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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 v2] virtio: add VIRTIO_F_NOTIFICATION_DATA feature support Message-ID: <20230321052407-mutt-send-email-mst@kernel.org> References: <20230320232115.1940587-1-viktor@daynix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230320232115.1940587-1-viktor@daynix.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 21, 2023 at 02:21:15AM +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 and PCI transports. Channel I/O > transport will not accept this feature. > > Signed-off-by: Viktor Prutyanov > --- > > v2: reject the feature in virtio_ccw, replace __le32 with u32 > > drivers/s390/virtio/virtio_ccw.c | 4 +--- > drivers/virtio/virtio_mmio.c | 15 ++++++++++++++- > 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, 56 insertions(+), 6 deletions(-) > > diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c > index a10dbe632ef9..d72a59415527 100644 > --- a/drivers/s390/virtio/virtio_ccw.c > +++ b/drivers/s390/virtio/virtio_ccw.c > @@ -789,9 +789,7 @@ static u64 virtio_ccw_get_features(struct virtio_device *vdev) > > static void ccw_transport_features(struct virtio_device *vdev) > { > - /* > - * Currently nothing to do here. > - */ > + __virtio_clear_bit(vdev, VIRTIO_F_NOTIFICATION_DATA); > } > > static int virtio_ccw_finalize_features(struct virtio_device *vdev) > diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c > index 3ff746e3f24a..0e13da17fe0a 100644 > --- a/drivers/virtio/virtio_mmio.c > +++ b/drivers/virtio/virtio_mmio.c > @@ -285,6 +285,19 @@ 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_fill_notification_data(vq); > + > + writel(data, vm_dev->base + VIRTIO_MMIO_QUEUE_NOTIFY); > + > + return true; > +} > + > +#define VM_NOTIFY(vdev) (__virtio_test_bit((vdev), VIRTIO_F_NOTIFICATION_DATA) \ > + ? vm_notify_with_data : vm_notify) > + > /* Notify all virtqueues on an interrupt. */ > static irqreturn_t vm_interrupt(int irq, void *opaque) > { > @@ -397,7 +410,7 @@ 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, VM_NOTIFY(vdev), 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..535263abc2bd 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_fill_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) > + > /* 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); > > 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 723c4e29e1d3..5e9e1800bb6e 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -2699,6 +2699,21 @@ void vring_del_virtqueue(struct virtqueue *_vq) > } > EXPORT_SYMBOL_GPL(vring_del_virtqueue); > > +u32 vring_fill_notification_data(struct virtqueue *_vq) btw what does "fill" mean here? why not just vring_notification_data? > +{ > + struct vring_virtqueue *vq = to_vvq(_vq); > + u16 next; > + > + if (vq->packed_ring) > + next = (vq->packed.next_avail_idx & ~(1 << 15)) | > + ((u16)vq->packed.avail_wrap_counter << 15); > + else > + next = virtio16_to_cpu(_vq->vdev, vq->split.vring.avail->idx); BTW it's annoying to poke at avail->idx here - will cause a bunch of cache misses. And the byte-swap is a waste. Isn't this why we have avail_idx_shadow? > + > + return ((u32)next << 16) | _vq->index; > +} > +EXPORT_SYMBOL_GPL(vring_fill_notification_data); > + > /* Manipulates transport-specific feature bits. */ > void vring_transport_features(struct virtio_device *vdev) > { > @@ -2718,6 +2733,8 @@ 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 8b8af1a38991..1f65d2f77012 100644 > --- a/include/linux/virtio_ring.h > +++ b/include/linux/virtio_ring.h > @@ -101,4 +101,6 @@ 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_fill_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