Merge tag 'for-upstream' of https://repo.or.cz/qemu/kevin into staging

Block layer patches

- Allow concurrent BB context changes
- virtio: Re-enable notifications after drain
- virtio-blk: Fix missing use of irqfd
- scsi: Don't ignore most usb-storage properties
- blkio: Respect memory-alignment for bounce buffer allocations
- iotests tmpdir fixes
- virtio-blk: Code cleanups

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* tag 'for-upstream' of https://repo.or.cz/qemu/kevin:
  virtio-blk: avoid using ioeventfd state in irqfd conditional
  virtio-blk: Use ioeventfd_attach in start_ioeventfd
  virtio: Re-enable notifications after drain
  virtio-scsi: Attach event vq notifier with no_poll
  blkio: Respect memory-alignment for bounce buffer allocations
  scsi: Don't ignore most usb-storage properties
  virtio-blk: do not use C99 mixed declarations
  iotests: give tempdir an identifying name
  iotests: fix leak of tmpdir in dry-run mode
  scsi: Await request purging
  block-backend: Allow concurrent context changes
  monitor: use aio_co_reschedule_self()
  virtio-blk: declare VirtIOBlock::rq with a type
  virtio-blk: add vq_rq[] bounds check in virtio_blk_dma_restart_cb()
  virtio-blk: clarify that there is at least 1 virtqueue
  virtio-blk: enforce iothread-vq-mapping validation

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 42 insertions, 0 deletions

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 7549094..d229755 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -3556,6 +3556,17 @@ static void virtio_queue_host_notifier_aio_poll_end(EventNotifier *n)
 
 void virtio_queue_aio_attach_host_notifier(VirtQueue *vq, AioContext *ctx)
 {
+    /*
+     * virtio_queue_aio_detach_host_notifier() can leave notifications disabled.
+     * Re-enable them.  (And if detach has not been used before, notifications
+     * being enabled is still the default state while a notifier is attached;
+     * see virtio_queue_host_notifier_aio_poll_end(), which will always leave
+     * notifications enabled once the polling section is left.)
+     */
+    if (!virtio_queue_get_notification(vq)) {
+        virtio_queue_set_notification(vq, 1);
+    }
+
     aio_set_event_notifier(ctx, &vq->host_notifier,
                            virtio_queue_host_notifier_read,
                            virtio_queue_host_notifier_aio_poll,
@@ -3563,6 +3574,13 @@ void virtio_queue_aio_attach_host_notifier(VirtQueue *vq, AioContext *ctx)
     aio_set_event_notifier_poll(ctx, &vq->host_notifier,
                                 virtio_queue_host_notifier_aio_poll_begin,
                                 virtio_queue_host_notifier_aio_poll_end);
+
+    /*
+     * We will have ignored notifications about new requests from the guest
+     * while no notifiers were attached, so "kick" the virt queue to process
+     * those requests now.
+     */
+    event_notifier_set(&vq->host_notifier);
 }
 
 /*
@@ -3573,14 +3591,38 @@ void virtio_queue_aio_attach_host_notifier(VirtQueue *vq, AioContext *ctx)
  */
 void virtio_queue_aio_attach_host_notifier_no_poll(VirtQueue *vq, AioContext *ctx)
 {
+    /* See virtio_queue_aio_attach_host_notifier() */
+    if (!virtio_queue_get_notification(vq)) {
+        virtio_queue_set_notification(vq, 1);
+    }
+
     aio_set_event_notifier(ctx, &vq->host_notifier,
                            virtio_queue_host_notifier_read,
                            NULL, NULL);
+
+    /*
+     * See virtio_queue_aio_attach_host_notifier().
+     * Note that this may be unnecessary for the type of virtqueues this
+     * function is used for.  Still, it will not hurt to have a quick look into
+     * whether we can/should process any of the virtqueue elements.
+     */
+    event_notifier_set(&vq->host_notifier);
 }
 
 void virtio_queue_aio_detach_host_notifier(VirtQueue *vq, AioContext *ctx)
 {
     aio_set_event_notifier(ctx, &vq->host_notifier, NULL, NULL, NULL);
+
+    /*
+     * aio_set_event_notifier_poll() does not guarantee whether io_poll_end()
+     * will run after io_poll_begin(), so by removing the notifier, we do not
+     * know whether virtio_queue_host_notifier_aio_poll_end() has run after a
+     * previous virtio_queue_host_notifier_aio_poll_begin(), i.e. whether
+     * notifications are enabled or disabled.  It does not really matter anyway;
+     * we just removed the notifier, so we do not care about notifications until
+     * we potentially re-attach it.  The attach_host_notifier functions will
+     * ensure that notifications are enabled again when they are needed.
+     */
 }
 
 void virtio_queue_host_notifier_read(EventNotifier *n)