KVM: mmu: add missing dirty page tracking cases

We fail to mark a page dirty in three cases:

- setting the accessed bit in a pte
- setting the dirty bit in a pte
- emulating a write into a pagetable

This fix adds the missing cases.

Signed-off-by: Avi Kivity <avi@qumranet.com>

diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h
index b6b90e9..6507ccb 100644 (file)
--- a/drivers/kvm/paging_tmpl.h
+++ b/drivers/kvm/paging_tmpl.h
@@ -128,8 +128,10 @@ static int FNAME(walk_addr)(struct guest_walker *walker,
                        goto access_error;
 #endif
 
-               if (!(*ptep & PT_ACCESSED_MASK))
-                       *ptep |= PT_ACCESSED_MASK;      /* avoid rmw */
+               if (!(*ptep & PT_ACCESSED_MASK)) {
+                       mark_page_dirty(vcpu->kvm, table_gfn);
+                       *ptep |= PT_ACCESSED_MASK;
+               }
 
                if (walker->level == PT_PAGE_TABLE_LEVEL) {
                        walker->gfn = (*ptep & PT_BASE_ADDR_MASK)
@@ -185,6 +187,12 @@ static void FNAME(release_walker)(struct guest_walker *walker)
                kunmap_atomic(walker->table, KM_USER0);
 }
 
+static void FNAME(mark_pagetable_dirty)(struct kvm *kvm,
+                                       struct guest_walker *walker)
+{
+       mark_page_dirty(kvm, walker->table_gfn[walker->level - 1]);
+}
+
 static void FNAME(set_pte)(struct kvm_vcpu *vcpu, u64 guest_pte,
                           u64 *shadow_pte, u64 access_bits, gfn_t gfn)
 {
@@ -348,12 +356,15 @@ static int FNAME(fix_write_pf)(struct kvm_vcpu *vcpu,
        } else if (kvm_mmu_lookup_page(vcpu, gfn)) {
                pgprintk("%s: found shadow page for %lx, marking ro\n",
                         __FUNCTION__, gfn);
+               mark_page_dirty(vcpu->kvm, gfn);
+               FNAME(mark_pagetable_dirty)(vcpu->kvm, walker);
                *guest_ent |= PT_DIRTY_MASK;
                *write_pt = 1;
                return 0;
        }
        mark_page_dirty(vcpu->kvm, gfn);
        *shadow_ent |= PT_WRITABLE_MASK;
+       FNAME(mark_pagetable_dirty)(vcpu->kvm, walker);
        *guest_ent |= PT_DIRTY_MASK;
        rmap_add(vcpu, shadow_ent);