Re: [Xen-devel] [PATCH 3/6] x86/vpmu: Remove core2_no_vpmu_ops

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 16/11/16 17:09, Boris Ostrovsky wrote:
> On 11/16/2016 12:04 PM, Andrew Cooper wrote:
>> On 16/11/16 16:27, Boris Ostrovsky wrote:
>>> On 11/16/2016 07:31 AM, Andrew Cooper wrote:
>>>> diff --git a/xen/arch/x86/cpu/vpmu.c b/xen/arch/x86/cpu/vpmu.c
>>>> index a542f4d..1f822ca 100644
>>>> --- a/xen/arch/x86/cpu/vpmu.c
>>>> +++ b/xen/arch/x86/cpu/vpmu.c
>>>> @@ -136,9 +136,10 @@ int vpmu_do_msr(unsigned int msr, uint64_t 
>>>> *msr_content,
>>>>      const struct arch_vpmu_ops *ops;
>>>>      int ret = 0;
>>>>  
>>>> +    /* Don't leak PMU MSRs to unprivileged domains. */
>>> This was a somewhat incorrect comment originally and since you are
>>> moving it then perhaps it's worth adding something along the lines of
>>> "if VPMU is off or if the privileged domain is profiling whole system".
>>> Otherwise it gives impression that unprivileged domains never access
>>> those MSRs.
>> /*
>>  * Hide the PMU MSRs if vpmu is not configured, or the hardware domain
>>  * is profiling the whole system.
>>  */
>>
>> ?
>
> Sure, thanks.
>
> (or, in fact, you can just drop the whole comment since I think it's
> pretty obvious what's going on).

I'd prefer to keep it.  I bet it won't be so obvious in 6 months time.

~Andrew

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