Re: [Xen-devel] [PATCH v2 1/4] xen/libxc: Allow changes to hypervisor CPUID leaf from config file

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 11.03.14 at 15:26, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
> On 11/03/14 14:07, Boris Ostrovsky wrote:
>> On 03/11/2014 06:10 AM, Andrew Cooper wrote:
>>> On 11/03/14 03:54, Boris Ostrovsky wrote:
>>>> --- a/tools/libxc/xc_cpuid_x86.c
>>>> +++ b/tools/libxc/xc_cpuid_x86.c
>>>> @@ -33,6 +33,8 @@
>>>>   #define DEF_MAX_INTELEXT  0x80000008u
>>>>   #define DEF_MAX_AMDEXT    0x8000001cu
>>>>   +#define HYPERVISOR_LEAF(idx) (((idx) & 0x40000000) == 0x40000000)
>>>> +
>>> This check is wrong.
>>
>> Because of Viridian leaves? Or something else?
> 
> It should be (((idx) & 0xf0000000) == 0x40000000)
> 
> According to the AMD and Intel manuals, it is strictly leaf 0x40000000
> reserved for hypervisor use, not 0xC0000000 or others.

And consequently the mask ought to be 0xffff0000.

Jan


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