On Fri, Oct 14, 2022 at 01:58:38PM +0800, Jason Wang wrote:
> On Thu, Oct 13, 2022 at 11:35 PM <sebastien.boeuf@xxxxxxxxx> wrote:
> >
> > From: Sebastien Boeuf <sebastien.boeuf@xxxxxxxxx>
> >
> > Userspace knows if the device can be resumed or not by checking this
> > feature bit.
> >
> > It's only exposed if the vdpa driver backend implements the resume()
> > operation callback. Userspace trying to negotiate this feature when it
> > hasn't been exposed will result in an error.
> >
> > Signed-off-by: Sebastien Boeuf <sebastien.boeuf@xxxxxxxxx>
> > ---
> > drivers/vhost/vdpa.c | 19 ++++++++++++++++++-
> > include/uapi/linux/vhost_types.h | 2 ++
> > 2 files changed, 20 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> > index 166044642fd5..161727e1a9a5 100644
> > --- a/drivers/vhost/vdpa.c
> > +++ b/drivers/vhost/vdpa.c
> > @@ -355,6 +355,14 @@ static bool vhost_vdpa_can_suspend(const struct vhost_vdpa *v)
> > return ops->suspend;
> > }
> >
> > +static bool vhost_vdpa_can_resume(const struct vhost_vdpa *v)
> > +{
> > + struct vdpa_device *vdpa = v->vdpa;
> > + const struct vdpa_config_ops *ops = vdpa->config;
> > +
> > + return ops->resume;
> > +}
> > +
> > static long vhost_vdpa_get_features(struct vhost_vdpa *v, u64 __user *featurep)
> > {
> > struct vdpa_device *vdpa = v->vdpa;
> > @@ -602,11 +610,18 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
> > if (copy_from_user(&features, featurep, sizeof(features)))
> > return -EFAULT;
> > if (features & ~(VHOST_VDPA_BACKEND_FEATURES |
> > - BIT_ULL(VHOST_BACKEND_F_SUSPEND)))
> > + BIT_ULL(VHOST_BACKEND_F_SUSPEND) |
> > + BIT_ULL(VHOST_BACKEND_F_RESUME)))
> > return -EOPNOTSUPP;
> > if ((features & BIT_ULL(VHOST_BACKEND_F_SUSPEND)) &&
> > !vhost_vdpa_can_suspend(v))
> > return -EOPNOTSUPP;
> > + if ((features & BIT_ULL(VHOST_BACKEND_F_RESUME)) &&
> > + !vhost_vdpa_can_resume(v))
> > + return -EOPNOTSUPP;
> > + if (!(features & BIT_ULL(VHOST_BACKEND_F_SUSPEND)) &&
> > + (features & BIT_ULL(VHOST_BACKEND_F_RESUME)))
> > + return -EINVAL;
>
> Is it better to do the check during the probe? It should be a bug that
> we're having a parent that can only do resume but not suspend.
>
> Thanks
well we separated them in the spec ...
suspend could have other uses, I won't say it's an invalid
config.
> > vhost_set_backend_features(&v->vdev, features);
> > return 0;
> > }
> > @@ -658,6 +673,8 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
> > features = VHOST_VDPA_BACKEND_FEATURES;
> > if (vhost_vdpa_can_suspend(v))
> > features |= BIT_ULL(VHOST_BACKEND_F_SUSPEND);
> > + if (vhost_vdpa_can_resume(v))
> > + features |= BIT_ULL(VHOST_BACKEND_F_RESUME);
> > 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 53601ce2c20a..c5690a8992d8 100644
> > --- a/include/uapi/linux/vhost_types.h
> > +++ b/include/uapi/linux/vhost_types.h
> > @@ -163,5 +163,7 @@ struct vhost_vdpa_iova_range {
> > #define VHOST_BACKEND_F_IOTLB_ASID 0x3
> > /* Device can be suspended */
> > #define VHOST_BACKEND_F_SUSPEND 0x4
> > +/* Device can be resumed */
> > +#define VHOST_BACKEND_F_RESUME 0x5
> >
> > #endif
> > --
> > 2.34.1
> >
> > ---------------------------------------------------------------------
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