[PATCH v4 2/9] vhost-vdpa: use bind_mm/unbind_mm device callbacks

[Stefano Garzarella <sgarzare@redhat.com>]

When the user call VHOST_SET_OWNER ioctl and the vDPA device
has `use_va` set to true, let's call the bind_mm callback.
In this way we can bind the device to the user address space
and directly use the user VA.

The unbind_mm callback is called during the release after
stopping the device.

Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---

Notes:
    v4:
    - added new switch after vhost_dev_ioctl() [Jason]
    v3:
    - added `case VHOST_SET_OWNER` in vhost_vdpa_unlocked_ioctl() [Jason]
    v2:
    - call the new unbind_mm callback during the release [Jason]
    - avoid to call bind_mm callback after the reset, since the device
      is not detaching it now during the reset

 drivers/vhost/vdpa.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 7be9d9d8f01c..3824c249612f 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -219,6 +219,28 @@ static int vhost_vdpa_reset(struct vhost_vdpa *v)
 	return vdpa_reset(vdpa);
 }
 
+static long vhost_vdpa_bind_mm(struct vhost_vdpa *v)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+
+	if (!vdpa->use_va || !ops->bind_mm)
+		return 0;
+
+	return ops->bind_mm(vdpa, v->vdev.mm);
+}
+
+static void vhost_vdpa_unbind_mm(struct vhost_vdpa *v)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+
+	if (!vdpa->use_va || !ops->unbind_mm)
+		return;
+
+	ops->unbind_mm(vdpa);
+}
+
 static long vhost_vdpa_get_device_id(struct vhost_vdpa *v, u8 __user *argp)
 {
 	struct vdpa_device *vdpa = v->vdpa;
@@ -716,6 +738,17 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
 		break;
 	}
 
+	if (r)
+		goto out;
+
+	switch (cmd) {
+	case VHOST_SET_OWNER:
+		r = vhost_vdpa_bind_mm(v);
+		if (r)
+			vhost_dev_reset_owner(d, NULL);
+		break;
+	}
+out:
 	mutex_unlock(&d->mutex);
 	return r;
 }
@@ -1287,6 +1320,7 @@ static int vhost_vdpa_release(struct inode *inode, struct file *filep)
 	vhost_vdpa_clean_irq(v);
 	vhost_vdpa_reset(v);
 	vhost_dev_stop(&v->vdev);
+	vhost_vdpa_unbind_mm(v);
 	vhost_vdpa_config_put(v);
 	vhost_vdpa_cleanup(v);
 	mutex_unlock(&d->mutex);
-- 
2.39.2