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| author | Avi Kivity <avi@qumranet.com> | 2007-01-05 16:36:48 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.osdl.org> | 2007-01-05 23:55:26 -0800 |
| commit | 0e7bc4b9610ed9fde0fa14f0b7a7f939805e5ae9 (patch) | |
| tree | 7466256bb2117e1ef5cbb42d2f9a405e80baf5c9 | |
| parent | 73f7198e738004671b885c443eb6f88df021c07f (diff) | |
| download | lwn-0e7bc4b9610ed9fde0fa14f0b7a7f939805e5ae9.tar.gz lwn-0e7bc4b9610ed9fde0fa14f0b7a7f939805e5ae9.zip | |
[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>
| -rw-r--r-- | drivers/kvm/mmu.c | 19 |
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) gfn_t gfn = gpa >> PAGE_SHIFT; struct kvm_mmu_page *page; struct kvm_mmu_page *child; - struct hlist_node *node; + struct hlist_node *node, *n; struct hlist_head *bucket; unsigned index; u64 *spte; u64 pte; unsigned offset = offset_in_page(gpa); + unsigned pte_size; unsigned page_offset; + unsigned misaligned; int level; pgprintk("%s: gpa %llx bytes %d\n", __FUNCTION__, gpa, bytes); index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES; bucket = &vcpu->kvm->mmu_page_hash[index]; - hlist_for_each_entry(page, node, bucket, hash_link) { + hlist_for_each_entry_safe(page, node, n, bucket, hash_link) { if (page->gfn != gfn || page->role.metaphysical) continue; + pte_size = page->role.glevels == PT32_ROOT_LEVEL ? 4 : 8; + misaligned = (offset ^ (offset + bytes - 1)) & ~(pte_size - 1); + if (misaligned) { + /* + * Misaligned accesses are too much trouble to fix + * up; also, they usually indicate a page is not used + * as a page table. + */ + pgprintk("misaligned: gpa %llx bytes %d role %x\n", + gpa, bytes, page->role.word); + kvm_mmu_zap_page(vcpu, page); + continue; + } page_offset = offset; level = page->role.level; if (page->role.glevels == PT32_ROOT_LEVEL) { |