From: "Michael S. Tsirkin" <m...@redhat.com>
In addition to handling IO in vcpu thread and in io thread, dataplane
introduces yet another mode: handling it by aio.
This reuses the same handler as previous modes, which triggers races as
these were not designed to be reentrant.
Use a separate handler just for aio, and disable regular handlers when
dataplane is active.
Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
hw/block/dataplane/virtio-blk.c | 13 +++++++++++++
hw/block/virtio-blk.c | 27 +++++++++++++++++----------
include/hw/virtio/virtio-blk.h | 2 ++
3 files changed, 32 insertions(+), 10 deletions(-)
diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
index 378feb3..4a137df 100644
--- a/hw/block/dataplane/virtio-blk.c
+++ b/hw/block/dataplane/virtio-blk.c
@@ -183,6 +183,17 @@ void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
g_free(s);
}
+static void virtio_blk_data_plane_handle_output(VirtIODevice *vdev,
+ VirtQueue *vq)
+{
+ VirtIOBlock *s = (VirtIOBlock *)vdev;
+
+ assert(s->dataplane);
+ assert(s->dataplane_started);
+
+ virtio_blk_handle_vq(s, vq);
+}
+
/* Context: QEMU global mutex held */
void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
{
@@ -225,6 +236,7 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
/* Get this show started by hooking up our callbacks */
aio_context_acquire(s->ctx);
+ virtio_set_queue_aio(s->vq, virtio_blk_data_plane_handle_output);
virtio_queue_aio_set_host_notifier_handler(s->vq, s->ctx, true, true);
aio_context_release(s->ctx);
return;
@@ -261,6 +273,7 @@ void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
/* Stop notifications for new requests from guest */
virtio_queue_aio_set_host_notifier_handler(s->vq, s->ctx, true, false);
+ virtio_set_queue_aio(s->vq, NULL);
/* Drain and switch bs back to the QEMU main loop */
blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context());
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index 77221c1..47ad9ed 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -577,20 +577,11 @@ void virtio_blk_handle_request(VirtIOBlockReq *req,
MultiReqBuffer *mrb)
}
}
-static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
+void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq)
{
- VirtIOBlock *s = VIRTIO_BLK(vdev);
VirtIOBlockReq *req;
MultiReqBuffer mrb = {};
- /* Some guests kick before setting VIRTIO_CONFIG_S_DRIVER_OK so start
- * dataplane here instead of waiting for .set_status().
- */
- if (s->dataplane && !s->dataplane_started) {
- virtio_blk_data_plane_start(s->dataplane);
- return;
- }
-
assert(atomic_fetch_inc(&s->reentrancy_test) == 0);
blk_io_plug(s->blk);
@@ -606,6 +597,22 @@ static void virtio_blk_handle_output(VirtIODevice *vdev,
VirtQueue *vq)
atomic_dec(&s->reentrancy_test);
}
+static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
+{
+ VirtIOBlock *s = (VirtIOBlock *)vdev;
+
+ if (s->dataplane) {
+ /* Some guests kick before setting VIRTIO_CONFIG_S_DRIVER_OK so start
+ * dataplane here instead of waiting for .set_status().
+ */
+ virtio_blk_data_plane_start(s->dataplane);
+ if (!s->dataplane_disabled) {
+ return;
+ }
+ }
+ virtio_blk_handle_vq(s, vq);
+}
+
static void virtio_blk_dma_restart_bh(void *opaque)
{
VirtIOBlock *s = opaque;
diff --git a/include/hw/virtio/virtio-blk.h b/include/hw/virtio/virtio-blk.h
index 073c632..b5117a8 100644
--- a/include/hw/virtio/virtio-blk.h
+++ b/include/hw/virtio/virtio-blk.h
@@ -87,4 +87,6 @@ void virtio_blk_handle_request(VirtIOBlockReq *req,
MultiReqBuffer *mrb);
void virtio_blk_submit_multireq(BlockBackend *blk, MultiReqBuffer *mrb);
+void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq);
+
#endif
--
1.8.3.1
