Commit 26b9b5fe authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Anthony Liguori
Browse files

virtio: fix vhost handling 



Commit b1f416aa 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: default avatarStefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Reviewed-by: default avatarStefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
parent 22d48de6

hw/virtio-pci.c

+7 −7
Original line number Diff line number Diff line
@@ -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)

hw/virtio.c

+5 −2
Original line number Diff line number Diff line
@@ -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);

hw/virtio.h

+2 −1
Original line number Diff line number Diff line
@@ -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