Re: [Qemu-devel] [PATCH 24/26] acpi, acpi_piix: factor out GPE logic

[Isaku Yamahata]

On Sun, Apr 17, 2011 at 06:53:12PM +0300, Avi Kivity wrote:
> On 04/17/2011 04:50 PM, Isaku Yamahata wrote:
>> 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?
>>
>
> Unforunately not.  The core is very similar though:

Hmm but it seems that there is another issue.
With the previous patch, I confirmed sts and en are saved as expected.

The related VMStateDescription are defined in acpi_piix.c in
the following order.
vmstate_acpi calls vmstate_gpe. and &vmstate_gpe < &vmstate_acpi.

However, your call trace shows something different.
(I'm assuming the stack trace is correct. gdb or compiler optimization?)

static const VMStateDescription vmstate_gpe = {
...

static const VMStateDescription vmstate_acpi = {
    .fields      = (VMStateField []) {
...
        VMSTATE_STRUCT(gpe, PIIX4PMState, 2, vmstate_gpe, ACPIGPE),


>
> #0  0x000000000049aff4 in qemu_put_be16s (f=0x2427490, pv=0x1ae7580,  
> size=2) at hw/hw.h:108
> #1  put_uint16 (f=0x2427490, pv=0x1ae7580, size=2) at savevm.c:855
> #2  0x000000000049c3e4 in vmstate_save_state (f=0x2427490,  
> vmsd=0x6f0b00, opaque=0x21f5ef0) at savevm.c:1436

vmsd = 0x6f0b00 = &vmstate_gpe <<<<<< correct???
opaque = 0x21f5ef0 = &PIIX4PMState->gpe

> #3  0x000000000049c3b6 in vmstate_save_state (f=0x2427490,  
> vmsd=0x6f0aa0, opaque=0x21f5b90) at savevm.c:1434

vmsd = 0x6f0aa0 = &vmstate_acpi  <<<<<<<<<<<<< correct?
opaque = 0x21f5b90 = &PIIX4PMState

opaque seems correct as 
0x21f5b90 - 0x21f5ef0 = 0x348 = offsetof(PIIX4PMState, gpe)


On my environment the stack trace looks like
(gdb) where
#0  vmstate_save_state (f=0x25d16d0, vmsd=0x695940, opaque=0x283a218)
    at savevm.c:1374
#1  0x00000000004bb4f7 in vmstate_save_state (f=0x25d16d0, vmsd=0x695a40, 
    opaque=0x2839ed0) at savevm.c:1412
...

(gdb) print &vmstate_gpe
$32 = (const VMStateDescription *) 0x695940
(gdb) print &vmstate_acpi
$33 = (const VMStateDescription *) 0x695a40

thanks,

> #4  0x000000000049c6f1 in vmstate_save (mon=<value optimized out>,  
> f=0x2427490) at savevm.c:1459
> #5  qemu_savevm_state_complete (mon=<value optimized out>, f=0x2427490)  
> at savevm.c:1600
> #6  0x000000000049455a in migrate_fd_put_ready (opaque=0x21fa8c0) 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

>
>
> -- 
> error compiling committee.c: too many arguments to function
>

-- 
yamahata