Re: [Xen-devel] [PATCH v6 11/19] x86/VPMU: Initialize PMU for PV guests

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 20.05.14 at 19:47, <boris.ostrovsky@xxxxxxxxxx> wrote:
> On 05/20/2014 11:51 AM, Jan Beulich wrote:
>>>>> On 13.05.14 at 17:53, <boris.ostrovsky@xxxxxxxxxx> wrote:
>>> --- a/xen/arch/x86/hvm/svm/svm.c
>>> +++ b/xen/arch/x86/hvm/svm/svm.c
>>> @@ -1150,7 +1150,8 @@ static int svm_vcpu_initialise(struct vcpu *v)
>>>           return rc;
>>>       }
>>>   
>>> -    vpmu_initialise(v);
>>> +    if ( is_hvm_domain(v->domain) )
>>> +        vpmu_initialise(v);
>> Why?
> 
> This patch adds initialization for PV domains, which is conditioned by 
> is_pv_domain() in amd_vpmu_initialise()/core2_vpmu_alloc_resource(). I 
> don't want PVH domains (which call these routines) to try to set up 
> their VPMUs from here. This is supposed to happen via pvpmu_init() 
> (which in this patch will return -EINVAL for PVH).

So what's the reason for making PVH PV-like here rather than
HVM-like? With the intended goal of making PVH a HVM sub-mode,
that'll require more exceptions in the long run.

Jan


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