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vhost-vdpa: introduce SUSPEND backend feature bit 

Userland knows if it can suspend the device or not by checking this feature
bit.

It's only offered if the vdpa driver backend implements the suspend()
operation callback, and to offer it or userland to ack it if the backend
does not offer that callback is an error.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20220810171512.2343333-3-eperezma@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Eugenio Pérez 2022-08-10 19:15:10 +02:00 committed by Michael S. Tsirkin
parent 848ecea184
commit 0723f1df5c
2 changed files with 17 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
drivers/vhost/vdpa.c
View File

@ -347,6 +347,14 @@ static long vhost_vdpa_set_config(struct vhost_vdpa *v,
return 0;
}
static bool vhost_vdpa_can_suspend(const struct vhost_vdpa *v)
{
struct vdpa_device *vdpa = v->vdpa;
const struct vdpa_config_ops *ops = vdpa->config;
return ops->suspend;
}
static long vhost_vdpa_get_features(struct vhost_vdpa *v, u64 __user *featurep)
{
struct vdpa_device *vdpa = v->vdpa;
@ -577,7 +585,11 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
if (cmd == VHOST_SET_BACKEND_FEATURES) {
if (copy_from_user(&features, featurep, sizeof(features)))
return -EFAULT;
if (features & ~VHOST_VDPA_BACKEND_FEATURES)
if (features & ~(VHOST_VDPA_BACKEND_FEATURES |
BIT_ULL(VHOST_BACKEND_F_SUSPEND)))
return -EOPNOTSUPP;
if ((features & BIT_ULL(VHOST_BACKEND_F_SUSPEND)) &&
!vhost_vdpa_can_suspend(v))
return -EOPNOTSUPP;
vhost_set_backend_features(&v->vdev, features);
return 0;
@ -628,6 +640,8 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
break;
case VHOST_GET_BACKEND_FEATURES:
features = VHOST_VDPA_BACKEND_FEATURES;
if (vhost_vdpa_can_suspend(v))
features |= BIT_ULL(VHOST_BACKEND_F_SUSPEND);
if (copy_to_user(featurep, &features, sizeof(features)))
r = -EFAULT;
break;

2
include/uapi/linux/vhost_types.h
View File

@ -161,5 +161,7 @@ struct vhost_vdpa_iova_range {
* message
*/
#define VHOST_BACKEND_F_IOTLB_ASID 0x3
/* Device can be suspended */
#define VHOST_BACKEND_F_SUSPEND 0x4
#endif