[Qemu-devel] [PULL 04/25] s390x/ipl: fix reboots for migration from different bios

[Cornelia Huck <cornelia.huck@de.ibm.com>]

From: David Hildenbrand <dahi@linux.vnet.ibm.com>

When migrating from a different QEMU version, the start_address and
bios_start_address may differ. During migration these values are migrated
and overwrite the values that were detected by QEMU itself.

On a reboot, QEMU will reload its own BIOS, but use the migrated start
addresses, which does not work if the values differ.

Fix this by not relying on the migrated values anymore, but still
provide them during migration, so existing QEMUs continue to work.

Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 hw/s390x/ipl.c | 11 +++++++++--
 hw/s390x/ipl.h |  2 ++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
index 78998cd..a54284c 100644
--- a/hw/s390x/ipl.c
+++ b/hw/s390x/ipl.c
@@ -69,8 +69,8 @@ static const VMStateDescription vmstate_ipl = {
     .version_id = 0,
     .minimum_version_id = 0,
     .fields = (VMStateField[]) {
-        VMSTATE_UINT64(start_addr, S390IPLState),
-        VMSTATE_UINT64(bios_start_addr, S390IPLState),
+        VMSTATE_UINT64(compat_start_addr, S390IPLState),
+        VMSTATE_UINT64(compat_bios_start_addr, S390IPLState),
         VMSTATE_STRUCT(iplb, S390IPLState, 0, vmstate_iplb, IplParameterBlock),
         VMSTATE_BOOL(iplb_valid, S390IPLState),
         VMSTATE_UINT8(cssid, S390IPLState),
@@ -192,6 +192,13 @@ static void s390_ipl_realize(DeviceState *dev, Error **errp)
             stq_p(rom_ptr(INITRD_PARM_SIZE), initrd_size);
         }
     }
+    /*
+     * Don't ever use the migrated values, they could come from a different
+     * BIOS and therefore don't work. But still migrate the values, so
+     * QEMUs relying on it don't break.
+     */
+    ipl->compat_start_addr = ipl->start_addr;
+    ipl->compat_bios_start_addr = ipl->bios_start_addr;
     qemu_register_reset(qdev_reset_all_fn, dev);
 error:
     error_propagate(errp, err);
diff --git a/hw/s390x/ipl.h b/hw/s390x/ipl.h
index ed3f2c8..c891095 100644
--- a/hw/s390x/ipl.h
+++ b/hw/s390x/ipl.h
@@ -93,7 +93,9 @@ struct S390IPLState {
     /*< private >*/
     DeviceState parent_obj;
     uint64_t start_addr;
+    uint64_t compat_start_addr;
     uint64_t bios_start_addr;
+    uint64_t compat_bios_start_addr;
     bool enforce_bios;
     IplParameterBlock iplb;
     bool iplb_valid;
-- 
2.9.0