[PATCH 27/33] KVM: MMU: Treat user-mode faults as a hint that a page is no longer a page table

Avi Kivity
2007-01-04T16:16:25Z

Index: linux-2.6/drivers/kvm/paging_tmpl.h
===================================================================
--- linux-2.6.orig/drivers/kvm/paging_tmpl.h
+++ linux-2.6/drivers/kvm/paging_tmpl.h
@@ -271,6 +271,7 @@ static int FNAME(fix_write_pf)(struct kv
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 kv
}

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;