On Fri, 11 Feb 2022 14:49:03 +0800, Jason Wang <jasowang@xxxxxxxxxx> wrote: > > 在 2022/2/9 下午8:28, Xuan Zhuo 写道: > > Performing reset on a queue is divided into four steps: > > > > 1. reset_vq: reset one vq > > 2. recycle the buffer from vq by virtqueue_detach_unused_buf() > > 3. release the ring of the vq by vring_release_virtqueue() > > 4. enable_reset_vq: re-enable the reset queue > > > > So add two callbacks reset_vq, enable_reset_vq to struct > > virtio_config_ops. > > > > Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> > > --- > > include/linux/virtio_config.h | 13 +++++++++++++ > > 1 file changed, 13 insertions(+) > > > > diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h > > index 4d107ad31149..0d01a64f2576 100644 > > --- a/include/linux/virtio_config.h > > +++ b/include/linux/virtio_config.h > > @@ -74,6 +74,17 @@ struct virtio_shm_region { > > * @set_vq_affinity: set the affinity for a virtqueue (optional). > > * @get_vq_affinity: get the affinity for a virtqueue (optional). > > * @get_shm_region: get a shared memory region based on the index. > > + * @reset_vq: reset a queue individually > > > This needs to be marked as optional I think. OK. > > > > + * vq: the virtqueue > > + * Returns 0 on success or error status > > > It looks to me the caller should also guarantee that the vring is not > accsed by any functions e.g NAPI. OK. > > > > + * After successfully calling this, be sure to call > > + * virtqueue_detach_unused_buf() to recycle the buffer in the ring, and > > + * then call vring_release_virtqueue() to release the vq ring. > > + * @enable_reset_vq: enable a reset queue > > + * vq: the virtqueue > > + * ring_num: specify ring num for the vq to be re-enabled. 0 means use the > > + * default value. MUST be a power of 2. > > > Note that we don't have power of 2 requirement for packed virtqueue. So the following check here does not seem reasonable. (virtio_pci_modern.c) static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev, struct virtio_pci_vq_info *info, unsigned index, void (*callback)(struct virtqueue *vq), const char *name, bool ctx, u16 msix_vec) { struct virtio_pci_modern_device *mdev = &vp_dev->mdev; struct virtqueue *vq; u16 num; int err; if (index >= vp_modern_get_num_queues(mdev)) return ERR_PTR(-ENOENT); /* Check if queue is either not available or already active. */ num = vp_modern_get_queue_size(mdev, index); if (!num || vp_modern_get_queue_enable(mdev, index)) return ERR_PTR(-ENOENT); if (num & (num - 1)) { dev_warn(&vp_dev->pci_dev->dev, "bad queue size %u", num); return ERR_PTR(-EINVAL); } ^^^^^^^^^^^^^^^^^^^^^^^ > > And I wonder if it's cleaner to have a find_vq() ops instead to dealing > with the re-allocation and possible size change, or have a dedicated > helper to set vring size so driver can do. > > reset_vq() > > virtqueue_set_vring_size() > > enable_reset_vq() I like to add a dedicated helper. > > > > + * Returns 0 on success or error status > > */ > > typedef void vq_callback_t(struct virtqueue *); > > struct virtio_config_ops { > > @@ -100,6 +111,8 @@ struct virtio_config_ops { > > int index); > > bool (*get_shm_region)(struct virtio_device *vdev, > > struct virtio_shm_region *region, u8 id); > > + int (*reset_vq)(struct virtqueue *vq); > > + int (*enable_reset_vq)(struct virtqueue *vq, u16 ring_num); > > > Note that the current implement is best-effort, so it's not guarantee > that we can have a vring with ring_num, we may get less under memory > pressure or even fail. We probably need to have a pamater to mandate the > ring_num otherwise user may surprise to see a decreased size of the ring > when a increasing is actually requested. 1. We can add a helper to specify max ring num. 2. Or after specifying ring num, in case of failure, return directly. I prefer #1 Thanks. > > Thanks > > > > }; > > > > /* If driver didn't advertise the feature, it will never appear. */ > _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization