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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: <20230321082101-mutt-send-email-mst@kernel.org> References: <20230320232115.1940587-1-viktor@daynix.com> <20230321050747-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 21, 2023 at 02:49:13PM +0300, Viktor Prutyanov wrote: > On Tue, Mar 21, 2023 at 12:23 PM Michael S. Tsirkin wrote: > > > > 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); > > > > I don't see why is this macro useful. > > > > > > > > > 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) > > > +{ > > > + 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); > > > > I don't think the cast is needed. Neither is () around << the second << > > here (first is needed because gcc chooses to complain: apparently it > > considers bitwise and a math operation for some obscure reason). > > > > > + else > > > + next = virtio16_to_cpu(_vq->vdev, vq->split.vring.avail->idx); > > > + > > > + return ((u32)next << 16) | _vq->index; > > > > I don't think the cast is needed. Neither is () around << needed. > > > > > +} > > > +EXPORT_SYMBOL_GPL(vring_fill_notification_data); > > > + > > > > I'd inline this - it's on data path ... > > As far as I see, to be inlined in virtio_mmio.c, virtio_pci_common.c > and virtio_ccw.c, the function should be defined in some header, but > definitions such as vring_virtqueue, vring_virtqueue_split, > vring_virtqueue_packed will not be available, because they are in > virtio_ring.c. Looks like, they must be moved to a separate header > in this case, isn't it? Oh you are right. OK, sorry. > > > > > /* 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 > >