[v6,2/4] vhost-vdpa: Introduce RESUME backend feature bit
Commit Message
From: Sebastien Boeuf <sebastien.boeuf@intel.com>
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.
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
---
drivers/vhost/vdpa.c | 16 +++++++++++++++-
include/uapi/linux/vhost_types.h | 2 ++
2 files changed, 17 insertions(+), 1 deletion(-)
Comments
On Tue, Jan 03, 2023 at 11:51:06AM +0100, sebastien.boeuf@intel.com wrote:
>From: Sebastien Boeuf <sebastien.boeuf@intel.com>
>
>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.
>
>Acked-by: Jason Wang <jasowang@redhat.com>
>Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
>---
> drivers/vhost/vdpa.c | 16 +++++++++++++++-
> include/uapi/linux/vhost_types.h | 2 ++
> 2 files changed, 17 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
>index 166044642fd5..833617d00ef6 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 +610,15 @@ 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;
Not for this patch, but I'd like to refactor this code a bit to fill a
`backend_features` field in vhost_vdpa during the vhost_vdpa_probe(), so
we don't need to change this code or the VHOST_GET_BACKEND_FEATURES for
every new backend feature.
I'll send a patch.
This LGTM:
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
> vhost_set_backend_features(&v->vdev, features);
> return 0;
> }
>@@ -658,6 +670,8 @@ 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
>--
>2.37.2
>
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@@ -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 +610,15 @@ 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;
vhost_set_backend_features(&v->vdev, features);
return 0;
}
@@ -658,6 +670,8 @@ 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;
@@ -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