Re: [PATCH v9 01/32] virtio: add helper virtqueue_get_vring_max_size()

[Xuan Zhuo <xuanzhuo@linux.alibaba.com>]

On Tue, 12 Apr 2022 10:41:03 +0800, Jason Wang <jasowang@redhat.com> wrote:
>
> 在 2022/4/6 上午11:43, Xuan Zhuo 写道:
> > Record the maximum queue num supported by the device.
> >
> > virtio-net can display the maximum (supported by hardware) ring size in
> > ethtool -g eth0.
> >
> > When the subsequent patch implements vring reset, it can judge whether
> > the ring size passed by the driver is legal based on this.
> >
> > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > ---
> >   arch/um/drivers/virtio_uml.c             |  1 +
> >   drivers/platform/mellanox/mlxbf-tmfifo.c |  2 ++
> >   drivers/remoteproc/remoteproc_virtio.c   |  2 ++
> >   drivers/s390/virtio/virtio_ccw.c         |  3 +++
> >   drivers/virtio/virtio_mmio.c             |  2 ++
> >   drivers/virtio/virtio_pci_legacy.c       |  2 ++
> >   drivers/virtio/virtio_pci_modern.c       |  2 ++
> >   drivers/virtio/virtio_ring.c             | 14 ++++++++++++++
> >   drivers/virtio/virtio_vdpa.c             |  2 ++
> >   include/linux/virtio.h                   |  2 ++
> >   10 files changed, 32 insertions(+)
> >
> > diff --git a/arch/um/drivers/virtio_uml.c b/arch/um/drivers/virtio_uml.c
> > index ba562d68dc04..904993d15a85 100644
> > --- a/arch/um/drivers/virtio_uml.c
> > +++ b/arch/um/drivers/virtio_uml.c
> > @@ -945,6 +945,7 @@ static struct virtqueue *vu_setup_vq(struct virtio_device *vdev,
> >   		goto error_create;
> >   	}
> >   	vq->priv = info;
> > +	vq->num_max = num;
> >   	num = virtqueue_get_vring_size(vq);
> >
> >   	if (vu_dev->protocol_features &
> > diff --git a/drivers/platform/mellanox/mlxbf-tmfifo.c b/drivers/platform/mellanox/mlxbf-tmfifo.c
> > index 38800e86ed8a..1ae3c56b66b0 100644
> > --- a/drivers/platform/mellanox/mlxbf-tmfifo.c
> > +++ b/drivers/platform/mellanox/mlxbf-tmfifo.c
> > @@ -959,6 +959,8 @@ static int mlxbf_tmfifo_virtio_find_vqs(struct virtio_device *vdev,
> >   			goto error;
> >   		}
> >
> > +		vq->num_max = vring->num;
> > +
> >   		vqs[i] = vq;
> >   		vring->vq = vq;
> >   		vq->priv = vring;
> > diff --git a/drivers/remoteproc/remoteproc_virtio.c b/drivers/remoteproc/remoteproc_virtio.c
> > index 70ab496d0431..7611755d0ae2 100644
> > --- a/drivers/remoteproc/remoteproc_virtio.c
> > +++ b/drivers/remoteproc/remoteproc_virtio.c
> > @@ -125,6 +125,8 @@ static struct virtqueue *rp_find_vq(struct virtio_device *vdev,
> >   		return ERR_PTR(-ENOMEM);
> >   	}
> >
> > +	vq->num_max = len;
>
>
> I wonder if this is correct.
>
> It looks to me len is counted in bytes:
>
> /**
>   * struct rproc_vring - remoteproc vring state
>   * @va: virtual address
>   * @len: length, in bytes
>   * @da: device address
>   * @align: vring alignment
>   * @notifyid: rproc-specific unique vring index
>   * @rvdev: remote vdev
>   * @vq: the virtqueue of this vring
>   */
> struct rproc_vring {
>          void *va;
>          int len;
>          u32 da;
>          u32 align;
>          int notifyid;
>          struct rproc_vdev *rvdev;
>          struct virtqueue *vq;
> };
>

I think this comment is incorrect because here len is passed as num to
vring_new_virtqueue().

There is also this usage:

	/* actual size of vring (in bytes) */
	size = PAGE_ALIGN(vring_size(rvring->len, rvring->align));


And this value comes from here:

	static int
	rproc_parse_vring(struct rproc_vdev *rvdev, struct fw_rsc_vdev *rsc, int i)
	{
		struct rproc *rproc = rvdev->rproc;
		struct device *dev = &rproc->dev;
		struct fw_rsc_vdev_vring *vring = &rsc->vring[i];
		struct rproc_vring *rvring = &rvdev->vring[i];

		dev_dbg(dev, "vdev rsc: vring%d: da 0x%x, qsz %d, align %d\n",
			i, vring->da, vring->num, vring->align);

		/* verify queue size and vring alignment are sane */
		if (!vring->num || !vring->align) {
			dev_err(dev, "invalid qsz (%d) or alignment (%d)\n",
				vring->num, vring->align);
			return -EINVAL;
		}

       >	rvring->len = vring->num;
		rvring->align = vring->align;
		rvring->rvdev = rvdev;

		return 0;
	}

/**
 * struct fw_rsc_vdev_vring - vring descriptor entry
 * @da: device address
 * @align: the alignment between the consumer and producer parts of the vring
 * @num: num of buffers supported by this vring (must be power of two)
 * @notifyid: a unique rproc-wide notify index for this vring. This notify
 * index is used when kicking a remote processor, to let it know that this
 * vring is triggered.
 * @pa: physical address
 *
 * This descriptor is not a resource entry by itself; it is part of the
 * vdev resource type (see below).
 *
 * Note that @da should either contain the device address where
 * the remote processor is expecting the vring, or indicate that
 * dynamically allocation of the vring's device address is supported.
 */
struct fw_rsc_vdev_vring {
	u32 da;
	u32 align;
	u32 num;
	u32 notifyid;
	u32 pa;
} __packed;

So I think the 'len' here may have changed its meaning in a version update.

Thanks.

>
> Other looks good.
>
> Thanks
>
>
> > +
> >   	rvring->vq = vq;
> >   	vq->priv = rvring;
> >
> > diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
> > index d35e7a3f7067..468da60b56c5 100644
> > --- a/drivers/s390/virtio/virtio_ccw.c
> > +++ b/drivers/s390/virtio/virtio_ccw.c
> > @@ -529,6 +529,9 @@ static struct virtqueue *virtio_ccw_setup_vq(struct virtio_device *vdev,
> >   		err = -ENOMEM;
> >   		goto out_err;
> >   	}
> > +
> > +	vq->num_max = info->num;
> > +
> >   	/* it may have been reduced */
> >   	info->num = virtqueue_get_vring_size(vq);
> >
> > diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
> > index 56128b9c46eb..a41abc8051b9 100644
> > --- a/drivers/virtio/virtio_mmio.c
> > +++ b/drivers/virtio/virtio_mmio.c
> > @@ -390,6 +390,8 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
> >   		goto error_new_virtqueue;
> >   	}
> >
> > +	vq->num_max = num;
> > +
> >   	/* Activate the queue */
> >   	writel(virtqueue_get_vring_size(vq), vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
> >   	if (vm_dev->version == 1) {
> > diff --git a/drivers/virtio/virtio_pci_legacy.c b/drivers/virtio/virtio_pci_legacy.c
> > index 34141b9abe27..b68934fe6b5d 100644
> > --- a/drivers/virtio/virtio_pci_legacy.c
> > +++ b/drivers/virtio/virtio_pci_legacy.c
> > @@ -135,6 +135,8 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
> >   	if (!vq)
> >   		return ERR_PTR(-ENOMEM);
> >
> > +	vq->num_max = num;
> > +
> >   	q_pfn = virtqueue_get_desc_addr(vq) >> VIRTIO_PCI_QUEUE_ADDR_SHIFT;
> >   	if (q_pfn >> 32) {
> >   		dev_err(&vp_dev->pci_dev->dev,
> > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
> > index 5455bc041fb6..86d301f272b8 100644
> > --- a/drivers/virtio/virtio_pci_modern.c
> > +++ b/drivers/virtio/virtio_pci_modern.c
> > @@ -218,6 +218,8 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
> >   	if (!vq)
> >   		return ERR_PTR(-ENOMEM);
> >
> > +	vq->num_max = num;
> > +
> >   	/* activate the queue */
> >   	vp_modern_set_queue_size(mdev, index, virtqueue_get_vring_size(vq));
> >   	vp_modern_queue_address(mdev, index, virtqueue_get_desc_addr(vq),
> > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> > index 962f1477b1fa..b87130c8f312 100644
> > --- a/drivers/virtio/virtio_ring.c
> > +++ b/drivers/virtio/virtio_ring.c
> > @@ -2371,6 +2371,20 @@ void vring_transport_features(struct virtio_device *vdev)
> >   }
> >   EXPORT_SYMBOL_GPL(vring_transport_features);
> >
> > +/**
> > + * virtqueue_get_vring_max_size - return the max size of the virtqueue's vring
> > + * @_vq: the struct virtqueue containing the vring of interest.
> > + *
> > + * Returns the max size of the vring.
> > + *
> > + * Unlike other operations, this need not be serialized.
> > + */
> > +unsigned int virtqueue_get_vring_max_size(struct virtqueue *_vq)
> > +{
> > +	return _vq->num_max;
> > +}
> > +EXPORT_SYMBOL_GPL(virtqueue_get_vring_max_size);
> > +
> >   /**
> >    * virtqueue_get_vring_size - return the size of the virtqueue's vring
> >    * @_vq: the struct virtqueue containing the vring of interest.
> > diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c
> > index 7767a7f0119b..39e4c08eb0f2 100644
> > --- a/drivers/virtio/virtio_vdpa.c
> > +++ b/drivers/virtio/virtio_vdpa.c
> > @@ -183,6 +183,8 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,
> >   		goto error_new_virtqueue;
> >   	}
> >
> > +	vq->num_max = max_num;
> > +
> >   	/* Setup virtqueue callback */
> >   	cb.callback = virtio_vdpa_virtqueue_cb;
> >   	cb.private = info;
> > diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> > index 72292a62cd90..d59adc4be068 100644
> > --- a/include/linux/virtio.h
> > +++ b/include/linux/virtio.h
> > @@ -31,6 +31,7 @@ struct virtqueue {
> >   	struct virtio_device *vdev;
> >   	unsigned int index;
> >   	unsigned int num_free;
> > +	unsigned int num_max;
> >   	void *priv;
> >   };
> >
> > @@ -80,6 +81,7 @@ bool virtqueue_enable_cb_delayed(struct virtqueue *vq);
> >
> >   void *virtqueue_detach_unused_buf(struct virtqueue *vq);
> >
> > +unsigned int virtqueue_get_vring_max_size(struct virtqueue *vq);
> >   unsigned int virtqueue_get_vring_size(struct virtqueue *vq);
> >
> >   bool virtqueue_is_broken(struct virtqueue *vq);
>