On 8/9/2023 8:49 PM, Jason Wang wrote:
On Wed, Aug 9, 2023 at 8:56 PM Si-Wei Liu <si-wei.liu@xxxxxxxxxx> wrote:
Userspace knows if the device has dedicated descriptor group or not
by checking this feature bit.
It's only exposed if the vdpa driver backend implements the
.get_vq_desc_group() operation callback. Userspace trying to negotiate
this feature when it or the dependent _F_IOTLB_ASID feature hasn't
been exposed will result in an error.
Signed-off-by: Si-Wei Liu <si-wei.liu@xxxxxxxxxx>
---
drivers/vhost/vdpa.c | 17 +++++++++++++++++
include/uapi/linux/vhost_types.h | 5 +++++
2 files changed, 22 insertions(+)
diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index b43e868..f2e5dce 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -389,6 +389,14 @@ static bool vhost_vdpa_can_resume(const struct vhost_vdpa *v)
return ops->resume;
}
+static bool vhost_vdpa_has_desc_group(const struct vhost_vdpa *v)
+{
+ struct vdpa_device *vdpa = v->vdpa;
+ const struct vdpa_config_ops *ops = vdpa->config;
+
+ return ops->get_vq_desc_group;
+}
+
static long vhost_vdpa_get_features(struct vhost_vdpa *v, u64 __user *featurep)
{
struct vdpa_device *vdpa = v->vdpa;
@@ -679,6 +687,7 @@ 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_DESC_ASID) |
BIT_ULL(VHOST_BACKEND_F_SUSPEND) |
BIT_ULL(VHOST_BACKEND_F_RESUME)))
return -EOPNOTSUPP;
@@ -688,6 +697,12 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
if ((features & BIT_ULL(VHOST_BACKEND_F_RESUME)) &&
!vhost_vdpa_can_resume(v))
return -EOPNOTSUPP;
+ if ((features & BIT_ULL(VHOST_BACKEND_F_DESC_ASID)) &&
+ !(features & BIT_ULL(VHOST_BACKEND_F_IOTLB_ASID)))
+ return -EINVAL;
+ if ((features & BIT_ULL(VHOST_BACKEND_F_DESC_ASID)) &&
+ !vhost_vdpa_has_desc_group(v))
+ return -EOPNOTSUPP;
vhost_set_backend_features(&v->vdev, features);
return 0;
}
@@ -741,6 +756,8 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
features |= BIT_ULL(VHOST_BACKEND_F_SUSPEND);
if (vhost_vdpa_can_resume(v))
features |= BIT_ULL(VHOST_BACKEND_F_RESUME);
+ if (vhost_vdpa_has_desc_group(v))
+ features |= BIT_ULL(VHOST_BACKEND_F_DESC_ASID);
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 d3aad12a..0856f84 100644
--- a/include/uapi/linux/vhost_types.h
+++ b/include/uapi/linux/vhost_types.h
@@ -181,5 +181,10 @@ struct vhost_vdpa_iova_range {
#define VHOST_BACKEND_F_SUSPEND 0x4
/* Device can be resumed */
#define VHOST_BACKEND_F_RESUME 0x5
+/* Device may expose the descriptor table, avail and used ring in a
+ * different group for ASID binding than the buffers it contains.
Nit:
s/a different group/different groups/?
Yep, I will try to rephrase. Would below work?
"Device may expose virtqueue's descriptor table, avail and used ring in a
different group for ASID binding than where buffers it contains reside."
Btw, not a native speaker but I think "descriptor" might be confusing
since as you explained above, it contains more than just a descriptor
table.
Yep. I chose "descriptor" because packed virtqueue doesn't have
"physical" avail and used ring other than descriptor table, but I think
I am open to a better name. I once thought of "descriptor ring" but that
might be too specific to packed virtqueue. Any suggestion?
Thanks,
-Siwei
Thanks
+ * Requires VHOST_BACKEND_F_IOTLB_ASID.
+ */
+#define VHOST_BACKEND_F_DESC_ASID 0x6
#endif
--
1.8.3.1
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