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Re: [Xen-devel] Failed vm entry with heavy use of emulator

On 05/01/16 14:01, Razvan Cojocaru wrote:
> On 01/05/2016 03:49 PM, Andrew Cooper wrote:
>> On 05/01/16 13:39, Razvan Cojocaru wrote:
>>> Here's a quick log of the emulated instructions on my setup:
>>> http://pastebin.com/raw/XXQ0Lnzh
>> Hmm - according to that, the final instruction emulated was
>> d1v0 32bit @ 0008:828925db -> fa
>> which is the 'cli' instruction.
>> I would start there - I doubt it is an instruction which is emulated often.
> My code (arch/x86/x86_emulate/x86_emulate.c) does have a case label for it:
> 3677     case 0xfa: /* cli */
> 3678         generate_exception_if(!mode_iopl(), EXC_GP, 0);
> 3679         _regs.eflags &= ~EFLG_IF;
> 3680         break;
> Maybe the IOPL test fails there? Tamas, does your guest die after a CLI
> as well?

The iopl test looks correct.  It is quite possible that eflags.IF is
expected to match a separate piece of control state in the vmcs, and
that is the cause of the vmentry failure.


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