This reverts commit b1f416aa8d870fab71030abc9401cfc77b948e8e. The above commit 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! Cc: Paolo Bonzini <pbonz...@redhat.com> Signed-off-by: Stefan Hajnoczi <stefa...@linux.vnet.ibm.com> --- hw/virtio-pci.c | 36 ++++++++++++++++++++++++++++++++++-- hw/virtio.c | 22 ---------------------- hw/virtio.h | 1 - 3 files changed, 34 insertions(+), 25 deletions(-) diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c index 3ab9747..34262cb 100644 --- a/hw/virtio-pci.c +++ b/hw/virtio-pci.c @@ -173,18 +173,46 @@ static int virtio_pci_set_host_notifier_internal(VirtIOPCIProxy *proxy, __func__, r); return r; } - virtio_queue_set_host_notifier_fd_handler(vq, true); 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); + /* Handle the race condition where the guest kicked and we deassigned + * before we got around to handling the kick. + */ + if (event_notifier_test_and_clear(notifier)) { + virtio_queue_notify_vq(vq); + } + event_notifier_cleanup(notifier); } return r; } +static void virtio_pci_host_notifier_read(void *opaque) +{ + VirtQueue *vq = opaque; + EventNotifier *n = virtio_queue_get_host_notifier(vq); + if (event_notifier_test_and_clear(n)) { + virtio_queue_notify_vq(vq); + } +} + +static void virtio_pci_set_host_notifier_fd_handler(VirtIOPCIProxy *proxy, + int n, bool assign) +{ + VirtQueue *vq = virtio_get_queue(proxy->vdev, n); + EventNotifier *notifier = virtio_queue_get_host_notifier(vq); + if (assign) { + qemu_set_fd_handler(event_notifier_get_fd(notifier), + virtio_pci_host_notifier_read, NULL, vq); + } else { + qemu_set_fd_handler(event_notifier_get_fd(notifier), + NULL, NULL, NULL); + } +} + static void virtio_pci_start_ioeventfd(VirtIOPCIProxy *proxy) { int n, r; @@ -204,6 +232,8 @@ static void virtio_pci_start_ioeventfd(VirtIOPCIProxy *proxy) if (r < 0) { goto assign_error; } + + virtio_pci_set_host_notifier_fd_handler(proxy, n, true); } proxy->ioeventfd_started = true; return; @@ -214,6 +244,7 @@ assign_error: continue; } + virtio_pci_set_host_notifier_fd_handler(proxy, n, false); r = virtio_pci_set_host_notifier_internal(proxy, n, false); assert(r >= 0); } @@ -235,6 +266,7 @@ static void virtio_pci_stop_ioeventfd(VirtIOPCIProxy *proxy) continue; } + virtio_pci_set_host_notifier_fd_handler(proxy, n, false); r = virtio_pci_set_host_notifier_internal(proxy, n, false); assert(r >= 0); } diff --git a/hw/virtio.c b/hw/virtio.c index d146f86..1fab9bb 100644 --- a/hw/virtio.c +++ b/hw/virtio.c @@ -1012,28 +1012,6 @@ EventNotifier *virtio_queue_get_guest_notifier(VirtQueue *vq) { return &vq->guest_notifier; } - -static void virtio_queue_host_notifier_read(EventNotifier *n) -{ - VirtQueue *vq = container_of(n, VirtQueue, host_notifier); - if (event_notifier_test_and_clear(n)) { - virtio_queue_notify_vq(vq); - } -} - -void virtio_queue_set_host_notifier_fd_handler(VirtQueue *vq, bool assign) -{ - if (assign) { - event_notifier_set_handler(&vq->host_notifier, - virtio_queue_host_notifier_read); - } else { - event_notifier_set_handler(&vq->host_notifier, NULL); - /* 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); - } -} - EventNotifier *virtio_queue_get_host_notifier(VirtQueue *vq) { return &vq->host_notifier; diff --git a/hw/virtio.h b/hw/virtio.h index f8b5535..6ae5b6e 100644 --- a/hw/virtio.h +++ b/hw/virtio.h @@ -233,7 +233,6 @@ 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_notify_vq(VirtQueue *vq); void virtio_irq(VirtQueue *vq); #endif -- 1.7.10.4