hw/vfio: Add helper to retrieve device feature

Add vfio_device_get_feature() as a common helper to retrieve
VFIO device features.

No functional change intended.

Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Shameer Kolothum <skolothumtho@nvidia.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Tested-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20260121114111.34045-3-skolothumtho@nvidia.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

hw/vfio/container.c

@@ -205,7 +205,7 @@ static int vfio_device_dma_logging_report(VFIODevice *vbasedev, hwaddr iova,
     feature->flags = VFIO_DEVICE_FEATURE_GET |
                      VFIO_DEVICE_FEATURE_DMA_LOGGING_REPORT;
 
-    return vbasedev->io_ops->device_feature(vbasedev, feature);
+    return vfio_device_get_feature(vbasedev, feature);
 }
 
 static int vfio_container_iommu_query_dirty_bitmap(

hw/vfio/device.c

@@ -547,6 +547,15 @@ bool vfio_device_get_host_iommu_quirk_bypass_ro(VFIODevice *vbasedev,
     return false;
 }
 
+int vfio_device_get_feature(VFIODevice *vbasedev,
+                            struct vfio_device_feature *feature)
+{
+    if (!vbasedev->io_ops || !vbasedev->io_ops->device_feature) {
+        return -EINVAL;
+    }
+    return vbasedev->io_ops->device_feature(vbasedev, feature);
+}
+
 /*
  * Traditional ioctl() based io
  */

hw/vfio/listener.c

@@ -909,7 +909,7 @@ static void vfio_devices_dma_logging_stop(VFIOContainer *bcontainer)
             continue;
         }
 
-        ret = vbasedev->io_ops->device_feature(vbasedev, feature);
+        ret = vfio_device_get_feature(vbasedev, feature);
 
         if (ret != 0) {
             warn_report("%s: Failed to stop DMA logging, err %d (%s)",
@@ -1014,7 +1014,7 @@ static bool vfio_devices_dma_logging_start(VFIOContainer *bcontainer,
             continue;
         }
 
-        ret = vbasedev->io_ops->device_feature(vbasedev, feature);
+        ret = vfio_device_get_feature(vbasedev, feature);
         if (ret) {
             error_setg_errno(errp, -ret, "%s: Failed to start DMA logging",
                              vbasedev->name);

include/hw/vfio/vfio-device.h

@@ -272,6 +272,9 @@ bool vfio_device_get_host_iommu_quirk_bypass_ro(VFIODevice *vbasedev,
                                                 uint32_t type, void *caps,
                                                 uint32_t size);
 
+int vfio_device_get_feature(VFIODevice *vbasedev,
+                            struct vfio_device_feature *feature);
+
 int vfio_device_get_region_info(VFIODevice *vbasedev, int index,
                                 struct vfio_region_info **info);
 int vfio_device_get_region_info_type(VFIODevice *vbasedev, uint32_t type,