RE: [Xen-devel] RE: [PATCH] Don't enable irq for machine check vmexit

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

Tim, thanks for review. I add printk here because that is something not always 
happen.

--jyh

>-----Original Message-----
>From: Tim Deegan [mailto:Tim.Deegan@xxxxxxxxxx]
>Sent: Friday, February 05, 2010 6:42 PM
>To: Jiang, Yunhong
>Cc: xen-devel@xxxxxxxxxxxxxxxxxxx; Keir Fraser
>Subject: Re: [Xen-devel] RE: [PATCH] Don't enable irq for machine check vmexit
>
>At 10:22 +0000 on 05 Feb (1265365365), Jiang, Yunhong wrote:
>> Keir/Tim, here is attached patch. Please have a look onit.
>
>Yep, that looks better.  Not sure that the dprintk is useful, though.
>
>Cheers,
>
>Tim.
>
>> Thanks
>> Yunhong Jiang
>>
>> # HG changeset patch
>> # User Yunhong Jiang <yunhong.jiang@xxxxxxxxx>
>> # Date 1265363638 -28800
>> # Node ID 01b2ce3f2cc95dd2e9c6defe2cee8a892e867187
>> # Parent  7b751b0e6f1bc7485b0718e634ed7cb9ce9ab68c
>> We should not enable irq for machine check VMExit
>>
>> In changeset 18658:824892134573, IRQ is enabled during VMExit except external
>interrupt. The exception should apply for machine check also, because :
>> a) The mce_logout_lock should be held in irq_disabled context.
>> b) The machine check event should be handled as quickly as possible, enable 
>> irq will
>increase the period greatly.
>>
>> Signed-off-by: Jiang, Yunhong <yunhong.jiang@xxxxxxxxx>
>>
>> diff -r 7b751b0e6f1b -r 01b2ce3f2cc9 xen/arch/x86/hvm/vmx/vmx.c
>> --- a/xen/arch/x86/hvm/vmx/vmx.c     Thu Feb 04 19:40:19 2010 +0000
>> +++ b/xen/arch/x86/hvm/vmx/vmx.c     Fri Feb 05 17:53:58 2010 +0800
>> @@ -2168,7 +2168,7 @@ static void vmx_failed_vmentry(unsigned
>>      case EXIT_REASON_MCE_DURING_VMENTRY:
>>          printk("caused by machine check.\n");
>>          HVMTRACE_0D(MCE);
>> -        do_machine_check(regs);
>> +        /* Handled already */
>>          break;
>>      default:
>>          printk("reason not known yet!");
>> @@ -2259,6 +2259,23 @@ err:
>>  err:
>>      vmx_inject_hw_exception(TRAP_gp_fault, 0);
>>      return -1;
>> +}
>> +
>> +int vmx_mce_exit(int exit_reason)
>> +{
>> +    if ( unlikely(exit_reason & VMX_EXIT_REASONS_FAILED_VMENTRY &&
>> +        (uint16_t)exit_reason == EXIT_REASON_MCE_DURING_VMENTRY) )
>> +            return 1;
>> +    else if (unlikely(exit_reason == EXIT_REASON_EXCEPTION_NMI))
>> +    {
>> +        uint32_t vector;
>> +
>> +        vector = __vmread(VM_EXIT_INTR_INFO) &
>INTR_INFO_VECTOR_MASK;
>> +        if (vector == TRAP_machine_check)
>> +            return 1;
>> +    }
>> +
>> +    return 0;
>>  }
>>
>>  asmlinkage void vmx_vmexit_handler(struct cpu_user_regs *regs)
>> @@ -2287,6 +2304,9 @@ asmlinkage void vmx_vmexit_handler(struc
>>      /* Handle the interrupt we missed before allowing any more in. */
>>      if ( exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT )
>>          vmx_do_extint(regs);
>> +
>> +    if ( vmx_mce_exit(exit_reason) )
>> +        do_machine_check(regs);
>>
>>      /* Now enable interrupts so it's safe to take locks. */
>>      local_irq_enable();
>> @@ -2447,8 +2467,9 @@ asmlinkage void vmx_vmexit_handler(struc
>>              self_nmi(); /* Real NMI, vector 2: normal processing. */
>>              break;
>>          case TRAP_machine_check:
>> +            dprintk(XENLOG_INFO, "VMexit for machine check\n");
>>              HVMTRACE_0D(MCE);
>> -            do_machine_check(regs);
>> +            /* Handled already */
>>              break;
>>          case TRAP_invalid_op:
>>              vmx_vmexit_ud_intercept(regs);
>>
>>
>
>
>Content-Description: ATT00001.txt
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>
>
>--
>Tim Deegan <Tim.Deegan@xxxxxxxxxx>
>Principal Software Engineer, Citrix Systems (R&D) Ltd.
>[Company #02300071, SL9 0DZ, UK.]

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