linux-kernel - Re: [PATCH] perf/x86/intel: Only check GP counters for PEBS constraints validation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <257afee5-f0ce-4311-9393-4f16084c07d0@linux.intel.com>
Date: Wed, 19 Nov 2025 16:56:26 +0800
From: "Mi, Dapeng" <dapeng1.mi@...ux.intel.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
 Arnaldo Carvalho de Melo <acme@...nel.org>,
 Namhyung Kim <namhyung@...nel.org>, Ian Rogers <irogers@...gle.com>,
 Adrian Hunter <adrian.hunter@...el.com>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Andi Kleen <ak@...ux.intel.com>, Eranian Stephane <eranian@...gle.com>
Cc: linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
 Dapeng Mi <dapeng1.mi@...el.com>, Zide Chen <zide.chen@...el.com>,
 Falcon Thomas <thomas.falcon@...el.com>, Xudong Hao <xudong.hao@...el.com>
Subject: Re: [PATCH] perf/x86/intel: Only check GP counters for PEBS
 constraints validation

Hi Peter,

Could you please review this patch? The PEBS constraints overlap validation
should be only limited in GP counters, otherwise it may cause some false
alarms on some platforms.

Thanks,

Dapeng Mi

On 11/12/2025 8:45 AM, Dapeng Mi wrote:
> It's good enough to only check GP counters for PEBS constraints
> validation since constraints overlap can only happen on GP counters.
>
> Besides opportunistically refine the code style and use pr_warn() to
> replace pr_info() as the message itself is a warning message.
>
> Signed-off-by: Dapeng Mi <dapeng1.mi@...ux.intel.com>
> ---
>  arch/x86/events/intel/core.c | 22 ++++++++++++++--------
>  1 file changed, 14 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
> index aad89c9d9514..81e6c8bcabde 100644
> --- a/arch/x86/events/intel/core.c
> +++ b/arch/x86/events/intel/core.c
> @@ -5506,7 +5506,7 @@ static void __intel_pmu_check_dyn_constr(struct event_constraint *constr,
>  			}
>  
>  			if (check_fail) {
> -				pr_info("The two events 0x%llx and 0x%llx may not be "
> +				pr_warn("The two events 0x%llx and 0x%llx may not be "
>  					"fully scheduled under some circumstances as "
>  					"%s.\n",
>  					c1->code, c2->code, dyn_constr_type_name[type]);
> @@ -5519,6 +5519,7 @@ static void intel_pmu_check_dyn_constr(struct pmu *pmu,
>  				       struct event_constraint *constr,
>  				       u64 cntr_mask)
>  {
> +	u64 gp_mask = GENMASK_ULL(INTEL_PMC_MAX_GENERIC - 1, 0);
>  	enum dyn_constr_type i;
>  	u64 mask;
>  
> @@ -5533,20 +5534,25 @@ static void intel_pmu_check_dyn_constr(struct pmu *pmu,
>  				mask = x86_pmu.lbr_counters;
>  			break;
>  		case DYN_CONSTR_ACR_CNTR:
> -			mask = hybrid(pmu, acr_cntr_mask64) & GENMASK_ULL(INTEL_PMC_MAX_GENERIC - 1, 0);
> +			mask = hybrid(pmu, acr_cntr_mask64) & gp_mask;
>  			break;
>  		case DYN_CONSTR_ACR_CAUSE:
> -			if (hybrid(pmu, acr_cntr_mask64) == hybrid(pmu, acr_cause_mask64))
> +			if (hybrid(pmu, acr_cntr_mask64) ==
> +					hybrid(pmu, acr_cause_mask64))
>  				continue;
> -			mask = hybrid(pmu, acr_cause_mask64) & GENMASK_ULL(INTEL_PMC_MAX_GENERIC - 1, 0);
> +			mask = hybrid(pmu, acr_cause_mask64) & gp_mask;
>  			break;
>  		case DYN_CONSTR_PEBS:
> -			if (x86_pmu.arch_pebs)
> -				mask = hybrid(pmu, arch_pebs_cap).counters;
> +			if (x86_pmu.arch_pebs) {
> +				mask = hybrid(pmu, arch_pebs_cap).counters &
> +				       gp_mask;
> +			}
>  			break;
>  		case DYN_CONSTR_PDIST:
> -			if (x86_pmu.arch_pebs)
> -				mask = hybrid(pmu, arch_pebs_cap).pdists;
> +			if (x86_pmu.arch_pebs) {
> +				mask = hybrid(pmu, arch_pebs_cap).pdists &
> +				       gp_mask;
> +			}
>  			break;
>  		default:
>  			pr_warn("Unsupported dynamic constraint type %d\n", i);
>
> base-commit: 2093d8cf80fa5552d1025a78a8f3a10bf3b6466e