Re: [Xen-devel] [PATCH v22 10/14] x86/VPMU: Use pre-computed masks when checking validity of MSRs

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 21.05.15 at 19:57, <boris.ostrovsky@xxxxxxxxxx> wrote:
> +/* Masks used for testing whether and MSR is valid */
> +#define ARCH_CTRL_MASK  (~((1ull << 32) - 1) | (1ull << 21))

Considering this and ...

> @@ -556,7 +558,7 @@ static int core2_vpmu_do_wrmsr(unsigned int msr, uint64_t 
> msr_content,
>              struct xen_pmu_cntr_pair *xen_pmu_cntr_pair =
>                  vpmu_reg_pointer(core2_vpmu_cxt, arch_counters);
>  
> -            if ( msr_content & (~((1ull << 32) - 1)) )
> +            if ( msr_content & ARCH_CTRL_MASK )

... this, the patch isn't a "no functional change" one, so perhaps its
description needs to be extended to explain the behavioral change?

Jan


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