> From: Michael S. Tsirkin <mst@xxxxxxxxxx>
> Sent: Monday, October 30, 2023 1:53 AM
>
> On Sun, Oct 29, 2023 at 05:59:45PM +0200, Yishai Hadas wrote:
> > From: Feng Liu <feliu@xxxxxxxxxx>
> >
> > Introduce support for the admin virtqueue. By negotiating
> > VIRTIO_F_ADMIN_VQ feature, driver detects capability and creates one
> > administration virtqueue. Administration virtqueue implementation in
> > virtio pci generic layer, enables multiple types of upper layer
> > drivers such as vfio, net, blk to utilize it.
> >
> > Signed-off-by: Feng Liu <feliu@xxxxxxxxxx>
> > Reviewed-by: Parav Pandit <parav@xxxxxxxxxx>
> > Reviewed-by: Jiri Pirko <jiri@xxxxxxxxxx>
> > Signed-off-by: Yishai Hadas <yishaih@xxxxxxxxxx>
> > ---
> > drivers/virtio/virtio.c | 37 ++++++++++++++--
> > drivers/virtio/virtio_pci_common.c | 3 ++
> > drivers/virtio/virtio_pci_common.h | 15 ++++++-
> > drivers/virtio/virtio_pci_modern.c | 61 +++++++++++++++++++++++++-
> > drivers/virtio/virtio_pci_modern_dev.c | 18 ++++++++
> > include/linux/virtio_config.h | 4 ++
> > include/linux/virtio_pci_modern.h | 5 +++
> > 7 files changed, 137 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c index
> > 3893dc29eb26..f4080692b351 100644
> > --- a/drivers/virtio/virtio.c
> > +++ b/drivers/virtio/virtio.c
> > @@ -302,9 +302,15 @@ static int virtio_dev_probe(struct device *_d)
> > if (err)
> > goto err;
> >
> > + if (dev->config->create_avq) {
> > + err = dev->config->create_avq(dev);
> > + if (err)
> > + goto err;
> > + }
> > +
> > err = drv->probe(dev);
> > if (err)
> > - goto err;
> > + goto err_probe;
> >
> > /* If probe didn't do it, mark device DRIVER_OK ourselves. */
> > if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
>
> Hmm I am not all that happy that we are just creating avq unconditionally.
> Can't we do it on demand to avoid wasting resources if no one uses it?
>
Virtio queues must be enabled before driver_ok as we discussed in F_DYNAMIC bit exercise.
So creating AQ when first legacy command is invoked, would be too late.
>
> > @@ -316,6 +322,10 @@ static int virtio_dev_probe(struct device *_d)
> > virtio_config_enable(dev);
> >
> > return 0;
> > +
> > +err_probe:
> > + if (dev->config->destroy_avq)
> > + dev->config->destroy_avq(dev);
> > err:
> > virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
> > return err;
> > @@ -331,6 +341,9 @@ static void virtio_dev_remove(struct device *_d)
> >
> > drv->remove(dev);
> >
> > + if (dev->config->destroy_avq)
> > + dev->config->destroy_avq(dev);
> > +
> > /* Driver should have reset device. */
> > WARN_ON_ONCE(dev->config->get_status(dev));
> >
> > @@ -489,13 +502,20 @@ EXPORT_SYMBOL_GPL(unregister_virtio_device);
> > int virtio_device_freeze(struct virtio_device *dev) {
> > struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
> > + int ret;
> >
> > virtio_config_disable(dev);
> >
> > dev->failed = dev->config->get_status(dev) &
> VIRTIO_CONFIG_S_FAILED;
> >
> > - if (drv && drv->freeze)
> > - return drv->freeze(dev);
> > + if (drv && drv->freeze) {
> > + ret = drv->freeze(dev);
> > + if (ret)
> > + return ret;
> > + }
> > +
> > + if (dev->config->destroy_avq)
> > + dev->config->destroy_avq(dev);
> >
> > return 0;
> > }
> > @@ -532,10 +552,16 @@ int virtio_device_restore(struct virtio_device *dev)
> > if (ret)
> > goto err;
> >
> > + if (dev->config->create_avq) {
> > + ret = dev->config->create_avq(dev);
> > + if (ret)
> > + goto err;
> > + }
> > +
> > if (drv->restore) {
> > ret = drv->restore(dev);
> > if (ret)
> > - goto err;
> > + goto err_restore;
> > }
> >
> > /* If restore didn't do it, mark device DRIVER_OK ourselves. */ @@
> > -546,6 +572,9 @@ int virtio_device_restore(struct virtio_device *dev)
> >
> > return 0;
> >
> > +err_restore:
> > + if (dev->config->destroy_avq)
> > + dev->config->destroy_avq(dev);
> > err:
> > virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
> > return ret;
> > diff --git a/drivers/virtio/virtio_pci_common.c
> > b/drivers/virtio/virtio_pci_common.c
> > index c2524a7207cf..6b4766d5abe6 100644
> > --- a/drivers/virtio/virtio_pci_common.c
> > +++ b/drivers/virtio/virtio_pci_common.c
> > @@ -236,6 +236,9 @@ void vp_del_vqs(struct virtio_device *vdev)
> > int i;
> >
> > list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
> > + if (vp_dev->is_avq(vdev, vq->index))
> > + continue;
> > +
> > if (vp_dev->per_vq_vectors) {
> > int v = vp_dev->vqs[vq->index]->msix_vector;
> >
> > diff --git a/drivers/virtio/virtio_pci_common.h
> > b/drivers/virtio/virtio_pci_common.h
> > index 4b773bd7c58c..e03af0966a4b 100644
> > --- a/drivers/virtio/virtio_pci_common.h
> > +++ b/drivers/virtio/virtio_pci_common.h
> > @@ -41,6 +41,14 @@ struct virtio_pci_vq_info {
> > unsigned int msix_vector;
> > };
> >
> > +struct virtio_pci_admin_vq {
> > + /* Virtqueue info associated with this admin queue. */
> > + struct virtio_pci_vq_info info;
> > + /* Name of the admin queue: avq.$index. */
> > + char name[10];
> > + u16 vq_index;
> > +};
> > +
> > /* Our device structure */
> > struct virtio_pci_device {
> > struct virtio_device vdev;
> > @@ -58,9 +66,13 @@ struct virtio_pci_device {
> > spinlock_t lock;
> > struct list_head virtqueues;
> >
> > - /* array of all queues for house-keeping */
> > + /* Array of all virtqueues reported in the
> > + * PCI common config num_queues field
> > + */
> > struct virtio_pci_vq_info **vqs;
> >
> > + struct virtio_pci_admin_vq admin_vq;
> > +
> > /* MSI-X support */
> > int msix_enabled;
> > int intx_enabled;
> > @@ -86,6 +98,7 @@ struct virtio_pci_device {
> > void (*del_vq)(struct virtio_pci_vq_info *info);
> >
> > u16 (*config_vector)(struct virtio_pci_device *vp_dev, u16 vector);
> > + bool (*is_avq)(struct virtio_device *vdev, unsigned int index);
> > };
> >
> > /* Constants for MSI-X */
> > diff --git a/drivers/virtio/virtio_pci_modern.c
> > b/drivers/virtio/virtio_pci_modern.c
> > index d6bb68ba84e5..01c5ba346471 100644
> > --- a/drivers/virtio/virtio_pci_modern.c
> > +++ b/drivers/virtio/virtio_pci_modern.c
> > @@ -26,6 +26,16 @@ static u64 vp_get_features(struct virtio_device *vdev)
> > return vp_modern_get_features(&vp_dev->mdev);
> > }
> >
> > +static bool vp_is_avq(struct virtio_device *vdev, unsigned int index)
> > +{
> > + struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> > +
> > + if (!virtio_has_feature(vdev, VIRTIO_F_ADMIN_VQ))
> > + return false;
> > +
> > + return index == vp_dev->admin_vq.vq_index; }
> > +
> > static void vp_transport_features(struct virtio_device *vdev, u64
> > features) {
> > struct virtio_pci_device *vp_dev = to_vp_device(vdev); @@ -37,6
> > +47,9 @@ static void vp_transport_features(struct virtio_device *vdev,
> > u64 features)
> >
> > if (features & BIT_ULL(VIRTIO_F_RING_RESET))
> > __virtio_set_bit(vdev, VIRTIO_F_RING_RESET);
> > +
> > + if (features & BIT_ULL(VIRTIO_F_ADMIN_VQ))
> > + __virtio_set_bit(vdev, VIRTIO_F_ADMIN_VQ);
> > }
> >
> > /* virtio config->finalize_features() implementation */ @@ -317,7
> > +330,8 @@ static struct virtqueue *setup_vq(struct virtio_pci_device
> *vp_dev,
> > else
> > notify = vp_notify;
> >
> > - if (index >= vp_modern_get_num_queues(mdev))
> > + if (index >= vp_modern_get_num_queues(mdev) &&
> > + !vp_is_avq(&vp_dev->vdev, index))
> > return ERR_PTR(-EINVAL);
> >
> > /* Check if queue is either not available or already active. */ @@
> > -491,6 +505,46 @@ static bool vp_get_shm_region(struct virtio_device
> *vdev,
> > return true;
> > }
> >
> > +static int vp_modern_create_avq(struct virtio_device *vdev) {
> > + struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> > + struct virtio_pci_admin_vq *avq;
> > + struct virtqueue *vq;
> > + u16 admin_q_num;
> > +
> > + if (!virtio_has_feature(vdev, VIRTIO_F_ADMIN_VQ))
> > + return 0;
> > +
> > + admin_q_num = vp_modern_avq_num(&vp_dev->mdev);
> > + if (!admin_q_num)
> > + return -EINVAL;
>
>
> We really just need 1 entry ATM. Limit to that?
>
Above check is only reading and validating that number of admin queues being nonzero from the device.
It is ok if its > 1.
Driver currently using only 1 aq of default depth (entries) reported by the device.
Did I misunderstand your question about 1 entry?
> > +
> > + avq = &vp_dev->admin_vq;
> > + avq->vq_index = vp_modern_avq_index(&vp_dev->mdev);
> > + sprintf(avq->name, "avq.%u", avq->vq_index);
> > + vq = vp_dev->setup_vq(vp_dev, &vp_dev->admin_vq.info, avq-
> >vq_index, NULL,
> > + avq->name, NULL, VIRTIO_MSI_NO_VECTOR);
> > + if (IS_ERR(vq)) {
> > + dev_err(&vdev->dev, "failed to setup admin virtqueue,
> err=%ld",
> > + PTR_ERR(vq));
> > + return PTR_ERR(vq);
> > + }
> > +
> > + vp_dev->admin_vq.info.vq = vq;
> > + vp_modern_set_queue_enable(&vp_dev->mdev, avq->info.vq->index,
> true);
> > + return 0;
> > +}
> > +
> > +static void vp_modern_destroy_avq(struct virtio_device *vdev) {
> > + struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> > +
> > + if (!virtio_has_feature(vdev, VIRTIO_F_ADMIN_VQ))
> > + return;
> > +
> > + vp_dev->del_vq(&vp_dev->admin_vq.info);
> > +}
> > +
> > static const struct virtio_config_ops virtio_pci_config_nodev_ops = {
> > .get = NULL,
> > .set = NULL,
> > @@ -509,6 +563,8 @@ static const struct virtio_config_ops
> virtio_pci_config_nodev_ops = {
> > .get_shm_region = vp_get_shm_region,
> > .disable_vq_and_reset = vp_modern_disable_vq_and_reset,
> > .enable_vq_after_reset = vp_modern_enable_vq_after_reset,
> > + .create_avq = vp_modern_create_avq,
> > + .destroy_avq = vp_modern_destroy_avq,
> > };
> >
> > static const struct virtio_config_ops virtio_pci_config_ops = { @@
> > -529,6 +585,8 @@ static const struct virtio_config_ops virtio_pci_config_ops
> = {
> > .get_shm_region = vp_get_shm_region,
> > .disable_vq_and_reset = vp_modern_disable_vq_and_reset,
> > .enable_vq_after_reset = vp_modern_enable_vq_after_reset,
> > + .create_avq = vp_modern_create_avq,
> > + .destroy_avq = vp_modern_destroy_avq,
> > };
> >
> > /* the PCI probing function */
> > @@ -552,6 +610,7 @@ int virtio_pci_modern_probe(struct virtio_pci_device
> *vp_dev)
> > vp_dev->config_vector = vp_config_vector;
> > vp_dev->setup_vq = setup_vq;
> > vp_dev->del_vq = del_vq;
> > + vp_dev->is_avq = vp_is_avq;
> > vp_dev->isr = mdev->isr;
> > vp_dev->vdev.id = mdev->id;
> >
> > diff --git a/drivers/virtio/virtio_pci_modern_dev.c
> > b/drivers/virtio/virtio_pci_modern_dev.c
> > index 9cb601e16688..4aab1727d121 100644
> > --- a/drivers/virtio/virtio_pci_modern_dev.c
> > +++ b/drivers/virtio/virtio_pci_modern_dev.c
> > @@ -714,6 +714,24 @@ void __iomem *vp_modern_map_vq_notify(struct
> > virtio_pci_modern_device *mdev, }
> > EXPORT_SYMBOL_GPL(vp_modern_map_vq_notify);
> >
> > +u16 vp_modern_avq_num(struct virtio_pci_modern_device *mdev) {
> > + struct virtio_pci_modern_common_cfg __iomem *cfg;
> > +
> > + cfg = (struct virtio_pci_modern_common_cfg __iomem *)mdev-
> >common;
> > + return vp_ioread16(&cfg->admin_queue_num);
> > +}
> > +EXPORT_SYMBOL_GPL(vp_modern_avq_num);
> > +
> > +u16 vp_modern_avq_index(struct virtio_pci_modern_device *mdev) {
> > + struct virtio_pci_modern_common_cfg __iomem *cfg;
> > +
> > + cfg = (struct virtio_pci_modern_common_cfg __iomem *)mdev-
> >common;
> > + return vp_ioread16(&cfg->admin_queue_index);
> > +}
> > +EXPORT_SYMBOL_GPL(vp_modern_avq_index);
> > +
> > MODULE_VERSION("0.1");
> > MODULE_DESCRIPTION("Modern Virtio PCI Device");
> MODULE_AUTHOR("Jason
> > Wang <jasowang@xxxxxxxxxx>"); diff --git
> > a/include/linux/virtio_config.h b/include/linux/virtio_config.h index
> > 2b3438de2c4d..da9b271b54db 100644
> > --- a/include/linux/virtio_config.h
> > +++ b/include/linux/virtio_config.h
> > @@ -93,6 +93,8 @@ typedef void vq_callback_t(struct virtqueue *);
> > * Returns 0 on success or error status
> > * If disable_vq_and_reset is set, then enable_vq_after_reset must also be
> > * set.
> > + * @create_avq: create admin virtqueue resource.
> > + * @destroy_avq: destroy admin virtqueue resource.
> > */
> > struct virtio_config_ops {
> > void (*get)(struct virtio_device *vdev, unsigned offset, @@ -120,6
> > +122,8 @@ struct virtio_config_ops {
> > struct virtio_shm_region *region, u8 id);
> > int (*disable_vq_and_reset)(struct virtqueue *vq);
> > int (*enable_vq_after_reset)(struct virtqueue *vq);
> > + int (*create_avq)(struct virtio_device *vdev);
> > + void (*destroy_avq)(struct virtio_device *vdev);
> > };
> >
> > /* If driver didn't advertise the feature, it will never appear. */
> > diff --git a/include/linux/virtio_pci_modern.h
> > b/include/linux/virtio_pci_modern.h
> > index 067ac1d789bc..0f8737c9ae7d 100644
> > --- a/include/linux/virtio_pci_modern.h
> > +++ b/include/linux/virtio_pci_modern.h
> > @@ -10,6 +10,9 @@ struct virtio_pci_modern_common_cfg {
> >
> > __le16 queue_notify_data; /* read-write */
> > __le16 queue_reset; /* read-write */
> > +
> > + __le16 admin_queue_index; /* read-only */
> > + __le16 admin_queue_num; /* read-only */
> > };
> >
> > struct virtio_pci_modern_device {
> > @@ -121,4 +124,6 @@ int vp_modern_probe(struct
> > virtio_pci_modern_device *mdev); void vp_modern_remove(struct
> > virtio_pci_modern_device *mdev); int vp_modern_get_queue_reset(struct
> > virtio_pci_modern_device *mdev, u16 index); void
> > vp_modern_set_queue_reset(struct virtio_pci_modern_device *mdev, u16
> > index);
> > +u16 vp_modern_avq_num(struct virtio_pci_modern_device *mdev);
> > +u16 vp_modern_avq_index(struct virtio_pci_modern_device *mdev);
> > #endif
> > --
> > 2.27.0
