vdpa: Track device suspended state

Set vdpa device suspended state on successful suspend. Clear it on
successful resume and reset.

The state will be locked by the vhost_vdpa mutex. The mutex is taken
during suspend, resume and reset in vhost_vdpa_unlocked_ioctl. The
exception is vhost_vdpa_open which does a device reset but that should
be safe because it can only happen before the other ops.

Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Suggested-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20231225134210.151540-2-dtatulea@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Author: dtatulea

drivers/vhost/vdpa.c

@@ -59,6 +59,7 @@ struct vhost_vdpa {
 	int in_batch;
 	struct vdpa_iova_range range;
 	u32 batch_asid;
+	bool suspended;
 };
 
 static DEFINE_IDA(vhost_vdpa_ida);
@@ -232,6 +233,8 @@ static int _compat_vdpa_reset(struct vhost_vdpa *v)
 	struct vdpa_device *vdpa = v->vdpa;
 	u32 flags = 0;
 
+	v->suspended = false;
+
 	if (v->vdev.vqs) {
 		flags |= !vhost_backend_has_feature(v->vdev.vqs[0],
 						    VHOST_BACKEND_F_IOTLB_PERSIST) ?
@@ -590,11 +593,16 @@ static long vhost_vdpa_suspend(struct vhost_vdpa *v)
 {
 	struct vdpa_device *vdpa = v->vdpa;
 	const struct vdpa_config_ops *ops = vdpa->config;
+	int ret;
 
 	if (!ops->suspend)
 		return -EOPNOTSUPP;
 
-	return ops->suspend(vdpa);
+	ret = ops->suspend(vdpa);
+	if (!ret)
+		v->suspended = true;
+
+	return ret;
 }
 
 /* After a successful return of this ioctl the device resumes processing
@@ -605,11 +613,16 @@ static long vhost_vdpa_resume(struct vhost_vdpa *v)
 {
 	struct vdpa_device *vdpa = v->vdpa;
 	const struct vdpa_config_ops *ops = vdpa->config;
+	int ret;
 
 	if (!ops->resume)
 		return -EOPNOTSUPP;
 
-	return ops->resume(vdpa);
+	ret = ops->resume(vdpa);
+	if (!ret)
+		v->suspended = false;
+
+	return ret;
 }
 
 static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,