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authorAvi Kivity <avi@qumranet.com>2007-01-05 19:36:48 -0500
committerLinus Torvalds <torvalds@woody.osdl.org>2007-01-06 02:55:26 -0500
commit0e7bc4b9610ed9fde0fa14f0b7a7f939805e5ae9 (patch)
tree7466256bb2117e1ef5cbb42d2f9a405e80baf5c9 /drivers
parent73f7198e738004671b885c443eb6f88df021c07f (diff)
[PATCH] KVM: MMU: Handle misaligned accesses to write protected guest page tables
A misaligned access affects two shadow ptes instead of just one. Since a misaligned access is unlikely to occur on a real page table, just zap the page out of existence, avoiding further trouble. 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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/kvm/mmu.c19
1 files changed, 17 insertions, 2 deletions
diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index 53c3643038bb..50b1432dceee 100644
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -954,21 +954,36 @@ void kvm_mmu_pre_write(struct kvm_vcpu *vcpu, gpa_t gpa, int bytes)
954 gfn_t gfn = gpa >> PAGE_SHIFT; 954 gfn_t gfn = gpa >> PAGE_SHIFT;
955 struct kvm_mmu_page *page; 955 struct kvm_mmu_page *page;
956 struct kvm_mmu_page *child; 956 struct kvm_mmu_page *child;
957 struct hlist_node *node; 957 struct hlist_node *node, *n;
958 struct hlist_head *bucket; 958 struct hlist_head *bucket;
959 unsigned index; 959 unsigned index;
960 u64 *spte; 960 u64 *spte;
961 u64 pte; 961 u64 pte;
962 unsigned offset = offset_in_page(gpa); 962 unsigned offset = offset_in_page(gpa);
963 unsigned pte_size;
963 unsigned page_offset; 964 unsigned page_offset;
965 unsigned misaligned;
964 int level; 966 int level;
965 967
966 pgprintk("%s: gpa %llx bytes %d\n", __FUNCTION__, gpa, bytes); 968 pgprintk("%s: gpa %llx bytes %d\n", __FUNCTION__, gpa, bytes);
967 index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES; 969 index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
968 bucket = &vcpu->kvm->mmu_page_hash[index]; 970 bucket = &vcpu->kvm->mmu_page_hash[index];
969 hlist_for_each_entry(page, node, bucket, hash_link) { 971 hlist_for_each_entry_safe(page, node, n, bucket, hash_link) {
970 if (page->gfn != gfn || page->role.metaphysical) 972 if (page->gfn != gfn || page->role.metaphysical)
971 continue; 973 continue;
974 pte_size = page->role.glevels == PT32_ROOT_LEVEL ? 4 : 8;
975 misaligned = (offset ^ (offset + bytes - 1)) & ~(pte_size - 1);
976 if (misaligned) {
977 /*
978 * Misaligned accesses are too much trouble to fix
979 * up; also, they usually indicate a page is not used
980 * as a page table.
981 */
982 pgprintk("misaligned: gpa %llx bytes %d role %x\n",
983 gpa, bytes, page->role.word);
984 kvm_mmu_zap_page(vcpu, page);
985 continue;
986 }
972 page_offset = offset; 987 page_offset = offset;
973 level = page->role.level; 988 level = page->role.level;
974 if (page->role.glevels == PT32_ROOT_LEVEL) { 989 if (page->role.glevels == PT32_ROOT_LEVEL) {