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From:   =?UTF-8?q?Eugenio=20P=C3=A9rez?= <eperezma@redhat.com>
To:     kvm@vger.kernel.org, Jason Wang <jasowang@redhat.com>,
        "Michael S. Tsirkin" <mst@redhat.com>,
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Cc:     Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
        Longpeng <longpeng2@huawei.com>,
        Stefano Garzarella <sgarzare@redhat.com>, dinang@xilinx.com,
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        hanand@xilinx.com, martinh@xilinx.com,
        Si-Wei Liu <si-wei.liu@oracle.com>, gautam.dawar@amd.com,
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        pabloc@xilinx.com, lvivier@redhat.com, Eli Cohen <elic@nvidia.com>,
        Wu Zongyong <wuzongyong@linux.alibaba.com>,
        Dan Carpenter <dan.carpenter@oracle.com>
Subject: [PATCH v5 0/4] Implement vdpasim suspend operation
Date:   Fri,  3 Jun 2022 12:09:40 +0200
Message-Id: <20220603100944.871727-1-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 with suspend =3D 1, the device must not=
=0D
process more virtqueue descriptors, and it must not send any config=0D
interrupt. The device can answer to read or writes of config fields as=0D
if it were not suspended. In particular, writing to "queue_enable" with=0D
a value of 1 will not make the device start processing buffers of the=0D
virtqueue until the device is resumed (suspend =3D 0).=0D
=0D
After a successful return of ioctl with suspend =3D 0, the device will=0D
start processing data of the virtqueues if other expected conditions are=0D
met (queue is enabled, DRIVER_OK has already been set to status, etc.)=0D
If not, the device should be in the same state as if no call to suspend=0D
callback with suspend =3D 1 has been performed.=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
Comments are welcome.=0D
=0D
v6:=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
Eugenio P=C3=A9rez (4):=0D
  vdpa: Add suspend operation=0D
  vhost-vdpa: introduce SUSPEND backend feature bit=0D
  vhost-vdpa: uAPI to suspend the device=0D
  vdpa_sim: Implement suspend 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                 | 47 +++++++++++++++++++++++++++-=0D
 include/linux/vdpa.h                 |  5 +++=0D
 include/uapi/linux/vhost.h           | 14 +++++++++=0D
 include/uapi/linux/vhost_types.h     |  2 ++=0D
 8 files changed, 95 insertions(+), 1 deletion(-)=0D
=0D
--=0D
2.31.1=0D
=0D