KVM: Add make_page_dirty() to kvm_clear_guest_page()

Every write access to guest pages should be tracked.

Signed-off-by: Dor Laor <dor.laor@qumranet.com>
Signed-off-by: Izik Eidus <izike@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 8665531..8d6e55f 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -706,6 +706,7 @@
 
 	kunmap_atomic(page_virt, KM_USER0);
 	kvm_release_page(page);
+	mark_page_dirty(kvm, gfn);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(kvm_clear_guest_page);