Re: [PATCH v6] virtio: add VIRTIO_F_NOTIFICATION_DATA feature support

Re: [PATCH v6] virtio: add VIRTIO_F_NOTIFICATION_DATA feature support

[Xuan Zhuo]

On Thu, 30 Mar 2023 01:49:23 +0300, Viktor Prutyanov <viktor@daynix.com> wrote:
> On Fri, Mar 24, 2023 at 10:50 PM Viktor Prutyanov <viktor@daynix.com> wrote:
> >
> > According to VirtIO spec v1.2, VIRTIO_F_NOTIFICATION_DATA feature
> > indicates that the driver passes extra data along with the queue
> > notifications.
> >
> > In a split queue case, the extra data is 16-bit available index. In a
> > packed queue case, the extra data is 1-bit wrap counter and 15-bit
> > available index.
> >
> > Add support for this feature for MMIO, channel I/O and modern PCI
> > transports.
> >
> > Signed-off-by: Viktor Prutyanov <viktor@daynix.com>
> > Acked-by: Jason Wang <jasowang@redhat.com>
> > Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > ---
> >  v6: use VRING_PACKED_EVENT_F_WRAP_CTR
> >  v5: replace ternary operator with if-else
> >  v4: remove VP_NOTIFY macro and legacy PCI support, add
> >     virtio_ccw_kvm_notify_with_data to virtio_ccw
> >  v3: support feature in virtio_ccw, remove VM_NOTIFY, use avail_idx_shadow,
> >     remove byte swap, rename to vring_notification_data
> >  v2: reject the feature in virtio_ccw, replace __le32 with u32
> >
> >  Tested with disabled VIRTIO_F_NOTIFICATION_DATA on qemu-system-s390x
> >  (virtio-blk-ccw), qemu-system-riscv64 (virtio-blk-device,
> >  virtio-rng-device), qemu-system-x86_64 (virtio-blk-pci, virtio-net-pci)
> >  to make sure nothing is broken.
> >  Tested with enabled VIRTIO_F_NOTIFICATION_DATA on 64-bit RISC-V Linux
> >  and my hardware implementation of virtio-rng with MMIO.
> >
> >  drivers/s390/virtio/virtio_ccw.c   | 22 +++++++++++++++++++---
> >  drivers/virtio/virtio_mmio.c       | 18 +++++++++++++++++-
> >  drivers/virtio/virtio_pci_modern.c | 17 ++++++++++++++++-
> >  drivers/virtio/virtio_ring.c       | 19 +++++++++++++++++++
> >  include/linux/virtio_ring.h        |  2 ++
> >  include/uapi/linux/virtio_config.h |  6 ++++++
> >  6 files changed, 79 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
> > index 954fc31b4bc7..02922768b129 100644
> > --- a/drivers/s390/virtio/virtio_ccw.c
> > +++ b/drivers/s390/virtio/virtio_ccw.c
> > @@ -391,7 +391,7 @@ static void virtio_ccw_drop_indicator(struct virtio_ccw_device *vcdev,
> >         ccw_device_dma_free(vcdev->cdev, thinint_area, sizeof(*thinint_area));
> >  }
> >
> > -static bool virtio_ccw_kvm_notify(struct virtqueue *vq)
> > +static inline bool virtio_ccw_do_kvm_notify(struct virtqueue *vq, u32 data)
> >  {
> >         struct virtio_ccw_vq_info *info = vq->priv;
> >         struct virtio_ccw_device *vcdev;
> > @@ -402,12 +402,22 @@ static bool virtio_ccw_kvm_notify(struct virtqueue *vq)
> >         BUILD_BUG_ON(sizeof(struct subchannel_id) != sizeof(unsigned int));
> >         info->cookie = kvm_hypercall3(KVM_S390_VIRTIO_CCW_NOTIFY,
> >                                       *((unsigned int *)&schid),
> > -                                     vq->index, info->cookie);
> > +                                     data, info->cookie);
> >         if (info->cookie < 0)
> >                 return false;
> >         return true;
> >  }
> >
> > +static bool virtio_ccw_kvm_notify(struct virtqueue *vq)
> > +{
> > +       return virtio_ccw_do_kvm_notify(vq, vq->index);
> > +}
> > +
> > +static bool virtio_ccw_kvm_notify_with_data(struct virtqueue *vq)
> > +{
> > +       return virtio_ccw_do_kvm_notify(vq, vring_notification_data(vq));
> > +}
> > +
> >  static int virtio_ccw_read_vq_conf(struct virtio_ccw_device *vcdev,
> >                                    struct ccw1 *ccw, int index)
> >  {
> > @@ -495,6 +505,7 @@ static struct virtqueue *virtio_ccw_setup_vq(struct virtio_device *vdev,
> >                                              struct ccw1 *ccw)
> >  {
> >         struct virtio_ccw_device *vcdev = to_vc_device(vdev);
> > +       bool (*notify)(struct virtqueue *vq);
> >         int err;
> >         struct virtqueue *vq = NULL;
> >         struct virtio_ccw_vq_info *info;
> > @@ -502,6 +513,11 @@ static struct virtqueue *virtio_ccw_setup_vq(struct virtio_device *vdev,
> >         unsigned long flags;
> >         bool may_reduce;
> >
> > +       if (__virtio_test_bit(vdev, VIRTIO_F_NOTIFICATION_DATA))
> > +               notify = virtio_ccw_kvm_notify_with_data;
> > +       else
> > +               notify = virtio_ccw_kvm_notify;
> > +
> >         /* Allocate queue. */
> >         info = kzalloc(sizeof(struct virtio_ccw_vq_info), GFP_KERNEL);
> >         if (!info) {
> > @@ -524,7 +540,7 @@ static struct virtqueue *virtio_ccw_setup_vq(struct virtio_device *vdev,
> >         may_reduce = vcdev->revision > 0;
> >         vq = vring_create_virtqueue(i, info->num, KVM_VIRTIO_CCW_RING_ALIGN,
> >                                     vdev, true, may_reduce, ctx,
> > -                                   virtio_ccw_kvm_notify, callback, name);
> > +                                   notify, callback, name);
> >
> >         if (!vq) {
> >                 /* For now, we fail if we can't get the requested size. */
> > diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
> > index 3ff746e3f24a..dd4424c14233 100644
> > --- a/drivers/virtio/virtio_mmio.c
> > +++ b/drivers/virtio/virtio_mmio.c
> > @@ -285,6 +285,16 @@ static bool vm_notify(struct virtqueue *vq)
> >         return true;
> >  }
> >
> > +static bool vm_notify_with_data(struct virtqueue *vq)
> > +{
> > +       struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
> > +       u32 data = vring_notification_data(vq);
> > +
> > +       writel(data, vm_dev->base + VIRTIO_MMIO_QUEUE_NOTIFY);
> > +
> > +       return true;
> > +}
> > +
> >  /* Notify all virtqueues on an interrupt. */
> >  static irqreturn_t vm_interrupt(int irq, void *opaque)
> >  {
> > @@ -363,12 +373,18 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned int in
> >                                   const char *name, bool ctx)
> >  {
> >         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
> > +       bool (*notify)(struct virtqueue *vq);
> >         struct virtio_mmio_vq_info *info;
> >         struct virtqueue *vq;
> >         unsigned long flags;
> >         unsigned int num;
> >         int err;
> >
> > +       if (__virtio_test_bit(vdev, VIRTIO_F_NOTIFICATION_DATA))
> > +               notify = vm_notify_with_data;
> > +       else
> > +               notify = vm_notify;
> > +
> >         if (!name)
> >                 return NULL;
> >
> > @@ -397,7 +413,7 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned int in
> >
> >         /* Create the vring */
> >         vq = vring_create_virtqueue(index, num, VIRTIO_MMIO_VRING_ALIGN, vdev,
> > -                                true, true, ctx, vm_notify, callback, name);
> > +                                true, true, ctx, notify, callback, name);
> >         if (!vq) {
> >                 err = -ENOMEM;
> >                 goto error_new_virtqueue;
> > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
> > index 9e496e288cfa..05deba5153bd 100644
> > --- a/drivers/virtio/virtio_pci_modern.c
> > +++ b/drivers/virtio/virtio_pci_modern.c
> > @@ -288,6 +288,15 @@ static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
> >         return vp_modern_config_vector(&vp_dev->mdev, vector);
> >  }
> >
> > +static bool vp_notify_with_data(struct virtqueue *vq)
> > +{
> > +       u32 data = vring_notification_data(vq);
> > +
> > +       iowrite32(data, (void __iomem *)vq->priv);
> > +
> > +       return true;
> > +}
> > +
> >  static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
> >                                   struct virtio_pci_vq_info *info,
> >                                   unsigned int index,
> > @@ -298,10 +307,16 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
> >  {
> >
> >         struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
> > +       bool (*notify)(struct virtqueue *vq);
> >         struct virtqueue *vq;
> >         u16 num;
> >         int err;
> >
> > +       if (__virtio_test_bit(&vp_dev->vdev, VIRTIO_F_NOTIFICATION_DATA))
> > +               notify = vp_notify_with_data;
> > +       else
> > +               notify = vp_notify;
> > +
> >         if (index >= vp_modern_get_num_queues(mdev))
> >                 return ERR_PTR(-EINVAL);
> >
> > @@ -321,7 +336,7 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
> >         vq = vring_create_virtqueue(index, num,
> >                                     SMP_CACHE_BYTES, &vp_dev->vdev,
> >                                     true, true, ctx,
> > -                                   vp_notify, callback, name);
> > +                                   notify, callback, name);
> >         if (!vq)
> >                 return ERR_PTR(-ENOMEM);
> >
> > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> > index 4c3bb0ddeb9b..f9c6604352b4 100644
> > --- a/drivers/virtio/virtio_ring.c
> > +++ b/drivers/virtio/virtio_ring.c
> > @@ -2752,6 +2752,23 @@ void vring_del_virtqueue(struct virtqueue *_vq)
> >  }
> >  EXPORT_SYMBOL_GPL(vring_del_virtqueue);
> >
> > +u32 vring_notification_data(struct virtqueue *_vq)
> > +{
> > +       struct vring_virtqueue *vq = to_vvq(_vq);
> > +       u16 next;
> > +
> > +       if (vq->packed_ring)
> > +               next = (vq->packed.next_avail_idx &
> > +                               ~(-(1 << VRING_PACKED_EVENT_F_WRAP_CTR))) |
> > +                       vq->packed.avail_wrap_counter <<
> > +                               VRING_PACKED_EVENT_F_WRAP_CTR;
> > +       else
> > +               next = vq->split.avail_idx_shadow;
> > +
> > +       return next << 16 | _vq->index;
> > +}
> > +EXPORT_SYMBOL_GPL(vring_notification_data);
> > +
> >  /* Manipulates transport-specific feature bits. */
> >  void vring_transport_features(struct virtio_device *vdev)
> >  {
> > @@ -2771,6 +2788,8 @@ void vring_transport_features(struct virtio_device *vdev)
> >                         break;
> >                 case VIRTIO_F_ORDER_PLATFORM:
> >                         break;
> > +               case VIRTIO_F_NOTIFICATION_DATA:
> > +                       break;
> >                 default:
> >                         /* We don't understand this bit. */
> >                         __virtio_clear_bit(vdev, i);
> > diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h
> > index 8b95b69ef694..2550c9170f4f 100644
> > --- a/include/linux/virtio_ring.h
> > +++ b/include/linux/virtio_ring.h
> > @@ -117,4 +117,6 @@ void vring_del_virtqueue(struct virtqueue *vq);
> >  void vring_transport_features(struct virtio_device *vdev);
> >
> >  irqreturn_t vring_interrupt(int irq, void *_vq);
> > +
> > +u32 vring_notification_data(struct virtqueue *_vq);
> >  #endif /* _LINUX_VIRTIO_RING_H */
> > diff --git a/include/uapi/linux/virtio_config.h b/include/uapi/linux/virtio_config.h
> > index 3c05162bc988..2c712c654165 100644
> > --- a/include/uapi/linux/virtio_config.h
> > +++ b/include/uapi/linux/virtio_config.h
> > @@ -99,6 +99,12 @@
> >   */
> >  #define VIRTIO_F_SR_IOV                        37
> >
> > +/*
> > + * This feature indicates that the driver passes extra data (besides
> > + * identifying the virtqueue) in its device notifications.
> > + */
> > +#define VIRTIO_F_NOTIFICATION_DATA     38
> > +
> >  /*
> >   * This feature indicates that the driver can reset a queue individually.
> >   */
> > --
> > 2.35.1
> >
>
> ping

Generally speaking, Michael will merge patch here and will not reply in the mail
list. You can see it here.

https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git/log/?h=linux-next

At present, this patch has not been merged, and you need to give Micheal some
time.

Thanks.
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Re: [PATCH v6] virtio: add VIRTIO_F_NOTIFICATION_DATA feature support

[Alvaro Karsz]

Hi Viktor,

> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 4c3bb0ddeb9b..f9c6604352b4 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -2752,6 +2752,23 @@ void vring_del_virtqueue(struct virtqueue *_vq)
>  }
>  EXPORT_SYMBOL_GPL(vring_del_virtqueue);
> 
> +u32 vring_notification_data(struct virtqueue *_vq)
> +{
> +       struct vring_virtqueue *vq = to_vvq(_vq);
> +       u16 next;
> +
> +       if (vq->packed_ring)
> +               next = (vq->packed.next_avail_idx &
> +                               ~(-(1 << VRING_PACKED_EVENT_F_WRAP_CTR))) |
> +                       vq->packed.avail_wrap_counter <<
> +                               VRING_PACKED_EVENT_F_WRAP_CTR;
> +       else
> +               next = vq->split.avail_idx_shadow;
> +
> +       return next << 16 | _vq->index;
> +}
> +EXPORT_SYMBOL_GPL(vring_notification_data);
> +
>  /* Manipulates transport-specific feature bits. */
>  void vring_transport_features(struct virtio_device *vdev)
>  {
> @@ -2771,6 +2788,8 @@ void vring_transport_features(struct virtio_device *vdev)
>                         break;
>                 case VIRTIO_F_ORDER_PLATFORM:
>                         break;
> +               case VIRTIO_F_NOTIFICATION_DATA:
> +                       break;

This function is used by virtio_vdpa as well (drivers/virtio/virtio_vdpa.c:virtio_vdpa_finalize_features).
A vDPA device can offer this feature and it will be accepted, even though VIRTIO_F_NOTIFICATION_DATA is not a thing for the vDPA transport at the moment.

I don't know if this is bad, since offering VIRTIO_F_NOTIFICATION_DATA is meaningless for a vDPA device at the moment.

I submitted a patch adding support for vDPA transport.
https://lore.kernel.org/virtualization/20230402081034.1021886-1-alvaro.karsz@solid-run.com/T/#u

>                 default:
>                         /* We don't understand this bit. */
>                         __virtio_clear_bit(vdev, i);
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Re: [PATCH v6] virtio: add VIRTIO_F_NOTIFICATION_DATA feature support

[Michael S. Tsirkin]

On Sun, Apr 02, 2023 at 08:17:49AM +0000, Alvaro Karsz wrote:
> Hi Viktor,
> 
> > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> > index 4c3bb0ddeb9b..f9c6604352b4 100644
> > --- a/drivers/virtio/virtio_ring.c
> > +++ b/drivers/virtio/virtio_ring.c
> > @@ -2752,6 +2752,23 @@ void vring_del_virtqueue(struct virtqueue *_vq)
> >  }
> >  EXPORT_SYMBOL_GPL(vring_del_virtqueue);
> > 
> > +u32 vring_notification_data(struct virtqueue *_vq)
> > +{
> > +       struct vring_virtqueue *vq = to_vvq(_vq);
> > +       u16 next;
> > +
> > +       if (vq->packed_ring)
> > +               next = (vq->packed.next_avail_idx &
> > +                               ~(-(1 << VRING_PACKED_EVENT_F_WRAP_CTR))) |
> > +                       vq->packed.avail_wrap_counter <<
> > +                               VRING_PACKED_EVENT_F_WRAP_CTR;
> > +       else
> > +               next = vq->split.avail_idx_shadow;
> > +
> > +       return next << 16 | _vq->index;
> > +}
> > +EXPORT_SYMBOL_GPL(vring_notification_data);
> > +
> >  /* Manipulates transport-specific feature bits. */
> >  void vring_transport_features(struct virtio_device *vdev)
> >  {
> > @@ -2771,6 +2788,8 @@ void vring_transport_features(struct virtio_device *vdev)
> >                         break;
> >                 case VIRTIO_F_ORDER_PLATFORM:
> >                         break;
> > +               case VIRTIO_F_NOTIFICATION_DATA:
> > +                       break;
> 
> This function is used by virtio_vdpa as well (drivers/virtio/virtio_vdpa.c:virtio_vdpa_finalize_features).
> A vDPA device can offer this feature and it will be accepted, even though VIRTIO_F_NOTIFICATION_DATA is not a thing for the vDPA transport at the moment.
> 
> I don't know if this is bad, since offering VIRTIO_F_NOTIFICATION_DATA is meaningless for a vDPA device at the moment.
> 
> I submitted a patch adding support for vDPA transport.
> https://lore.kernel.org/virtualization/20230402081034.1021886-1-alvaro.karsz@solid-run.com/T/#u

Hmm.  So it seems we need to first apply yours then this patch,
is that right? Or the other way around? What is the right way to make it not break bisect?
Do you mind including this patch with yours in a patchset
in the correct order?




> >                 default:
> >                         /* We don't understand this bit. */
> >                         __virtio_clear_bit(vdev, i);
> 

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Re: [PATCH v6] virtio: add VIRTIO_F_NOTIFICATION_DATA feature support

[Alvaro Karsz]

> > This function is used by virtio_vdpa as well (drivers/virtio/virtio_vdpa.c:virtio_vdpa_finalize_features).
> > A vDPA device can offer this feature and it will be accepted, even though VIRTIO_F_NOTIFICATION_DATA is not a thing for the vDPA transport at the moment.
> >
> > I don't know if this is bad, since offering VIRTIO_F_NOTIFICATION_DATA is meaningless for a vDPA device at the moment.
> >
> > I submitted a patch adding support for vDPA transport.
> > https://lore.kernel.org/virtualization/20230402081034.1021886-1-alvaro.karsz@solid-run.com/T/#u
> 
> Hmm.  So it seems we need to first apply yours then this patch,
> is that right? Or the other way around? What is the right way to make it not break bisect?

My patch should be applied on top of Viktor's, it uses one of the functions created by Viktor: vring_notification_data.
Viktor's patch without mine won't break bisect, it will just accept the feature for a virtio_vdpa without any meaning.

> Do you mind including this patch with yours in a patchset
> in the correct order?

Viktor, since you did most of the work here, maybe you want to create the patchset?
I can do it myself if you prefer so.

Thanks,
Alvaro
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Re: [PATCH v6] virtio: add VIRTIO_F_NOTIFICATION_DATA feature support

[Alvaro Karsz]

> Hmm.  So it seems we need to first apply yours then this patch,
> is that right? Or the other way around? What is the right way to make it not break bisect?
> Do you mind including this patch with yours in a patchset
> in the correct order?

Ok, I'll create a patchset.

Thanks,
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