On Tue, Apr 11, 2023 at 01:25:53PM +0800, Jason Wang wrote:
> On Sun, Apr 9, 2023 at 3:07 PM Alvaro Karsz <[email protected]>
> 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:
> > 16 bits vqn and 16 bits next available index for split virtqueues.
> > 16 bits vqs, 15 least significant bits of next available index
> > and 1 bit 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/[email protected]/
> >
> > Signed-off-by: Alvaro Karsz <[email protected]>
> > ---
> > v2:
> > - clear the feature bit if kick_vq_with_data is not implemented.
> > - Fix kick_vq_with_data comment in include/linux/vdpa.h
> > - Write in more detail about the extra data in the commit log
> >
> > drivers/virtio/virtio_vdpa.c | 23 +++++++++++++++++++++--
> > include/linux/vdpa.h | 9 +++++++++
> > 2 files changed, 30 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c
> > index d7f5af62dda..737c1f36d32 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) = virtio_vdpa_notify;
> > struct vdpa_callback cb;
> > struct virtqueue *vq;
> > u64 desc_addr, driver_addr, device_addr;
> > @@ -154,6 +166,14 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev,
> > unsigned int index,
> > if (index >= vdpa->nvqs)
> > return ERR_PTR(-ENOENT);
> >
> > + /* We cannot accept VIRTIO_F_NOTIFICATION_DATA without
> > kick_vq_with_data */
> > + if (__virtio_test_bit(vdev, VIRTIO_F_NOTIFICATION_DATA)) {
> > + if (ops->kick_vq_with_data)
> > + notify = virtio_vdpa_notify_with_data;
> > + else
>
> If we do this, I wonder if we need to fail or at least warn in this case.
>
> Thanks
Nope. Either device can work without VIRTIO_F_NOTIFICATION_DATA
and then all is well or it can't and then it will fail FEATURES_OK.
If drivers start failing when seeing new features we'll never
be able to extend virtio again.
Same for warns, some people run with panic on warn.
> > + __virtio_clear_bit(vdev,
> > VIRTIO_F_NOTIFICATION_DATA);
> > + }
> > +
> > /* Queue shouldn't already be set up. */
> > if (ops->get_vq_ready(vdpa, index))
> > return ERR_PTR(-ENOENT);
> > @@ -183,8 +203,7 @@ 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..04cdaad77dd 100644
> > --- a/include/linux/vdpa.h
> > +++ b/include/linux/vdpa.h
> > @@ -143,6 +143,14 @@ 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 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.
> > * @set_vq_cb: Set the interrupt callback function for
> > * a virtqueue
> > * @vdev: vdpa device
> > @@ -300,6 +308,7 @@ 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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