On Thu, 20 Jan 2022 05:55:14 -0500, Michael S. Tsirkin <mst@xxxxxxxxxx> wrote:
> On Thu, Jan 20, 2022 at 02:42:58PM +0800, Xuan Zhuo wrote:
> > 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. delete the vq
> >
> > 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>
>
> There's something I don't understand here. It looks like
> you assume that when you reset a queue, you also
> reset the mapping from queue to event vector.
> The spec does not say it should, and I don't think it's
> useful to extend spec to do it - we already have a simple
> way to tweak the mapping.
>
Sorry, what is the already existing method you are referring to, I didn't find
it.
I think you mean that we don't have to reset the event vector, I think you are
right.
Thanks.
> Avoid doing that, and things will be much easier, with no need
> to interact with a transport, won't they?
>
>
> > ---
> > drivers/virtio/virtio_pci_common.c | 49 ++++++++++++++++++++
> > drivers/virtio/virtio_pci_common.h | 4 ++
> > drivers/virtio/virtio_pci_modern.c | 73 ++++++++++++++++++++++++++++++
> > 3 files changed, 126 insertions(+)
> >
> > diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
> > index 5afe207ce28a..28b5ffde4621 100644
> > --- a/drivers/virtio/virtio_pci_common.c
> > +++ b/drivers/virtio/virtio_pci_common.c
> > @@ -464,6 +464,55 @@ 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))
> > +
> > +void 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;
> > +
> > + 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);
> > +}
> > +
> > +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..96c13b1398f8 100644
> > --- a/drivers/virtio/virtio_pci_common.h
> > +++ b/drivers/virtio/virtio_pci_common.h
> > @@ -115,6 +115,10 @@ 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_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..fbf87239c920 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 +179,72 @@ 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,
> > + vq_reset_callback_t *callback, void *data)
> > +{
> > + struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> > + struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
> > + struct virtio_pci_vq_info *info;
> > + u16 msix_vec;
> > + void *buf;
> > +
> > + 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);
> > +
> > + 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));
> > +
> > + while ((buf = virtqueue_detach_unused_buf(info->vq)) != NULL)
> > + callback(vdev, buf, data);
> > +
> > + vp_del_reset_vq(vdev, queue_index);
> > +
> > + return 0;
> > +}
> > +
> > +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 +464,8 @@ 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 = {
> > @@ -413,6 +484,8 @@ 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 */
> > --
> > 2.31.0
>
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