Re: [PATCH v4 14/14] virtio_pci: queue_reset: support VIRTIO_F_RING_RESET

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

On Fri, 11 Feb 2022 15:05:40 +0800, Jason Wang <jasowang@redhat.com> wrote:
>
> 在 2022/2/9 下午8:29, Xuan Zhuo 写道:
> > This patch implements virtio pci support for QUEUE RESET.
> >
> > Performing reset on a queue is divided into these 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
> >
> > This patch implements reset_vq, enable_reset_vq in the pci scenario
> >
> > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > ---
> >   drivers/virtio/virtio_pci_common.c |  8 +--
> >   drivers/virtio/virtio_pci_modern.c | 80 ++++++++++++++++++++++++++++--
> >   drivers/virtio/virtio_ring.c       |  2 +
> >   include/linux/virtio.h             |  1 +
> >   4 files changed, 85 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
> > index cb01eb0cb2e4..303637ac4914 100644
> > --- a/drivers/virtio/virtio_pci_common.c
> > +++ b/drivers/virtio/virtio_pci_common.c
> > @@ -255,9 +255,11 @@ static void vp_del_vq(struct virtqueue *vq)
> >   	struct virtio_pci_vq_info *info = vp_dev->vqs[vq->index];
> >   	unsigned long flags;
> >
> > -	spin_lock_irqsave(&vp_dev->lock, flags);
> > -	list_del(&info->node);
> > -	spin_unlock_irqrestore(&vp_dev->lock, flags);
> > +	if (!vq->reset) {
> > +		spin_lock_irqsave(&vp_dev->lock, flags);
> > +		list_del(&info->node);
> > +		spin_unlock_irqrestore(&vp_dev->lock, flags);
> > +	}
> >
> >   	vp_dev->del_vq(info);
> >   	kfree(info);
> > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
> > index d29d40bf0b45..cc45515eda50 100644
> > --- a/drivers/virtio/virtio_pci_modern.c
> > +++ b/drivers/virtio/virtio_pci_modern.c
> > @@ -34,6 +34,9 @@ static void vp_transport_features(struct virtio_device *vdev, u64 features)
> >   	if ((features & BIT_ULL(VIRTIO_F_SR_IOV)) &&
> >   			pci_find_ext_capability(pci_dev, PCI_EXT_CAP_ID_SRIOV))
> >   		__virtio_set_bit(vdev, VIRTIO_F_SR_IOV);
> > +
> > +	if (features & BIT_ULL(VIRTIO_F_RING_RESET))
> > +		__virtio_set_bit(vdev, VIRTIO_F_RING_RESET);
> >   }
> >
> >   /* virtio config->finalize_features() implementation */
> > @@ -176,6 +179,70 @@ static void vp_reset(struct virtio_device *vdev)
> >   	vp_disable_cbs(vdev);
> >   }
> >
> > +static int vp_modern_reset_vq(struct virtqueue *vq)
> > +{
> > +	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
> > +	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
> > +	struct virtio_pci_vq_info *info;
> > +	unsigned long flags;
> > +	u16 msix_vec;
> > +
> > +	if (!virtio_has_feature(vq->vdev, VIRTIO_F_RING_RESET))
> > +		return -ENOENT;
> > +
> > +	vp_modern_set_queue_reset(mdev, vq->index);
> > +
> > +	info = vp_dev->vqs[vq->index];
> > +	msix_vec = info->msix_vector;
> > +
> > +	/* Disable VQ callback. */
> > +	if (vp_dev->per_vq_vectors && msix_vec != VIRTIO_MSI_NO_VECTOR)
> > +		disable_irq(pci_irq_vector(vp_dev->pci_dev, msix_vec));
>
>
> I think we need a comment to explain why per_vq_mode needs to be dealt
> with differently.

OK.

>
>
> > +
> > +	/* delete vq */
> > +	spin_lock_irqsave(&vp_dev->lock, flags);
> > +	list_del(&info->node);
> > +	spin_unlock_irqrestore(&vp_dev->lock, flags);
>
>
> So I don't see where vring is freed and vp_setup_vq() may try to
> allocate new memory, won't it be a memory leak in this case?

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

vring_release_virtqueue() (#8 patch) will release the vring.
That is called by the driver.

I think I should add a check to vp_modern_enable_reset_vq() that
vring_release_virtqueue() has already been called.

Thanks

>
> Thanks
>
>
> > +
> > +	vq->reset = true;
> > +
> > +	INIT_LIST_HEAD(&info->node);
> > +
> > +	return 0;
> > +}
> > +
> > +static int vp_modern_enable_reset_vq(struct virtqueue *vq, u16 ring_num)
> > +{
> > +	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
> > +	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
> > +	struct virtio_pci_vq_info *info;
> > +	struct virtqueue *_vq;
> > +	u16 msix_vec;
> > +
> > +	if (!vq->reset)
> > +		return -EPERM;
> > +
> > +	/* check queue reset status */
> > +	if (vp_modern_get_queue_reset(mdev, vq->index) != 1)
> > +		return -EBUSY;
> > +
> > +	info = vp_dev->vqs[vq->index];
> > +	_vq = vp_setup_vq(vq->vdev, vq->index, NULL, NULL, NULL,
> > +			 info->msix_vector, ring_num);
> > +	if (IS_ERR(_vq)) {
> > +		vq->reset = true;
> > +		return PTR_ERR(_vq);
> > +	}
> > +
> > +	vp_modern_set_queue_enable(&vp_dev->mdev, vq->index, true);
> > +
> > +	msix_vec = vp_dev->vqs[vq->index]->msix_vector;
> > +	if (vp_dev->per_vq_vectors && msix_vec != VIRTIO_MSI_NO_VECTOR)
> > +		enable_irq(pci_irq_vector(vp_dev->pci_dev, msix_vec));
> > +
> > +	return 0;
> > +}
> > +
> >   static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
> >   {
> >   	return vp_modern_config_vector(&vp_dev->mdev, vector);
> > @@ -231,10 +298,13 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
> >   				virtqueue_get_avail_addr(vq),
> >   				virtqueue_get_used_addr(vq));
> >
> > -	vq->priv = (void __force *)vp_modern_map_vq_notify(mdev, index, NULL);
> >   	if (!vq->priv) {
> > -		err = -ENOMEM;
> > -		goto err_map_notify;
> > +		vq->priv = (void __force *)vp_modern_map_vq_notify(mdev, index,
> > +								   NULL);
> > +		if (!vq->priv) {
> > +			err = -ENOMEM;
> > +			goto err_map_notify;
> > +		}
>
>
> This seems unrelated or an artifact of previous patches?
>
> Thanks
>
>
> >   	}
> >
> >   	if (msix_vec != VIRTIO_MSI_NO_VECTOR) {
> > @@ -402,6 +472,8 @@ static const struct virtio_config_ops virtio_pci_config_nodev_ops = {
> >   	.set_vq_affinity = vp_set_vq_affinity,
> >   	.get_vq_affinity = vp_get_vq_affinity,
> >   	.get_shm_region  = vp_get_shm_region,
> > +	.reset_vq	 = vp_modern_reset_vq,
> > +	.enable_reset_vq = vp_modern_enable_reset_vq,
> >   };
> >
> >   static const struct virtio_config_ops virtio_pci_config_ops = {
> > @@ -420,6 +492,8 @@ static const struct virtio_config_ops virtio_pci_config_ops = {
> >   	.set_vq_affinity = vp_set_vq_affinity,
> >   	.get_vq_affinity = vp_get_vq_affinity,
> >   	.get_shm_region  = vp_get_shm_region,
> > +	.reset_vq	 = vp_modern_reset_vq,
> > +	.enable_reset_vq = vp_modern_enable_reset_vq,
> >   };
> >
> >   /* the PCI probing function */
> > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> > index b8747df8dc1f..4f6028e1e2d9 100644
> > --- a/drivers/virtio/virtio_ring.c
> > +++ b/drivers/virtio/virtio_ring.c
> > @@ -1731,6 +1731,7 @@ static struct virtqueue *vring_create_virtqueue_packed(
> >   	vq->vq.vdev = vdev;
> >   	vq->vq.num_free = num;
> >   	vq->vq.index = index;
> > +	vq->vq.reset = false;
> >   	vq->we_own_ring = true;
> >   	vq->notify = notify;
> >   	vq->weak_barriers = weak_barriers;
> > @@ -2220,6 +2221,7 @@ static int __vring_init_virtqueue(struct virtqueue *_vq,
> >   	vq->vq.vdev = vdev;
> >   	vq->vq.num_free = vring.num;
> >   	vq->vq.index = index;
> > +	vq->vq.reset = false;
> >   	vq->we_own_ring = false;
> >   	vq->notify = notify;
> >   	vq->weak_barriers = weak_barriers;
> > diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> > index dd1657c3a488..5d4817d79f3f 100644
> > --- a/include/linux/virtio.h
> > +++ b/include/linux/virtio.h
> > @@ -32,6 +32,7 @@ struct virtqueue {
> >   	unsigned int index;
> >   	unsigned int num_free;
> >   	void *priv;
> > +	bool reset;
> >   };
> >
> >   int virtqueue_add_outbuf(struct virtqueue *vq,
>