fcccb271e0
Host notifiers are used in several cases: 1. Traditional ioeventfd where virtqueue notifications are handled in the main loop thread. 2. IOThreads (aio_handle_output) where virtqueue notifications are handled in an IOThread AioContext. 3. vhost where virtqueue notifications are handled by kernel vhost or a vhost-user device backend. Most virtqueue notifications from the guest use the ioeventfd mechanism, but there are corner cases where QEMU code calls virtio_queue_notify(). This currently honors the host notifier for the IOThreads aio_handle_output case, but not for the vhost case. The result is that vhost does not receive virtqueue notifications from QEMU when virtio_queue_notify() is called. This patch extends virtio_queue_notify() to set the host notifier whenever it is enabled instead of calling the vq->(aio_)handle_output() function directly. We track the host notifier state for each virtqueue separately since some devices may use it only for certain virtqueues. This fixes the vhost case although it does add a trip through the eventfd for the traditional ioeventfd case. I don't think it's worth adding a fast path for the traditional ioeventfd case because calling virtio_queue_notify() is rare when ioeventfd is enabled. Reported-by: Felipe Franciosi <felipe@nutanix.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Message-Id: <20191105140946.165584-1-stefanha@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> |
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.. | ||
Kconfig | ||
Makefile.objs | ||
trace-events | ||
vhost-backend.c | ||
vhost-scsi-pci.c | ||
vhost-stub.c | ||
vhost-user-blk-pci.c | ||
vhost-user-fs-pci.c | ||
vhost-user-fs.c | ||
vhost-user-input-pci.c | ||
vhost-user-scsi-pci.c | ||
vhost-user.c | ||
vhost-vsock-pci.c | ||
vhost-vsock.c | ||
vhost.c | ||
virtio-9p-pci.c | ||
virtio-balloon-pci.c | ||
virtio-balloon.c | ||
virtio-blk-pci.c | ||
virtio-bus.c | ||
virtio-crypto-pci.c | ||
virtio-crypto.c | ||
virtio-input-host-pci.c | ||
virtio-input-pci.c | ||
virtio-mmio.c | ||
virtio-net-pci.c | ||
virtio-pci.c | ||
virtio-pci.h | ||
virtio-pmem-pci.c | ||
virtio-pmem-pci.h | ||
virtio-pmem.c | ||
virtio-rng-pci.c | ||
virtio-rng.c | ||
virtio-scsi-pci.c | ||
virtio-serial-pci.c | ||
virtio.c |