Re: [PATCH v2 09/13] vfio/migration: Add Error ** parameter to vfio_migration_init()

[Avihai Horon]

On 6/3/2026 2:38 PM, Philippe Mathieu-Daudé wrote:

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Hi Avihai,

On 2/6/26 11:26, Avihai Horon wrote:

vfio_migration_init() already has many failure points and a new one will
be added in next patch.

Add Error ** parameter to vfio_migration_init() to report a detailed
error message through it.

Signed-off-by: Avihai Horon <avih...@nvidia.com>
---
  hw/vfio/migration.c | 25 +++++++++++++------------
  1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index a15e877fd3..02ef216712 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c

@@ -1055,7 +1055,7 @@ static bool vfio_dma_logging_supported(VFIODevice *vbasedev)

      return !ioctl(vbasedev->fd, VFIO_DEVICE_FEATURE, feature);
  }

-static int vfio_migration_init(VFIODevice *vbasedev)
+static int vfio_migration_init(VFIODevice *vbasedev, Error **errp)
  {
      int ret;
      Object *obj;

@@ -1066,21 +1066,31 @@ static int vfio_migration_init(VFIODevice *vbasedev)

      VMChangeStateHandler *prepare_cb;

      if (!vbasedev->ops->vfio_get_object) {
+        error_setg(errp, "no vfio_get_object handler");
          return -EINVAL;
      }

      obj = vbasedev->ops->vfio_get_object(vbasedev);
      if (!obj) {
+        error_setg(errp, "failed to get object");
          return -EINVAL;
      }

      ret = vfio_migration_query_flags(vbasedev, &mig_flags);
      if (ret) {
+        if (ret == -ENOTTY) {
+            error_setg_errno(errp, -ret,
+                             "migration is not supported in kernel");
+        } else {

+            error_setg_errno(errp, -ret, "failed to query migration flags");

+        }
+
          return ret;
      }

      /* Basic migration functionality must be supported */
      if (!(mig_flags & VFIO_MIGRATION_STOP_COPY)) {
+        error_setg(errp, "VFIO_MIGRATION_STOP_COPY is not supported");
          return -EOPNOTSUPP;
      }

@@ -1278,18 +1288,9 @@ bool vfio_migration_realize(VFIODevice *vbasedev, Error **errp)

          return !vfio_block_migration(vbasedev, err, errp);
      }

-    ret = vfio_migration_init(vbasedev);
+    ret = vfio_migration_init(vbasedev, &err);
      if (ret) {

Only 'ret' boolean part is used now, have the method return a boolean
instead, like other methods with Error **errp last param?

Sure, I will change it.

Thanks.

-        if (ret == -ENOTTY) {

-            error_setg(&err, "%s: VFIO migration is not supported in kernel",

-                       vbasedev->name);
-        } else {
-            error_setg(&err,

-                       "%s: Migration couldn't be initialized for VFIO device, "

-                       "err: %d (%s)",
-                       vbasedev->name, ret, strerror(-ret));
-        }
-

+        error_prepend(&err, "%s: VFIO migration init failed: ", vbasedev->name);

          return !vfio_block_migration(vbasedev, err, errp);
      }