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vhost-vdpa: uAPI to resume the device

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This new ioctl adds support for resuming the device from userspace.

This is required when trying to restore the device in a functioning
state after it's been suspended. It is already possible to reset a
suspended device, but that means the device must be reconfigured and
all the IOMMU/IOTLB mappings must be recreated. This new operation
allows the device to be resumed without going through a full reset.

This is particularly useful when trying to perform offline migration of
a virtual machine (also known as snapshot/restore) as it allows the VMM
to resume the virtual machine back to a running state after the snapshot
is performed.

Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Message-Id: <73b75fb87d25cff59768b4955a81fe7ffe5b4770.1672742878.git.sebastien.boeuf@intel.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
This commit is contained in:
Sebastien Boeuf 2023-01-03 11:51:07 +01:00 committed by Michael S. Tsirkin
parent 69106b6fb3
commit 3b688d7a08
2 changed files with 26 additions and 0 deletions
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18
drivers/vhost/vdpa.c
View File

@ -506,6 +506,21 @@ static long vhost_vdpa_suspend(struct vhost_vdpa *v)
return ops->suspend(vdpa);
}
/* After a successful return of this ioctl the device resumes processing
* virtqueue descriptors. The device becomes fully operational the same way it
* was before it was suspended.
*/
static long vhost_vdpa_resume(struct vhost_vdpa *v)
{
struct vdpa_device *vdpa = v->vdpa;
const struct vdpa_config_ops *ops = vdpa->config;
if (!ops->resume)
return -EOPNOTSUPP;
return ops->resume(vdpa);
}
static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,
void __user *argp)
{
@ -691,6 +706,9 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
case VHOST_VDPA_SUSPEND:
r = vhost_vdpa_suspend(v);
break;
case VHOST_VDPA_RESUME:
r = vhost_vdpa_resume(v);
break;
default:
r = vhost_dev_ioctl(&v->vdev, cmd, argp);
if (r == -ENOIOCTLCMD)

8
include/uapi/linux/vhost.h
View File

@ -180,4 +180,12 @@
*/
#define VHOST_VDPA_SUSPEND _IO(VHOST_VIRTIO, 0x7D)
/* Resume a device so it can resume processing virtqueue requests
*
* After the return of this ioctl the device will have restored all the
* necessary states and it is fully operational to continue processing the
* virtqueue descriptors.
*/
#define VHOST_VDPA_RESUME _IO(VHOST_VIRTIO, 0x7E)
#endif