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virtio-blk: multiqueue batch notify

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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>
This commit is contained in:
Stefan Hajnoczi 2016-06-21 13:13:11 +01:00
parent 84419863f7
commit e21737ab15
1 changed files with 23 additions and 6 deletions
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29
hw/block/dataplane/virtio-blk.c
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@ -34,8 +34,8 @@ struct VirtIOBlockDataPlane {
VirtIODevice *vdev;
VirtQueue *vq; /* virtqueue vring */
EventNotifier *guest_notifier; /* irq */
QEMUBH *bh; /* bh for guest notification */
unsigned long *batch_notify_vqs;
/* Note that these EventNotifiers are assigned by value. This is
* fine as long as you do not call event_notifier_cleanup on them
@ -49,18 +49,34 @@ struct VirtIOBlockDataPlane {
/* Raise an interrupt to signal guest, if necessary */
void virtio_blk_data_plane_notify(VirtIOBlockDataPlane *s)
{
set_bit(0, s->batch_notify_vqs);
qemu_bh_schedule(s->bh);
}
static void notify_guest_bh(void *opaque)
{
VirtIOBlockDataPlane *s = opaque;
unsigned nvqs = s->conf->num_queues;
unsigned long bitmap[BITS_TO_LONGS(nvqs)];
unsigned j;
if (!virtio_should_notify(s->vdev, s->vq)) {
return;
memcpy(bitmap, s->batch_notify_vqs, sizeof(bitmap));
memset(s->batch_notify_vqs, 0, sizeof(bitmap));
for (j = 0; j < nvqs; j += BITS_PER_LONG) {
unsigned long bits = bitmap[j];
while (bits != 0) {
unsigned i = j + ctzl(bits);
VirtQueue *vq = virtio_get_queue(s->vdev, i);
if (virtio_should_notify(s->vdev, vq)) {
event_notifier_set(virtio_queue_get_guest_notifier(vq));
}
bits &= bits - 1; /* clear right-most bit */
}
}
event_notifier_set(s->guest_notifier);
}
/* Context: QEMU global mutex held */
@ -104,6 +120,7 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
}
s->ctx = iothread_get_aio_context(s->iothread);
s->bh = aio_bh_new(s->ctx, notify_guest_bh, s);
s->batch_notify_vqs = bitmap_new(conf->num_queues);
*dataplane = s;
}
@ -116,6 +133,7 @@ void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
}
virtio_blk_data_plane_stop(s);
g_free(s->batch_notify_vqs);
qemu_bh_delete(s->bh);
object_unref(OBJECT(s->iothread));
g_free(s);
@ -154,7 +172,6 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
"ensure -enable-kvm is set\n", r);
goto fail_guest_notifiers;
}
s->guest_notifier = virtio_queue_get_guest_notifier(s->vq);
/* Set up virtqueue notify */
r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), 0, true);