[PATCH] KVM: MMU: Treat user-mode faults as a hint that a page is no longer a page table

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>

1 files changed, 12 insertions, 1 deletions

diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h
index 03c474aaedde..6acb16ea5ce2 100644
--- a/drivers/kvm/paging_tmpl.h
+++ b/drivers/kvm/paging_tmpl.h
@@ -271,6 +271,7 @@ static int FNAME(fix_write_pf)(struct kvm_vcpu *vcpu,
         pt_element_t *guest_ent;
         int writable_shadow;
         gfn_t gfn;
+        struct kvm_mmu_page *page;
 
         if (is_writeble_pte(*shadow_ent))
                 return 0;
@@ -303,7 +304,17 @@ static int FNAME(fix_write_pf)(struct kvm_vcpu *vcpu,
         }
 
         gfn = walker->gfn;
-        if (kvm_mmu_lookup_page(vcpu, gfn)) {
+
+        if (user) {
+                /*
+                 * Usermode page faults won't be for page table updates.
+                 */
+                while ((page = kvm_mmu_lookup_page(vcpu, gfn)) != NULL) {
+                        pgprintk("%s: zap %lx %x\n",
+                                 __FUNCTION__, gfn, page->role.word);
+                        kvm_mmu_zap_page(vcpu, page);
+                }
+        } else if (kvm_mmu_lookup_page(vcpu, gfn)) {
                 pgprintk("%s: found shadow page for %lx, marking ro\n",
                          __FUNCTION__, gfn);
                 *write_pt = 1;