vfio/migration: Add x-migration-load-config-after-iter VFIO property

This property allows configuring whether to start the config load only
after all iterables were loaded, during non-iterables loading phase.
Such interlocking is required for ARM64 due to this platform VFIO
dependency on interrupt controller being loaded first.

The property defaults to AUTO, which means ON for ARM, OFF for other
platforms.

Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Avihai Horon <avihaih@nvidia.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Link: https://lore.kernel.org/qemu-devel/0e03c60dbc91f9a9ba2516929574df605b7dfcb4.1752589295.git.maciej.szmigiero@oracle.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/hw/vfio/helpers.c b/hw/vfio/helpers.c
index 9a5f621545..23d13e5db5 100644
--- a/hw/vfio/helpers.c
+++ b/hw/vfio/helpers.c
@@ -209,3 +209,20 @@ retry:
 
     return info;
 }
+
+bool vfio_arch_wants_loading_config_after_iter(void)
+{
+    /*
+     * Starting the config load only after all iterables were loaded (during
+     * non-iterables loading phase) is required for ARM64 due to this platform
+     * VFIO dependency on interrupt controller being loaded first.
+     *
+     * See commit d329f5032e17 ("vfio: Move the saving of the config space to
+     * the right place in VFIO migration").
+     */
+#if defined(TARGET_ARM)
+    return true;
+#else
+    return false;
+#endif
+}