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Subject: [PATCH v8 0/3] Implement vdpasim suspend operation
Date:   Thu, 11 Aug 2022 15:53:50 +0200
Message-Id: <20220811135353.2549658-1-eperezma@redhat.com>
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Implement suspend operation for vdpa_sim devices, so vhost-vdpa will offer=
=0D
that backend feature and userspace can effectively suspend the device.=0D
=0D
This is a must before getting virtqueue indexes (base) for live migration,=
=0D
since the device could modify them after userland gets them. There are=0D
individual ways to perform that action for some devices=0D
(VHOST_NET_SET_BACKEND, VHOST_VSOCK_SET_RUNNING, ...) but there was no=0D
way to perform it for any vhost device (and, in particular, vhost-vdpa).=0D
=0D
After a successful return of ioctl the device must not process more virtque=
ue=0D
descriptors. The device can answer to read or writes of config fields as if=
 it=0D
were not suspended. In particular, writing to "queue_enable" with a value o=
f 1=0D
will not make the device start processing virtqueue buffers.=0D
=0D
In the future, we will provide features similar to=0D
VHOST_USER_GET_INFLIGHT_FD so the device can save pending operations.=0D
=0D
Applied on top of vhost branch.=0D
=0D
Comments are welcome.=0D
=0D
v8:=0D
* v7 but incremental from vhost instead of isolated.=0D
=0D
v7:=0D
* Remove ioctl leftover argument and update doc accordingly.=0D
=0D
v6:=0D
* Remove the resume operation, making the ioctl simpler. We can always add=
=0D
  another ioctl for VM_STOP/VM_RESUME operation later.=0D
* s/stop/suspend/ to differentiate more from reset.=0D
* Clarify scope of the suspend operation.=0D
=0D
v5:=0D
* s/not stop/resume/ in doc.=0D
=0D
v4:=0D
* Replace VHOST_STOP to VHOST_VDPA_STOP in vhost ioctl switch case too.=0D
=0D
v3:=0D
* s/VHOST_STOP/VHOST_VDPA_STOP/=0D
* Add documentation and requirements of the ioctl above its definition.=0D
=0D
v2:=0D
* Replace raw _F_STOP with BIT_ULL(_F_STOP).=0D
* Fix obtaining of stop ioctl arg (it was not obtained but written).=0D
* Add stop to vdpa_sim_blk.=0D
=0D
[1] git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git=0D
=0D
Eugenio P=C3=A9rez (3):=0D
  vdpa: delete unreachable branch on vdpasim_suspend=0D
  vdpa: Remove wrong doc of VHOST_VDPA_SUSPEND ioctl=0D
  vhost: Remove invalid parameter of VHOST_VDPA_SUSPEND ioctl=0D
=0D
 drivers/vdpa/vdpa_sim/vdpa_sim.c |  7 -------=0D
 include/linux/vdpa.h             |  2 +-=0D
 include/uapi/linux/vhost.h       | 17 ++++++-----------=0D
 3 files changed, 7 insertions(+), 19 deletions(-)=0D
=0D
-- =0D
2.31.1=0D
=0D