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Subject: [PATCH v3 0/4] Implement vdpasim stop operation
Date:   Wed, 25 May 2022 12:59:18 +0200
Message-Id: <20220525105922.2413991-1-eperezma@redhat.com>
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Implement stop operation for vdpa_sim devices, so vhost-vdpa will offer=0D
that backend feature and userspace can effectively stop the device.=0D
=0D
This is a must before get 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 the return of ioctl with stop !=3D 0, the device MUST finish any=0D
pending operations like in flight requests. It must also preserve all=0D
the necessary state (the virtqueue vring base plus the possible device=0D
specific states) that is required for restoring in the future. The=0D
device must not change its configuration after that point.=0D
=0D
After the return of ioctl with stop =3D=3D 0, the device can continue=0D
processing buffers as long as typical conditions are met (vq is enabled,=0D
DRIVER_OK status bit is enabled, etc).=0D
=0D
In the future, we will provide features similar to VHOST_USER_GET_INFLIGHT_=
FD=0D
so the device can save pending operations.=0D
=0D
Comments are welcome.=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
Eugenio P=C3=A9rez (4):=0D
  vdpa: Add stop operation=0D
  vhost-vdpa: introduce STOP backend feature bit=0D
  vhost-vdpa: uAPI to stop the device=0D
  vdpa_sim: Implement stop vdpa op=0D
=0D
 drivers/vdpa/vdpa_sim/vdpa_sim.c     | 21 +++++++++++++++++=0D
 drivers/vdpa/vdpa_sim/vdpa_sim.h     |  1 +=0D
 drivers/vdpa/vdpa_sim/vdpa_sim_blk.c |  3 +++=0D
 drivers/vdpa/vdpa_sim/vdpa_sim_net.c |  3 +++=0D
 drivers/vhost/vdpa.c                 | 34 +++++++++++++++++++++++++++-=0D
 include/linux/vdpa.h                 |  6 +++++=0D
 include/uapi/linux/vhost.h           | 14 ++++++++++++=0D
 include/uapi/linux/vhost_types.h     |  2 ++=0D
 8 files changed, 83 insertions(+), 1 deletion(-)=0D
=0D
-- =0D
2.27.0=0D
=0D