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RE: [Xen-ia64-devel] VT-i: general exception


  • To: "Tristan Gingold" <Tristan.Gingold@xxxxxxxx>, <xen-ia64-devel@xxxxxxxxxxxxxxxxxxx>
  • From: "Xu, Anthony" <anthony.xu@xxxxxxxxx>
  • Date: Tue, 11 Apr 2006 16:49:06 +0800
  • Delivery-date: Tue, 11 Apr 2006 01:49:59 -0700
  • List-id: Discussion of the ia64 port of Xen <xen-ia64-devel.lists.xensource.com>
  • Thread-index: AcZdRAPjmJjYtmP5RkyjgmdZwwRMeQAAD9pg
  • Thread-topic: [Xen-ia64-devel] VT-i: general exception

>From: Tristan Gingold 
>Sent: 2006?4?11? 16:47
>Le Mardi 11 Avril 2006 03:17, Xu, Anthony a écrit :
>> From: Tristan Gingold
>>
>> >Sent: 2006?4?11? 0:03
>> >To: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
>> >Subject: [Xen-ia64-devel] VT-i: general exception
>> >
>> >Hi,
>> >
>> >inside vmx_ivt.S:
>> >
>> >// 0x5400 Entry 24 (size 16 bundles) General Exception (5,32,34,36,38,39)
>> >ENTRY(vmx_general_exception)
>> >    VMX_DBG_FAULT(24)
>> >    VMX_FAULT(24)
>> >//    VMX_REFLECT(24)
>> >END(vmx_general_exception)
>> >
>> >IIRC, VMX_FAULT is an infinite loop.  Therefore, in case of general
>> > exception raised at the hots IVT, xen locks.
>> >
>> >Is it a bug or something not finished ?
>>
>> It's not a bug, normally general exception will not happen in guest,
>> If it does happen, that means something wrong, it was used for
>> debugging.
>???
>
>Try this program:
>
>int main(void)
>{
>  int a = *(volatile int *)0xf000000000000000;
>}
>
>This locks up Xen!
Ideally gp fault should be injected into guest.
Again, this was only used for debugging tricky issue
happening inside VMM.

Thanks,
Anthony


>
>Tristan.

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