Si-Wei Liu
2022-May-21 10:24 UTC
[PATCH 2/4] vhost-vdpa: introduce STOP backend feature bit
On 5/20/2022 10:23 AM, Eugenio P?rez wrote:> Userland knows if it can stop the device or not by checking this feature > bit. > > It's only offered if the vdpa driver backend implements the stop() > operation callback, and try to set it if the backend does not offer that > callback is an error. > > Signed-off-by: Eugenio P?rez <eperezma at redhat.com> > --- > drivers/vhost/vdpa.c | 13 +++++++++++++ > include/uapi/linux/vhost_types.h | 2 ++ > 2 files changed, 15 insertions(+) > > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c > index 1f1d1c425573..a325bc259afb 100644 > --- a/drivers/vhost/vdpa.c > +++ b/drivers/vhost/vdpa.c > @@ -347,6 +347,14 @@ static long vhost_vdpa_set_config(struct vhost_vdpa *v, > return 0; > } > > +static bool vhost_vdpa_can_stop(const struct vhost_vdpa *v) > +{ > + struct vdpa_device *vdpa = v->vdpa; > + const struct vdpa_config_ops *ops = vdpa->config; > + > + return ops->stop; > +} > + > static long vhost_vdpa_get_features(struct vhost_vdpa *v, u64 __user *featurep) > { > struct vdpa_device *vdpa = v->vdpa; > @@ -577,6 +585,9 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep, > return -EFAULT; > if (features & ~VHOST_VDPA_BACKEND_FEATURES) > return -EOPNOTSUPP; > + if ((features & VHOST_BACKEND_F_STOP) &&VHOST_BACKEND_F_STOP is not part of VHOST_VDPA_BACKEND_FEATURES. There's no chance for VHOST_BACKEND_F_STOP to get here. -Siwei> + !vhost_vdpa_can_stop(v)) > + return -EOPNOTSUPP; > vhost_set_backend_features(&v->vdev, features); > return 0; > } > @@ -624,6 +635,8 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep, > break; > case VHOST_GET_BACKEND_FEATURES: > features = VHOST_VDPA_BACKEND_FEATURES; > + if (vhost_vdpa_can_stop(v)) > + features |= VHOST_BACKEND_F_STOP; > if (copy_to_user(featurep, &features, sizeof(features))) > r = -EFAULT; > break; > diff --git a/include/uapi/linux/vhost_types.h b/include/uapi/linux/vhost_types.h > index 634cee485abb..2758e665791b 100644 > --- a/include/uapi/linux/vhost_types.h > +++ b/include/uapi/linux/vhost_types.h > @@ -161,5 +161,7 @@ struct vhost_vdpa_iova_range { > * message > */ > #define VHOST_BACKEND_F_IOTLB_ASID 0x3 > +/* Stop device from processing virtqueue buffers */ > +#define VHOST_BACKEND_F_STOP 0x4 > > #endif