KVM: MMU: Flush tlbs after clearing write permission when accessing dirty log

Otherwise, the cpu may allow writes to the tracked pages, and we lose
some display bits or fail to migrate correctly.
Signed-off-by: Avi Kivity <avi@qumranet.com>

arch/x86/kvm/mmu.c

@@ -2111,6 +2111,7 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
 			if (pt[i] & PT_WRITABLE_MASK)
 				pt[i] &= ~PT_WRITABLE_MASK;
 	}
+	kvm_flush_remote_tlbs(kvm);
 	spin_unlock(&kvm->mmu_lock);
 }