From 7ddca7e43c8f28f9419da81a0e7730b66aa60fe9 Mon Sep 17 00:00:00 2001 From: Takuya Yoshikawa Date: Thu, 21 Mar 2013 19:33:43 +0900 Subject: [PATCH 1/2] KVM: MMU: Move kvm_mmu_free_some_pages() into kvm_mmu_alloc_page() What this function is doing is to ensure that the number of shadow pages does not exceed the maximum limit stored in n_max_mmu_pages: so this is placed at every code path that can reach kvm_mmu_alloc_page(). Although it might have some sense to spread this function in each such code path when it could be called before taking mmu_lock, the rule was changed not to do so. Taking this background into account, this patch moves it into kvm_mmu_alloc_page() and simplifies the code. Note: the unlikely hint in kvm_mmu_free_some_pages() guarantees that the overhead of this function is almost zero except when we actually need to allocate some shadow pages, so we do not need to care about calling it multiple times in one path by doing kvm_mmu_get_page() a few times. Signed-off-by: Takuya Yoshikawa Signed-off-by: Marcelo Tosatti --- arch/x86/kvm/mmu.c | 9 +++------ arch/x86/kvm/paging_tmpl.h | 1 - 2 files changed, 3 insertions(+), 7 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index c1a9b7b08ab7..38f34c5361f4 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -1505,6 +1505,9 @@ static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, u64 *parent_pte, int direct) { struct kvm_mmu_page *sp; + + kvm_mmu_free_some_pages(vcpu); + sp = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache); sp->spt = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_cache); if (!direct) @@ -2842,7 +2845,6 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, u32 error_code, spin_lock(&vcpu->kvm->mmu_lock); if (mmu_notifier_retry(vcpu->kvm, mmu_seq)) goto out_unlock; - kvm_mmu_free_some_pages(vcpu); if (likely(!force_pt_level)) transparent_hugepage_adjust(vcpu, &gfn, &pfn, &level); r = __direct_map(vcpu, v, write, map_writable, level, gfn, pfn, @@ -2920,7 +2922,6 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu) if (vcpu->arch.mmu.shadow_root_level == PT64_ROOT_LEVEL) { spin_lock(&vcpu->kvm->mmu_lock); - kvm_mmu_free_some_pages(vcpu); sp = kvm_mmu_get_page(vcpu, 0, 0, PT64_ROOT_LEVEL, 1, ACC_ALL, NULL); ++sp->root_count; @@ -2932,7 +2933,6 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu) ASSERT(!VALID_PAGE(root)); spin_lock(&vcpu->kvm->mmu_lock); - kvm_mmu_free_some_pages(vcpu); sp = kvm_mmu_get_page(vcpu, i << (30 - PAGE_SHIFT), i << 30, PT32_ROOT_LEVEL, 1, ACC_ALL, @@ -2971,7 +2971,6 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu) ASSERT(!VALID_PAGE(root)); spin_lock(&vcpu->kvm->mmu_lock); - kvm_mmu_free_some_pages(vcpu); sp = kvm_mmu_get_page(vcpu, root_gfn, 0, PT64_ROOT_LEVEL, 0, ACC_ALL, NULL); root = __pa(sp->spt); @@ -3005,7 +3004,6 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu) return 1; } spin_lock(&vcpu->kvm->mmu_lock); - kvm_mmu_free_some_pages(vcpu); sp = kvm_mmu_get_page(vcpu, root_gfn, i << 30, PT32_ROOT_LEVEL, 0, ACC_ALL, NULL); @@ -3311,7 +3309,6 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code, spin_lock(&vcpu->kvm->mmu_lock); if (mmu_notifier_retry(vcpu->kvm, mmu_seq)) goto out_unlock; - kvm_mmu_free_some_pages(vcpu); if (likely(!force_pt_level)) transparent_hugepage_adjust(vcpu, &gfn, &pfn, &level); r = __direct_map(vcpu, gpa, write, map_writable, diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index 105dd5bd550e..af143f065532 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -627,7 +627,6 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code, goto out_unlock; kvm_mmu_audit(vcpu, AUDIT_PRE_PAGE_FAULT); - kvm_mmu_free_some_pages(vcpu); if (!force_pt_level) transparent_hugepage_adjust(vcpu, &walker.gfn, &pfn, &level); r = FNAME(fetch)(vcpu, addr, &walker, write_fault, From 81f4f76bbc712a2dff8bb020057c554e285370e1 Mon Sep 17 00:00:00 2001 From: Takuya Yoshikawa Date: Thu, 21 Mar 2013 19:34:27 +0900 Subject: [PATCH 2/2] KVM: MMU: Rename kvm_mmu_free_some_pages() to make_mmu_pages_available() The current name "kvm_mmu_free_some_pages" should be used for something that actually frees some shadow pages, as we expect from the name, but what the function is doing is to make some, KVM_MIN_FREE_MMU_PAGES, shadow pages available: it does nothing when there are enough. This patch changes the name to reflect this meaning better; while doing this renaming, the code in the wrapper function is inlined into the main body since the whole function will be inlined into the only caller now. Signed-off-by: Takuya Yoshikawa Signed-off-by: Marcelo Tosatti --- arch/x86/kvm/mmu.c | 9 +++++++-- arch/x86/kvm/mmu.h | 6 ------ 2 files changed, 7 insertions(+), 8 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 38f34c5361f4..633e30cfbd63 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -1501,12 +1501,14 @@ static void drop_parent_pte(struct kvm_mmu_page *sp, mmu_spte_clear_no_track(parent_pte); } +static void make_mmu_pages_available(struct kvm_vcpu *vcpu); + static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, u64 *parent_pte, int direct) { struct kvm_mmu_page *sp; - kvm_mmu_free_some_pages(vcpu); + make_mmu_pages_available(vcpu); sp = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache); sp->spt = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_cache); @@ -4010,10 +4012,13 @@ int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva) } EXPORT_SYMBOL_GPL(kvm_mmu_unprotect_page_virt); -void __kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu) +static void make_mmu_pages_available(struct kvm_vcpu *vcpu) { LIST_HEAD(invalid_list); + if (likely(kvm_mmu_available_pages(vcpu->kvm) >= KVM_MIN_FREE_MMU_PAGES)) + return; + while (kvm_mmu_available_pages(vcpu->kvm) < KVM_REFILL_PAGES) { if (!prepare_zap_oldest_mmu_page(vcpu->kvm, &invalid_list)) break; diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h index 3b1ad0049ea4..2adcbc2cac6d 100644 --- a/arch/x86/kvm/mmu.h +++ b/arch/x86/kvm/mmu.h @@ -64,12 +64,6 @@ static inline unsigned int kvm_mmu_available_pages(struct kvm *kvm) return 0; } -static inline void kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu) -{ - if (unlikely(kvm_mmu_available_pages(vcpu->kvm)< KVM_MIN_FREE_MMU_PAGES)) - __kvm_mmu_free_some_pages(vcpu); -} - static inline int kvm_mmu_reload(struct kvm_vcpu *vcpu) { if (likely(vcpu->arch.mmu.root_hpa != INVALID_PAGE))