From: "Xu, Like" <like.xu@intel.com>
To: Peter Zijlstra <peterz@infradead.org>
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,
Like Xu <like.xu@linux.intel.com>
Subject: Re: [PATCH v6 07/16] KVM: x86/pmu: Reprogram PEBS event to emulate guest PEBS counter
Date: Tue, 18 May 2021 21:28:52 +0800 [thread overview]
Message-ID: <2d874bce-2823-13b4-0714-3de5b7c475f0@intel.com> (raw)
In-Reply-To: <YKIz/J1HoOvbmR42@hirez.programming.kicks-ass.net>
On 2021/5/17 17:14, Peter Zijlstra wrote:
> On Tue, May 11, 2021 at 10:42:05AM +0800, Like Xu wrote:
>> @@ -99,6 +109,7 @@ static void pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type,
>> bool exclude_kernel, bool intr,
>> bool in_tx, bool in_tx_cp)
>> {
>> + struct kvm_pmu *pmu = vcpu_to_pmu(pmc->vcpu);
>> struct perf_event *event;
>> struct perf_event_attr attr = {
>> .type = type,
>> @@ -110,6 +121,7 @@ static void pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type,
>> .exclude_kernel = exclude_kernel,
>> .config = config,
>> };
>> + bool pebs = test_bit(pmc->idx, (unsigned long *)&pmu->pebs_enable);
>>
>> attr.sample_period = get_sample_period(pmc, pmc->counter);
>>
>> @@ -124,9 +136,23 @@ static void pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type,
>> attr.sample_period = 0;
>> attr.config |= HSW_IN_TX_CHECKPOINTED;
>> }
>> + if (pebs) {
>> + /*
>> + * The non-zero precision level of guest event makes the ordinary
>> + * guest event becomes a guest PEBS event and triggers the host
>> + * PEBS PMI handler to determine whether the PEBS overflow PMI
>> + * comes from the host counters or the guest.
>> + *
>> + * For most PEBS hardware events, the difference in the software
>> + * precision levels of guest and host PEBS events will not affect
>> + * the accuracy of the PEBS profiling result, because the "event IP"
>> + * in the PEBS record is calibrated on the guest side.
>> + */
>> + attr.precise_ip = 1;
>> + }
>>
>> event = perf_event_create_kernel_counter(&attr, -1, current,
>> - intr ? kvm_perf_overflow_intr :
>> + (intr || pebs) ? kvm_perf_overflow_intr :
>> kvm_perf_overflow, pmc);
> How would pebs && !intr be possible?
I don't think it's possible.
> Also; wouldn't this be more legible
> when written like:
>
> perf_overflow_handler_t ovf = kvm_perf_overflow;
>
> ...
>
> if (intr)
> ovf = kvm_perf_overflow_intr;
>
> ...
>
> event = perf_event_create_kernel_counter(&attr, -1, current, ovf, pmc);
>
Please yell if you don't like this:
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 711294babb97..a607f5a1b9cd 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -122,6 +122,8 @@ static void pmc_reprogram_counter(struct kvm_pmc *pmc,
u32 type,
.config = config,
};
bool pebs = test_bit(pmc->idx, (unsigned long *)&pmu->pebs_enable);
+ perf_overflow_handler_t ovf = (intr || pebs) ?
+ kvm_perf_overflow_intr : kvm_perf_overflow;
attr.sample_period = get_sample_period(pmc, pmc->counter);
@@ -151,9 +153,7 @@ static void pmc_reprogram_counter(struct kvm_pmc *pmc,
u32 type,
attr.precise_ip = 1;
}
- event = perf_event_create_kernel_counter(&attr, -1, current,
- (intr || pebs) ?
kvm_perf_overflow_intr :
- kvm_perf_overflow, pmc);
+ event = perf_event_create_kernel_counter(&attr, -1, current, ovf, pmc);
if (IS_ERR(event)) {
pr_debug_ratelimited("kvm_pmu: event creation failed %ld
for pmc->idx = %d\n",
PTR_ERR(event), pmc->idx);
next prev parent reply other threads:[~2021-05-18 13:29 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
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 [this message]
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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