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Tsirkin" To: Viktor Prutyanov Cc: jasowang@redhat.com, cohuck@redhat.com, pasic@linux.ibm.com, farman@linux.ibm.com, linux-s390@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, yan@daynix.com Subject: Re: [PATCH v3] virtio: add VIRTIO_F_NOTIFICATION_DATA feature support Message-ID: <20230321100956-mutt-send-email-mst@kernel.org> References: <20230321134410.2097163-1-viktor@daynix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230321134410.2097163-1-viktor@daynix.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, Mar 21, 2023 at 04:44:10PM +0300, Viktor Prutyanov 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, PCI and channel I/O transports. > > Signed-off-by: Viktor Prutyanov Can you pls report what was tested and how? Thanks! > --- > 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 > > drivers/s390/virtio/virtio_ccw.c | 4 +++- > drivers/virtio/virtio_mmio.c | 14 +++++++++++++- > drivers/virtio/virtio_pci_common.c | 10 ++++++++++ > drivers/virtio/virtio_pci_common.h | 4 ++++ > drivers/virtio/virtio_pci_legacy.c | 2 +- > drivers/virtio/virtio_pci_modern.c | 2 +- > drivers/virtio/virtio_ring.c | 17 +++++++++++++++++ > include/linux/virtio_ring.h | 2 ++ > include/uapi/linux/virtio_config.h | 6 ++++++ > 9 files changed, 57 insertions(+), 4 deletions(-) > > diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c > index 954fc31b4bc7..c33172c5b8d5 100644 > --- a/drivers/s390/virtio/virtio_ccw.c > +++ b/drivers/s390/virtio/virtio_ccw.c > @@ -396,13 +396,15 @@ static bool virtio_ccw_kvm_notify(struct virtqueue *vq) > struct virtio_ccw_vq_info *info = vq->priv; > struct virtio_ccw_device *vcdev; > struct subchannel_id schid; > + u32 data = __virtio_test_bit(vq->vdev, VIRTIO_F_NOTIFICATION_DATA) ? > + vring_notification_data(vq) : vq->index; > > vcdev = to_vc_device(info->vq->vdev); > ccw_device_get_schid(vcdev->cdev, &schid); > 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; > diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c > index 3ff746e3f24a..7c16e622c33d 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) > { > @@ -368,6 +378,8 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned int in > unsigned long flags; > unsigned int num; > int err; > + bool (*notify)(struct virtqueue *vq) = __virtio_test_bit(vdev, > + VIRTIO_F_NOTIFICATION_DATA) ? vm_notify_with_data : vm_notify; > > if (!name) > return NULL; > @@ -397,7 +409,7 @@ 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_common.c b/drivers/virtio/virtio_pci_common.c > index a6c86f916dbd..e915c22f2384 100644 > --- a/drivers/virtio/virtio_pci_common.c > +++ b/drivers/virtio/virtio_pci_common.c > @@ -43,6 +43,16 @@ bool vp_notify(struct virtqueue *vq) > /* we write the queue's selector into the notification register to > * signal the other end */ > iowrite16(vq->index, (void __iomem *)vq->priv); > + > + return true; > +} > + > +bool vp_notify_with_data(struct virtqueue *vq) > +{ > + u32 data = vring_notification_data(vq); > + > + iowrite32(data, (void __iomem *)vq->priv); > + > return true; > } > > diff --git a/drivers/virtio/virtio_pci_common.h b/drivers/virtio/virtio_pci_common.h > index 23112d84218f..9a7212dcbb32 100644 > --- a/drivers/virtio/virtio_pci_common.h > +++ b/drivers/virtio/virtio_pci_common.h > @@ -105,6 +105,7 @@ static struct virtio_pci_device *to_vp_device(struct virtio_device *vdev) > void vp_synchronize_vectors(struct virtio_device *vdev); > /* the notify function used when creating a virt queue */ > bool vp_notify(struct virtqueue *vq); > +bool vp_notify_with_data(struct virtqueue *vq); > /* the config->del_vqs() implementation */ > void vp_del_vqs(struct virtio_device *vdev); > /* the config->find_vqs() implementation */ > @@ -114,6 +115,9 @@ int vp_find_vqs(struct virtio_device *vdev, unsigned int nvqs, > struct irq_affinity *desc); > const char *vp_bus_name(struct virtio_device *vdev); > > +#define VP_NOTIFY(vdev) (__virtio_test_bit((vdev), VIRTIO_F_NOTIFICATION_DATA) \ > + ? vp_notify : vp_notify_with_data) > + I still think this macro is pointless. > /* Setup the affinity for a virtqueue: > * - force the affinity for per vq vector > * - OR over all affinities for shared MSI > diff --git a/drivers/virtio/virtio_pci_legacy.c b/drivers/virtio/virtio_pci_legacy.c > index 2257f1b3d8ae..b98e994cae48 100644 > --- a/drivers/virtio/virtio_pci_legacy.c > +++ b/drivers/virtio/virtio_pci_legacy.c > @@ -131,7 +131,7 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev, > vq = vring_create_virtqueue(index, num, > VIRTIO_PCI_VRING_ALIGN, &vp_dev->vdev, > true, false, ctx, > - vp_notify, callback, name); > + VP_NOTIFY(&vp_dev->vdev), callback, name); > if (!vq) > return ERR_PTR(-ENOMEM); And this is completely poinless because legacy can never enable VIRTIO_F_NOTIFICATION_DATA. > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c > index 9e496e288cfa..7fcd8af5af7e 100644 > --- a/drivers/virtio/virtio_pci_modern.c > +++ b/drivers/virtio/virtio_pci_modern.c > @@ -321,7 +321,7 @@ 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); > + VP_NOTIFY(&vp_dev->vdev), callback, name); > if (!vq) > return ERR_PTR(-ENOMEM); > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index 4c3bb0ddeb9b..837875cc3190 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -2752,6 +2752,21 @@ 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 << 15)) | > + vq->packed.avail_wrap_counter << 15; > + 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 +2786,8 @@ 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