Re: [PATCH v12 30/40] virtio_pci: support VIRTIO_F_RING_RESET

Xuan Zhuo
2022-07-22T03:06:11Z

On Thu, 21 Jul 2022 17:15:11 +0800, Jason Wang <jasowang@redhat.com> wrote:
>
> 在 2022/7/20 11:04, Xuan Zhuo 写道:
> > This patch implements virtio pci support for QUEUE RESET.
> >
> > Performing reset on a queue is divided into these steps:
> >
> > 1. notify the device to reset the queue
> > 2. recycle the buffer submitted
> > 3. reset the vring (may re-alloc)
> > 4. mmap vring to device, and enable the queue
> >
> > This patch implements virtio_reset_vq(), virtio_enable_resetq() in the
> > pci scenario.
> >
> > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > ---
> > drivers/virtio/virtio_pci_common.c | 12 +++-
> > drivers/virtio/virtio_pci_modern.c | 96 ++++++++++++++++++++++++++++++
> > 2 files changed, 105 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
> > index ca51fcc9daab..ad258a9d3b9f 100644
> > --- a/drivers/virtio/virtio_pci_common.c
> > +++ b/drivers/virtio/virtio_pci_common.c
> > @@ -214,9 +214,15 @@ 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 it fails during re-enable reset vq. This way we won't rejoin
> > + * info->node to the queue. Prevent unexpected irqs.
> > + */
> > + 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 9041d9a41b7d..4d28b6918c80 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 */
> > @@ -199,6 +202,95 @@ static int vp_active_vq(struct virtqueue *vq, u16 msix_vec)
> > return 0;
> > }
> >
> > +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;
> > +
> > + 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];
> > +
> > + /* delete vq from irq handler */
> > + spin_lock_irqsave(&vp_dev->lock, flags);
> > + list_del(&info->node);
> > + spin_unlock_irqrestore(&vp_dev->lock, flags);
> > +
> > + INIT_LIST_HEAD(&info->node);
> > +
> > + /* For the case where vq has an exclusive irq, to prevent the irq from
> > + * being received again and the pending irq, call synchronize_irq(), and
> > + * break it.
> > + *
> > + * We can't use disable_irq() since it conflicts with the affinity
> > + * managed IRQ that is used by some drivers. So this is done on top of
> > + * IRQ hardening.
> > + *
> > + * In the scenario based on shared interrupts, vq will be searched from
> > + * the queue virtqueues. Since the previous list_del() has been deleted
> > + * from the queue, it is impossible for vq to be called in this case.
> > + * There is no need to close the corresponding interrupt.
> > + */
> > + if (vp_dev->per_vq_vectors && info->msix_vector != VIRTIO_MSI_NO_VECTOR) {
> > +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
> > + __virtqueue_break(vq);
> > +#endif
>
>
> I think we should do this unconditionally since it's an independent
> feature, though the list_del() above should be sufficient.

Yes.

>
>
> > + synchronize_irq(pci_irq_vector(vp_dev->pci_dev, info->msix_vector));
> > + }
> > +
> > + vq->reset = true;
> > +
> > + return 0;
> > +}
> > +
> > +static int vp_modern_enable_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, index;
> > + int err;
> > +
> > + if (!vq->reset)
> > + return -EBUSY;
> > +
> > + index = vq->index;
> > + info = vp_dev->vqs[index];
> > +
> > + if (vp_modern_get_queue_reset(mdev, index))
> > + return -EBUSY;
> > +
> > + if (vp_modern_get_queue_enable(mdev, index))
> > + return -EBUSY;
> > +
> > + err = vp_active_vq(vq, info->msix_vector);
> > + if (err)
> > + return err;
> > +
> > + if (vq->callback) {
> > + spin_lock_irqsave(&vp_dev->lock, flags);
> > + list_add(&info->node, &vp_dev->virtqueues);
> > + spin_unlock_irqrestore(&vp_dev->lock, flags);
> > + } else {
> > + INIT_LIST_HEAD(&info->node);
> > + }
> > +
> > +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
> > + if (vp_dev->per_vq_vectors && info->msix_vector != VIRTIO_MSI_NO_VECTOR)
> > + __virtqueue_unbreak(vq);
> > +#endif
> > +
> > + vp_modern_set_queue_enable(&vp_dev->mdev, index, true);
> > + vq->reset = false;
> > +
> > + return 0;
> > +}
> > +
> > static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
> > {
> > return vp_modern_config_vector(&vp_dev->mdev, vector);
> > @@ -413,6 +505,8 @@ 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,
> > + .disable_vq_and_reset = vp_modern_reset_vq,
> > + .enable_vq_after_reset = vp_modern_enable_reset_vq,
>
>
> Nit:
>
> To be consistent, let's use vp_modern_disable_vq_and_reset() and
> vp_modern_enable_vq_after_reset()

Will fix.

Thanks.

>
> Thanks
>
>
> > };
> >
> > static const struct virtio_config_ops virtio_pci_config_ops = {
> > @@ -431,6 +525,8 @@ 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,
> > + .disable_vq_and_reset = vp_modern_reset_vq,
> > + .enable_vq_after_reset = vp_modern_enable_reset_vq,
> > };
> >
> > /* the PCI probing function */
>