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Commit ebeace86 authored by Avi Kivity's avatar Avi Kivity Committed by Linus Torvalds
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[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: default avatarAvi Kivity <avi@qumranet.com>
Acked-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent cc4529ef

drivers/kvm/kvm.h

+12 −0
Original line number Diff line number Diff line
@@ -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)

{

drivers/kvm/mmu.c

+21 −28
Original line number Diff line number Diff line
@@ -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);



	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;

	}



	/*

drivers/kvm/paging_tmpl.h

+2 −13
Original line number Diff line number Diff line
@@ -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;

	}



	/*

	 * The page is not mapped by the guest.  Let the guest handle it.

drivers/kvm/svm.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

	}

drivers/kvm/vmx.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

		}