On 11.12.2017 07:35, Michael S. Tsirkin wrote:
> On Fri, Dec 08, 2017 at 05:54:18PM +0300, Ilya Maximets wrote:
>> On 07.12.2017 20:27, Michael S. Tsirkin wrote:
>>> On Thu, Dec 07, 2017 at 09:39:36AM +0300, Ilya Maximets wrote:
>>>> On 06.12.2017 19:45, Michael S. Tsirkin wrote:
>>>>> On Wed, Dec 06, 2017 at 04:06:18PM +0300, Ilya Maximets wrote:
>>>>>> In case virtio error occured after vhost_dev_close(), qemu will crash
>>>>>> in nested cleanup while checking IOMMU flag because dev->vdev already
>>>>>> set to zero and resources are already freed.
>>>>>>
>>>>>> Example:
>>>>>>
>>>>>> Program received signal SIGSEGV, Segmentation fault.
>>>>>> vhost_virtqueue_stop at hw/virtio/vhost.c:1155
>>>>>>
>>>>>> #0 vhost_virtqueue_stop at hw/virtio/vhost.c:1155
>>>>>> #1 vhost_dev_stop at hw/virtio/vhost.c:1594
>>>>>> #2 vhost_net_stop_one at hw/net/vhost_net.c:289
>>>>>> #3 vhost_net_stop at hw/net/vhost_net.c:368
>>>>>>
>>>>>> Nested call to vhost_net_stop(). First time was at #14.
>>>>>>
>>>>>> #4 virtio_net_vhost_status at hw/net/virtio-net.c:180
>>>>>> #5 virtio_net_set_status (status=79) at hw/net/virtio-net.c:254
>>>>>> #6 virtio_set_status at hw/virtio/virtio.c:1146
>>>>>> #7 virtio_error at hw/virtio/virtio.c:2455
>>>>>>
>>>>>> virtqueue_get_head() failed here.
>>>>>>
>>>>>> #8 virtqueue_get_head at hw/virtio/virtio.c:543
>>>>>> #9 virtqueue_drop_all at hw/virtio/virtio.c:984
>>>>>> #10 virtio_net_drop_tx_queue_data at hw/net/virtio-net.c:240
>>>>>> #11 virtio_bus_set_host_notifier at hw/virtio/virtio-bus.c:297
>>>>>> #12 vhost_dev_disable_notifiers at hw/virtio/vhost.c:1431
>>>>>>
>>>>>> vhost_dev_stop() was executed here. dev->vdev == NULL now.
>>>>>>
>>>>>> #13 vhost_net_stop_one at hw/net/vhost_net.c:290
>>>>>> #14 vhost_net_stop at hw/net/vhost_net.c:368
>>>>>> #15 virtio_net_vhost_status at hw/net/virtio-net.c:180
>>>>>> #16 virtio_net_set_status (status=15) at hw/net/virtio-net.c:254
>>>>>> #17 qmp_set_link ("hostnet0", up=false) at net/net.c:1430
>>>>>> #18 chr_closed_bh at net/vhost-user.c:214
>>>>>> #19 aio_bh_call at util/async.c:90
>>>>>> #20 aio_bh_poll at util/async.c:118
>>>>>> #21 aio_dispatch at util/aio-posix.c:429
>>>>>> #22 aio_ctx_dispatch at util/async.c:261
>>>>>> #23 g_main_context_dispatch
>>>>>> #24 glib_pollfds_poll at util/main-loop.c:213
>>>>>> #25 os_host_main_loop_wait at util/main-loop.c:261
>>>>>> #26 main_loop_wait at util/main-loop.c:515
>>>>>> #27 main_loop () at vl.c:1917
>>>>>> #28 main at vl.c:4795
>>>>>>
>>>>>> Above backtrace captured from qemu crash on vhost disconnect while
>>>>>> virtio driver in guest was in failed state.
>>>>>>
>>>>>> We can just add checking for 'vdev' in 'vhost_dev_has_iommu()' but
>>>>>> it will assert further trying to free already freed ioeventfds. The
>>>>>> real problem is that we're allowing nested calls to 'vhost_net_stop'.
>>>>>>
>>>>>> This patch is aimed to forbid nested calls to 'vhost_net_stop' to avoid
>>>>>> any possible double frees and segmentation faults doue to using of
>>>>>> already freed resources by setting 'vhost_started' flag to zero prior
>>>>>> to 'vhost_net_stop' call.
>>>>>>
>>>>>> Signed-off-by: Ilya Maximets <i.maxim...@samsung.com>
>>>>>> ---
>>>>>>
>>>>>> This issue was already addressed more than a year ago by the following
>>>>>> patch:
>>>>>> https://lists.gnu.org/archive/html/qemu-devel/2016-03/msg06732.html
>>>>>> but it was dropped without review due to not yet implemented
>>>>>> re-connection
>>>>>> of vhost-user. Re-connection implementation lately fixed most of the
>>>>>> nested calls, but few of them still exists. For example, above backtrace
>>>>>> captured after 'virtqueue_get_head()' failure on vhost-user
>>>>>> disconnection.
>>>>>>
>>>>>> hw/net/virtio-net.c | 2 +-
>>>>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>>
>>>>>> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
>>>>>> index 38674b0..4d95a18 100644
>>>>>> --- a/hw/net/virtio-net.c
>>>>>> +++ b/hw/net/virtio-net.c
>>>>>> @@ -177,8 +177,8 @@ static void virtio_net_vhost_status(VirtIONet *n,
>>>>>> uint8_t status)
>>>>>> n->vhost_started = 0;
>>>>>> }
>>>>>> } else {
>>>>>> - vhost_net_stop(vdev, n->nic->ncs, queues);
>>>>>> n->vhost_started = 0;
>>>>>> + vhost_net_stop(vdev, n->nic->ncs, queues);
>>>>>> }
>>>>>> }
>>>>>
>>>>> Well the wider context is
>>>>>
>>>>>
>>>>> n->vhost_started = 1;
>>>>> r = vhost_net_start(vdev, n->nic->ncs, queues);
>>>>> if (r < 0) {
>>>>> error_report("unable to start vhost net: %d: "
>>>>> "falling back on userspace virtio", -r);
>>>>> n->vhost_started = 0;
>>>>> }
>>>>> } else {
>>>>> vhost_net_stop(vdev, n->nic->ncs, queues);
>>>>> n->vhost_started = 0;
>>>>>
>>>>> So we set it to 1 before start, we should clear after stop.
>>>>
>>>> OK. I agree that clearing after is a bit safer. But in this case we need
>>>> a separate flag or other way to detect that we're already inside the
>>>> 'vhost_net_stop()'.
>>>>
>>>> What do you think about that old patch:
>>>> https://lists.gnu.org/archive/html/qemu-devel/2016-03/msg06732.html ?
>>>>
>>>> It implements the same thing but introduces additional flag. It even could
>>>> be still applicable.
>>>
>>> So the issue is that if someone calls set_status nested
>>> from within set_status, then status gets over-written
>>> because status is only set at the last moment,
>>> it's thus actually incorrect most of the time.
>>>
>>> But most people just want the new status,
>>> so it is better to keep that as part of status.
>>>
>>> I think something like the following should do the trick.
>>> Thoughts?
>>
>> Maybe you're right, but it's really hard to understand the patch below.
>> The function 'set_status' doesn't set the status anymore, instead we
>> need to set status manually before calling the 'set_status'.
>
> I don't understand this comment. status is set in virtio_set_status,
> same as it was previously. set_status is a callback.
>
> The issue was that if set_status callback changed the status
> again, it would overwrite the old value.
> Fix is to firsdt set status then do a callback.
>
> This means we can not pass new value as parameter any longer.
> We pass the old one, new value is in vdev->status.
>
> It's true that virtio_net_set_status checks vdev->status
> now, so it must be set correctly on unrealize.
>
>> That
>> looks very strange. Some of the functions gets 'old_status', others
>> the 'new_status'. I'm a bit confused.
>
> OK, fair enough. Fixed - let's pass old status everywhere,
> users that need the new one can get it from the vdev.
>
>> And it's not functional in current state:
>>
>> hw/net/virtio-net.c:264:28: error: ‘status’ undeclared
>
> Fixed too. new version below.
This doesn't fix the segmentation fault.
I have exactly same crash stacktrace:
#0 vhost_memory_unmap hw/virtio/vhost.c:446
#1 vhost_virtqueue_stop hw/virtio/vhost.c:1155
#2 vhost_dev_stop hw/virtio/vhost.c:1594
#3 vhost_net_stop_one hw/net/vhost_net.c:289
#4 vhost_net_stop hw/net/vhost_net.c:368
#5 virtio_net_vhost_status (old_status=15 '\017', n=0x5625f3901100) at
hw/net/virtio-net.c:180
#6 virtio_net_set_status (vdev=0x5625f3901100, old_status=<optimized out>) at
hw/net/virtio-net.c:254
#7 virtio_set_status (vdev=vdev@entry=0x5625f3901100, val=<optimized out>) at
hw/virtio/virtio.c:1152
#8 virtio_error (vdev=0x5625f3901100, fmt=fmt@entry=0x5625f014f688 "Guest says
index %u is available") at hw/virtio/virtio.c:2460
#9 virtqueue_get_head at hw/virtio/virtio.c:543
#10 virtqueue_drop_all hw/virtio/virtio.c:984
#11 virtio_net_drop_tx_queue_data hw/net/virtio-net.c:240
#12 virtio_bus_set_host_notifier at hw/virtio/virtio-bus.c:297
#13 vhost_dev_disable_notifiers at hw/virtio/vhost.c:1431
#14 vhost_net_stop_one at hw/net/vhost_net.c:290
#15 vhost_net_stop at hw/net/vhost_net.c:368
#16 virtio_net_vhost_status (old_status=15 '\017', n=0x5625f3901100) at
hw/net/virtio-net.c:180
#17 virtio_net_set_status (vdev=0x5625f3901100, old_status=<optimized out>) at
hw/net/virtio-net.c:254
#18 qmp_set_link at net/net.c:1430
#19 chr_closed_bh at net/vhost-user.c:214
#20 aio_bh_call at util/async.c:90
#21 aio_bh_poll at util/async.c:118
#22 aio_dispatch at util/aio-posix.c:429
#23 aio_ctx_dispatch at util/async.c:261
#24 g_main_context_dispatch () from /lib64/libglib-2.0.so.0
#25 glib_pollfds_poll () at util/main-loop.c:213
#26 os_host_main_loop_wait at util/main-loop.c:261
#27 main_loop_wait at util/main-loop.c:515
#28 main_loop () at vl.c:1917
#29 main
Actually the logic doesn't change. In function virtio_net_vhost_status():
- if ((virtio_net_started(n, status) && !nc->peer->link_down) ==
+ if ((virtio_net_started(n, vdev->status) && !nc->peer->link_down) ==
!!n->vhost_started) {
return;
}
previously new 'status' was checked and the new 'vdev->status' checked now.
It's the same condition that doesn't work because vhost_started flag is still
set to 1.
Anyway, nc->peer->link_down is true in our case, so there is no difference if
we'll change the vdev->status.
>>>
>>> Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
>
> Still completely untested, sorry about that - hope you can help here.
>
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index 098bdaa..f5d0ee1 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -115,7 +115,7 @@ typedef struct VirtioDeviceClass {
> void (*get_config)(VirtIODevice *vdev, uint8_t *config);
> void (*set_config)(VirtIODevice *vdev, const uint8_t *config);
> void (*reset)(VirtIODevice *vdev);
> - void (*set_status)(VirtIODevice *vdev, uint8_t val);
> + void (*set_status)(VirtIODevice *vdev, uint8_t old_status);
> /* For transitional devices, this is a bitmap of features
> * that are only exposed on the legacy interface but not
> * the modern one.
> diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
> index 05d1440..b8b07ba 100644
> --- a/hw/block/virtio-blk.c
> +++ b/hw/block/virtio-blk.c
> @@ -814,15 +814,15 @@ static uint64_t virtio_blk_get_features(VirtIODevice
> *vdev, uint64_t features,
> return features;
> }
>
> -static void virtio_blk_set_status(VirtIODevice *vdev, uint8_t status)
> +static void virtio_blk_set_status(VirtIODevice *vdev, uint8_t old_status)
> {
> VirtIOBlock *s = VIRTIO_BLK(vdev);
>
> - if (!(status & (VIRTIO_CONFIG_S_DRIVER | VIRTIO_CONFIG_S_DRIVER_OK))) {
> + if (!(vdev->status & (VIRTIO_CONFIG_S_DRIVER |
> VIRTIO_CONFIG_S_DRIVER_OK))) {
> assert(!s->dataplane_started);
> }
>
> - if (!(status & VIRTIO_CONFIG_S_DRIVER_OK)) {
> + if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
> return;
> }
>
> diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c
> index 9470bd7..881b1ff 100644
> --- a/hw/char/virtio-serial-bus.c
> +++ b/hw/char/virtio-serial-bus.c
> @@ -616,7 +616,7 @@ static void guest_reset(VirtIOSerial *vser)
> }
> }
>
> -static void set_status(VirtIODevice *vdev, uint8_t status)
> +static void set_status(VirtIODevice *vdev, uint8_t old_status)
> {
> VirtIOSerial *vser;
> VirtIOSerialPort *port;
> @@ -625,7 +625,7 @@ static void set_status(VirtIODevice *vdev, uint8_t status)
> port = find_port_by_id(vser, 0);
>
> if (port && !use_multiport(port->vser)
> - && (status & VIRTIO_CONFIG_S_DRIVER_OK)) {
> + && (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
> /*
> * Non-multiport guests won't be able to tell us guest
> * open/close status. Such guests can only have a port at id
> @@ -634,7 +634,7 @@ static void set_status(VirtIODevice *vdev, uint8_t status)
> */
> port->guest_connected = true;
> }
> - if (!(status & VIRTIO_CONFIG_S_DRIVER_OK)) {
> + if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
> guest_reset(vser);
> }
>
> diff --git a/hw/input/virtio-input.c b/hw/input/virtio-input.c
> index 0e42f0d..abb817b 100644
> --- a/hw/input/virtio-input.c
> +++ b/hw/input/virtio-input.c
> @@ -188,12 +188,12 @@ static uint64_t virtio_input_get_features(VirtIODevice
> *vdev, uint64_t f,
> return f;
> }
>
> -static void virtio_input_set_status(VirtIODevice *vdev, uint8_t val)
> +static void virtio_input_set_status(VirtIODevice *vdev, uint8_t old_val)
> {
> VirtIOInputClass *vic = VIRTIO_INPUT_GET_CLASS(vdev);
> VirtIOInput *vinput = VIRTIO_INPUT(vdev);
>
> - if (val & VIRTIO_CONFIG_S_DRIVER_OK) {
> + if (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK) {
> if (!vinput->active) {
> vinput->active = true;
> if (vic->change_active) {
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 38674b0..7851968 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -124,7 +124,7 @@ static void virtio_net_announce_timer(void *opaque)
> virtio_notify_config(vdev);
> }
>
> -static void virtio_net_vhost_status(VirtIONet *n, uint8_t status)
> +static void virtio_net_vhost_status(VirtIONet *n, uint8_t old_status)
> {
> VirtIODevice *vdev = VIRTIO_DEVICE(n);
> NetClientState *nc = qemu_get_queue(n->nic);
> @@ -134,7 +134,7 @@ static void virtio_net_vhost_status(VirtIONet *n, uint8_t
> status)
> return;
> }
>
> - if ((virtio_net_started(n, status) && !nc->peer->link_down) ==
> + if ((virtio_net_started(n, vdev->status) && !nc->peer->link_down) ==
> !!n->vhost_started) {
> return;
> }
> @@ -212,12 +212,12 @@ static bool virtio_net_set_vnet_endian(VirtIODevice
> *vdev, NetClientState *ncs,
> return false;
> }
>
> -static void virtio_net_vnet_endian_status(VirtIONet *n, uint8_t status)
> +static void virtio_net_vnet_endian_status(VirtIONet *n, uint8_t old_status)
> {
> VirtIODevice *vdev = VIRTIO_DEVICE(n);
> int queues = n->multiqueue ? n->max_queues : 1;
>
> - if (virtio_net_started(n, status)) {
> + if (virtio_net_started(n, vdev->status)) {
> /* Before using the device, we tell the network backend about the
> * endianness to use when parsing vnet headers. If the backend
> * can't do it, we fallback onto fixing the headers in the core
> @@ -225,7 +225,7 @@ static void virtio_net_vnet_endian_status(VirtIONet *n,
> uint8_t status)
> */
> n->needs_vnet_hdr_swap = virtio_net_set_vnet_endian(vdev,
> n->nic->ncs,
> queues, true);
> - } else if (virtio_net_started(n, vdev->status)) {
> + } else if (virtio_net_started(n, old_status)) {
> /* After using the device, we need to reset the network backend to
> * the default (guest native endianness), otherwise the guest may
> * lose network connectivity if it is rebooted into a different
> @@ -243,15 +243,15 @@ static void virtio_net_drop_tx_queue_data(VirtIODevice
> *vdev, VirtQueue *vq)
> }
> }
>
> -static void virtio_net_set_status(struct VirtIODevice *vdev, uint8_t status)
> +static void virtio_net_set_status(struct VirtIODevice *vdev, uint8_t
> old_status)
> {
> VirtIONet *n = VIRTIO_NET(vdev);
> VirtIONetQueue *q;
> int i;
> uint8_t queue_status;
>
> - virtio_net_vnet_endian_status(n, status);
> - virtio_net_vhost_status(n, status);
> + virtio_net_vnet_endian_status(n, old_status);
> + virtio_net_vhost_status(n, old_status);
>
> for (i = 0; i < n->max_queues; i++) {
> NetClientState *ncs = qemu_get_subqueue(n->nic, i);
> @@ -261,7 +261,7 @@ static void virtio_net_set_status(struct VirtIODevice
> *vdev, uint8_t status)
> if ((!n->multiqueue && i != 0) || i >= n->curr_queues) {
> queue_status = 0;
> } else {
> - queue_status = status;
> + queue_status = vdev->status;
> }
> queue_started =
> virtio_net_started(n, queue_status) && !n->vhost_started;
> @@ -2048,9 +2048,11 @@ static void virtio_net_device_unrealize(DeviceState
> *dev, Error **errp)
> VirtIODevice *vdev = VIRTIO_DEVICE(dev);
> VirtIONet *n = VIRTIO_NET(dev);
> int i, max_queues;
> + uint8_t old_status = vdev->status;
>
> /* This will stop vhost backend if appropriate. */
> - virtio_net_set_status(vdev, 0);
> + vdev->status = 0;
> + virtio_net_set_status(vdev, old_status);
>
> g_free(n->netclient_name);
> n->netclient_name = NULL;
> diff --git a/hw/scsi/vhost-scsi.c b/hw/scsi/vhost-scsi.c
> index 9c1bea8..5a561e4 100644
> --- a/hw/scsi/vhost-scsi.c
> +++ b/hw/scsi/vhost-scsi.c
> @@ -108,11 +108,11 @@ static void vhost_scsi_stop(VHostSCSI *s)
> vhost_scsi_common_stop(vsc);
> }
>
> -static void vhost_scsi_set_status(VirtIODevice *vdev, uint8_t val)
> +static void vhost_scsi_set_status(VirtIODevice *vdev, uint8_t old_val)
> {
> VHostSCSI *s = VHOST_SCSI(vdev);
> VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
> - bool start = (val & VIRTIO_CONFIG_S_DRIVER_OK);
> + bool start = vdev->status & VIRTIO_CONFIG_S_DRIVER_OK;
>
> if (vsc->dev.started == start) {
> return;
> diff --git a/hw/scsi/vhost-user-scsi.c b/hw/scsi/vhost-user-scsi.c
> index f7561e2..289a27e 100644
> --- a/hw/scsi/vhost-user-scsi.c
> +++ b/hw/scsi/vhost-user-scsi.c
> @@ -38,11 +38,11 @@ static const int user_feature_bits[] = {
> VHOST_INVALID_FEATURE_BIT
> };
>
> -static void vhost_user_scsi_set_status(VirtIODevice *vdev, uint8_t status)
> +static void vhost_user_scsi_set_status(VirtIODevice *vdev, uint8_t
> old_status)
> {
> VHostUserSCSI *s = (VHostUserSCSI *)vdev;
> VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
> - bool start = (status & VIRTIO_CONFIG_S_DRIVER_OK) && vdev->vm_running;
> + bool start = (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK) &&
> vdev->vm_running;
>
> if (vsc->dev.started == start) {
> return;
> diff --git a/hw/virtio/vhost-vsock.c b/hw/virtio/vhost-vsock.c
> index 5ec1c6a..d3f445b 100644
> --- a/hw/virtio/vhost-vsock.c
> +++ b/hw/virtio/vhost-vsock.c
> @@ -154,10 +154,10 @@ static void vhost_vsock_stop(VirtIODevice *vdev)
> vhost_dev_disable_notifiers(&vsock->vhost_dev, vdev);
> }
>
> -static void vhost_vsock_set_status(VirtIODevice *vdev, uint8_t status)
> +static void vhost_vsock_set_status(VirtIODevice *vdev, uint8_t old_status)
> {
> VHostVSock *vsock = VHOST_VSOCK(vdev);
> - bool should_start = status & VIRTIO_CONFIG_S_DRIVER_OK;
> + bool should_start = vdev->status & VIRTIO_CONFIG_S_DRIVER_OK;
>
> if (!vdev->vm_running) {
> should_start = false;
> @@ -370,11 +370,14 @@ static void vhost_vsock_device_unrealize(DeviceState
> *dev, Error **errp)
> {
> VirtIODevice *vdev = VIRTIO_DEVICE(dev);
> VHostVSock *vsock = VHOST_VSOCK(dev);
> + uint8_t old_status;
>
> vhost_vsock_post_load_timer_cleanup(vsock);
>
> /* This will stop vhost backend if appropriate. */
> - vhost_vsock_set_status(vdev, 0);
> + old_status = vdev->status;
> + vdev->status = 0;
> + vhost_vsock_set_status(vdev, old_status);
>
> vhost_dev_cleanup(&vsock->vhost_dev);
> virtio_cleanup(vdev);
> diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
> index 37cde38..84e897a 100644
> --- a/hw/virtio/virtio-balloon.c
> +++ b/hw/virtio/virtio-balloon.c
> @@ -468,12 +468,12 @@ static void virtio_balloon_device_reset(VirtIODevice
> *vdev)
> }
> }
>
> -static void virtio_balloon_set_status(VirtIODevice *vdev, uint8_t status)
> +static void virtio_balloon_set_status(VirtIODevice *vdev, uint8_t old_status)
> {
> VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
>
> if (!s->stats_vq_elem && vdev->vm_running &&
> - (status & VIRTIO_CONFIG_S_DRIVER_OK) && virtqueue_rewind(s->svq, 1))
> {
> + (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK) &&
> virtqueue_rewind(s->svq, 1)) {
> /* poll stats queue for the element we have discarded when the VM
> * was stopped */
> virtio_balloon_receive_stats(vdev, s->svq);
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index ad564b0..4981858 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -1128,6 +1128,8 @@ static int virtio_validate_features(VirtIODevice *vdev)
> int virtio_set_status(VirtIODevice *vdev, uint8_t val)
> {
> VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
> + uint8_t old_status;
> +
> trace_virtio_set_status(vdev, val);
>
> if (virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) {
> @@ -1140,10 +1142,13 @@ int virtio_set_status(VirtIODevice *vdev, uint8_t val)
> }
> }
> }
> +
> + old_status = vdev->status;
> + vdev->status = val;
> +
> if (k->set_status) {
> - k->set_status(vdev, val);
> + k->set_status(vdev, old_status);
> }
> - vdev->status = val;
> return 0;
> }
>
>
>
>
