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

[Dragos Tatulea]

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 <dtatu...@nvidia.com>
Suggested-by: Eugenio Pérez <epere...@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