From ebeace8609205bf5e1b96fe325b7dea148042232 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Fri, 5 Jan 2007 16:36:47 -0800 Subject: [PATCH] [PATCH] KVM: MMU: oom handling When beginning to process a page fault, make sure we have enough shadow pages available to service the fault. If not, free some pages. Signed-off-by: Avi Kivity Acked-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/kvm/kvm.h | 12 ++++++++++++ drivers/kvm/mmu.c | 49 ++++++++++++++++++++--------------------------- drivers/kvm/paging_tmpl.h | 15 ++------------- drivers/kvm/svm.c | 2 +- drivers/kvm/vmx.c | 2 +- 5 files changed, 37 insertions(+), 43 deletions(-) diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h index 34c43bb..1d0be85 100644 --- a/drivers/kvm/kvm.h +++ b/drivers/kvm/kvm.h @@ -52,6 +52,8 @@ #define KVM_MAX_VCPUS 1 #define KVM_MEMORY_SLOTS 4 #define KVM_NUM_MMU_PAGES 256 +#define KVM_MIN_FREE_MMU_PAGES 5 +#define KVM_REFILL_PAGES 25 #define FX_IMAGE_SIZE 512 #define FX_IMAGE_ALIGN 16 @@ -278,6 +280,7 @@ struct kvm { * Hash table of struct kvm_mmu_page. */ struct list_head active_mmu_pages; + int n_free_mmu_pages; struct hlist_head mmu_page_hash[KVM_NUM_MMU_PAGES]; struct kvm_vcpu vcpus[KVM_MAX_VCPUS]; int memory_config_version; @@ -451,6 +454,15 @@ unsigned long segment_base(u16 selector); void kvm_mmu_pre_write(struct kvm_vcpu *vcpu, gpa_t gpa, int bytes); void kvm_mmu_post_write(struct kvm_vcpu *vcpu, gpa_t gpa, int bytes); int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva); +void kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu); + +static inline int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t gva, + u32 error_code) +{ + if (unlikely(vcpu->kvm->n_free_mmu_pages < KVM_MIN_FREE_MMU_PAGES)) + kvm_mmu_free_some_pages(vcpu); + return vcpu->mmu.page_fault(vcpu, gva, error_code); +} static inline struct page *_gfn_to_page(struct kvm *kvm, gfn_t gfn) { diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c index d788866..e4a20a4 100644 --- a/drivers/kvm/mmu.c +++ b/drivers/kvm/mmu.c @@ -310,6 +310,7 @@ static void kvm_mmu_free_page(struct kvm_vcpu *vcpu, hpa_t page_hpa) list_del(&page_head->link); page_head->page_hpa = page_hpa; list_add(&page_head->link, &vcpu->free_pages); + ++vcpu->kvm->n_free_mmu_pages; } static int is_empty_shadow_page(hpa_t page_hpa) @@ -344,6 +345,7 @@ static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, page->global = 1; page->multimapped = 0; page->parent_pte = parent_pte; + --vcpu->kvm->n_free_mmu_pages; return page; } @@ -544,8 +546,7 @@ static void kvm_mmu_zap_page(struct kvm_vcpu *vcpu, } kvm_mmu_page_unlink_children(vcpu, page); hlist_del(&page->hash_link); - list_del(&page->link); - list_add(&page->link, &vcpu->free_pages); + kvm_mmu_free_page(vcpu, page->page_hpa); } static int kvm_mmu_unprotect_page(struct kvm_vcpu *vcpu, gfn_t gfn) @@ -743,18 +744,6 @@ static void mmu_alloc_roots(struct kvm_vcpu *vcpu) vcpu->mmu.root_hpa = __pa(vcpu->mmu.pae_root); } -static void nonpaging_flush(struct kvm_vcpu *vcpu) -{ - hpa_t root = vcpu->mmu.root_hpa; - - ++kvm_stat.tlb_flush; - pgprintk("nonpaging_flush\n"); - mmu_free_roots(vcpu); - mmu_alloc_roots(vcpu); - kvm_arch_ops->set_cr3(vcpu, root); - kvm_arch_ops->tlb_flush(vcpu); -} - static gpa_t nonpaging_gva_to_gpa(struct kvm_vcpu *vcpu, gva_t vaddr) { return vaddr; @@ -763,28 +752,19 @@ static gpa_t nonpaging_gva_to_gpa(struct kvm_vcpu *vcpu, gva_t vaddr) static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva, u32 error_code) { - int ret; gpa_t addr = gva; + hpa_t paddr; ASSERT(vcpu); ASSERT(VALID_PAGE(vcpu->mmu.root_hpa)); - for (;;) { - hpa_t paddr; - paddr = gpa_to_hpa(vcpu , addr & PT64_BASE_ADDR_MASK); + paddr = gpa_to_hpa(vcpu , addr & PT64_BASE_ADDR_MASK); - if (is_error_hpa(paddr)) - return 1; + if (is_error_hpa(paddr)) + return 1; - ret = nonpaging_map(vcpu, addr & PAGE_MASK, paddr); - if (ret) { - nonpaging_flush(vcpu); - continue; - } - break; - } - return ret; + return nonpaging_map(vcpu, addr & PAGE_MASK, paddr); } static void nonpaging_inval_page(struct kvm_vcpu *vcpu, gva_t addr) @@ -1093,6 +1073,18 @@ int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva) return kvm_mmu_unprotect_page(vcpu, gpa >> PAGE_SHIFT); } +void kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu) +{ + while (vcpu->kvm->n_free_mmu_pages < KVM_REFILL_PAGES) { + struct kvm_mmu_page *page; + + page = container_of(vcpu->kvm->active_mmu_pages.prev, + struct kvm_mmu_page, link); + kvm_mmu_zap_page(vcpu, page); + } +} +EXPORT_SYMBOL_GPL(kvm_mmu_free_some_pages); + static void free_mmu_pages(struct kvm_vcpu *vcpu) { while (!list_empty(&vcpu->free_pages)) { @@ -1124,6 +1116,7 @@ static int alloc_mmu_pages(struct kvm_vcpu *vcpu) page_header->page_hpa = (hpa_t)page_to_pfn(page) << PAGE_SHIFT; memset(__va(page_header->page_hpa), 0, PAGE_SIZE); list_add(&page_header->link, &vcpu->free_pages); + ++vcpu->kvm->n_free_mmu_pages; } /* diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h index cf4b74c..03c474a 100644 --- a/drivers/kvm/paging_tmpl.h +++ b/drivers/kvm/paging_tmpl.h @@ -246,8 +246,6 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, } shadow_page = kvm_mmu_get_page(vcpu, table_gfn, addr, level-1, metaphysical, shadow_ent); - if (!shadow_page) - return ERR_PTR(-ENOMEM); shadow_addr = shadow_page->page_hpa; shadow_pte = shadow_addr | PT_PRESENT_MASK | PT_ACCESSED_MASK | PT_WRITABLE_MASK | PT_USER_MASK; @@ -347,17 +345,8 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, /* * Look up the shadow pte for the faulting address. */ - for (;;) { - FNAME(walk_addr)(&walker, vcpu, addr); - shadow_pte = FNAME(fetch)(vcpu, addr, &walker); - if (IS_ERR(shadow_pte)) { /* must be -ENOMEM */ - printk("%s: oom\n", __FUNCTION__); - nonpaging_flush(vcpu); - FNAME(release_walker)(&walker); - continue; - } - break; - } + FNAME(walk_addr)(&walker, vcpu, addr); + shadow_pte = FNAME(fetch)(vcpu, addr, &walker); /* * The page is not mapped by the guest. Let the guest handle it. diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c index 91c7f60..869b524 100644 --- a/drivers/kvm/svm.c +++ b/drivers/kvm/svm.c @@ -861,7 +861,7 @@ static int pf_interception(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) fault_address = vcpu->svm->vmcb->control.exit_info_2; error_code = vcpu->svm->vmcb->control.exit_info_1; - if (!vcpu->mmu.page_fault(vcpu, fault_address, error_code)) { + if (!kvm_mmu_page_fault(vcpu, fault_address, error_code)) { spin_unlock(&vcpu->kvm->lock); return 1; } diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c index aaa98e3..2a1c37e 100644 --- a/drivers/kvm/vmx.c +++ b/drivers/kvm/vmx.c @@ -1318,7 +1318,7 @@ static int handle_exception(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) cr2 = vmcs_readl(EXIT_QUALIFICATION); spin_lock(&vcpu->kvm->lock); - if (!vcpu->mmu.page_fault(vcpu, cr2, error_code)) { + if (!kvm_mmu_page_fault(vcpu, cr2, error_code)) { spin_unlock(&vcpu->kvm->lock); return 1; } -- 2.7.4