[PATCH vhost v4 07/15] vdpa: Block vq address change in DRIVER_OK unless device supports it

[Dragos Tatulea <dtatulea@nvidia.com>]

Virtqueue address change during DRIVE_OK is not supported by the virtio
standard. Allow this op in DRIVER_OK only for devices that support
changing the address during DRIVER_OK if the device is suspended.

Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Suggested-by: Eugenio Pérez <eperezma@redhat.com>
---
 drivers/vhost/vdpa.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 00b4fa8e89f2..6bfa3391935a 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -625,6 +625,29 @@ static long vhost_vdpa_resume(struct vhost_vdpa *v)
 	return ret;
 }
 
+static bool vhost_vdpa_vq_config_allowed(struct vhost_vdpa *v, unsigned int cmd)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	int feature;
+
+	if (!(ops->get_status(vdpa) & VIRTIO_CONFIG_S_DRIVER_OK))
+		return true;
+
+	if (!v->suspended)
+		return false;
+
+	switch (cmd) {
+	case VHOST_SET_VRING_ADDR:
+		feature = VHOST_BACKEND_F_CHANGEABLE_VQ_ADDR_IN_SUSPEND;
+		break;
+	default:
+		return false;
+	}
+
+	return v->vdev.vqs && vhost_backend_has_feature(v->vdev.vqs[0], feature);
+}
+
 static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,
 				   void __user *argp)
 {
@@ -703,6 +726,9 @@ static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,
 
 	switch (cmd) {
 	case VHOST_SET_VRING_ADDR:
+		if (!vhost_vdpa_vq_config_allowed(v, cmd))
+			return -EOPNOTSUPP;
+
 		if (ops->set_vq_address(vdpa, idx,
 					(u64)(uintptr_t)vq->desc,
 					(u64)(uintptr_t)vq->avail,
-- 
2.43.0