[PATCH v3 13/17] virtio_pci: queue_reset: support VIRTIO_F_RING_RESET

Xuan Zhuo
2022-02-07T07:59:10Z

On Mon, 7 Feb 2022 14:57:13 +0800, Jason Wang <jasowang at redhat.com>
wrote:
>
> ? 2022/1/26 ??3:35, Xuan Zhuo ??:
> > This patch implements virtio pci support for QUEUE RESET.
> >
> > Performing reset on a queue is divided into two steps:
> >
> > 1. reset_vq: reset one vq
> > 2. enable_reset_vq: re-enable the reset queue
> >
> > In the first step, these tasks will be completed:
> >     1. notify the hardware queue to reset
> >     2. recycle the buffer from vq
> >     3. release the ring of the vq
> >
> > The process of enable reset vq:
> >      vp_modern_enable_reset_vq()
> >      vp_enable_reset_vq()
> >      __vp_setup_vq()
> >      setup_vq()
> >      vring_setup_virtqueue()
> >
> > In this process, we added two parameters, vq and num, and finally
passed
> > them to vring_setup_virtqueue().  And reuse the original info and vq.
> >
> > Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
> > ---
> >   drivers/virtio/virtio_pci_common.c |  36 +++++++----
> >   drivers/virtio/virtio_pci_common.h |   5 ++
> >   drivers/virtio/virtio_pci_modern.c | 100
+++++++++++++++++++++++++++++
> >   3 files changed, 128 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio_pci_common.c
b/drivers/virtio/virtio_pci_common.c
> > index c02936d29a31..ad21638fbf66 100644
> > --- a/drivers/virtio/virtio_pci_common.c
> > +++ b/drivers/virtio/virtio_pci_common.c
> > @@ -205,23 +205,28 @@ static int vp_request_msix_vectors(struct
virtio_device *vdev, int nvectors,
> >   	return err;
> >   }
> >
> > -static struct virtqueue *vp_setup_vq(struct virtio_device *vdev,
unsigned index,
> > -				     void (*callback)(struct virtqueue *vq),
> > -				     const char *name,
> > -				     bool ctx,
> > -				     u16 msix_vec, u16 num)
> > +struct virtqueue *vp_setup_vq(struct virtio_device *vdev, unsigned
index,
> > +			      void (*callback)(struct virtqueue *vq),
> > +			      const char *name,
> > +			      bool ctx,
> > +			      u16 msix_vec, u16 num)
> >   {
> >   	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> > -	struct virtio_pci_vq_info *info = kmalloc(sizeof *info, GFP_KERNEL);
> > +	struct virtio_pci_vq_info *info;
> >   	struct virtqueue *vq;
> >   	unsigned long flags;
> >
> > -	/* fill out our structure that represents an active queue */
> > -	if (!info)
> > -		return ERR_PTR(-ENOMEM);
> > +	info = vp_dev->vqs[index];
> > +	if (!info) {
> > +		info = kzalloc(sizeof *info, GFP_KERNEL);
> > +
> > +		/* fill out our structure that represents an active queue */
> > +		if (!info)
> > +			return ERR_PTR(-ENOMEM);
> > +	}
> >
> >   	vq = vp_dev->setup_vq(vp_dev, info, index, callback, name, ctx,
> > -			      msix_vec, NULL, num);
> > +			      msix_vec, info->vq, num);
> >   	if (IS_ERR(vq))
> >   		goto out_info;
> >
> > @@ -238,6 +243,9 @@ static struct virtqueue *vp_setup_vq(struct
virtio_device *vdev, unsigned index,
> >   	return vq;
> >
> >   out_info:
> > +	if (info->vq && info->vq->reset)
> > +		return vq;
> > +
> >   	kfree(info);
> >   	return vq;
> >   }
> > @@ -248,9 +256,11 @@ 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_common.h
b/drivers/virtio/virtio_pci_common.h
> > index 65db92245e41..c1d15f7c0be4 100644
> > --- a/drivers/virtio/virtio_pci_common.h
> > +++ b/drivers/virtio/virtio_pci_common.h
> > @@ -119,6 +119,11 @@ int vp_find_vqs(struct virtio_device *vdev,
unsigned nvqs,
> >   		struct virtqueue *vqs[], vq_callback_t *callbacks[],
> >   		const char * const names[], const bool *ctx,
> >   		struct irq_affinity *desc);
> > +struct virtqueue *vp_setup_vq(struct virtio_device *vdev, unsigned
index,
> > +			      void (*callback)(struct virtqueue *vq),
> > +			      const char *name,
> > +			      bool ctx,
> > +			      u16 msix_vec, u16 num);
> >   const char *vp_bus_name(struct virtio_device *vdev);
> >
> >   /* Setup the affinity for a virtqueue:
> > diff --git a/drivers/virtio/virtio_pci_modern.c
b/drivers/virtio/virtio_pci_modern.c
> > index 2ce58de549de..6789411169e4 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 +179,94 @@ static void vp_reset(struct virtio_device *vdev)
> >   	vp_disable_cbs(vdev);
> >   }
> >
> > +static int vp_modern_reset_vq(struct virtio_reset_vq *param)
> > +{
> > +	struct virtio_pci_device *vp_dev = to_vp_device(param->vdev);
> > +	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
> > +	struct virtio_pci_vq_info *info;
> > +	u16 msix_vec, queue_index;
> > +	unsigned long flags;
> > +	void *buf;
> > +
> > +	if (!virtio_has_feature(param->vdev, VIRTIO_F_RING_RESET))
> > +		return -ENOENT;
> > +
> > +	queue_index = param->queue_index;
> > +
> > +	vp_modern_set_queue_reset(mdev, queue_index);
> > +
> > +	/* After write 1 to queue reset, the driver MUST wait for a read of
> > +	 * queue reset to return 1.
> > +	 */
> > +	while (vp_modern_get_queue_reset(mdev, queue_index) != 1)
> > +		msleep(1);
>
>
> Is this better to move this logic into vp_modern_set_queue_reset()?
>

OK.

>
> > +
> > +	info = vp_dev->vqs[queue_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));
>
>
> How about the INTX case where irq is shared? I guess we need to disable
> and enable the irq as well.

For the INTX scenario, I don't think we need to disable/enable the irq. But
I do
have a mistake, I should put the following list_del(&info->node) here, so
that
when the irq comes, it will no longer operate this vq.

In fact, for no INTX case, the disable_irq here is not necessary, according to
the requirements of the spec, after reset, the device should not generate irq
anymore. Here just to prevent accidents.

>
>
> > +
> > +	while ((buf = virtqueue_detach_unused_buf(info->vq)) != NULL)
> > +		param->free_unused_cb(param, buf);
>
>
> Any reason that we can't leave this logic to driver? (Or is there any
> operations that must be done before the following operations?)

As you commented before, we merged free unused buf and reset queue.

I think it's a good note, otherwise, we're going to

	1. reset vq
	2. free unused(by driver)
	3. free ring of vq


>
>
> > +
> > +	/* delete vq */
> > +	spin_lock_irqsave(&vp_dev->lock, flags);
> > +	list_del(&info->node);
> > +	spin_unlock_irqrestore(&vp_dev->lock, flags);
> > +
> > +	INIT_LIST_HEAD(&info->node);
> > +
> > +	if (vp_dev->msix_enabled)
> > +		vp_modern_queue_vector(mdev, info->vq->index,
> > +				       VIRTIO_MSI_NO_VECTOR);
>
>
> I wonder if this is a must.
>
>
> > +
> > +	if (!mdev->notify_base)
> > +		pci_iounmap(mdev->pci_dev,
> > +			    (void __force __iomem *)info->vq->priv);
>
>
> Is this a must? what happens if we simply don't do this?
>

The purpose of these two operations is mainly to be symmetrical with del_vq().


>
> > +
> > +	vring_reset_virtqueue(info->vq);
> > +
> > +	return 0;
> > +}
> > +
> > +static struct virtqueue *vp_modern_enable_reset_vq(struct
virtio_reset_vq *param)
> > +{
> > +	struct virtio_pci_device *vp_dev = to_vp_device(param->vdev);
> > +	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
> > +	struct virtio_pci_vq_info *info;
> > +	u16 msix_vec, queue_index;
> > +	struct virtqueue *vq;
> > +
> > +	if (!virtio_has_feature(param->vdev, VIRTIO_F_RING_RESET))
> > +		return ERR_PTR(-ENOENT);
> > +
> > +	queue_index = param->queue_index;
> > +
> > +	info = vp_dev->vqs[queue_index];
> > +
> > +	if (!info->vq->reset)
> > +		return ERR_PTR(-EPERM);
> > +
> > +	/* check queue reset status */
> > +	if (vp_modern_get_queue_reset(mdev, queue_index) != 1)
> > +		return ERR_PTR(-EBUSY);
> > +
> > +	vq = vp_setup_vq(param->vdev, queue_index, param->callback,
param->name,
> > +			 param->ctx, info->msix_vector, param->ring_num);
> > +	if (IS_ERR(vq))
> > +		return vq;
> > +
> > +	vp_modern_set_queue_enable(&vp_dev->mdev, vq->index,
true);
> > +
> > +	msix_vec = vp_dev->vqs[queue_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));
>
>
> How about the INT-X case?

Explained above.

Thanks.

>
> Thanks
>
>
> > +
> > +	return vq;
> > +}
> > +
> >   static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16
vector)
> >   {
> >   	return vp_modern_config_vector(&vp_dev->mdev, vector);
> > @@ -284,6 +375,11 @@ static void del_vq(struct virtio_pci_vq_info
*info)
> >   	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
> >   	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
> >
> > +	if (vq->reset) {
> > +		vring_del_virtqueue(vq);
> > +		return;
> > +	}
> > +
> >   	if (vp_dev->msix_enabled)
> >   		vp_modern_queue_vector(mdev, vq->index,
> >   				       VIRTIO_MSI_NO_VECTOR);
> > @@ -403,6 +499,8 @@ 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 = {
> > @@ -421,6 +519,8 @@ 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 */
>