qemu-kvm 1.2 -> qemu-1.3 migration fails with
Unknown savevm section type 48
load of migration failed
Due to a fix in acpi_piix4 in qemu-kvm (attached at the end of the
message).
The problem is that qemu-kvm correctly uses 2 bytes for sts and
2 bytes for en fields (which is their allocated size), while qemu
uses 4*2 bytes for each.
The fix present in qemu-kvm is correct, but, having it in qemu 1.3 would break
qemu 1.2 -> qemu 1.3 migration (while allowing qemu-kvm 1.2 -> qemu 1.3
migration).
Any opinions on what to do?
commit b2e4a396f71ace63df6fa7e853f8835c4db6c920
Author: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>
Date: Sun Apr 17 22:50:45 2011 +0900
acpi, acpi_piix: factor out GPE logic
On Sun, Apr 17, 2011 at 04:17:51PM +0300, Avi Kivity wrote:
> On 03/16/2011 11:29 AM, Isaku Yamahata wrote:
>> factor out ACPI GPE logic. Later it will be used by ICH9 ACPI.
>>
>
> I think this patch is causing qemu-kvm failures on migration:
> (gdb) bt
> #0 0x000000000049aff4 in qemu_put_be16s (f=0x1a74490, pv=0x2c02580,
> size=2) at hw/hw.h:108
> #1 put_uint16 (f=0x1a74490, pv=0x2c02580, size=2) at savevm.c:855
> #2 0x000000000049c3e4 in vmstate_save_state (f=0x1a74490,
> vmsd=0x6f0b00, opaque=0x1842ef0) at savevm.c:1436
> #3 0x000000000049c3b6 in vmstate_save_state (f=0x1a74490,
> vmsd=0x6f0aa0, opaque=0x1842b90) at savevm.c:1434
> #4 0x000000000049c6f1 in vmstate_save (mon=<value optimized out>,
> f=0x1a74490) at savevm.c:1459
> #5 qemu_savevm_state_complete (mon=<value optimized out>, f=0x1a74490)
> at savevm.c:1600
> #6 0x000000000049455a in migrate_fd_put_ready (opaque=0x1847890) at
> migration.c:383
> #7 0x00000000004ce2eb in qemu_run_timers (clock=<value optimized out>)
> at qemu-timer.c:505
> #8 0x00000000004ce806 in qemu_run_all_timers () at qemu-timer.c:619
> #9 0x0000000000419463 in main_loop_wait (nonblocking=<value optimized
> out>) at /build/home/tlv/akivity/qemu-kvm/vl.c:1339
> #10 0x0000000000433927 in kvm_main_loop () at
> /build/home/tlv/akivity/qemu-kvm/qemu-kvm.c:1590
> #11 0x000000000041a3a6 in main_loop (argc=<value optimized out>,
> argv=<value optimized out>, envp=<value optimized out>)
> at /build/home/tlv/akivity/qemu-kvm/vl.c:1369
> #12 main (argc=<value optimized out>, argv=<value optimized out>,
> envp=<value optimized out>) at /build/home/tlv/akivity/qemu-kvm/vl.c:3257
>
> The vmstate being migrated is "gpe".
>
>
>
>>
>> +#define VMSTATE_GPE_ARRAY(_field, _state) \
>> + { \
>> + .name = (stringify(_field)), \
>> + .version_id = 0, \
>> + .num = GPE_LEN, \
>> + .info =&vmstate_info_uint16, \
>> + .size = sizeof(uint16_t), \
>> + .flags = VMS_ARRAY | VMS_POINTER, \
>> + .offset = vmstate_offset_pointer(_state, _field, uint8_t), \
>> + }
>> +
>> static const VMStateDescription vmstate_gpe = {
>> .name = "gpe",
>> .version_id = 1,
>> .minimum_version_id = 1,
>> .minimum_version_id_old = 1,
>> .fields = (VMStateField []) {
>> - VMSTATE_UINT16(sts, struct gpe_regs),
>> - VMSTATE_UINT16(en, struct gpe_regs),
>> + VMSTATE_GPE_ARRAY(sts, ACPIGPE),
>> + VMSTATE_GPE_ARRAY(en, ACPIGPE),
>> VMSTATE_END_OF_LIST()
>> }
>> };
>
> I'm no vmstate expert, but this does look odd. Why both VMS_ARRAY and
> VMS_POINTER? aren't we trying to save/restore a simple 16-bit value? Or
> at least we did before this patch.
That's right. the difference is, the new member type became uint8_t*.
Does the following help?
Signed-off-by: Avi Kivity <avi@xxxxxxxxxx>
diff --git a/hw/acpi_piix4.c b/hw/acpi_piix4.c
index d65a7e9..9dc6f43 100644
--- a/hw/acpi_piix4.c
+++ b/hw/acpi_piix4.c
@@ -221,10 +221,9 @@ static int vmstate_acpi_post_load(void *opaque, int version_id)
{ \
.name = (stringify(_field)), \
.version_id = 0, \
- .num = GPE_LEN, \
.info = &vmstate_info_uint16, \
.size = sizeof(uint16_t), \
- .flags = VMS_ARRAY | VMS_POINTER, \
+ .flags = VMS_SINGLE | VMS_POINTER, \
.offset = vmstate_offset_pointer(_state, _field, uint8_t), \
}
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