Re: [Xen-devel] fsincos emulation on AMD CPUs

[Keir Fraser <keir@xxxxxxx>]

On 15/12/2011 12:27, "Keir Fraser" <keir@xxxxxxx> wrote:

> On 15/12/2011 11:15, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
> 
>> +#define AMD_ERRATUM_573       \
>> +    AMD_LEGACY_ERRATUM(AMD_MODEL_RANGE(0x0f, 0x0, 0x0, 0xff, 0xf), \
>> +                       AMD_MODEL_RANGE(0x10, 0x0, 0x0, 0xff, 0xf), \
>> +                       AMD_MODEL_RANGE(0x11, 0x0, 0x0, 0xff, 0xf), \
>> +                       AMD_MODEL_RANGE(0x12, 0x0, 0x0, 0xff, 0xf))
>> +
>>  struct cpuinfo_x86;
>>  int cpu_has_amd_erratum(const struct cpuinfo_x86 *, int, ...);
>>  
>> Keir, what's your opinion here?
> 
> Bail. :-)

More detail: the full patch is ugly and hard to test all cases. And there's
no practical scenario where we want to emulate FSINCOS on AMD -- we don't
emulate realmode on AMD, FSINCOS on a shadowed page certainly indicates that
we should unshadow the page, FSINCOS on MMIO is mad or malicious.

Pretty much the whole x87 emulation thing is for realmode on Intel.

 -- Keir

>  -- Keir
> 
> 



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