[Qemu-devel] [PATCH v2] We should check the virtio_load return code

[Qemu-devel] [PATCH v2] We should check the virtio_load return code

[Orit Wasserman]

Otherwise we crash on error.
Instruction to reporduce the crash with migration:
1) run a guest with -device virtio-blk-pci,drive=drive_name,scsi=on
2) run destination with
   -device virtio-blk-pci,drive=drive_name,scsi=off ... -incoming ...
3) migrate from 1 to 2.

Signed-off-by: Ulrich Obergfell <uobergfe@redhat.com>
Signed-off-by: Orit Wasserman <owasserm@redhat.com>
---
 hw/virtio-balloon.c    |    6 +++++-
 hw/virtio-blk.c        |    7 ++++++-
 hw/virtio-net.c        |    6 +++++-
 hw/virtio-scsi.c       |    7 ++++++-
 hw/virtio-serial-bus.c |    6 +++++-
 5 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/hw/virtio-balloon.c b/hw/virtio-balloon.c
index ce9d2c9..075ed87 100644
--- a/hw/virtio-balloon.c
+++ b/hw/virtio-balloon.c
@@ -211,11 +211,15 @@ static void virtio_balloon_save(QEMUFile *f, void *opaque)
 static int virtio_balloon_load(QEMUFile *f, void *opaque, int version_id)
 {
     VirtIOBalloon *s = opaque;
+    int ret;
 
     if (version_id != 1)
         return -EINVAL;
 
-    virtio_load(&s->vdev, f);
+    ret = virtio_load(&s->vdev, f);
+    if (ret) {
+        return ret;
+    }
 
     s->num_pages = qemu_get_be32(f);
     s->actual = qemu_get_be32(f);
diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
index 49990f8..d4bb400 100644
--- a/hw/virtio-blk.c
+++ b/hw/virtio-blk.c
@@ -537,11 +537,16 @@ static void virtio_blk_save(QEMUFile *f, void *opaque)
 static int virtio_blk_load(QEMUFile *f, void *opaque, int version_id)
 {
     VirtIOBlock *s = opaque;
+    int ret;
 
     if (version_id != 2)
         return -EINVAL;
 
-    virtio_load(&s->vdev, f);
+    ret = virtio_load(&s->vdev, f);
+    if (ret) {
+        return ret;
+    }
+
     while (qemu_get_sbyte(f)) {
         VirtIOBlockReq *req = virtio_blk_alloc_request(s);
         qemu_get_buffer(f, (unsigned char*)&req->elem, sizeof(req->elem));
diff --git a/hw/virtio-net.c b/hw/virtio-net.c
index bc5e3a8..3f190d4 100644
--- a/hw/virtio-net.c
+++ b/hw/virtio-net.c
@@ -891,11 +891,15 @@ static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
 {
     VirtIONet *n = opaque;
     int i;
+    int ret;
 
     if (version_id < 2 || version_id > VIRTIO_NET_VM_VERSION)
         return -EINVAL;
 
-    virtio_load(&n->vdev, f);
+    ret = virtio_load(&n->vdev, f);
+    if (ret) {
+        return ret;
+    }
 
     qemu_get_buffer(f, n->mac, ETH_ALEN);
     n->tx_waiting = qemu_get_be32(f);
diff --git a/hw/virtio-scsi.c b/hw/virtio-scsi.c
index e607edc..9797847 100644
--- a/hw/virtio-scsi.c
+++ b/hw/virtio-scsi.c
@@ -558,7 +558,12 @@ static void virtio_scsi_save(QEMUFile *f, void *opaque)
 static int virtio_scsi_load(QEMUFile *f, void *opaque, int version_id)
 {
     VirtIOSCSI *s = opaque;
-    virtio_load(&s->vdev, f);
+    int ret;
+
+    ret = virtio_load(&s->vdev, f);
+    if (ret) {
+        return ret;
+    }
     return 0;
 }
 
diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c
index e22940e..4a33872 100644
--- a/hw/virtio-serial-bus.c
+++ b/hw/virtio-serial-bus.c
@@ -590,13 +590,17 @@ static int virtio_serial_load(QEMUFile *f, void *opaque, int version_id)
     VirtIOSerialPort *port;
     uint32_t max_nr_ports, nr_active_ports, ports_map;
     unsigned int i;
+    int ret;
 
     if (version_id > 3) {
         return -EINVAL;
     }
 
     /* The virtio device */
-    virtio_load(&s->vdev, f);
+    ret = virtio_load(&s->vdev, f);
+    if (ret) {
+        return ret;
+    }
 
     if (version_id < 2) {
         return 0;
-- 
1.7.6.5

Re: [Qemu-devel] [PATCH v2] We should check the virtio_load return code

[Amit Shah]

On (Thu) 01 Mar 2012 [13:28:08], Orit Wasserman wrote:
> Otherwise we crash on error.
> Instruction to reporduce the crash with migration:
> 1) run a guest with -device virtio-blk-pci,drive=drive_name,scsi=on
> 2) run destination with
>    -device virtio-blk-pci,drive=drive_name,scsi=off ... -incoming ...
> 3) migrate from 1 to 2.

Thanks.

Acked-by: Amit Shah <amit.shah@redhat.com>



		Amit

Re: [Qemu-devel] [PATCH v2] We should check the virtio_load return code

[Michael S. Tsirkin]

On Thu, Mar 01, 2012 at 01:28:08PM +0200, Orit Wasserman wrote:
> Otherwise we crash on error.
> Instruction to reporduce the crash with migration:
> 1) run a guest with -device virtio-blk-pci,drive=drive_name,scsi=on
> 2) run destination with
>    -device virtio-blk-pci,drive=drive_name,scsi=off ... -incoming ...
> 3) migrate from 1 to 2.
> 
> Signed-off-by: Ulrich Obergfell <uobergfe@redhat.com>
> Signed-off-by: Orit Wasserman <owasserm@redhat.com>


Acked-by: Michael S. Tsirkin <mst@redhat.com>

> ---
>  hw/virtio-balloon.c    |    6 +++++-
>  hw/virtio-blk.c        |    7 ++++++-
>  hw/virtio-net.c        |    6 +++++-
>  hw/virtio-scsi.c       |    7 ++++++-
>  hw/virtio-serial-bus.c |    6 +++++-
>  5 files changed, 27 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/virtio-balloon.c b/hw/virtio-balloon.c
> index ce9d2c9..075ed87 100644
> --- a/hw/virtio-balloon.c
> +++ b/hw/virtio-balloon.c
> @@ -211,11 +211,15 @@ static void virtio_balloon_save(QEMUFile *f, void *opaque)
>  static int virtio_balloon_load(QEMUFile *f, void *opaque, int version_id)
>  {
>      VirtIOBalloon *s = opaque;
> +    int ret;
>  
>      if (version_id != 1)
>          return -EINVAL;
>  
> -    virtio_load(&s->vdev, f);
> +    ret = virtio_load(&s->vdev, f);
> +    if (ret) {
> +        return ret;
> +    }
>  
>      s->num_pages = qemu_get_be32(f);
>      s->actual = qemu_get_be32(f);
> diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
> index 49990f8..d4bb400 100644
> --- a/hw/virtio-blk.c
> +++ b/hw/virtio-blk.c
> @@ -537,11 +537,16 @@ static void virtio_blk_save(QEMUFile *f, void *opaque)
>  static int virtio_blk_load(QEMUFile *f, void *opaque, int version_id)
>  {
>      VirtIOBlock *s = opaque;
> +    int ret;
>  
>      if (version_id != 2)
>          return -EINVAL;
>  
> -    virtio_load(&s->vdev, f);
> +    ret = virtio_load(&s->vdev, f);
> +    if (ret) {
> +        return ret;
> +    }
> +
>      while (qemu_get_sbyte(f)) {
>          VirtIOBlockReq *req = virtio_blk_alloc_request(s);
>          qemu_get_buffer(f, (unsigned char*)&req->elem, sizeof(req->elem));
> diff --git a/hw/virtio-net.c b/hw/virtio-net.c
> index bc5e3a8..3f190d4 100644
> --- a/hw/virtio-net.c
> +++ b/hw/virtio-net.c
> @@ -891,11 +891,15 @@ static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
>  {
>      VirtIONet *n = opaque;
>      int i;
> +    int ret;
>  
>      if (version_id < 2 || version_id > VIRTIO_NET_VM_VERSION)
>          return -EINVAL;
>  
> -    virtio_load(&n->vdev, f);
> +    ret = virtio_load(&n->vdev, f);
> +    if (ret) {
> +        return ret;
> +    }
>  
>      qemu_get_buffer(f, n->mac, ETH_ALEN);
>      n->tx_waiting = qemu_get_be32(f);
> diff --git a/hw/virtio-scsi.c b/hw/virtio-scsi.c
> index e607edc..9797847 100644
> --- a/hw/virtio-scsi.c
> +++ b/hw/virtio-scsi.c
> @@ -558,7 +558,12 @@ static void virtio_scsi_save(QEMUFile *f, void *opaque)
>  static int virtio_scsi_load(QEMUFile *f, void *opaque, int version_id)
>  {
>      VirtIOSCSI *s = opaque;
> -    virtio_load(&s->vdev, f);
> +    int ret;
> +
> +    ret = virtio_load(&s->vdev, f);
> +    if (ret) {
> +        return ret;
> +    }
>      return 0;
>  }
>  
> diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c
> index e22940e..4a33872 100644
> --- a/hw/virtio-serial-bus.c
> +++ b/hw/virtio-serial-bus.c
> @@ -590,13 +590,17 @@ static int virtio_serial_load(QEMUFile *f, void *opaque, int version_id)
>      VirtIOSerialPort *port;
>      uint32_t max_nr_ports, nr_active_ports, ports_map;
>      unsigned int i;
> +    int ret;
>  
>      if (version_id > 3) {
>          return -EINVAL;
>      }
>  
>      /* The virtio device */
> -    virtio_load(&s->vdev, f);
> +    ret = virtio_load(&s->vdev, f);
> +    if (ret) {
> +        return ret;
> +    }
>  
>      if (version_id < 2) {
>          return 0;
> -- 
> 1.7.6.5

Re: [Qemu-devel] [PATCH v2] We should check the virtio_load return code

[Ulrich Obergfell]

While I investigated and reproduced the problem, the qemu process itself
did not crash/abort. I observed that a Linux guest (KVM virtual machine)
became unresponsive after a migration because requests to a virtio disk
did not complete.

If virtio_load() returns via the following section of code ...

    if (virtio_set_features(vdev, features) < 0) {
        supported_features = vdev->binding->get_features(vdev->binding_opaque);
        error_report("Features 0x%x unsupported. Allowed features: 0x%x",
                     features, supported_features);
        return -1;
    }

... various data structures are not fully set up. Execution of the above
code is - for example - triggered by passing "scsi=on" to the source qemu
and "scsi=off" to the destination qemu process. Since the data structures
are in an incomplete state, virtio disk requests from the guest cannot be
processed.


Regards,

Uli


----- Original Message -----
> From: "Orit Wasserman" <owasserm@redhat.com>
...
> Sent: Thursday, March 1, 2012 12:28:08 PM
> Subject: [PATCH v2] We should check the virtio_load return code
> 
> Otherwise we crash on error.
> Instruction to reporduce the crash with migration:
> 1) run a guest with -device virtio-blk-pci,drive=drive_name,scsi=on
> 2) run destination with
>    -device virtio-blk-pci,drive=drive_name,scsi=off ... -incoming ...
> 3) migrate from 1 to 2.
> 
> Signed-off-by: Ulrich Obergfell <uobergfe@redhat.com>
> Signed-off-by: Orit Wasserman <owasserm@redhat.com>
...