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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 28.09.17 at 11:04, <jgross@xxxxxxxx> wrote:
> 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.

I don't see how this addresses the question: Just to repeat with
slightly different wording - why are you using generic_flsl() instead
of just flsl()?

Jan


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