[PATCH v2] virtio: add VIRTIO_F_NOTIFICATION_DATA feature support

Viktor Prutyanov
2023-03-20T23:21:33Z

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 <viktor@daynix.com>
---

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)
+{
+ 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);
+
+ 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