[Xen-devel] RE: [pvops-dom0]Let PV ops guest could handle Machine Check trap

["Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>]

Jeremy Fitzhardinge wrote:
> On 09/21/09 23:32, Ke, Liping wrote:
>> Hi, Jeremy and all
>> 
>> This small patch lets pv ops guest handle machine check trap. When
>> non fatal mce error happens, xen will inject vMCE# to the impacted
>> pv ops guest. This patch allows pv ops guest could receive machine
>> check trap and enter its own machine check handler.
>> 
> 
> Have you tested this?  This code is specifically to deal with traps
> installed using an IST stack.  If the machine_check handler just works
> as-is then there's no need for that whole ifdef block.  If it doesn't
> work, then we need a variant which has the right exception
> frame format.

I remember Criping has tested the patch already and it works.

After checking the machine check code in dom0, I think it should be ok to use 
normal handler, I didn't find any dependency for the IST stack in the machine 
check handler.

One potential issue is, if it is a MCA is for current thread, i.e. the EIPV == 
1, RIPV==0, the current thread may be killed. It will depends on how dom0's 
implementation will handle such situation, but most likely dom0 will do error 
handling when return from MCA, and that will be ok. BTW, I don't think we have 
such MCA now.

Thanks
--jyh

> 
> Thanks,
>    J
> 
>> Thanks & Regards,
>> Criping
>> 
>> 
>> From 5efc12fe8214d55e2becc2c4b6ec4a30531d7b60 Mon Sep 17 00:00:00
>> 2001 From: Liping Ke <liping.ke@xxxxxxxxx>
>> Date: Tue, 22 Sep 2009 10:46:05 +0800
>> Subject: [PATCH] Let PV guest handle machine check trap.
>> 
>> This patch lets pv ops guest handle machine check trap. When non
>> fatal mce error happens, XEN will inject vMCE# to the pv ops guest
>> This patch allows pv ops guest could receive machine check trap
>> and enter its own machine check handler.
>> 
>> Signed-off-by: Liping Ke <liping.ke@xxxxxxxxx>
>> ---
>>  arch/x86/xen/enlighten.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>> 
>> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
>> index 1edf6a8..3399a40 100644 --- a/arch/x86/xen/enlighten.c
>> +++ b/arch/x86/xen/enlighten.c
>> @@ -476,7 +476,7 @@ static int cvt_gate_to_trap(int vector, const
>>  gate_desc *val,             return 0; #ifdef CONFIG_X86_MCE
>>      } else if (addr == (unsigned long)machine_check) { -            return 
>> 0;
>> +            addr = (unsigned long)machine_check;
>>  #endif
>>      } else {
>>              /* Some other trap using IST? */
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