Re: [PATCH v7 05/26] virtio_ring: split: extract the logic of init vq and attach vring

Xuan Zhuo
2022-03-09T09:22:04Z

On Wed, 9 Mar 2022 15:36:59 +0800, Jason Wang <jasowang@redhat.com> wrote:
>
> 在 2022/3/8 下午8:34, Xuan Zhuo 写道:
> > Split the logic of split assignment vq into three parts.
> >
> > 1. The assignment passed from the function parameter
> > 2. The part that attaches vring to vq. -- __vring_virtqueue_attach_split()
> > 3. The part that initializes vq to a fixed value --
> > __vring_virtqueue_init_split()
> >
> > This feature is required for subsequent virtuqueue reset vring
> >
> > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > ---
> > drivers/virtio/virtio_ring.c | 111 +++++++++++++++++++++--------------
> > 1 file changed, 67 insertions(+), 44 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> > index d32793615451..dc6313b79305 100644
> > --- a/drivers/virtio/virtio_ring.c
> > +++ b/drivers/virtio/virtio_ring.c
> > @@ -2196,34 +2196,40 @@ irqreturn_t vring_interrupt(int irq, void *_vq)
> > }
> > EXPORT_SYMBOL_GPL(vring_interrupt);
> >
> > -/* Only available for split ring */
> > -struct virtqueue *__vring_new_virtqueue(unsigned int index,
> > - struct vring vring,
> > - struct virtio_device *vdev,
> > - bool weak_barriers,
> > - bool context,
> > - bool (*notify)(struct virtqueue *),
> > - void (*callback)(struct virtqueue *),
> > - const char *name)
> > +static int __vring_virtqueue_attach_split(struct vring_virtqueue *vq,
> > + struct virtio_device *vdev,
> > + struct vring vring)
> > {
> > - struct vring_virtqueue *vq;
> > + vq->vq.num_free = vring.num;
> >
> > - if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED))
> > - return NULL;
> > + vq->split.vring = vring;
> > + vq->split.queue_dma_addr = 0;
> > + vq->split.queue_size_in_bytes = 0;
> >
> > - vq = kmalloc(sizeof(*vq), GFP_KERNEL);
> > - if (!vq)
> > - return NULL;
> > + vq->split.desc_state = kmalloc_array(vring.num,
> > + sizeof(struct vring_desc_state_split), GFP_KERNEL);
> > + if (!vq->split.desc_state)
> > + goto err_state;
> >
> > + vq->split.desc_extra = vring_alloc_desc_extra(vq, vring.num);
> > + if (!vq->split.desc_extra)
> > + goto err_extra;
>
>
> So this contains stuffs more than just attach. I wonder if it's better
> to split the allocation out to an dedicated helper (we have dedicated
> helper to allocate vring).

I will try in next version.

Thanks.

>
> Thanks
>
>
> > +
> > + memset(vq->split.desc_state, 0, vring.num *
> > + sizeof(struct vring_desc_state_split));
> > + return 0;
> > +
> > +err_extra:
> > + kfree(vq->split.desc_state);
> > +err_state:
> > + return -ENOMEM;
> > +}
> > +
> > +static void __vring_virtqueue_init_split(struct vring_virtqueue *vq,
> > + struct virtio_device *vdev)
> > +{
> > vq->packed_ring = false;
> > - vq->vq.callback = callback;
> > - vq->vq.vdev = vdev;
> > - vq->vq.name = name;
> > - vq->vq.num_free = vring.num;
> > - vq->vq.index = index;
> > vq->we_own_ring = false;
> > - vq->notify = notify;
> > - vq->weak_barriers = weak_barriers;
> > vq->broken = false;
> > vq->last_used_idx = 0;
> > vq->event_triggered = false;
> > @@ -2234,50 +2240,67 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
> > vq->last_add_time_valid = false;
> > #endif
> >
> > - vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) &&
> > - !context;
> > vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
> >
> > if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
> > vq->weak_barriers = false;
> >
> > - vq->split.queue_dma_addr = 0;
> > - vq->split.queue_size_in_bytes = 0;
> > -
> > - vq->split.vring = vring;
> > vq->split.avail_flags_shadow = 0;
> > vq->split.avail_idx_shadow = 0;
> >
> > /* No callback? Tell other side not to bother us. */
> > - if (!callback) {
> > + if (!vq->vq.callback) {
> > vq->split.avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
> > if (!vq->event)
> > vq->split.vring.avail->flags = cpu_to_virtio16(vdev,
> > vq->split.avail_flags_shadow);
> > }
> >
> > - vq->split.desc_state = kmalloc_array(vring.num,
> > - sizeof(struct vring_desc_state_split), GFP_KERNEL);
> > - if (!vq->split.desc_state)
> > - goto err_state;
> > -
> > - vq->split.desc_extra = vring_alloc_desc_extra(vq, vring.num);
> > - if (!vq->split.desc_extra)
> > - goto err_extra;
> > -
> > /* Put everything in free lists. */
> > vq->free_head = 0;
> > - memset(vq->split.desc_state, 0, vring.num *
> > - sizeof(struct vring_desc_state_split));
> > +}
> > +
> > +/* Only available for split ring */
> > +struct virtqueue *__vring_new_virtqueue(unsigned int index,
> > + struct vring vring,
> > + struct virtio_device *vdev,
> > + bool weak_barriers,
> > + bool context,
> > + bool (*notify)(struct virtqueue *),
> > + void (*callback)(struct virtqueue *),
> > + const char *name)
> > +{
> > + struct vring_virtqueue *vq;
> > + int err;
> > +
> > + if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED))
> > + return NULL;
> > +
> > + vq = kmalloc(sizeof(*vq), GFP_KERNEL);
> > + if (!vq)
> > + return NULL;
> > +
> > + vq->vq.callback = callback;
> > + vq->vq.vdev = vdev;
> > + vq->vq.name = name;
> > + vq->vq.index = index;
> > + vq->notify = notify;
> > + vq->weak_barriers = weak_barriers;
> > + vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) &&
> > + !context;
> > +
> > + err = __vring_virtqueue_attach_split(vq, vdev, vring);
> > + if (err)
> > + goto err;
> > +
> > + __vring_virtqueue_init_split(vq, vdev);
> >
> > spin_lock(&vdev->vqs_list_lock);
> > list_add_tail(&vq->vq.list, &vdev->vqs);
> > spin_unlock(&vdev->vqs_list_lock);
> > - return &vq->vq;
> >
> > -err_extra:
> > - kfree(vq->split.desc_state);
> > -err_state:
> > + return &vq->vq;
> > +err:
> > kfree(vq);
> > return NULL;
> > }