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From: Peter Zijlstra <peterz@infradead.org>
To: Like Xu <like.xu@linux.intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Borislav Petkov <bp@alien8.de>,
	Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	weijiang.yang@intel.com, Kan Liang <kan.liang@linux.intel.com>,
	ak@linux.intel.com, wei.w.wang@intel.com, eranian@google.com,
	liuxiangdong5@huawei.com, linux-kernel@vger.kernel.org,
	x86@kernel.org, kvm@vger.kernel.org,
	Luwei Kang <luwei.kang@intel.com>
Subject: Re: [PATCH v6 06/16] KVM: x86/pmu: Add IA32_PEBS_ENABLE MSR emulation for extended PEBS
Date: Mon, 17 May 2021 10:33:50 +0200	[thread overview]
Message-ID: <YKIqbph62oclxjnt@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210511024214.280733-7-like.xu@linux.intel.com>

On Tue, May 11, 2021 at 10:42:04AM +0800, Like Xu wrote:
> diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
> index 2f89fd599842..c791765f4761 100644
> --- a/arch/x86/events/intel/core.c
> +++ b/arch/x86/events/intel/core.c
> @@ -3898,31 +3898,49 @@ static struct perf_guest_switch_msr *intel_guest_get_msrs(int *nr, void *data)
>  	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
>  	struct perf_guest_switch_msr *arr = cpuc->guest_switch_msrs;
>  	u64 intel_ctrl = hybrid(cpuc->pmu, intel_ctrl);
> +	u64 pebs_mask = (x86_pmu.flags & PMU_FL_PEBS_ALL) ?
> +		cpuc->pebs_enabled : (cpuc->pebs_enabled & PEBS_COUNTER_MASK);

> -	if (x86_pmu.flags & PMU_FL_PEBS_ALL)
> -		arr[0].guest &= ~cpuc->pebs_enabled;
> -	else
> -		arr[0].guest &= ~(cpuc->pebs_enabled & PEBS_COUNTER_MASK);
> -	*nr = 1;

Instead of endlessly mucking about with branches, do we want something
like this instead?

---
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 2521d03de5e0..bcfba11196c8 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -2819,10 +2819,7 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status)
 	 * counters from the GLOBAL_STATUS mask and we always process PEBS
 	 * events via drain_pebs().
 	 */
-	if (x86_pmu.flags & PMU_FL_PEBS_ALL)
-		status &= ~cpuc->pebs_enabled;
-	else
-		status &= ~(cpuc->pebs_enabled & PEBS_COUNTER_MASK);
+	status &= ~(cpuc->pebs_enabled & x86_pmu.pebs_capable);
 
 	/*
 	 * PEBS overflow sets bit 62 in the global status register
@@ -3862,10 +3859,7 @@ static struct perf_guest_switch_msr *intel_guest_get_msrs(int *nr)
 	arr[0].msr = MSR_CORE_PERF_GLOBAL_CTRL;
 	arr[0].host = intel_ctrl & ~cpuc->intel_ctrl_guest_mask;
 	arr[0].guest = intel_ctrl & ~cpuc->intel_ctrl_host_mask;
-	if (x86_pmu.flags & PMU_FL_PEBS_ALL)
-		arr[0].guest &= ~cpuc->pebs_enabled;
-	else
-		arr[0].guest &= ~(cpuc->pebs_enabled & PEBS_COUNTER_MASK);
+	arr[0].guest &= ~(cpuc->pebs_enabled & x86_pmu.pebs_capable);
 	*nr = 1;
 
 	if (x86_pmu.pebs && x86_pmu.pebs_no_isolation) {
@@ -5546,6 +5540,7 @@ __init int intel_pmu_init(void)
 	x86_pmu.events_mask_len		= eax.split.mask_length;
 
 	x86_pmu.max_pebs_events		= min_t(unsigned, MAX_PEBS_EVENTS, x86_pmu.num_counters);
+	x86_pmu.pebs_capable		= PEBS_COUNTER_MASK;
 
 	/*
 	 * Quirk: v2 perfmon does not report fixed-purpose events, so
@@ -5730,6 +5725,7 @@ __init int intel_pmu_init(void)
 		x86_pmu.pebs_aliases = NULL;
 		x86_pmu.pebs_prec_dist = true;
 		x86_pmu.lbr_pt_coexist = true;
+		x86_pmu.pebs_capable = ~0ULL;
 		x86_pmu.flags |= PMU_FL_HAS_RSP_1;
 		x86_pmu.flags |= PMU_FL_PEBS_ALL;
 		x86_pmu.get_event_constraints = glp_get_event_constraints;
@@ -6080,6 +6076,7 @@ __init int intel_pmu_init(void)
 		x86_pmu.pebs_aliases = NULL;
 		x86_pmu.pebs_prec_dist = true;
 		x86_pmu.pebs_block = true;
+		x86_pmu.pebs_capable = ~0ULL;
 		x86_pmu.flags |= PMU_FL_HAS_RSP_1;
 		x86_pmu.flags |= PMU_FL_NO_HT_SHARING;
 		x86_pmu.flags |= PMU_FL_PEBS_ALL;
@@ -6123,6 +6120,7 @@ __init int intel_pmu_init(void)
 		x86_pmu.pebs_aliases = NULL;
 		x86_pmu.pebs_prec_dist = true;
 		x86_pmu.pebs_block = true;
+		x86_pmu.pebs_capable = ~0ULL;
 		x86_pmu.flags |= PMU_FL_HAS_RSP_1;
 		x86_pmu.flags |= PMU_FL_NO_HT_SHARING;
 		x86_pmu.flags |= PMU_FL_PEBS_ALL;
diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
index 27fa85e7d4fd..6f3cf81ccb1b 100644
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -805,6 +805,7 @@ struct x86_pmu {
 	void		(*pebs_aliases)(struct perf_event *event);
 	unsigned long	large_pebs_flags;
 	u64		rtm_abort_event;
+	u64		pebs_capable;
 
 	/*
 	 * Intel LBR

  parent reply	other threads:[~2021-05-17  8:34 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-11  2:41 [PATCH v6 00/16] KVM: x86/pmu: Add *basic* support to enable guest PEBS via DS Like Xu
2021-05-11  2:41 ` [PATCH v6 01/16] perf/x86/intel: Add EPT-Friendly PEBS for Ice Lake Server Like Xu
2021-05-11  2:42 ` [PATCH v6 02/16] perf/x86/intel: Handle guest PEBS overflow PMI for KVM guest Like Xu
2021-05-17  8:16   ` Peter Zijlstra
2021-05-18  7:38     ` Xu, Like
2021-05-18  8:37       ` Peter Zijlstra
2021-05-11  2:42 ` [PATCH v6 03/16] perf/x86/core: Pass "struct kvm_pmu *" to determine the guest values Like Xu
2021-05-11  2:42 ` [PATCH v6 04/16] KVM: x86/pmu: Set MSR_IA32_MISC_ENABLE_EMON bit when vPMU is enabled Like Xu
2021-05-12  1:58   ` Venkatesh Srinivas
2021-05-12  5:00     ` Xu, Like
2021-05-12 15:18       ` Sean Christopherson
2021-05-13  2:50         ` Xu, Like
2021-05-17 18:43           ` Venkatesh Srinivas
2021-05-17 21:19             ` Sean Christopherson
2021-05-17 21:16           ` Sean Christopherson
2021-05-17 23:51             ` Sean Christopherson
2021-05-18  7:49               ` Xu, Like
2021-05-11  2:42 ` [PATCH v6 05/16] KVM: x86/pmu: Introduce the ctrl_mask value for fixed counter Like Xu
2021-05-17  8:18   ` Peter Zijlstra
2021-05-18  7:55     ` Xu, Like
2021-05-18  8:35       ` Peter Zijlstra
2021-05-11  2:42 ` [PATCH v6 06/16] KVM: x86/pmu: Add IA32_PEBS_ENABLE MSR emulation for extended PEBS Like Xu
2021-05-17  8:32   ` Peter Zijlstra
2021-05-18  8:44     ` Xu, Like
2021-05-18 13:42       ` Peter Zijlstra
2021-05-17  8:33   ` Peter Zijlstra [this message]
2021-05-18  8:13     ` Xu, Like
2021-05-11  2:42 ` [PATCH v6 07/16] KVM: x86/pmu: Reprogram PEBS event to emulate guest PEBS counter Like Xu
2021-05-17  8:39   ` Peter Zijlstra
2021-05-17 14:44     ` Andi Kleen
2021-05-18  8:47       ` Peter Zijlstra
2021-05-18 13:15         ` Xu, Like
2021-05-18 15:58           ` Andi Kleen
2021-05-17  9:14   ` Peter Zijlstra
2021-05-18 13:28     ` Xu, Like
2021-05-18 13:36       ` Peter Zijlstra
2021-05-18 14:05         ` Xu, Like
2021-05-11  2:42 ` [PATCH v6 08/16] KVM: x86/pmu: Add IA32_DS_AREA MSR emulation to support guest DS Like Xu
2021-05-12  5:16   ` Xu, Like
2021-05-17 13:26   ` Peter Zijlstra
2021-05-17 14:50     ` Andi Kleen
2021-05-11  2:42 ` [PATCH v6 09/16] KVM: x86/pmu: Add PEBS_DATA_CFG MSR emulation to support adaptive PEBS Like Xu
2021-05-11  2:42 ` [PATCH v6 10/16] KVM: x86: Set PEBS_UNAVAIL in IA32_MISC_ENABLE when PEBS is enabled Like Xu
2021-05-11  2:42 ` [PATCH v6 11/16] KVM: x86/pmu: Adjust precise_ip to emulate Ice Lake guest PDIR counter Like Xu
2021-05-11  2:42 ` [PATCH v6 12/16] KVM: x86/pmu: Move pmc_speculative_in_use() to arch/x86/kvm/pmu.h Like Xu
2021-05-11  2:42 ` [PATCH v6 13/16] KVM: x86/pmu: Disable guest PEBS temporarily in two rare situations Like Xu
2021-05-11  2:42 ` [PATCH v6 14/16] KVM: x86/pmu: Add kvm_pmu_cap to optimize perf_get_x86_pmu_capability Like Xu
2021-05-11  2:42 ` [PATCH v6 15/16] KVM: x86/cpuid: Refactor host/guest CPU model consistency check Like Xu
2021-05-11  2:42 ` [PATCH v6 16/16] KVM: x86/pmu: Expose CPUIDs feature bits PDCM, DS, DTES64 Like Xu
2021-05-15 10:30 ` [PATCH v6 00/16] KVM: x86/pmu: Add *basic* support to enable guest PEBS via DS Liuxiangdong
2021-05-17  6:38   ` Like Xu
2021-05-18 12:23     ` Liuxiangdong
2021-05-18 12:40       ` Xu, Like
2021-05-18 13:15         ` Liuxiangdong
2021-05-19  1:44         ` Liuxiangdong
2021-05-21  1:37           ` Like Xu

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