Re: [PATCH v6 2/4] vhost-vdpa: introduce SUSPEND backend feature bit
On Fri, Jul 08, 2022 at 01:38:45PM +0200, Eugenio Perez Martin wrote: On Tue, Jun 28, 2022 at 3:43 PM Stefano Garzarella wrote: On Thu, Jun 23, 2022 at 06:07:36PM +0200, Eugenio Pérez wrote: >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. Should we document in the previous patch that the callback must be implemented only if the drive/device support it? It's marked as optional in the doc, following other optional callbacks like set_group_asid for example. But I'm ok with documenting this behavior further. The rest LGTM although I have a doubt whether it is better to move this patch after patch 3, or merge it with patch 3, for bisectability since we enable the feature here but if the userspace calls ioctl() with VHOST_VDPA_SUSPEND we reply back that it is not supported. I'm fine with moving it, but we will have that behavior with all the devices anyway. Regarding userspace, we just replace ENOIOCTL with EOPNOTSUPP. Or I'm missing something? Yep, you're right, this is fine! ;-) Stefano ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v6 2/4] vhost-vdpa: introduce SUSPEND backend feature bit
On Fri, Jun 24, 2022 at 12:08 AM Eugenio Pérez wrote:
>
> 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
> ---
> 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 23dcbfdfa13b..3d636e192061 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_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(, 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))
Do we need to advertise this to the management?
Thanks
> return -EOPNOTSUPP;
> vhost_set_backend_features(>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, , sizeof(features)))
> r = -EFAULT;
> break;
> diff --git a/include/uapi/linux/vhost_types.h
> b/include/uapi/linux/vhost_types.h
> index 634cee485abb..1bdd6e363f4c 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
> +/* Device can be suspended */
> +#define VHOST_BACKEND_F_SUSPEND 0x4
>
> #endif
> --
> 2.31.1
>
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Re: [PATCH v6 2/4] vhost-vdpa: introduce SUSPEND backend feature bit
On Thu, Jun 23, 2022 at 06:07:36PM +0200, Eugenio Pérez wrote:
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.
Should we document in the previous patch that the callback must be
implemented only if the drive/device support it?
The rest LGTM although I have a doubt whether it is better to move this
patch after patch 3, or merge it with patch 3, for bisectability since
we enable the feature here but if the userspace calls ioctl() with
VHOST_VDPA_SUSPEND we reply back that it is not supported.
Thanks,
Stefano
Signed-off-by: Eugenio Pérez
---
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 23dcbfdfa13b..3d636e192061 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_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(, 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(>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, , sizeof(features)))
r = -EFAULT;
break;
diff --git a/include/uapi/linux/vhost_types.h b/include/uapi/linux/vhost_types.h
index 634cee485abb..1bdd6e363f4c 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
+/* Device can be suspended */
+#define VHOST_BACKEND_F_SUSPEND 0x4
#endif
--
2.31.1
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