Jason Wang
2022-Mar-22 06:02 UTC
[PATCH v8 16/16] virtio_ring: introduce virtqueue_resize()
? 2022/3/14 ??5:34, Xuan Zhuo ??:> 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 <xuanzhuo at linux.alibaba.com> > --- > 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;Any reason we need to check a packed specific attribute here?> + > + 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); > + > + 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;So this assumes that the -ENOMEM is the only possible error value for virtqueue_resize_xxx(). Is this true? (E.g wrong size)> + > + 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));I wonder what's the advantages of coupling virtqueue_reset in virtqueue_resize(). It looks to me it wold be more flexible to let the driver do: rest() detach() resize() enable_reset() One reason is that in the future we may want to add more functionality e.g switching PASID during virtqueue reset. Thanks> + > /** > * virtio_device - representation of a device using virtio > * @index: unique position on the virtio bus
Xuan Zhuo
2022-Mar-24 08:34 UTC
[PATCH v8 16/16] virtio_ring: introduce virtqueue_resize()
On Tue, 22 Mar 2022 14:02:47 +0800, Jason Wang <jasowang at redhat.com> wrote:> > ? 2022/3/14 ??5:34, Xuan Zhuo ??: > > 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 <xuanzhuo at linux.alibaba.com> > > --- > > 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; > > > Any reason we need to check a packed specific attribute here?This is a mistake. Sorry for this.> > > > + > > + 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); > > + > > + 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; > > > So this assumes that the -ENOMEM is the only possible error value for > virtqueue_resize_xxx(). Is this true? (E.g wrong size)Yes, I want the user to know at which step the error is returned.> > > > + > > + 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)); > > > I wonder what's the advantages of coupling virtqueue_reset in > virtqueue_resize().This is Michael's comment on the previous version> > It looks to me it wold be more flexible to let the driver do: > > rest() > > detach() > > resize() > > enable_reset() > > One reason is that in the future we may want to add more functionality > e.g switching PASID during virtqueue reset.Michael, from Jason Wang's plan, should we go back to the original 4 api model? Thanks.> > Thanks > > > > + > > /** > > * virtio_device - representation of a device using virtio > > * @index: unique position on the virtio bus >