Commit 3b688d7a authored by Sebastien Boeuf's avatar Sebastien Boeuf Committed by Michael S. Tsirkin
Browse files

vhost-vdpa: uAPI to resume the device 



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: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarSebastien Boeuf <sebastien.boeuf@intel.com>
Message-Id: <73b75fb87d25cff59768b4955a81fe7ffe5b4770.1672742878.git.sebastien.boeuf@intel.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: default avatarStefano Garzarella <sgarzare@redhat.com>
parent 69106b6f

drivers/vhost/vdpa.c

+18 −0
Original line number Diff line number Diff line
@@ -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)

include/uapi/linux/vhost.h

+8 −0
Original line number Diff line number Diff line
@@ -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