Linux Virtualization - Apr 2023 - [PATCH 2/3] vhost: support PACKED when setting-getting vring_base

While testing our vDPA driver with QEMU we found that vhost_vdpa seems to
be missing some support for PACKED VQs.  Adding these helped us get further
in our testing.  The first patch makes sure that the vhost_vdpa vqs are given
the feature flags, as done in other vhost variants.  The second and third 
patches use the feature flags to properly format and pass set/get_vq requests.

Shannon Nelson (3):
  vhost_vdpa: tell vqs about the negotiated
  vhost: support PACKED when setting-getting vring_base
  vhost_vdpa: support PACKED when setting-getting vring_base

 drivers/vhost/vdpa.c  | 32 ++++++++++++++++++++++++++++----
 drivers/vhost/vhost.c | 18 +++++++++++++-----
 2 files changed, 41 insertions(+), 9 deletions(-)

-- 
2.17.1

As is done in the net, iscsi, and vsock vhost support, let the vdpa vqs
know about the features that have been negotiated.  This allows vhost
to more safely make decisions based on the features, such as when using
PACKED vs split queues.

Signed-off-by: Shannon Nelson <shannon.nelson at amd.com>
---
 drivers/vhost/vdpa.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 7be9d9d8f01c..599b8cc238c7 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -385,7 +385,10 @@ static long vhost_vdpa_set_features(struct vhost_vdpa *v,
u64 __user *featurep)
 {
 	struct vdpa_device *vdpa = v->vdpa;
 	const struct vdpa_config_ops *ops = vdpa->config;
+	struct vhost_dev *d = &v->vdev;
+	u64 actual_features;
 	u64 features;
+	int i;
 
 	/*
 	 * It's not allowed to change the features after they have
@@ -400,6 +403,16 @@ static long vhost_vdpa_set_features(struct vhost_vdpa *v,
u64 __user *featurep)
 	if (vdpa_set_features(vdpa, features))
 		return -EINVAL;
 
+	/* let the vqs know what has been configured */
+	actual_features = ops->get_driver_features(vdpa);
+	for (i = 0; i < d->nvqs; ++i) {
+		struct vhost_virtqueue *vq = d->vqs[i];
+
+		mutex_lock(&vq->mutex);
+		vq->acked_features = actual_features;
+		mutex_unlock(&vq->mutex);
+	}
+
 	return 0;
 }
 
-- 
2.17.1

Use the right structs for PACKED or split vqs when setting and
getting the vring base.

Signed-off-by: Shannon Nelson <shannon.nelson at amd.com>
---
 drivers/vhost/vhost.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index f11bdbe4c2c5..f64efda48f21 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1633,17 +1633,25 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int
ioctl, void __user *arg
 			r = -EFAULT;
 			break;
 		}
-		if (s.num > 0xffff) {
-			r = -EINVAL;
-			break;
+		if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) {
+			vq->last_avail_idx = s.num & 0xffff;
+			vq->last_used_idx = (s.num >> 16) & 0xffff;
+		} else {
+			if (s.num > 0xffff) {
+				r = -EINVAL;
+				break;
+			}
+			vq->last_avail_idx = s.num;
 		}
-		vq->last_avail_idx = s.num;
 		/* Forget the cached index value. */
 		vq->avail_idx = vq->last_avail_idx;
 		break;
 	case VHOST_GET_VRING_BASE:
 		s.index = idx;
-		s.num = vq->last_avail_idx;
+		if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED))
+			s.num = (u32)vq->last_avail_idx | ((u32)vq->last_used_idx <<
16);
+		else
+			s.num = vq->last_avail_idx;
 		if (copy_to_user(argp, &s, sizeof s))
 			r = -EFAULT;
 		break;
-- 
2.17.1

Use the right structs for PACKED or split vqs when setting and
getting the vring base.

Signed-off-by: Shannon Nelson <shannon.nelson at amd.com>
---
 drivers/vhost/vdpa.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 599b8cc238c7..2543ae9d5939 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -585,7 +585,12 @@ static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v,
unsigned int cmd,
 		if (r)
 			return r;
 
-		vq->last_avail_idx = vq_state.split.avail_index;
+		if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) {
+			vq->last_avail_idx = vq_state.packed.last_avail_idx;
+			vq->last_used_idx = vq_state.packed.last_used_idx;
+		} else {
+			vq->last_avail_idx = vq_state.split.avail_index;
+		}
 		break;
 	}
 
@@ -603,9 +608,15 @@ static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v,
unsigned int cmd,
 		break;
 
 	case VHOST_SET_VRING_BASE:
-		vq_state.split.avail_index = vq->last_avail_idx;
-		if (ops->set_vq_state(vdpa, idx, &vq_state))
-			r = -EINVAL;
+		if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) {
+			vq_state.packed.last_avail_idx = vq->last_avail_idx & 0x7fff;
+			vq_state.packed.last_avail_counter = !!(vq->last_avail_idx & 0x8000);
+			vq_state.packed.last_used_idx = vq->last_used_idx & 0x7fff;
+			vq_state.packed.last_used_counter = !!(vq->last_used_idx & 0x8000);
+		} else {
+			vq_state.split.avail_index = vq->last_avail_idx;
+		}
+		r = ops->set_vq_state(vdpa, idx, &vq_state);
 		break;
 
 	case VHOST_SET_VRING_CALL:
-- 
2.17.1