 +4324,7 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt, if (!exchanged) return X86EMUL_CMPXCHG_FAILED; - kvm_mmu_pte_write(vcpu, gpa, new, bytes, 1); + kvm_mmu_pte_write(vcpu, gpa, new, bytes); return X86EMUL_CONTINUE; -- GitLab