[PATCH 0/3] vhost: clean up device reset

[Stefan Hajnoczi <stefanha@redhat.com>]

Stateful vhost devices may need to free resources or clear device state upon
device reset. The vhost-user protocol has a VHOST_USER_RESET_DEVICE message for
this and vDPA has SET_STATUS 0, but only QEMU's vhost-user-scsi device actually
implements this today.

This patch series performs device reset across all device types. When
virtio_reset() is called, the associated vhost_dev's ->vhost_reset_device() is
called. vhost-user-scsi's one-off implementation is obsoleted and removed.

This patch affects behavior as follows:
- vhost-kernel: no change in behavior. No ioctl calls are made.
- vhost-user: back-ends that negotiate
  VHOST_USER_PROTOCOL_F_RESET_DEVICE now receive a
  VHOST_USER_DEVICE_RESET message upon device reset. Otherwise there is
  no change in behavior. DPDK, SPDK, libvhost-user, and the
  vhost-user-backend crate do not negotiate
  VHOST_USER_PROTOCOL_F_RESET_DEVICE automatically.
- vhost-vdpa: an extra SET_STATUS 0 call is made during device reset.

I have tested this series with vhost-net (kernel), vhost-user-blk, and
vhost-user-fs (both Rust and legacy C).

Stefan Hajnoczi (3):
  vhost-user: do not send RESET_OWNER on device reset
  vhost-backend: remove vhost_kernel_reset_device()
  virtio: call ->vhost_reset_device() during reset

 include/hw/virtio/vhost.h |  3 +++
 hw/scsi/vhost-user-scsi.c | 20 --------------------
 hw/virtio/vhost-backend.c |  6 ------
 hw/virtio/vhost-user.c    | 13 +++++++++----
 hw/virtio/vhost.c         |  9 +++++++++
 hw/virtio/virtio.c        |  4 ++++
 6 files changed, 25 insertions(+), 30 deletions(-)

-- 
2.41.0