[v4,20/33] vfio/migration: Add x-migration-load-config-after-iter VFIO property

Commit Message

Maciej S. Szmigiero Jan. 30, 2025, 10:08 a.m. UTC

From: "Maciej S. Szmigiero" <[e-mail]>

This property allows configuring whether to start the config load only
after all iterables were loaded.
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.

Signed-off-by: Maciej S. Szmigiero <[e-mail]>
---
 hw/vfio/migration.c           | 25 +++++++++++++++++++++++++
 hw/vfio/pci.c                 |  3 +++
 include/hw/vfio/vfio-common.h |  1 +
 3 files changed, 29 insertions(+)

Patch

diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index adfa752db527..d801c861d202 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -254,6 +254,31 @@  static int vfio_load_buffer(QEMUFile *f, VFIODevice *vbasedev,
     return ret;
 }
 
+static bool vfio_load_config_after_iter(VFIODevice *vbasedev)
+{
+    if (vbasedev->migration_load_config_after_iter == ON_OFF_AUTO_ON) {
+        return true;
+    } else if (vbasedev->migration_load_config_after_iter == ON_OFF_AUTO_OFF) {
+        return false;
+    }
+
+    assert(vbasedev->migration_load_config_after_iter == ON_OFF_AUTO_AUTO);
+
+    /*
+     * Starting the config load only after all iterables were loaded 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
+}
+
 static int vfio_save_device_config_state(QEMUFile *f, void *opaque,
                                          Error **errp)
 {
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index ab17a98ee5b6..83090c544d95 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -3377,6 +3377,9 @@  static const Property vfio_pci_dev_properties[] = {
                     VFIO_FEATURE_ENABLE_IGD_OPREGION_BIT, false),
     DEFINE_PROP_ON_OFF_AUTO("enable-migration", VFIOPCIDevice,
                             vbasedev.enable_migration, ON_OFF_AUTO_AUTO),
+    DEFINE_PROP_ON_OFF_AUTO("x-migration-load-config-after-iter", VFIOPCIDevice,
+                            vbasedev.migration_load_config_after_iter,
+                            ON_OFF_AUTO_AUTO),
     DEFINE_PROP_BOOL("migration-events", VFIOPCIDevice,
                      vbasedev.migration_events, false),
     DEFINE_PROP_BOOL("x-no-mmap", VFIOPCIDevice, vbasedev.no_mmap, false),
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 0c60be5b15c7..153d03745dc7 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -133,6 +133,7 @@  typedef struct VFIODevice {
     bool no_mmap;
     bool ram_block_discard_allowed;
     OnOffAuto enable_migration;
+    OnOffAuto migration_load_config_after_iter;
     bool migration_events;
     VFIODeviceOps *ops;
     unsigned int num_irqs;