[PATCH v11 30/40] virtio_pci: support VIRTIO_F_RING_RESET

Xuan Zhuo
2022-06-29T06:59:52Z

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 ++++++++++++++++++++++++++++++
drivers/virtio/virtio_ring.c | 2 +
include/linux/virtio.h | 1 +
4 files changed, 108 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..754e5e10386b 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
+ 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,
+ .reset_vq = vp_modern_reset_vq,
+ .enable_reset_vq = vp_modern_enable_reset_vq,
};

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,
+ .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 7b02be7fce67..82b058e8ce34 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -2008,6 +2008,7 @@ static struct virtqueue *vring_create_virtqueue_packed(
vq->vq.vdev = vdev;
vq->vq.name = name;
vq->vq.index = index;
+ vq->vq.reset = false;
vq->we_own_ring = true;
vq->notify = notify;
vq->weak_barriers = weak_barriers;
@@ -2487,6 +2488,7 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
vq->vq.vdev = vdev;
vq->vq.name = name;
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 dc474a0d48d1..88f21796b1c3 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -33,6 +33,7 @@ struct virtqueue {
unsigned int num_free;
unsigned int num_max;
void *priv;
+ bool reset;
};

int virtqueue_add_outbuf(struct virtqueue *vq,
--
2.31.0