Re: [Xen-devel] [PATCH v10 10/11] xen: add new Xen cpuid node for max address width info

[Juergen Gross <jgross@xxxxxxxx>]

On 28/09/17 10:59, Jan Beulich wrote:
>>>> On 25.09.17 at 12:00, <jgross@xxxxxxxx> wrote:
>> --- a/xen/arch/x86/traps.c
>> +++ b/xen/arch/x86/traps.c
>> @@ -930,6 +930,13 @@ void cpuid_hypervisor_leaves(const struct vcpu *v, 
>> uint32_t leaf,
>>          res->b = v->vcpu_id;
>>          break;
>>  
>> +    case 5: /* PV-specific parameters */
>> +        if ( is_hvm_domain(d) || subleaf != 0 )
>> +            break;
>> +
>> +        res->a = generic_flsl(get_upper_mfn_bound()) + PAGE_SHIFT;
> 
> While preparing to commit this I wondered why this isn't just
> flsl(). Can you explain this, or can I just change it?

It is meant to be similar to CPUID leaf 0x80000008: the width of the
max. machine address, not that of the max. MFN.


Juergen

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