[PATCH] virtio-vdpa: add VIRTIO_F_NOTIFICATION_DATA feature support

[PATCH] virtio-vdpa: add VIRTIO_F_NOTIFICATION_DATA feature support

[Alvaro Karsz]

Add VIRTIO_F_NOTIFICATION_DATA support for vDPA transport.
If this feature is negotiated, the driver passes extra data when kicking
a virtqueue.

A device that offers this feature needs to implement the
kick_vq_with_data callback.

kick_vq_with_data receives the vDPA device and data.
data includes the vqn, next_off and next_wrap for packed virtqueues.

This patch follows a patch [1] by Viktor Prutyanov which adds support
for the MMIO, channel I/O and modern PCI transports.

This patch needs to be applied on top of Viktor's patch.

[1] https://lore.kernel.org/lkml/20230324195029.2410503-1-viktor@daynix.com/

Signed-off-by: Alvaro Karsz <alvaro.karsz@solid-run.com>
---
 drivers/virtio/virtio_vdpa.c | 20 ++++++++++++++++++--
 include/linux/vdpa.h         |  6 ++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c
index d7f5af62dda..bdaf30f7fbf 100644
--- a/drivers/virtio/virtio_vdpa.c
+++ b/drivers/virtio/virtio_vdpa.c
@@ -112,6 +112,17 @@ static bool virtio_vdpa_notify(struct virtqueue *vq)
 	return true;
 }
 
+static bool virtio_vdpa_notify_with_data(struct virtqueue *vq)
+{
+	struct vdpa_device *vdpa = vd_get_vdpa(vq->vdev);
+	const struct vdpa_config_ops *ops = vdpa->config;
+	u32 data = vring_notification_data(vq);
+
+	ops->kick_vq_with_data(vdpa, data);
+
+	return true;
+}
+
 static irqreturn_t virtio_vdpa_config_cb(void *private)
 {
 	struct virtio_vdpa_device *vd_dev = private;
@@ -138,6 +149,7 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,
 	struct device *dma_dev;
 	const struct vdpa_config_ops *ops = vdpa->config;
 	struct virtio_vdpa_vq_info *info;
+	bool (*notify)(struct virtqueue *vq);
 	struct vdpa_callback cb;
 	struct virtqueue *vq;
 	u64 desc_addr, driver_addr, device_addr;
@@ -154,6 +166,11 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,
 	if (index >= vdpa->nvqs)
 		return ERR_PTR(-ENOENT);
 
+	if (__virtio_test_bit(vdev, VIRTIO_F_NOTIFICATION_DATA))
+		notify = virtio_vdpa_notify_with_data;
+	else
+		notify = virtio_vdpa_notify;
+
 	/* Queue shouldn't already be set up. */
 	if (ops->get_vq_ready(vdpa, index))
 		return ERR_PTR(-ENOENT);
@@ -183,8 +200,7 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,
 		dma_dev = vdpa_get_dma_dev(vdpa);
 	vq = vring_create_virtqueue_dma(index, max_num, align, vdev,
 					true, may_reduce_num, ctx,
-					virtio_vdpa_notify, callback,
-					name, dma_dev);
+					notify, callback, name, dma_dev);
 	if (!vq) {
 		err = -ENOMEM;
 		goto error_new_virtqueue;
diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
index 43f59ef10cc..a83bb0501c5 100644
--- a/include/linux/vdpa.h
+++ b/include/linux/vdpa.h
@@ -143,6 +143,11 @@ struct vdpa_map_file {
  * @kick_vq:			Kick the virtqueue
  *				@vdev: vdpa device
  *				@idx: virtqueue index
+ * @kick_vq_with_data:		Kick the virtqueue and supply extra data
+ *				(only if VIRTIO_F_NOTIFICATION_DATA is negotiated)
+ *				@vdev: vdpa device
+ *				@data: includes vqn, next_off and next_wrap for
+ *				packed virtqueues
  * @set_vq_cb:			Set the interrupt callback function for
  *				a virtqueue
  *				@vdev: vdpa device
@@ -300,6 +305,7 @@ struct vdpa_config_ops {
 			      u64 device_area);
 	void (*set_vq_num)(struct vdpa_device *vdev, u16 idx, u32 num);
 	void (*kick_vq)(struct vdpa_device *vdev, u16 idx);
+	void (*kick_vq_with_data)(struct vdpa_device *vdev, u32 data);
 	void (*set_vq_cb)(struct vdpa_device *vdev, u16 idx,
 			  struct vdpa_callback *cb);
 	void (*set_vq_ready)(struct vdpa_device *vdev, u16 idx, bool ready);
-- 
2.34.1

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Re: [PATCH] virtio-vdpa: add VIRTIO_F_NOTIFICATION_DATA feature support

[Jason Wang]

On Sun, Apr 2, 2023 at 4:10 PM Alvaro Karsz <alvaro.karsz@solid-run.com> wrote:
>
> Add VIRTIO_F_NOTIFICATION_DATA support for vDPA transport.
> If this feature is negotiated, the driver passes extra data when kicking
> a virtqueue.
>
> A device that offers this feature needs to implement the
> kick_vq_with_data callback.
>
> kick_vq_with_data receives the vDPA device and data.
> data includes the vqn, next_off and next_wrap for packed virtqueues.
>
> This patch follows a patch [1] by Viktor Prutyanov which adds support
> for the MMIO, channel I/O and modern PCI transports.
>
> This patch needs to be applied on top of Viktor's patch.
>
> [1] https://lore.kernel.org/lkml/20230324195029.2410503-1-viktor@daynix.com/
>
> Signed-off-by: Alvaro Karsz <alvaro.karsz@solid-run.com>
> ---
>  drivers/virtio/virtio_vdpa.c | 20 ++++++++++++++++++--
>  include/linux/vdpa.h         |  6 ++++++
>  2 files changed, 24 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c
> index d7f5af62dda..bdaf30f7fbf 100644
> --- a/drivers/virtio/virtio_vdpa.c
> +++ b/drivers/virtio/virtio_vdpa.c
> @@ -112,6 +112,17 @@ static bool virtio_vdpa_notify(struct virtqueue *vq)
>         return true;
>  }
>
> +static bool virtio_vdpa_notify_with_data(struct virtqueue *vq)
> +{
> +       struct vdpa_device *vdpa = vd_get_vdpa(vq->vdev);
> +       const struct vdpa_config_ops *ops = vdpa->config;
> +       u32 data = vring_notification_data(vq);
> +
> +       ops->kick_vq_with_data(vdpa, data);
> +
> +       return true;
> +}
> +
>  static irqreturn_t virtio_vdpa_config_cb(void *private)
>  {
>         struct virtio_vdpa_device *vd_dev = private;
> @@ -138,6 +149,7 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,
>         struct device *dma_dev;
>         const struct vdpa_config_ops *ops = vdpa->config;
>         struct virtio_vdpa_vq_info *info;
> +       bool (*notify)(struct virtqueue *vq);
>         struct vdpa_callback cb;
>         struct virtqueue *vq;
>         u64 desc_addr, driver_addr, device_addr;
> @@ -154,6 +166,11 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,
>         if (index >= vdpa->nvqs)
>                 return ERR_PTR(-ENOENT);
>
> +       if (__virtio_test_bit(vdev, VIRTIO_F_NOTIFICATION_DATA))
> +               notify = virtio_vdpa_notify_with_data;
> +       else
> +               notify = virtio_vdpa_notify;
> +
>         /* Queue shouldn't already be set up. */
>         if (ops->get_vq_ready(vdpa, index))
>                 return ERR_PTR(-ENOENT);
> @@ -183,8 +200,7 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,
>                 dma_dev = vdpa_get_dma_dev(vdpa);
>         vq = vring_create_virtqueue_dma(index, max_num, align, vdev,
>                                         true, may_reduce_num, ctx,
> -                                       virtio_vdpa_notify, callback,
> -                                       name, dma_dev);
> +                                       notify, callback, name, dma_dev);
>         if (!vq) {
>                 err = -ENOMEM;
>                 goto error_new_virtqueue;
> diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> index 43f59ef10cc..a83bb0501c5 100644
> --- a/include/linux/vdpa.h
> +++ b/include/linux/vdpa.h
> @@ -143,6 +143,11 @@ struct vdpa_map_file {
>   * @kick_vq:                   Kick the virtqueue
>   *                             @vdev: vdpa device
>   *                             @idx: virtqueue index
> + * @kick_vq_with_data:         Kick the virtqueue and supply extra data
> + *                             (only if VIRTIO_F_NOTIFICATION_DATA is negotiated)
> + *                             @vdev: vdpa device
> + *                             @data: includes vqn, next_off and next_wrap for
> + *                             packed virtqueues

This needs some tweaking, VIRTIO_F_NOTIFICATION_DATA works for split
virtqueue as well.

Thanks

>   * @set_vq_cb:                 Set the interrupt callback function for
>   *                             a virtqueue
>   *                             @vdev: vdpa device
> @@ -300,6 +305,7 @@ struct vdpa_config_ops {
>                               u64 device_area);
>         void (*set_vq_num)(struct vdpa_device *vdev, u16 idx, u32 num);
>         void (*kick_vq)(struct vdpa_device *vdev, u16 idx);
> +       void (*kick_vq_with_data)(struct vdpa_device *vdev, u32 data);
>         void (*set_vq_cb)(struct vdpa_device *vdev, u16 idx,
>                           struct vdpa_callback *cb);
>         void (*set_vq_ready)(struct vdpa_device *vdev, u16 idx, bool ready);
> --
> 2.34.1
>

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Re: [PATCH] virtio-vdpa: add VIRTIO_F_NOTIFICATION_DATA feature support

[Alvaro Karsz]

> > + * @kick_vq_with_data:         Kick the virtqueue and supply extra data
> > + *                             (only if VIRTIO_F_NOTIFICATION_DATA is negotiated)
> > + *                             @vdev: vdpa device
> > + *                             @data: includes vqn, next_off and next_wrap for
> > + *                             packed virtqueues
> 
> This needs some tweaking, VIRTIO_F_NOTIFICATION_DATA works for split
> virtqueue as well.
> 

I meant that next_wrap is for packed VQs, but I see your point, it's no clear from the comment.
I'll fix it in v2.

Thanks
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Re: [PATCH] virtio-vdpa: add VIRTIO_F_NOTIFICATION_DATA feature support

[Jason Wang]

On Tue, Apr 4, 2023 at 3:20 PM Alvaro Karsz <alvaro.karsz@solid-run.com> wrote:
>
> > > + * @kick_vq_with_data:         Kick the virtqueue and supply extra data
> > > + *                             (only if VIRTIO_F_NOTIFICATION_DATA is negotiated)
> > > + *                             @vdev: vdpa device
> > > + *                             @data: includes vqn, next_off and next_wrap for
> > > + *                             packed virtqueues
> >
> > This needs some tweaking, VIRTIO_F_NOTIFICATION_DATA works for split
> > virtqueue as well.
> >
>
> I meant that next_wrap is for packed VQs, but I see your point, it's no clear from the comment.
> I'll fix it in v2.

next_wrap works for split as well, spec said

"
Without VIRTIO_F_RING_PACKED this is the most significant bit (bit 15)
of the available index.
"

Thanks

>
> Thanks
>

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Re: [PATCH] virtio-vdpa: add VIRTIO_F_NOTIFICATION_DATA feature support

[Alvaro Karsz]

> > I meant that next_wrap is for packed VQs, but I see your point, it's no clear from the comment.
> > I'll fix it in v2.
> 
> next_wrap works for split as well, spec said
> 
> "
> Without VIRTIO_F_RING_PACKED this is the most significant bit (bit 15)
> of the available index.
> "

You're right, so we can write:

 @kick_vq_with_data:		Kick the virtqueue and supply extra data
				(only if VIRTIO_F_NOTIFICATION_DATA is negotiated)
				@vdev: vdpa device
				@data for split virtqueue:
				16 bits vqn and 16 bits next available index.
				@data for packed virtqueue:
				16 bits vqn, 15 least significant bits of
				next available index and 1 bit next_wrap.
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Re: [PATCH] virtio-vdpa: add VIRTIO_F_NOTIFICATION_DATA feature support

[Michael S. Tsirkin]

On Sun, Apr 02, 2023 at 11:10:34AM +0300, Alvaro Karsz wrote:
> Add VIRTIO_F_NOTIFICATION_DATA support for vDPA transport.
> If this feature is negotiated, the driver passes extra data when kicking
> a virtqueue.
> 
> A device that offers this feature needs to implement the
> kick_vq_with_data callback.
> 
> kick_vq_with_data receives the vDPA device and data.
> data includes the vqn, next_off and next_wrap for packed virtqueues.
> 
> This patch follows a patch [1] by Viktor Prutyanov which adds support
> for the MMIO, channel I/O and modern PCI transports.
> 
> This patch needs to be applied on top of Viktor's patch.
> 
> [1] https://lore.kernel.org/lkml/20230324195029.2410503-1-viktor@daynix.com/
> 
> Signed-off-by: Alvaro Karsz <alvaro.karsz@solid-run.com>

Hmm so I conclude that drivers without kick_vq_with_data
should not accept VIRTIO_F_NOTIFICATION_DATA then?


> ---
>  drivers/virtio/virtio_vdpa.c | 20 ++++++++++++++++++--
>  include/linux/vdpa.h         |  6 ++++++
>  2 files changed, 24 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c
> index d7f5af62dda..bdaf30f7fbf 100644
> --- a/drivers/virtio/virtio_vdpa.c
> +++ b/drivers/virtio/virtio_vdpa.c
> @@ -112,6 +112,17 @@ static bool virtio_vdpa_notify(struct virtqueue *vq)
>  	return true;
>  }
>  
> +static bool virtio_vdpa_notify_with_data(struct virtqueue *vq)
> +{
> +	struct vdpa_device *vdpa = vd_get_vdpa(vq->vdev);
> +	const struct vdpa_config_ops *ops = vdpa->config;
> +	u32 data = vring_notification_data(vq);
> +
> +	ops->kick_vq_with_data(vdpa, data);
> +
> +	return true;
> +}
> +
>  static irqreturn_t virtio_vdpa_config_cb(void *private)
>  {
>  	struct virtio_vdpa_device *vd_dev = private;
> @@ -138,6 +149,7 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,
>  	struct device *dma_dev;
>  	const struct vdpa_config_ops *ops = vdpa->config;
>  	struct virtio_vdpa_vq_info *info;
> +	bool (*notify)(struct virtqueue *vq);
>  	struct vdpa_callback cb;
>  	struct virtqueue *vq;
>  	u64 desc_addr, driver_addr, device_addr;
> @@ -154,6 +166,11 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,
>  	if (index >= vdpa->nvqs)
>  		return ERR_PTR(-ENOENT);
>  
> +	if (__virtio_test_bit(vdev, VIRTIO_F_NOTIFICATION_DATA))
> +		notify = virtio_vdpa_notify_with_data;
> +	else
> +		notify = virtio_vdpa_notify;
> +
>  	/* Queue shouldn't already be set up. */
>  	if (ops->get_vq_ready(vdpa, index))
>  		return ERR_PTR(-ENOENT);
> @@ -183,8 +200,7 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,
>  		dma_dev = vdpa_get_dma_dev(vdpa);
>  	vq = vring_create_virtqueue_dma(index, max_num, align, vdev,
>  					true, may_reduce_num, ctx,
> -					virtio_vdpa_notify, callback,
> -					name, dma_dev);
> +					notify, callback, name, dma_dev);
>  	if (!vq) {
>  		err = -ENOMEM;
>  		goto error_new_virtqueue;
> diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> index 43f59ef10cc..a83bb0501c5 100644
> --- a/include/linux/vdpa.h
> +++ b/include/linux/vdpa.h
> @@ -143,6 +143,11 @@ struct vdpa_map_file {
>   * @kick_vq:			Kick the virtqueue
>   *				@vdev: vdpa device
>   *				@idx: virtqueue index
> + * @kick_vq_with_data:		Kick the virtqueue and supply extra data
> + *				(only if VIRTIO_F_NOTIFICATION_DATA is negotiated)
> + *				@vdev: vdpa device
> + *				@data: includes vqn, next_off and next_wrap for
> + *				packed virtqueues
>   * @set_vq_cb:			Set the interrupt callback function for
>   *				a virtqueue
>   *				@vdev: vdpa device
> @@ -300,6 +305,7 @@ struct vdpa_config_ops {
>  			      u64 device_area);
>  	void (*set_vq_num)(struct vdpa_device *vdev, u16 idx, u32 num);
>  	void (*kick_vq)(struct vdpa_device *vdev, u16 idx);
> +	void (*kick_vq_with_data)(struct vdpa_device *vdev, u32 data);
>  	void (*set_vq_cb)(struct vdpa_device *vdev, u16 idx,
>  			  struct vdpa_callback *cb);
>  	void (*set_vq_ready)(struct vdpa_device *vdev, u16 idx, bool ready);
> -- 
> 2.34.1

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Re: [PATCH] virtio-vdpa: add VIRTIO_F_NOTIFICATION_DATA feature support

[Alvaro Karsz]

> Hmm so I conclude that drivers without kick_vq_with_data
> should not accept VIRTIO_F_NOTIFICATION_DATA then?

Yes, vDPA drivers without kick_vq_with_data should not offer VIRTIO_F_NOTIFICATION_DATA  in the first place.

We can be more forgiving in such cases and clear the feature bit + print a warning.
It may be easier to debug when creating a new vDPA driver.
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Re: [PATCH] virtio-vdpa: add VIRTIO_F_NOTIFICATION_DATA feature support

[Michael S. Tsirkin]

On Sat, Apr 08, 2023 at 07:32:52AM +0000, Alvaro Karsz wrote:
> > Hmm so I conclude that drivers without kick_vq_with_data
> > should not accept VIRTIO_F_NOTIFICATION_DATA then?
> 
> Yes, vDPA drivers without kick_vq_with_data should not offer VIRTIO_F_NOTIFICATION_DATA  in the first place.
> 
> We can be more forgiving in such cases and clear the feature bit + print a warning.
> It may be easier to debug when creating a new vDPA driver.

No need to warn I think, it might not be mandatory.

-- 
MST

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