[PATCH v5] virtio: add VIRTIO_F_NOTIFICATION_DATA feature support
From: Viktor Prutyanov
Date: Thu Mar 23 2023 - 04:56:32 EST
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@xxxxxxxxxx>
---
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 | 17 +++++++++++++++++
include/linux/virtio_ring.h | 2 ++
include/uapi/linux/virtio_config.h | 6 ++++++
6 files changed, 77 insertions(+), 5 deletions(-)
diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
index 954fc31b4bc7..9a9c5d34454c 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)
{
@@ -501,6 +511,12 @@ static struct virtqueue *virtio_ccw_setup_vq(struct virtio_device *vdev,
u64 queue;
unsigned long flags;
bool may_reduce;
+ bool (*notify)(struct virtqueue *vq);
+
+ 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);
@@ -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..7e87f745f68d 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 +378,12 @@ 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);
+
+ 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..3bfc368b279e 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,
@@ -301,6 +310,12 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
struct virtqueue *vq;
u16 num;
int err;
+ bool (*notify)(struct virtqueue *vq);
+
+ 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..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