[v2,0/3] vhost: clean up device reset

Message

Stefan Hajnoczi Oct. 4, 2023, 1:45 a.m. UTC

v2:
- Fix compilation error when vhost is not built [Michael]

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

 meson.build               |  1 +
 include/hw/virtio/vhost.h | 10 ++++++++++
 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 ++++
 7 files changed, 33 insertions(+), 30 deletions(-)

Comments

Raphael Norwitz Oct. 4, 2023, 2:07 a.m. UTC | #1

> On Oct 3, 2023, at 9:45 PM, Stefan Hajnoczi <[e-mail]> wrote:
> 
> v2:
> - Fix compilation error when vhost is not built [Michael]
> 
> 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

For the series:

Reviewed-by: Raphael Norwitz <[e-mail]>

> 
> meson.build               |  1 +
> include/hw/virtio/vhost.h | 10 ++++++++++
> 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 ++++
> 7 files changed, 33 insertions(+), 30 deletions(-)
> 
> -- 
> 2.41.0
>