Re: [Xen-devel] [PATCH] xen: disable reporting hw virtualized lapic availability on PVH guests

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 04.06.14 at 12:53, <roger.pau@xxxxxxxxxx> wrote:
> On 04/06/14 12:45, Jan Beulich wrote:
>>>>> On 04.06.14 at 12:12, <roger.pau@xxxxxxxxxx> wrote:
>>> --- a/xen/arch/x86/hvm/vmx/vmx.c
>>> +++ b/xen/arch/x86/hvm/vmx/vmx.c
>>> @@ -1660,7 +1660,7 @@ void vmx_hypervisor_cpuid_leaf(uint32_t sub_idx,
>>>                                 uint32_t *eax, uint32_t *ebx,
>>>                                 uint32_t *ecx, uint32_t *edx)
>>>  {
>>> -    if ( sub_idx != 0 )
>>> +    if ( sub_idx != 0 || is_pvh_vcpu(current) )
>>>          return;
>>>      if ( cpu_has_vmx_apic_reg_virt )
>> 
>> The addition would belong on this line imo (in the && !is_pvh form).
> 
> Then I would also have to add another is_pvh gate on the next if:
> 
>     if ( cpu_has_vmx_virtualize_x2apic_mode && cpu_has_vmx_apic_reg_virt &&
>          cpu_has_vmx_virtual_intr_delivery && !is_pvh_vcpu(current) )
>         *eax |= XEN_HVM_CPUID_X2APIC_VIRT;
> 
> IMHO it seems easier to gate it on the first if and just
> return, although I understand it is more correct to gate
> it on a feature by feature basis.

Right, also to avoid unnecessary future code churn.

Jan


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