Re: [Xen-devel] [PATCH] x86/vPMU: constrain MSR_IA32_DS_AREA loads

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 17.12.15 at 15:26, <boris.ostrovsky@xxxxxxxxxx> wrote:
> On 12/17/2015 09:18 AM, Jan Beulich wrote:
>>>>> On 17.12.15 at 15:12, <boris.ostrovsky@xxxxxxxxxx> wrote:
>>> On 12/17/2015 09:01 AM, Jan Beulich wrote:
>>>> @@ -415,8 +416,10 @@ static int core2_vpmu_verify(struct vcpu
>>>>                enabled_cntrs |= (1ULL << i);
>>>>        }
>>>>    
>>>> -    if ( vpmu_is_set(vcpu_vpmu(v), VPMU_CPU_HAS_DS) &&
>>>> -         !is_canonical_address(core2_vpmu_cxt->ds_area) )
>>>> +    if ( vpmu_is_set(vpmu, VPMU_CPU_HAS_DS) &&
>>>> +         !(has_hvm_container_vcpu(v)
>>>> +           ? is_canonical_address(core2_vpmu_cxt->ds_area)
>>>> +           : __addr_ok(core2_vpmu_cxt->ds_area)) )
>>> Should we instead of (or in addition to) this also make the same change
>>> in core2_vpmu_do_wrmsr()?
>> Currently there's no need for this since - afaict - PV guests can't
>> write this MSR directly (it's not among the white listed set in
>> traps.c).
> 
> Then we probably shouldn't set VPMU_CPU_HAS_DS for PV guests.

Or add the MSR to the permitted set. You know better than I
what the best route here is.

Jan


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