Re: [Xen-devel] [PATCH for-xen-4.5] x86/pvh/vpmu: Disable VPMU for PVH guests

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 25.11.14 at 15:38, <boris.ostrovsky@xxxxxxxxxx> wrote:
> On 11/25/2014 03:45 AM, Jan Beulich wrote:
>> @@ -1429,6 +1429,12 @@ int vlapic_init(struct vcpu *v)
>>   
>>       HVM_DBG_LOG(DBG_LEVEL_VLAPIC, "%d", v->vcpu_id);
>>   
>> +    if ( is_pvh_vcpu(v) )
>> +    {
>> +        vlapic->hw.disabled = VLAPIC_HW_DISABLED;
> 
> 
> I did consider doing that but I thought that this flag is meant to be 
> set when the guest clears MSR_IA32_APICBASE_ENABLE to disable APIC and 
> therefore I'd be overloading it (the flag) in a way.

There's no overloading here - we're then simply treating all PVH
vCPU-s as having permanently hardware-disabled LAPICs (reflecting
current reality).

> Regardless, do you think that disabling VPMU for PVH is worth anyway?

That depends on what (bad) consequences not doing so has.

Jan


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