RE: [PATCH] vtdt: add a missing change (RE: [Xen-devel] Re: xen guest hang with TSC_DEADLINE)

["Wei, Gang" <gang.wei@xxxxxxxxx>]

Christoph Egger wrote on 2011-01-04:
>>>>> c/s 22529 and 22530 cause a xen guest hang.
>>>>> 
>>>>> While "normal" guests like Linux and NetBSD boot fine I boot Xen
>>>>> itself as a xen guest for my nested virtualization.
>>>>> 
>>>>> When I do that then the guest dom0 hangs at boot when it tries
>>>>> to initialize the first vcpu.
>>>>> The bug is introduced somewhere in c/s 22529 and triggers with
>>>>> c/s 22530.
>>>> 
>>>> Can you enable apic_timer debug info var hvm_debug and give more
>>>> serial port log around the guest dom0 hangs? I used to test xen
>>>> guest, it works well expect that it boot a little bit slowly.
>>> 
>>> This is the log output I get with TSC_DEADLINE feature enabled:
>> 
>> Just found one change was missed while the whole patch was checked in.
>> Apply below patch, it should be ok now.
>> 
>> diff -r 0133cf2a72f5 xen/arch/x86/hvm/vlapic.c
>> --- a/xen/arch/x86/hvm/vlapic.c      Fri Dec 24 10:56:29 2010 +0000
>> +++ b/xen/arch/x86/hvm/vlapic.c      Tue Dec 28 16:53:06 2010 +0800
>> @@ -56,7 +56,7 @@ static unsigned int vlapic_lvt_mask[VLAP  static
>> unsigned int vlapic_lvt_mask[VLAPIC_LVT_NUM] =  {
>>       /* LVTT */
>> -     LVT_MASK | APIC_TIMER_MODE_PERIODIC,
>> +     LVT_MASK | APIC_TIMER_MODE_MASK,
>>       /* LVTTHMR */
>>       LVT_MASK | APIC_MODE_MASK,
>>       /* LVTPC */
>> Jimmy
> 
> The hang is still reproducable with this change. Sorry.

Can you still see below line in the serial log? Is there anything different?

(XEN) [HVM:1.0] <vlapic_tdt_msr_set> ignore tsc deadline msr write

In my side, I can see above line, and nested dom0 will hang while booting if 
without this change. But things become ok after applying this change. So could 
you give more details after apply this change (again, serial log, nested dom0 
output, etc) ?

Jimmy



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