[Qemu-devel] [PATCH for-2.1 v2 2/2] acpi: mark ACPI tables ROM blob as extend-able on migration

[Igor Mammedov <imammedo@redhat.com>]

It fixes migration failure for machine type pc-i440fx-1.7 from
QEMU 1.7/2.0 to QEMU 2.1

Migration fails due to ACPI tables size grows across 1.7-2.1
versions. That causes ACPI tables ROM blob to change its size
differently for the same configurations on different QEMU versions.
As result migration code bails out when attempting to load
smaller ROM blob into a bigger one on a newer QEMU.
To trigger failure it's enough to add pci-bridge device to QEMU CLI

Marking ACPI tables ROM blob as extend-able on migration allows
QEMU to load smaller ACPI tables from QEMU 1.7/2.0, fixing
forward migration failure introduced since 2.0 which affects
only configurations that cause ACPI ROM blob size change.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
---
 hw/core/loader.c     | 6 +++++-
 hw/i386/acpi-build.c | 2 +-
 include/hw/loader.h  | 5 +++--
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/hw/core/loader.c b/hw/core/loader.c
index 2bf6b8f..d09b894 100644
--- a/hw/core/loader.c
+++ b/hw/core/loader.c
@@ -722,7 +722,8 @@ err:
 
 void *rom_add_blob(const char *name, const void *blob, size_t len,
                    hwaddr addr, const char *fw_file_name,
-                   FWCfgReadCallback fw_callback, void *callback_opaque)
+                   FWCfgReadCallback fw_callback, void *callback_opaque,
+                   bool extendable)
 {
     Rom *rom;
     void *data = NULL;
@@ -742,6 +743,9 @@ void *rom_add_blob(const char *name, const void *blob, size_t len,
 
         if (rom_file_has_mr) {
             data = rom_set_mr(rom, OBJECT(fw_cfg), devpath);
+            if (extendable) {
+                memory_region_permit_extendable_migration(rom->mr);
+            }
         } else {
             data = rom->data;
         }
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index ebc5f03..651c06b 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -1558,7 +1558,7 @@ static void *acpi_add_rom_blob(AcpiBuildState *build_state, GArray *blob,
                                const char *name)
 {
     return rom_add_blob(name, blob->data, acpi_data_len(blob), -1, name,
-                        acpi_build_update, build_state);
+                        acpi_build_update, build_state, true);
 }
 
 static const VMStateDescription vmstate_acpi_build = {
diff --git a/include/hw/loader.h b/include/hw/loader.h
index 796cbf9..e5a24ac 100644
--- a/include/hw/loader.h
+++ b/include/hw/loader.h
@@ -57,7 +57,8 @@ int rom_add_file(const char *file, const char *fw_dir,
                  bool option_rom);
 void *rom_add_blob(const char *name, const void *blob, size_t len,
                    hwaddr addr, const char *fw_file_name,
-                   FWCfgReadCallback fw_callback, void *callback_opaque);
+                   FWCfgReadCallback fw_callback, void *callback_opaque,
+                   bool extendable);
 int rom_add_elf_program(const char *name, void *data, size_t datasize,
                         size_t romsize, hwaddr addr);
 int rom_load_all(void);
@@ -70,7 +71,7 @@ void do_info_roms(Monitor *mon, const QDict *qdict);
 #define rom_add_file_fixed(_f, _a, _i)          \
     rom_add_file(_f, NULL, _a, _i, false)
 #define rom_add_blob_fixed(_f, _b, _l, _a)      \
-    rom_add_blob(_f, _b, _l, _a, NULL, NULL, NULL)
+    rom_add_blob(_f, _b, _l, _a, NULL, NULL, NULL, false)
 
 #define PC_ROM_MIN_VGA     0xc0000
 #define PC_ROM_MIN_OPTION  0xc8000
-- 
1.8.3.1