在 2022/3/10 下午4:20, Xuan Zhuo 写道:
On Wed, 9 Mar 2022 16:54:10 +0800, Jason Wang <jasowang@xxxxxxxxxx> wrote:
在 2022/3/8 下午8:35, Xuan Zhuo 写道:
This patch implements virtio pci support for QUEUE RESET.
Performing reset on a queue is divided into these steps:
1. virtio_reset_vq() - notify the device to reset the queue
2. virtqueue_detach_unused_buf() - recycle the buffer submitted
3. virtqueue_reset_vring() - reset the vring (may re-alloc)
4. virtio_enable_resetq() - 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@xxxxxxxxxxxxxxxxx>
---
drivers/virtio/virtio_pci_common.c | 8 +--
drivers/virtio/virtio_pci_modern.c | 83 ++++++++++++++++++++++++++++++
2 files changed, 88 insertions(+), 3 deletions(-)
diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index fdbde1db5ec5..863d3a8a0956 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -248,9 +248,11 @@ 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 49a4493732cf..3c67d3607802 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 +202,82 @@ 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;
+ unsigned int irq;
+
+ 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);
+
+ vq->reset = VIRTIO_VQ_RESET_STEP_DEVICE;
+
+ /* sync irq callback. */
+ if (vp_dev->intx_enabled) {
+ irq = vp_dev->pci_dev->irq;
+
+ } else {
+ if (info->msix_vector == VIRTIO_MSI_NO_VECTOR)
+ return 0;
+
+ irq = pci_irq_vector(vp_dev->pci_dev, info->msix_vector);
+ }
+
+ synchronize_irq(irq);
Synchronize_irq() is not sufficient here since it breaks the effort of
the interrupt hardening which is done by commits:
080cd7c3ac87 virtio-pci: harden INTX interrupts
9e35276a5344 virtio_pci: harden MSI-X interrupts
Unfortunately 080cd7c3ac87 introduces an issue that disable_irq() were
used for the affinity managed irq but we're discussing a fix.
ok, I think disable_irq() is still used here.
I want to determine the solution for this detail first. So I posted the code, I
hope Jason can help confirm this point first.
There are three situations in which vq corresponds to an interrupt
1. intx
2. msix: per vq vectors
2. msix: share irq
Essentially can be divided into two categories: per vq vectors and share irq.
For share irq is based on virtqueues to find vq, so I think it is safe as long
as list_del() is executed under the protection of the lock.
In the case of per vq vectors, disable_irq() is used.
See the discussion here[1], disable_irq() could be problematic for the
block and scsi device that using affinity managed irq. We're waiting for
the IRQ maintainer to comment on a solution. Other looks sane.
Thanks
[1] https://lkml.org/lkml/2022/3/8/743
Thanks.
+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;
+ unsigned int irq;
+
+ 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);
+ 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 disable_irq().
+ *
+ * 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 && msix_vec != VIRTIO_MSI_NO_VECTOR)
+ disable_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];
+
+ /* check queue reset status */
+ if (vp_modern_get_queue_reset(mdev, index) != 1)
+ 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);
+ }
+
+ vp_modern_set_queue_enable(&vp_dev->mdev, index, true);
+ vq->reset = false;
+
+ if (vp_dev->per_vq_vectors && msix_vec != VIRTIO_MSI_NO_VECTOR)
+ enable_irq(pci_irq_vector(vp_dev->pci_dev, info->msix_vector));
+
+ return 0;
+}
