vDPA/ifcvf: verify mandatory feature bits for vDPA

vDPA requres VIRTIO_F_ACCESS_PLATFORM as a must, this commit
examines this when set features.
Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210317094933.16417-7-lingshan.zhu@intel.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vdpa/ifcvf/ifcvf_base.c

@@ -224,6 +224,18 @@ u64 ifcvf_get_features(struct ifcvf_hw *hw)
 	return hw->hw_features;
 }
 
+int ifcvf_verify_min_features(struct ifcvf_hw *hw, u64 features)
+{
+	struct ifcvf_adapter *ifcvf = vf_to_adapter(hw);
+
+	if (!(features & BIT_ULL(VIRTIO_F_ACCESS_PLATFORM)) && features) {
+		IFCVF_ERR(ifcvf->pdev, "VIRTIO_F_ACCESS_PLATFORM is not negotiated\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 void ifcvf_read_net_config(struct ifcvf_hw *hw, u64 offset,
 			   void *dst, int length)
 {

drivers/vdpa/ifcvf/ifcvf_base.h

@@ -123,6 +123,7 @@ void io_write64_twopart(u64 val, u32 *lo, u32 *hi);
 void ifcvf_reset(struct ifcvf_hw *hw);
 u64 ifcvf_get_features(struct ifcvf_hw *hw);
 u64 ifcvf_get_hw_features(struct ifcvf_hw *hw);
+int ifcvf_verify_min_features(struct ifcvf_hw *hw, u64 features);
 u16 ifcvf_get_vq_state(struct ifcvf_hw *hw, u16 qid);
 int ifcvf_set_vq_state(struct ifcvf_hw *hw, u16 qid, u16 num);
 struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw);

drivers/vdpa/ifcvf/ifcvf_main.c

@@ -179,6 +179,11 @@ static u64 ifcvf_vdpa_get_features(struct vdpa_device *vdpa_dev)
 static int ifcvf_vdpa_set_features(struct vdpa_device *vdpa_dev, u64 features)
 {
 	struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
+	int ret;
+
+	ret = ifcvf_verify_min_features(vf, features);
+	if (ret)
+		return ret;
 
 	vf->req_features = features;