On Mon, Mar 14, 2022 at 05:34:55PM +0800, Xuan Zhuo wrote: > Introduce virtqueue_resize() to implement the resize of vring. > Based on these, the driver can dynamically adjust the size of the vring. > For example: ethtool -G. > > virtqueue_resize() implements resize based on the vq reset function. In > case of failure to allocate a new vring, it will give up resize and use > the original vring. > > During this process, if the re-enable reset vq fails, the vq can no > longer be used. Although the probability of this situation is not high. > > The parameter recycle is used to recycle the buffer that is no longer > used. > > Signed-off-by: Xuan Zhuo <[email protected]> > --- > drivers/virtio/virtio_ring.c | 67 ++++++++++++++++++++++++++++++++++++ > include/linux/virtio.h | 3 ++ > 2 files changed, 70 insertions(+) > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index fb0abf9a2f57..b1dde086a8a4 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -2528,6 +2528,73 @@ struct virtqueue *vring_create_virtqueue( > } > EXPORT_SYMBOL_GPL(vring_create_virtqueue); > > +/** > + * virtqueue_resize - resize the vring of vq > + * @vq: the struct virtqueue we're talking about. > + * @num: new ring num > + * @recycle: callback for recycle the useless buffer > + * > + * When it is really necessary to create a new vring, it will set the > current vq > + * into the reset state. Then call the passed cb to recycle the buffer that > is > + * no longer used. Only after the new vring is successfully created, the old > + * vring will be released. > + * > + * Caller must ensure we don't call this with other virtqueue operations > + * at the same time (except where noted). > + * > + * Returns zero or a negative error. > + * -ENOMEM: create new vring fail. But vq can still work > + * -EBUSY: reset/re-enable vq fail. vq may cannot work > + * -ENOENT: not support resize > + * -E2BIG/-EINVAL: param num error > + */ > +int virtqueue_resize(struct virtqueue *vq, u32 num, > + void (*recycle)(struct virtqueue *vq, void *buf)) > +{ > + struct virtio_device *vdev = vq->vdev; > + void *buf; > + int err; > + > + if (num > vq->num_max) > + return -E2BIG; > + > + if (!num) > + return -EINVAL; > + > + if (to_vvq(vq)->packed.vring.num == num) > + return 0; > + > + if (!vq->vdev->config->reset_vq) > + return -ENOENT; > + > + if (!vq->vdev->config->enable_reset_vq) > + return -ENOENT; > + > + err = vq->vdev->config->reset_vq(vq); > + if (err) { > + if (err != -ENOENT) > + err = -EBUSY; > + return err; > + } > + > + while ((buf = virtqueue_detach_unused_buf(vq)) != NULL) > + recycle(vq, buf);
So all this callback can do now is drop all buffers, and I think that is not great. Can we store them and invoke the callback after queue is enabled? > + > + if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED)) > + err = virtqueue_resize_packed(vq, num); > + else > + err = virtqueue_resize_split(vq, num); > + > + if (err) > + err = -ENOMEM; > + > + if (vq->vdev->config->enable_reset_vq(vq)) > + return -EBUSY; > + > + return err; > +} > +EXPORT_SYMBOL_GPL(virtqueue_resize); > + > /* Only available for split ring */ > struct virtqueue *vring_new_virtqueue(unsigned int index, > unsigned int num, > diff --git a/include/linux/virtio.h b/include/linux/virtio.h > index d59adc4be068..c86ff02e0ca0 100644 > --- a/include/linux/virtio.h > +++ b/include/linux/virtio.h > @@ -91,6 +91,9 @@ dma_addr_t virtqueue_get_desc_addr(struct virtqueue *vq); > dma_addr_t virtqueue_get_avail_addr(struct virtqueue *vq); > dma_addr_t virtqueue_get_used_addr(struct virtqueue *vq); > > +int virtqueue_resize(struct virtqueue *vq, u32 num, > + void (*recycle)(struct virtqueue *vq, void *buf)); > + > /** > * virtio_device - representation of a device using virtio > * @index: unique position on the virtio bus > -- > 2.31.0 _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
