[PATCH v4 17/25] vfio: Add Error** argument to vfio_devices_dma_logging_start()

["Cédric Le Goater" <clg@redhat.com>]

This allows to update the Error argument of the VFIO log_global_start()
handler. Errors detected when device level logging is started will be
propagated up to qemu_savevm_state_setup() when the ram save_setup()
handler is executed.

The vfio_set_migration_error() call becomes redundant. Remove it.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---

 Changes in v4:

 - Dropped log_global_stop() and log_global_sync() changes
   
 Changes in v3:

 - Use error_setg_errno() in vfio_devices_dma_logging_start() 
 - ERRP_GUARD() because of error_prepend use in
   vfio_listener_log_global_start()
   
 hw/vfio/common.c | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 5598a508399a6c0b3a20ba17311cbe83d84250c5..d6790557da2f2890398fa03dbbef18129cd2c1bb 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -1036,7 +1036,8 @@ static void vfio_device_feature_dma_logging_start_destroy(
     g_free(feature);
 }
 
-static int vfio_devices_dma_logging_start(VFIOContainerBase *bcontainer)
+static int vfio_devices_dma_logging_start(VFIOContainerBase *bcontainer,
+                                          Error **errp)
 {
     struct vfio_device_feature *feature;
     VFIODirtyRanges ranges;
@@ -1058,8 +1059,8 @@ static int vfio_devices_dma_logging_start(VFIOContainerBase *bcontainer)
         ret = ioctl(vbasedev->fd, VFIO_DEVICE_FEATURE, feature);
         if (ret) {
             ret = -errno;
-            error_report("%s: Failed to start DMA logging, err %d (%s)",
-                         vbasedev->name, ret, strerror(errno));
+            error_setg_errno(errp, errno, "%s: Failed to start DMA logging",
+                             vbasedev->name);
             goto out;
         }
         vbasedev->dirty_tracking = true;
@@ -1078,20 +1079,19 @@ out:
 static bool vfio_listener_log_global_start(MemoryListener *listener,
                                            Error **errp)
 {
+    ERRP_GUARD(); /* error_prepend use */
     VFIOContainerBase *bcontainer = container_of(listener, VFIOContainerBase,
                                                  listener);
     int ret;
 
     if (vfio_devices_all_device_dirty_tracking(bcontainer)) {
-        ret = vfio_devices_dma_logging_start(bcontainer);
+        ret = vfio_devices_dma_logging_start(bcontainer, errp);
     } else {
-        ret = vfio_container_set_dirty_page_tracking(bcontainer, true, NULL);
+        ret = vfio_container_set_dirty_page_tracking(bcontainer, true, errp);
     }
 
     if (ret) {
-        error_report("vfio: Could not start dirty page tracking, err: %d (%s)",
-                     ret, strerror(-ret));
-        vfio_set_migration_error(ret);
+        error_prepend(errp, "vfio: Could not start dirty page tracking - ");
     }
     return !ret;
 }
@@ -1100,17 +1100,20 @@ static void vfio_listener_log_global_stop(MemoryListener *listener)
 {
     VFIOContainerBase *bcontainer = container_of(listener, VFIOContainerBase,
                                                  listener);
+    Error *local_err = NULL;
     int ret = 0;
 
     if (vfio_devices_all_device_dirty_tracking(bcontainer)) {
         vfio_devices_dma_logging_stop(bcontainer);
     } else {
-        ret = vfio_container_set_dirty_page_tracking(bcontainer, false, NULL);
+        ret = vfio_container_set_dirty_page_tracking(bcontainer, false,
+                                                     &local_err);
     }
 
     if (ret) {
-        error_report("vfio: Could not stop dirty page tracking, err: %d (%s)",
-                     ret, strerror(-ret));
+        error_prepend(&local_err,
+                      "vfio: Could not stop dirty page tracking - ");
+        error_report_err(local_err);
         vfio_set_migration_error(ret);
     }
 }
-- 
2.44.0