[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 <avi@qumranet.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Avi Kivity 2007-01-05 16:36:47 -08:00 committed by Linus Torvalds
parent cc4529efc7
commit ebeace8609
5 changed files with 37 additions and 43 deletions

View File

@ -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)
{

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@ -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;
}
/*

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@ -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.

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@ -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;
}

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@ -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;
}