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virtio: add aio handler 

In addition to handling IO in vcpu thread and in io thread, blk dataplane
introduces yet another mode: handling it by AioContext.

Currently, this reuses the same handler as previous modes,
which triggers races as these were not designed to be reentrant.
Add instead a separate handler just for aio; this will make
it possible to disable regular handlers when dataplane is active.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Michael S. Tsirkin 2016-04-06 12:16:25 +02:00
parent 43c696a298
commit 344dc16fae
2 changed files with 35 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
hw/virtio/virtio.c
View File

@ -96,6 +96,7 @@ struct VirtQueue
uint16_t vector;
void (*handle_output)(VirtIODevice *vdev, VirtQueue *vq);
void (*handle_aio_output)(VirtIODevice *vdev, VirtQueue *vq);
VirtIODevice *vdev;
EventNotifier guest_notifier;
EventNotifier host_notifier;
@ -1088,6 +1089,16 @@ void virtio_queue_set_align(VirtIODevice *vdev, int n, int align)
virtio_queue_update_rings(vdev, n);
}
static void virtio_queue_notify_aio_vq(VirtQueue *vq)
{
if (vq->vring.desc && vq->handle_aio_output) {
VirtIODevice *vdev = vq->vdev;
trace_virtio_queue_notify(vdev, vq - vdev->vq, vq);
vq->handle_aio_output(vdev, vq);
}
}
static void virtio_queue_notify_vq(VirtQueue *vq)
{
if (vq->vring.desc && vq->handle_output) {
@ -1143,10 +1154,19 @@ VirtQueue *virtio_add_queue(VirtIODevice *vdev, int queue_size,
vdev->vq[i].vring.num_default = queue_size;
vdev->vq[i].vring.align = VIRTIO_PCI_VRING_ALIGN;
vdev->vq[i].handle_output = handle_output;
vdev->vq[i].handle_aio_output = NULL;
return &vdev->vq[i];
}
void virtio_set_queue_aio(VirtQueue *vq,
void (*handle_output)(VirtIODevice *, VirtQueue *))
{
assert(vq->handle_output);
vq->handle_aio_output = handle_output;
}
void virtio_del_queue(VirtIODevice *vdev, int n)
{
if (n < 0 || n >= VIRTIO_QUEUE_MAX) {
@ -1780,11 +1800,11 @@ EventNotifier *virtio_queue_get_guest_notifier(VirtQueue *vq)
return &vq->guest_notifier;
}
static void virtio_queue_host_notifier_read(EventNotifier *n)
static void virtio_queue_host_notifier_aio_read(EventNotifier *n)
{
VirtQueue *vq = container_of(n, VirtQueue, host_notifier);
if (event_notifier_test_and_clear(n)) {
virtio_queue_notify_vq(vq);
virtio_queue_notify_aio_vq(vq);
}
}
@ -1793,14 +1813,22 @@ void virtio_queue_aio_set_host_notifier_handler(VirtQueue *vq, AioContext *ctx,
{
if (assign && set_handler) {
aio_set_event_notifier(ctx, &vq->host_notifier, true,
virtio_queue_host_notifier_read);
virtio_queue_host_notifier_aio_read);
} else {
aio_set_event_notifier(ctx, &vq->host_notifier, true, 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);
virtio_queue_host_notifier_aio_read(&vq->host_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);
}
}

3
include/hw/virtio/virtio.h
View File

@ -142,6 +142,9 @@ VirtQueue *virtio_add_queue(VirtIODevice *vdev, int queue_size,
void (*handle_output)(VirtIODevice *,
VirtQueue *));
void virtio_set_queue_aio(VirtQueue *vq,
void (*handle_output)(VirtIODevice *, VirtQueue *));
void virtio_del_queue(VirtIODevice *vdev, int n);
void *virtqueue_alloc_element(size_t sz, unsigned out_num, unsigned in_num);