Patchwork virtio: fix vhost handling

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Submitter Paolo Bonzini
Date Aug. 6, 2012, 2:56 p.m.
Message ID <1344264970-25242-1-git-send-email-pbonzini@redhat.com>
Download mbox | patch
Permalink /patch/175381/
State New
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Comments

Paolo Bonzini - Aug. 6, 2012, 2:56 p.m.
Commit b1f416aa8d870fab71030abc9401cfc77b948e8e breaks vhost_net
because it always registers the virtio_pci_host_notifier_read() handler
function on the ioeventfd, even when vhost_net.ko is using the ioeventfd.
The result is both QEMU and vhost_net.ko polling on the same eventfd
and the virtio_net.ko guest driver seeing inconsistent results:

  # ifconfig eth0 192.168.0.1 netmask 255.255.255.0
  virtio_net virtio0: output:id 0 is not a head!

To fix this, proceed the same as we do for irqfd: add a parameter to
virtio_queue_set_host_notifier_fd_handler and in that case only set
the notifier, not the handler.

Cc: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
        The patch is a bit different from what I posted before,
        so I didn't add Stefan's *-by tags.

 hw/virtio-pci.c | 14 +++++++-------
 hw/virtio.c     |  7 +++++--
 hw/virtio.h     |  3 ++-
 3 file modificati, 14 inserzioni(+), 10 rimozioni(-)
Stefan Hajnoczi - Aug. 6, 2012, 3:47 p.m.
On Mon, Aug 6, 2012 at 3:56 PM, Paolo Bonzini <pbonzini@redhat.com> wrote:
> Commit b1f416aa8d870fab71030abc9401cfc77b948e8e breaks vhost_net
> because it always registers the virtio_pci_host_notifier_read() handler
> function on the ioeventfd, even when vhost_net.ko is using the ioeventfd.
> The result is both QEMU and vhost_net.ko polling on the same eventfd
> and the virtio_net.ko guest driver seeing inconsistent results:
>
>   # ifconfig eth0 192.168.0.1 netmask 255.255.255.0
>   virtio_net virtio0: output:id 0 is not a head!
>
> To fix this, proceed the same as we do for irqfd: add a parameter to
> virtio_queue_set_host_notifier_fd_handler and in that case only set
> the notifier, not the handler.
>
> Cc: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>         The patch is a bit different from what I posted before,
>         so I didn't add Stefan's *-by tags.
>
>  hw/virtio-pci.c | 14 +++++++-------
>  hw/virtio.c     |  7 +++++--
>  hw/virtio.h     |  3 ++-
>  3 file modificati, 14 inserzioni(+), 10 rimozioni(-)

Tested-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Michael S. Tsirkin - Aug. 12, 2012, 8:58 a.m.
On Mon, Aug 06, 2012 at 04:56:10PM +0200, Paolo Bonzini wrote:
> Commit b1f416aa8d870fab71030abc9401cfc77b948e8e breaks vhost_net
> because it always registers the virtio_pci_host_notifier_read() handler
> function on the ioeventfd, even when vhost_net.ko is using the ioeventfd.
> The result is both QEMU and vhost_net.ko polling on the same eventfd
> and the virtio_net.ko guest driver seeing inconsistent results:
> 
>   # ifconfig eth0 192.168.0.1 netmask 255.255.255.0
>   virtio_net virtio0: output:id 0 is not a head!
> 
> To fix this, proceed the same as we do for irqfd: add a parameter to
> virtio_queue_set_host_notifier_fd_handler and in that case only set
> the notifier, not the handler.
> 
> Cc: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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

Anthony, could you pick this bugfix up please?

> ---
>         The patch is a bit different from what I posted before,
>         so I didn't add Stefan's *-by tags.
> 
>  hw/virtio-pci.c | 14 +++++++-------
>  hw/virtio.c     |  7 +++++--
>  hw/virtio.h     |  3 ++-
>  3 file modificati, 14 inserzioni(+), 10 rimozioni(-)
> 
> diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
> index 3ab9747..6133626 100644
> --- a/hw/virtio-pci.c
> +++ b/hw/virtio-pci.c
> @@ -160,7 +160,7 @@ static int virtio_pci_load_queue(void * opaque, int n, QEMUFile *f)
>  }
>  
>  static int virtio_pci_set_host_notifier_internal(VirtIOPCIProxy *proxy,
> -                                                 int n, bool assign)
> +                                                 int n, bool assign, bool set_handler)
>  {
>      VirtQueue *vq = virtio_get_queue(proxy->vdev, n);
>      EventNotifier *notifier = virtio_queue_get_host_notifier(vq);
> @@ -173,13 +173,13 @@ static int virtio_pci_set_host_notifier_internal(VirtIOPCIProxy *proxy,
>                           __func__, r);
>              return r;
>          }
> -        virtio_queue_set_host_notifier_fd_handler(vq, true);
> +        virtio_queue_set_host_notifier_fd_handler(vq, true, set_handler);
>          memory_region_add_eventfd(&proxy->bar, VIRTIO_PCI_QUEUE_NOTIFY, 2,
>                                    true, n, notifier);
>      } else {
>          memory_region_del_eventfd(&proxy->bar, VIRTIO_PCI_QUEUE_NOTIFY, 2,
>                                    true, n, notifier);
> -        virtio_queue_set_host_notifier_fd_handler(vq, false);
> +        virtio_queue_set_host_notifier_fd_handler(vq, false, false);
>          event_notifier_cleanup(notifier);
>      }
>      return r;
> @@ -200,7 +200,7 @@ static void virtio_pci_start_ioeventfd(VirtIOPCIProxy *proxy)
>              continue;
>          }
>  
> -        r = virtio_pci_set_host_notifier_internal(proxy, n, true);
> +        r = virtio_pci_set_host_notifier_internal(proxy, n, true, true);
>          if (r < 0) {
>              goto assign_error;
>          }
> @@ -214,7 +214,7 @@ assign_error:
>              continue;
>          }
>  
> -        r = virtio_pci_set_host_notifier_internal(proxy, n, false);
> +        r = virtio_pci_set_host_notifier_internal(proxy, n, false, false);
>          assert(r >= 0);
>      }
>      proxy->ioeventfd_started = false;
> @@ -235,7 +235,7 @@ static void virtio_pci_stop_ioeventfd(VirtIOPCIProxy *proxy)
>              continue;
>          }
>  
> -        r = virtio_pci_set_host_notifier_internal(proxy, n, false);
> +        r = virtio_pci_set_host_notifier_internal(proxy, n, false, false);
>          assert(r >= 0);
>      }
>      proxy->ioeventfd_started = false;
> @@ -683,7 +683,7 @@ static int virtio_pci_set_host_notifier(void *opaque, int n, bool assign)
>       * currently only stops on status change away from ok,
>       * reset, vmstop and such. If we do add code to start here,
>       * need to check vmstate, device state etc. */
> -    return virtio_pci_set_host_notifier_internal(proxy, n, assign);
> +    return virtio_pci_set_host_notifier_internal(proxy, n, assign, false);
>  }
>  
>  static void virtio_pci_vmstate_change(void *opaque, bool running)
> diff --git a/hw/virtio.c b/hw/virtio.c
> index d146f86..89e6d6f 100644
> --- a/hw/virtio.c
> +++ b/hw/virtio.c
> @@ -1021,13 +1021,16 @@ static void virtio_queue_host_notifier_read(EventNotifier *n)
>      }
>  }
>  
> -void virtio_queue_set_host_notifier_fd_handler(VirtQueue *vq, bool assign)
> +void virtio_queue_set_host_notifier_fd_handler(VirtQueue *vq, bool assign,
> +                                               bool set_handler)
>  {
> -    if (assign) {
> +    if (assign && set_handler) {
>          event_notifier_set_handler(&vq->host_notifier,
>                                     virtio_queue_host_notifier_read);
>      } else {
>          event_notifier_set_handler(&vq->host_notifier, NULL);
> +    }
> +    if (!assign) {
>          /* Test and clear notifier before after disabling event,
>           * in case poll callback didn't have time to run. */
>          virtio_queue_host_notifier_read(&vq->host_notifier);
> diff --git a/hw/virtio.h b/hw/virtio.h
> index f8b5535..d6a8ea3 100644
> --- a/hw/virtio.h
> +++ b/hw/virtio.h
> @@ -233,7 +233,8 @@ EventNotifier *virtio_queue_get_guest_notifier(VirtQueue *vq);
>  void virtio_queue_set_guest_notifier_fd_handler(VirtQueue *vq, bool assign,
>                                                  bool with_irqfd);
>  EventNotifier *virtio_queue_get_host_notifier(VirtQueue *vq);
> -void virtio_queue_set_host_notifier_fd_handler(VirtQueue *vq, bool assign);
> +void virtio_queue_set_host_notifier_fd_handler(VirtQueue *vq, bool assign,
> +                                               bool set_handler);
>  void virtio_queue_notify_vq(VirtQueue *vq);
>  void virtio_irq(VirtQueue *vq);
>  #endif
> -- 
> 1.7.11.2
>
Michael Tokarev - Aug. 12, 2012, 10:08 a.m.
On 06.08.2012 18:56, Paolo Bonzini wrote:
> Commit b1f416aa8d870fab71030abc9401cfc77b948e8e breaks vhost_net
> because it always registers the virtio_pci_host_notifier_read() handler
> function on the ioeventfd, even when vhost_net.ko is using the ioeventfd.
> The result is both QEMU and vhost_net.ko polling on the same eventfd
> and the virtio_net.ko guest driver seeing inconsistent results:
> 
>   # ifconfig eth0 192.168.0.1 netmask 255.255.255.0
>   virtio_net virtio0: output:id 0 is not a head!
> 
> To fix this, proceed the same as we do for irqfd: add a parameter to
> virtio_queue_set_host_notifier_fd_handler and in that case only set
> the notifier, not the handler.

Stable-1.1 material?  The mentioned commit is included into 1.1 release.

Thanks,

/mjt

> Cc: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>         The patch is a bit different from what I posted before,
>         so I didn't add Stefan's *-by tags.
> 
>  hw/virtio-pci.c | 14 +++++++-------
>  hw/virtio.c     |  7 +++++--
>  hw/virtio.h     |  3 ++-
>  3 file modificati, 14 inserzioni(+), 10 rimozioni(-)
> 
> diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
> index 3ab9747..6133626 100644
> --- a/hw/virtio-pci.c
> +++ b/hw/virtio-pci.c
> @@ -160,7 +160,7 @@ static int virtio_pci_load_queue(void * opaque, int n, QEMUFile *f)
>  }
>  
>  static int virtio_pci_set_host_notifier_internal(VirtIOPCIProxy *proxy,
> -                                                 int n, bool assign)
> +                                                 int n, bool assign, bool set_handler)
>  {
>      VirtQueue *vq = virtio_get_queue(proxy->vdev, n);
>      EventNotifier *notifier = virtio_queue_get_host_notifier(vq);
> @@ -173,13 +173,13 @@ static int virtio_pci_set_host_notifier_internal(VirtIOPCIProxy *proxy,
>                           __func__, r);
>              return r;
>          }
> -        virtio_queue_set_host_notifier_fd_handler(vq, true);
> +        virtio_queue_set_host_notifier_fd_handler(vq, true, set_handler);
>          memory_region_add_eventfd(&proxy->bar, VIRTIO_PCI_QUEUE_NOTIFY, 2,
>                                    true, n, notifier);
>      } else {
>          memory_region_del_eventfd(&proxy->bar, VIRTIO_PCI_QUEUE_NOTIFY, 2,
>                                    true, n, notifier);
> -        virtio_queue_set_host_notifier_fd_handler(vq, false);
> +        virtio_queue_set_host_notifier_fd_handler(vq, false, false);
>          event_notifier_cleanup(notifier);
>      }
>      return r;
> @@ -200,7 +200,7 @@ static void virtio_pci_start_ioeventfd(VirtIOPCIProxy *proxy)
>              continue;
>          }
>  
> -        r = virtio_pci_set_host_notifier_internal(proxy, n, true);
> +        r = virtio_pci_set_host_notifier_internal(proxy, n, true, true);
>          if (r < 0) {
>              goto assign_error;
>          }
> @@ -214,7 +214,7 @@ assign_error:
>              continue;
>          }
>  
> -        r = virtio_pci_set_host_notifier_internal(proxy, n, false);
> +        r = virtio_pci_set_host_notifier_internal(proxy, n, false, false);
>          assert(r >= 0);
>      }
>      proxy->ioeventfd_started = false;
> @@ -235,7 +235,7 @@ static void virtio_pci_stop_ioeventfd(VirtIOPCIProxy *proxy)
>              continue;
>          }
>  
> -        r = virtio_pci_set_host_notifier_internal(proxy, n, false);
> +        r = virtio_pci_set_host_notifier_internal(proxy, n, false, false);
>          assert(r >= 0);
>      }
>      proxy->ioeventfd_started = false;
> @@ -683,7 +683,7 @@ static int virtio_pci_set_host_notifier(void *opaque, int n, bool assign)
>       * currently only stops on status change away from ok,
>       * reset, vmstop and such. If we do add code to start here,
>       * need to check vmstate, device state etc. */
> -    return virtio_pci_set_host_notifier_internal(proxy, n, assign);
> +    return virtio_pci_set_host_notifier_internal(proxy, n, assign, false);
>  }
>  
>  static void virtio_pci_vmstate_change(void *opaque, bool running)
> diff --git a/hw/virtio.c b/hw/virtio.c
> index d146f86..89e6d6f 100644
> --- a/hw/virtio.c
> +++ b/hw/virtio.c
> @@ -1021,13 +1021,16 @@ static void virtio_queue_host_notifier_read(EventNotifier *n)
>      }
>  }
>  
> -void virtio_queue_set_host_notifier_fd_handler(VirtQueue *vq, bool assign)
> +void virtio_queue_set_host_notifier_fd_handler(VirtQueue *vq, bool assign,
> +                                               bool set_handler)
>  {
> -    if (assign) {
> +    if (assign && set_handler) {
>          event_notifier_set_handler(&vq->host_notifier,
>                                     virtio_queue_host_notifier_read);
>      } else {
>          event_notifier_set_handler(&vq->host_notifier, NULL);
> +    }
> +    if (!assign) {
>          /* Test and clear notifier before after disabling event,
>           * in case poll callback didn't have time to run. */
>          virtio_queue_host_notifier_read(&vq->host_notifier);
> diff --git a/hw/virtio.h b/hw/virtio.h
> index f8b5535..d6a8ea3 100644
> --- a/hw/virtio.h
> +++ b/hw/virtio.h
> @@ -233,7 +233,8 @@ EventNotifier *virtio_queue_get_guest_notifier(VirtQueue *vq);
>  void virtio_queue_set_guest_notifier_fd_handler(VirtQueue *vq, bool assign,
>                                                  bool with_irqfd);
>  EventNotifier *virtio_queue_get_host_notifier(VirtQueue *vq);
> -void virtio_queue_set_host_notifier_fd_handler(VirtQueue *vq, bool assign);
> +void virtio_queue_set_host_notifier_fd_handler(VirtQueue *vq, bool assign,
> +                                               bool set_handler);
>  void virtio_queue_notify_vq(VirtQueue *vq);
>  void virtio_irq(VirtQueue *vq);
>  #endif
Paolo Bonzini - Aug. 18, 2012, 6:56 p.m.
Il 12/08/2012 12:08, Michael Tokarev ha scritto:
>> > Commit b1f416aa8d870fab71030abc9401cfc77b948e8e breaks vhost_net
>> > because it always registers the virtio_pci_host_notifier_read() handler
>> > function on the ioeventfd, even when vhost_net.ko is using the ioeventfd.
>> > The result is both QEMU and vhost_net.ko polling on the same eventfd
>> > and the virtio_net.ko guest driver seeing inconsistent results:
>> > 
>> >   # ifconfig eth0 192.168.0.1 netmask 255.255.255.0
>> >   virtio_net virtio0: output:id 0 is not a head!
>> > 
>> > To fix this, proceed the same as we do for irqfd: add a parameter to
>> > virtio_queue_set_host_notifier_fd_handler and in that case only set
>> > the notifier, not the handler.
> Stable-1.1 material?  The mentioned commit is included into 1.1 release.

Are you sure?

Paolo
Michael Tokarev - Aug. 18, 2012, 6:58 p.m.
On 18.08.2012 22:56, Paolo Bonzini wrote:
> Il 12/08/2012 12:08, Michael Tokarev ha scritto:
>>>> Commit b1f416aa8d870fab71030abc9401cfc77b948e8e breaks vhost_net
>>>> because it always registers the virtio_pci_host_notifier_read() handler
>>>> function on the ioeventfd, even when vhost_net.ko is using the ioeventfd.
>>>> The result is both QEMU and vhost_net.ko polling on the same eventfd
>>>> and the virtio_net.ko guest driver seeing inconsistent results:
>>>>
>>>>   # ifconfig eth0 192.168.0.1 netmask 255.255.255.0
>>>>   virtio_net virtio0: output:id 0 is not a head!
>>>>
>>>> To fix this, proceed the same as we do for irqfd: add a parameter to
>>>> virtio_queue_set_host_notifier_fd_handler and in that case only set
>>>> the notifier, not the handler.
>> Stable-1.1 material?  The mentioned commit is included into 1.1 release.
> 
> Are you sure?

Oh. Indeed. It is 625 commits after 1.1.0 :)  Sorry for the noize.

/mjt

Patch

diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
index 3ab9747..6133626 100644
--- a/hw/virtio-pci.c
+++ b/hw/virtio-pci.c
@@ -160,7 +160,7 @@  static int virtio_pci_load_queue(void * opaque, int n, QEMUFile *f)
 }
 
 static int virtio_pci_set_host_notifier_internal(VirtIOPCIProxy *proxy,
-                                                 int n, bool assign)
+                                                 int n, bool assign, bool set_handler)
 {
     VirtQueue *vq = virtio_get_queue(proxy->vdev, n);
     EventNotifier *notifier = virtio_queue_get_host_notifier(vq);
@@ -173,13 +173,13 @@  static int virtio_pci_set_host_notifier_internal(VirtIOPCIProxy *proxy,
                          __func__, r);
             return r;
         }
-        virtio_queue_set_host_notifier_fd_handler(vq, true);
+        virtio_queue_set_host_notifier_fd_handler(vq, true, set_handler);
         memory_region_add_eventfd(&proxy->bar, VIRTIO_PCI_QUEUE_NOTIFY, 2,
                                   true, n, notifier);
     } else {
         memory_region_del_eventfd(&proxy->bar, VIRTIO_PCI_QUEUE_NOTIFY, 2,
                                   true, n, notifier);
-        virtio_queue_set_host_notifier_fd_handler(vq, false);
+        virtio_queue_set_host_notifier_fd_handler(vq, false, false);
         event_notifier_cleanup(notifier);
     }
     return r;
@@ -200,7 +200,7 @@  static void virtio_pci_start_ioeventfd(VirtIOPCIProxy *proxy)
             continue;
         }
 
-        r = virtio_pci_set_host_notifier_internal(proxy, n, true);
+        r = virtio_pci_set_host_notifier_internal(proxy, n, true, true);
         if (r < 0) {
             goto assign_error;
         }
@@ -214,7 +214,7 @@  assign_error:
             continue;
         }
 
-        r = virtio_pci_set_host_notifier_internal(proxy, n, false);
+        r = virtio_pci_set_host_notifier_internal(proxy, n, false, false);
         assert(r >= 0);
     }
     proxy->ioeventfd_started = false;
@@ -235,7 +235,7 @@  static void virtio_pci_stop_ioeventfd(VirtIOPCIProxy *proxy)
             continue;
         }
 
-        r = virtio_pci_set_host_notifier_internal(proxy, n, false);
+        r = virtio_pci_set_host_notifier_internal(proxy, n, false, false);
         assert(r >= 0);
     }
     proxy->ioeventfd_started = false;
@@ -683,7 +683,7 @@  static int virtio_pci_set_host_notifier(void *opaque, int n, bool assign)
      * currently only stops on status change away from ok,
      * reset, vmstop and such. If we do add code to start here,
      * need to check vmstate, device state etc. */
-    return virtio_pci_set_host_notifier_internal(proxy, n, assign);
+    return virtio_pci_set_host_notifier_internal(proxy, n, assign, false);
 }
 
 static void virtio_pci_vmstate_change(void *opaque, bool running)
diff --git a/hw/virtio.c b/hw/virtio.c
index d146f86..89e6d6f 100644
--- a/hw/virtio.c
+++ b/hw/virtio.c
@@ -1021,13 +1021,16 @@  static void virtio_queue_host_notifier_read(EventNotifier *n)
     }
 }
 
-void virtio_queue_set_host_notifier_fd_handler(VirtQueue *vq, bool assign)
+void virtio_queue_set_host_notifier_fd_handler(VirtQueue *vq, bool assign,
+                                               bool set_handler)
 {
-    if (assign) {
+    if (assign && set_handler) {
         event_notifier_set_handler(&vq->host_notifier,
                                    virtio_queue_host_notifier_read);
     } else {
         event_notifier_set_handler(&vq->host_notifier, NULL);
+    }
+    if (!assign) {
         /* Test and clear notifier before after disabling event,
          * in case poll callback didn't have time to run. */
         virtio_queue_host_notifier_read(&vq->host_notifier);
diff --git a/hw/virtio.h b/hw/virtio.h
index f8b5535..d6a8ea3 100644
--- a/hw/virtio.h
+++ b/hw/virtio.h
@@ -233,7 +233,8 @@  EventNotifier *virtio_queue_get_guest_notifier(VirtQueue *vq);
 void virtio_queue_set_guest_notifier_fd_handler(VirtQueue *vq, bool assign,
                                                 bool with_irqfd);
 EventNotifier *virtio_queue_get_host_notifier(VirtQueue *vq);
-void virtio_queue_set_host_notifier_fd_handler(VirtQueue *vq, bool assign);
+void virtio_queue_set_host_notifier_fd_handler(VirtQueue *vq, bool assign,
+                                               bool set_handler);
 void virtio_queue_notify_vq(VirtQueue *vq);
 void virtio_irq(VirtQueue *vq);
 #endif