From 26b9b5fe17cc1b6be2e8bf8b9d16094f420bb8ad Mon Sep 17 00:00:00 2001

From: Paolo Bonzini <pbonzini@redhat.com>

Date: Mon, 6 Aug 2012 15:26:14 +0200

Subject: [PATCH] virtio: fix vhost handling

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>

Tested-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

---

 hw/virtio-pci.c |   14 +++++++-------

 hw/virtio.c     |    7 +++++--

 hw/virtio.h     |    3 ++-

 3 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c

index 3ab9747..125eded 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..209c763 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..7a4f564 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

-- 

1.7.10.4