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

Jason Wang <jasowang@xxxxxxxxxx> · Fri, 11 Feb 2022 15:05:40 +0800

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@xxxxxxxxxxxxxxxxx>
---
  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.


+
+	/* 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?

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,

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