Re: [Xen-devel] [PATCH] x86/vpmu_intel: Handle SMT consistently for programmable and fixed counters

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 03/31/2017 10:46 AM, Mohit Gambhir wrote:
> This patch masks .AnyThread bits in IA32_FIXED_CTR_CTRL MSR for all
> versions of Intel Arhcitectural Performance Monitoring. Note that
> .AnyThread bit (21) is already masked in IA32_PERFEVTSELx MSRs since
> hyperthreading is not exposed to guests and Intel SDM discourages the use of
> .AnyThread bit in virtualized environments (per section 18.2.3.1
> AnyThread Counting and Software Evolution)
>
> Signed-off-by: Mohit Gambhir <mohit.gambhir@xxxxxxxxxx>

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>

(+Andrew and Jan)

> ---
>  xen/arch/x86/cpu/vpmu_intel.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/xen/arch/x86/cpu/vpmu_intel.c b/xen/arch/x86/cpu/vpmu_intel.c
> index 0d66ecb..7944e22 100644
> --- a/xen/arch/x86/cpu/vpmu_intel.c
> +++ b/xen/arch/x86/cpu/vpmu_intel.c
> @@ -979,8 +979,7 @@ int __init core2_vpmu_init(void)
>      full_width_write = (caps >> 13) & 1;
>  
>      fixed_ctrl_mask = ~((1ull << (fixed_pmc_cnt * FIXED_CTR_CTRL_BITS)) - 1);
> -    if ( version == 2 )
> -        fixed_ctrl_mask |= 0x444;
> +    fixed_ctrl_mask |= 0x444;
>      fixed_counters_mask = ~((1ull << core2_get_bitwidth_fix_count()) - 1);
>      global_ctrl_mask = ~((((1ULL << fixed_pmc_cnt) - 1) << 32) |
>                           ((1ULL << arch_pmc_cnt) - 1));


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