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Commit 697fe2e2 authored by Avi Kivity's avatar Avi Kivity Committed by Linus Torvalds
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[PATCH] KVM: MMU: Implement child shadow unlinking 



When removing a page table, we must maintain the parent_pte field all child
shadow page tables.

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 a436036b

drivers/kvm/mmu.c

+38 −4
Original line number Diff line number Diff line
@@ -402,12 +402,21 @@ static void mmu_page_remove_parent_pte(struct kvm_mmu_page *page, 
				break;

			if (pte_chain->parent_ptes[i] != parent_pte)

				continue;

			while (i + 1 < NR_PTE_CHAIN_ENTRIES) {

			while (i + 1 < NR_PTE_CHAIN_ENTRIES

				&& pte_chain->parent_ptes[i + 1]) {

				pte_chain->parent_ptes[i]

					= pte_chain->parent_ptes[i + 1];

				++i;

			}

			pte_chain->parent_ptes[i] = NULL;

			if (i == 0) {

				hlist_del(&pte_chain->link);

				kfree(pte_chain);

				if (hlist_empty(&page->parent_ptes)) {

					page->multimapped = 0;

					page->parent_pte = NULL;

				}

			}

			return;

		}

	BUG();
@@ -481,7 +490,30 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, 
static void kvm_mmu_page_unlink_children(struct kvm_vcpu *vcpu,

					 struct kvm_mmu_page *page)

{

	BUG();

	unsigned i;

	u64 *pt;

	u64 ent;



	pt = __va(page->page_hpa);



	if (page->role.level == PT_PAGE_TABLE_LEVEL) {

		for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {

			if (pt[i] & PT_PRESENT_MASK)

				rmap_remove(vcpu->kvm, &pt[i]);

			pt[i] = 0;

		}

		return;

	}



	for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {

		ent = pt[i];



		pt[i] = 0;

		if (!(ent & PT_PRESENT_MASK))

			continue;

		ent &= PT64_BASE_ADDR_MASK;

		mmu_page_remove_parent_pte(page_header(ent), &pt[i]);

	}

}



static void kvm_mmu_put_page(struct kvm_vcpu *vcpu,
@@ -489,7 +521,6 @@ static void kvm_mmu_put_page(struct kvm_vcpu *vcpu, 
			     u64 *parent_pte)

{

	mmu_page_remove_parent_pte(page, parent_pte);

	if (page->role.level > PT_PAGE_TABLE_LEVEL)

	kvm_mmu_page_unlink_children(vcpu, page);

	hlist_del(&page->hash_link);

	list_del(&page->link);
@@ -511,6 +542,7 @@ static void kvm_mmu_zap_page(struct kvm_vcpu *vcpu, 
					     struct kvm_pte_chain, link);

			parent_pte = chain->parent_ptes[0];

		}

		BUG_ON(!parent_pte);

		kvm_mmu_put_page(vcpu, page, parent_pte);

		*parent_pte = 0;

	}
@@ -530,6 +562,8 @@ static int kvm_mmu_unprotect_page(struct kvm_vcpu *vcpu, gfn_t gfn) 
	bucket = &vcpu->kvm->mmu_page_hash[index];

	hlist_for_each_entry_safe(page, node, n, bucket, hash_link)

		if (page->gfn == gfn && !page->role.metaphysical) {

			pgprintk("%s: gfn %lx role %x\n", __FUNCTION__, gfn,

				 page->role.word);

			kvm_mmu_zap_page(vcpu, page);

			r = 1;

		}