virtio-blk: multiqueue batch notify
The batch notification BH needs to know which virtqueues to notify when multiqueue is enabled. Use a bitmap to track the virtqueues with pending notifications. At this point there is only one virtqueue so hard-code virtqueue index 0. A later patch will switch to real virtqueue indices. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Message-id: 1466511196-12612-3-git-send-email-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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@ -34,8 +34,8 @@ struct VirtIOBlockDataPlane {
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VirtIODevice *vdev;
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VirtQueue *vq; /* virtqueue vring */
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EventNotifier *guest_notifier; /* irq */
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QEMUBH *bh; /* bh for guest notification */
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unsigned long *batch_notify_vqs;
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/* Note that these EventNotifiers are assigned by value. This is
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* fine as long as you do not call event_notifier_cleanup on them
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@ -49,18 +49,34 @@ struct VirtIOBlockDataPlane {
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/* Raise an interrupt to signal guest, if necessary */
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void virtio_blk_data_plane_notify(VirtIOBlockDataPlane *s)
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{
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set_bit(0, s->batch_notify_vqs);
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qemu_bh_schedule(s->bh);
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}
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static void notify_guest_bh(void *opaque)
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{
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VirtIOBlockDataPlane *s = opaque;
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unsigned nvqs = s->conf->num_queues;
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unsigned long bitmap[BITS_TO_LONGS(nvqs)];
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unsigned j;
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if (!virtio_should_notify(s->vdev, s->vq)) {
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return;
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memcpy(bitmap, s->batch_notify_vqs, sizeof(bitmap));
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memset(s->batch_notify_vqs, 0, sizeof(bitmap));
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for (j = 0; j < nvqs; j += BITS_PER_LONG) {
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unsigned long bits = bitmap[j];
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while (bits != 0) {
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unsigned i = j + ctzl(bits);
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VirtQueue *vq = virtio_get_queue(s->vdev, i);
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if (virtio_should_notify(s->vdev, vq)) {
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event_notifier_set(virtio_queue_get_guest_notifier(vq));
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}
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event_notifier_set(s->guest_notifier);
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bits &= bits - 1; /* clear right-most bit */
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}
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}
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}
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/* Context: QEMU global mutex held */
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@ -104,6 +120,7 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
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}
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s->ctx = iothread_get_aio_context(s->iothread);
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s->bh = aio_bh_new(s->ctx, notify_guest_bh, s);
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s->batch_notify_vqs = bitmap_new(conf->num_queues);
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*dataplane = s;
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}
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@ -116,6 +133,7 @@ void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
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}
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virtio_blk_data_plane_stop(s);
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g_free(s->batch_notify_vqs);
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qemu_bh_delete(s->bh);
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object_unref(OBJECT(s->iothread));
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g_free(s);
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@ -154,7 +172,6 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
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"ensure -enable-kvm is set\n", r);
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goto fail_guest_notifiers;
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}
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s->guest_notifier = virtio_queue_get_guest_notifier(s->vq);
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/* Set up virtqueue notify */
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r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), 0, true);
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