Re: [PATCH v2 16/16] vfio/migration: Add tracepoints for precopy/stopcopy query ioctls

[Cédric Le Goater]

On 4/21/26 22:21, Peter Xu wrote:

Add two tracepoints for both precopy and stopcopy query ioctls.  When at
it, add one warn_report_once() for each of them when it fails.

Signed-off-by: Peter Xu <pet...@redhat.com>

Tested-by: Cédric Le Goater <c...@redhat.com>

Thanks,

C.

---
  hw/vfio/migration.c  | 33 +++++++++++++++++++++++----------
  hw/vfio/trace-events |  2 ++
  2 files changed, 25 insertions(+), 10 deletions(-)

diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index e6e6a0d53d..04d9f94edb 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -329,6 +329,7 @@ static int vfio_query_stop_copy_size(VFIODevice *vbasedev)
      struct vfio_device_feature_mig_data_size *mig_data_size =
          (struct vfio_device_feature_mig_data_size *)feature->data;
      VFIOMigration *migration = vbasedev->migration;
+    int ret;

feature->argsz = sizeof(buf);

      feature->flags =
@@ -340,12 +341,18 @@ static int vfio_query_stop_copy_size(VFIODevice *vbasedev)
           * is reported so downtime limit won't be violated.
           */
          migration->stopcopy_size = VFIO_MIG_STOP_COPY_SIZE;
-        return -errno;
+        ret = -errno;
+        warn_report_once("VFIO device %s ioctl(VFIO_DEVICE_FEATURE) on "
+                         "VFIO_DEVICE_FEATURE_MIG_DATA_SIZE failed (%d)",
+                         vbasedev->name, ret);
+    } else {
+        migration->stopcopy_size = mig_data_size->stop_copy_length;
+        ret = 0;
      }

- migration->stopcopy_size = mig_data_size->stop_copy_length;

+    trace_vfio_query_stop_copy_size(migration->stopcopy_size, ret);

- return 0;

+    return ret;
  }

static int vfio_query_precopy_size(VFIOMigration *migration)

@@ -353,18 +360,24 @@ static int vfio_query_precopy_size(VFIOMigration 
*migration)
      struct vfio_precopy_info precopy = {
          .argsz = sizeof(precopy),
      };
-
-    migration->precopy_init_size = 0;
-    migration->precopy_dirty_size = 0;
+    int ret;

if (ioctl(migration->data_fd, VFIO_MIG_GET_PRECOPY_INFO, &precopy)) {

-        return -errno;
+        migration->precopy_init_size = 0;
+        migration->precopy_dirty_size = 0;
+        ret = -errno;
+        warn_report_once("VFIO device %s ioctl(VFIO_MIG_GET_PRECOPY_INFO) "
+                         "failed (%d)", migration->vbasedev->name, ret);
+    } else {
+        migration->precopy_init_size = precopy.initial_bytes;
+        migration->precopy_dirty_size = precopy.dirty_bytes;
+        ret = 0;
      }

- migration->precopy_init_size = precopy.initial_bytes;

-    migration->precopy_dirty_size = precopy.dirty_bytes;
+    trace_vfio_query_precopy_size(migration->precopy_init_size,
+                                  migration->precopy_dirty_size, ret);

- return 0;

+    return ret;
  }

/* Returns the size of saved data on success and -errno on error */

diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
index 287df0b8cb..854a7e4b19 100644
--- a/hw/vfio/trace-events
+++ b/hw/vfio/trace-events
@@ -176,6 +176,8 @@ vfio_save_setup(const char *name, uint64_t data_buffer_size) 
" (%s) data buffer
  vfio_state_pending(const char *name, uint64_t stopcopy_size, uint64_t precopy_init_size, uint64_t precopy_dirty_size, 
bool exact) " (%s) stopcopy size %"PRIu64" precopy initial size %"PRIu64" precopy dirty size 
%"PRIu64 " exact %d"
  vfio_vmstate_change(const char *name, int running, const char *reason, const char 
*dev_state) " (%s) running %d reason %s device state %s"
  vfio_vmstate_change_prepare(const char *name, int running, const char *reason, const 
char *dev_state) " (%s) running %d reason %s device state %s"
+vfio_query_stop_copy_size(uint64_t size, int ret) "stopcopy size %"PRIu64" ret 
%d"
+vfio_query_precopy_size(uint64_t init_size, uint64_t dirty_size, int ret) "init %"PRIu64" 
dirty %"PRIu64" ret %d"

#iommufd.c