Re: [PATCH v2] xen: Add acpu_sleep=s3_fake command-line option for testing

[George Dunlap <george.dunlap@citrix.com>]

On 05/22/2018 03:50 PM, George Dunlap wrote:
> On 05/22/2018 03:43 PM, George Dunlap wrote:
>> On 05/22/2018 03:37 PM, Andrew Cooper wrote:
>>> On 22/05/18 14:48, George Dunlap wrote:
>>>> On 05/22/2018 02:40 PM, Jan Beulich wrote:
>>>>>>>> On 22.05.18 at 15:35, <george.dunlap@citrix.com> wrote:
>>>>>> --- a/xen/arch/x86/acpi/power.c
>>>>>> +++ b/xen/arch/x86/acpi/power.c
>>>>>> @@ -33,6 +33,8 @@
>>>>>>  
>>>>>>  uint32_t system_reset_counter = 1;
>>>>>>  
>>>>>> +static bool __read_mostly opt_fake_s3 = false;
>>>>> With the typo in the title (wants to be acpi_sleep) corrected 
>>>> Oops -- I can fix this on check-in (once the development window opens).
>>>
>>> If this patch is necessary, or at least a useful aid to track down an S3
>>> bug in Xen 4.11, I vote for its inclusion.
>>>
>>> As far as the change itself goes, it is very simple, with a minimal
>>> change of any unintended side effects.
>>>
>>> CC'ing the RM for his decision on the subject.
>>
>> Using `rtcwake -s 10 -m mem`, the only difference I've seen between
>> suspend with this patch and without is that it doesn't actually sleep
>> for 10 seconds -- not surprising, as it was never asleep. :-)
> 
> In fact, with `s3_fake` enabled, Xen just hangs when XPTI / BTI are
> enabled; but with it disabled, I actually get a stack trace.  Serial
> output and xen-syms.map attached.

With your code dump patch (sorry for the wrapping):

(XEN) *** DOUBLE FAULT ***

(XEN) ----[ Xen-4.11-rc  x86_64  debug=y   Not tainted ]----

(XEN) CPU:    0

(XEN) RIP:    e008:[<ffff82d080378964>] handle_exception+0x9c/0xff

(XEN) RFLAGS: 0000000000010006   CONTEXT: hypervisor

(XEN) rax: ffffc900402040d8   rbx: 0000000000000000   rcx: 0000000000000003

(XEN) rdx: 0000000000000000   rsi: 0000000000000000   rdi: 0000000000000000

(XEN) rbp: 000036ffbfdfbf07   rsp: ffffc90040204000   r8:  0000000000000000

(XEN) r9:  0000000000000000   r10: 0000000000000000   r11: 0000000000000000

(XEN) r12: 0000000000000000   r13: 0000000000000000   r14: ffffc90040207fff

(XEN) r15: 0000000000000000   cr0: 000000008005003b   cr4: 0000000000002660

(XEN) cr3: 000000019200a000   cr2: ffffc90040203ff8

(XEN) fsb: 00007f800083d700   gsb: ffff88003dc40000   gss: 0000000000000000

(XEN) ds: 002b   es: 002b   fs: 0000   gs: 0000   ss: e010   cs: e008

(XEN) Xen code around <ffff82d080378964> (handle_exception+0x9c/0xff):

(XEN)  00 f3 90 0f ae e8 eb f9 <e8> 07 00 00 00 f3 90 0f ae e8 eb f9 83
e9 01 75

(XEN) Current stack base ffffc90040200000 differs from expected
ffff8300dfa80000

(XEN) Valid stack range: ffffc90040206000-ffffc90040208000,
sp=ffffc90040204000, tss.rsp0=ffff8300dfa87fa0

(XEN) No stack overflow detected. Skipping stack trace.

(XEN)

(XEN) ****************************************

(XEN) Panic on CPU 0:

(XEN) DOUBLE FAULT -- system shutdown

(XEN) ****************************************

(XEN)

(XEN) Reboot in five seconds...


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