On Wed, Jan 19, 2022 at 10:35 AM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote:
>
> This patch implements virtio pci support for QUEUE RESET.
>
> Performing reset on a queue is divided into three steps:
>
> 1. reset_vq: notify the hardware queue to reset
> 2. del_reset_vq: delete the reset queue
> 3. enable_reset_vq: re-enable the reset queue
>
> Between steps 1 and 2, generally call virtqueue_detach_unused_buf() to
> recycle the buffer.
I wonder if it's better to squash 1, 2 and
virtqueue_detach_unused_buf() into a single helper.
>
> When deleting a vq, vp_del_vq() will be called to release all the memory
> of the vq. But this does not affect the process of deleting vqs, because
> that is based on the queue to release all the vqs. During this process,
> the vq has been removed from the queue.
>
> When deleting vq, info and vq will be released, and I save msix_vec in
> vp_dev->vqs[queue_index]. When re-enable, the current msix_vec can be
> reused. And based on intx_enabled to determine which method to use to
> enable this queue.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
> ---
> drivers/virtio/virtio_pci_common.c | 54 ++++++++++++++++++++
> drivers/virtio/virtio_pci_common.h | 5 ++
> drivers/virtio/virtio_pci_modern.c | 81 ++++++++++++++++++++++++++++++
> include/linux/virtio_config.h | 21 ++++++++
> 4 files changed, 161 insertions(+)
>
> diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
> index 5afe207ce28a..615a5a5f757c 100644
> --- a/drivers/virtio/virtio_pci_common.c
> +++ b/drivers/virtio/virtio_pci_common.c
> @@ -464,6 +464,60 @@ int vp_find_vqs(struct virtio_device *vdev, unsigned nvqs,
> return vp_find_vqs_intx(vdev, nvqs, vqs, callbacks, names, ctx);
> }
>
> +#define VQ_IS_DELETED(vp_dev, idx) ((unsigned long)vp_dev->vqs[idx] & 1)
> +#define VQ_RESET_MSIX_VEC(vp_dev, idx) ((unsigned long)vp_dev->vqs[idx] >> 2)
> +#define VQ_RESET_MARK(msix_vec) ((void *)(long)((msix_vec << 2) + 1))
> +
> +int vp_del_reset_vq(struct virtio_device *vdev, u16 queue_index)
> +{
> + struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> + struct virtio_pci_vq_info *info;
> + u16 msix_vec;
> +
> + if (VQ_IS_DELETED(vp_dev, queue_index))
> + return -EPERM;
> +
> + info = vp_dev->vqs[queue_index];
> +
> + msix_vec = info->msix_vector;
> +
> + /* delete vq */
> + vp_del_vq(info->vq);
> +
> + /* Mark the vq has been deleted, and save the msix_vec. */
> + vp_dev->vqs[queue_index] = VQ_RESET_MARK(msix_vec);
> +
> + return 0;
> +}
> +
> +struct virtqueue *vp_enable_reset_vq(struct virtio_device *vdev,
> + int queue_index,
> + vq_callback_t *callback,
> + const char *name,
> + const bool ctx)
> +{
> + struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> + struct virtqueue *vq;
> + u16 msix_vec;
> +
> + if (!VQ_IS_DELETED(vp_dev, queue_index))
> + return ERR_PTR(-EPERM);
> +
> + msix_vec = VQ_RESET_MSIX_VEC(vp_dev, queue_index);
> +
> + if (vp_dev->intx_enabled)
> + vq = vp_setup_vq(vdev, queue_index, callback, name, ctx,
> + VIRTIO_MSI_NO_VECTOR);
> + else
> + vq = vp_enable_vq_msix(vdev, queue_index, callback, name, ctx,
> + msix_vec);
> +
> + if (IS_ERR(vq))
> + vp_dev->vqs[queue_index] = VQ_RESET_MARK(msix_vec);
> +
> + return vq;
> +}
> +
> const char *vp_bus_name(struct virtio_device *vdev)
> {
> struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> diff --git a/drivers/virtio/virtio_pci_common.h b/drivers/virtio/virtio_pci_common.h
> index 23f6c5c678d5..a92c99cc010e 100644
> --- a/drivers/virtio/virtio_pci_common.h
> +++ b/drivers/virtio/virtio_pci_common.h
> @@ -115,6 +115,11 @@ 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);
> +void vp_reset_vq(struct virtio_device *vdev, u16 queue_index);
> +int vp_del_reset_vq(struct virtio_device *vdev, u16 queue_index);
> +struct virtqueue *vp_enable_reset_vq(struct virtio_device *vdev, int queue_index,
> + vq_callback_t *callback, const char *name,
> + const bool ctx);
> 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 5455bc041fb6..74e0b2b2f4dc 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 +179,78 @@ static void vp_reset(struct virtio_device *vdev)
> vp_disable_cbs(vdev);
> }
>
> +static int vp_modern_reset_vq(struct virtio_device *vdev, u16 queue_index)
> +{
> + struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> + struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
> + u16 msix_vec;
> +
> + if (!virtio_has_feature(vdev, VIRTIO_F_RING_RESET))
> + return -ENOENT;
> +
> + 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);
> +
> + msix_vec = vp_dev->vqs[queue_index]->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));
What happens if the irq is shared among virtqueues?
> +
> + return 0;
> +}
> +
> +static int vp_modern_del_reset_vq(struct virtio_device *vdev, u16 queue_index)
> +{
> + struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> + struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
> +
> + if (!virtio_has_feature(vdev, VIRTIO_F_RING_RESET))
> + return -ENOENT;
> +
> + /* check queue reset status */
> + if (vp_modern_get_queue_reset(mdev, queue_index) != 1)
> + return -EBUSY;
> +
> + return vp_del_reset_vq(vdev, queue_index);
> +}
> +
> +static struct virtqueue *vp_modern_enable_reset_vq(struct virtio_device *vdev,
> + u16 queue_index,
> + vq_callback_t *callback,
> + const char *name,
> + const bool *ctx)
> +{
> + struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> + struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
> + struct virtqueue *vq;
> + u16 msix_vec;
> +
> + if (!virtio_has_feature(vdev, VIRTIO_F_RING_RESET))
> + return ERR_PTR(-ENOENT);
> +
> + /* check queue reset status */
> + if (vp_modern_get_queue_reset(mdev, queue_index) != 1)
> + return ERR_PTR(-EBUSY);
> +
> + vq = vp_enable_reset_vq(vdev, queue_index, callback, name, ctx);
> + 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));
> +
> + return vq;
> +}
> +
> static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
> {
> return vp_modern_config_vector(&vp_dev->mdev, vector);
> @@ -395,6 +470,9 @@ 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,
> + .del_reset_vq = vp_modern_del_reset_vq,
> + .enable_reset_vq = vp_modern_enable_reset_vq,
> };
>
> static const struct virtio_config_ops virtio_pci_config_ops = {
> @@ -413,6 +491,9 @@ 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,
> + .del_reset_vq = vp_modern_del_reset_vq,
> + .enable_reset_vq = vp_modern_enable_reset_vq,
> };
>
> /* the PCI probing function */
> diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
> index 4d107ad31149..6e94f7d0e153 100644
> --- a/include/linux/virtio_config.h
> +++ b/include/linux/virtio_config.h
> @@ -74,6 +74,21 @@ struct virtio_shm_region {
> * @set_vq_affinity: set the affinity for a virtqueue (optional).
> * @get_vq_affinity: get the affinity for a virtqueue (optional).
> * @get_shm_region: get a shared memory region based on the index.
> + * @reset_vq: reset a queue individually
> + * vdev: the device
> + * queue_index: the queue index
> + * returns 0 on success or error status
> + * @del_reset_vq: del a reset queue
> + * vdev: the device
> + * queue_index: the queue index
> + * returns 0 on success or error status.
> + * @enable_reset_vq: enable a reset queue
> + * vdev: the device
> + * queue_index: the queue index
> + * callback: callback for the virtqueue, NULL for vq that do not need a callback
> + * name: virtqueue names (mainly for debugging), NULL for vq unused by driver
> + * ctx: ctx
> + * returns vq on success or error status
> */
> typedef void vq_callback_t(struct virtqueue *);
> struct virtio_config_ops {
> @@ -100,6 +115,12 @@ struct virtio_config_ops {
> int index);
> bool (*get_shm_region)(struct virtio_device *vdev,
> struct virtio_shm_region *region, u8 id);
> + int (*reset_vq)(struct virtio_device *vdev, u16 queue_index);
> + int (*del_reset_vq)(struct virtio_device *vdev, u16 queue_index);
> + struct virtqueue *(*enable_reset_vq)(struct virtio_device *vdev,
> + u16 queue_index,
> + vq_callback_t *callback,
> + const char *name, const bool *ctx);
> };
>
> /* If driver didn't advertise the feature, it will never appear. */
> --
> 2.31.0
>
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