KVM: Remove write access permissions when dirty-page-logging is enabled

Enabling dirty page logging is done using KVM_SET_MEMORY_REGION ioctl.
If the memory region already exists, we need to remove write accesses,
so writes will be caught, and dirty pages will be logged.
Signed-off-by: Uri Lublin <uril@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

drivers/kvm/kvm_main.c

@@ -748,6 +748,8 @@ static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
 		vcpu = vcpu_load_slot(kvm, i);
 		if (!vcpu)
 			continue;
+		if (new.flags & KVM_MEM_LOG_DIRTY_PAGES)
+			do_remove_write_access(vcpu, mem->slot);
 		kvm_mmu_reset_context(vcpu);
 		vcpu_put(vcpu);
 	}