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From: "Liuxiangdong (Aven, Cloud Infrastructure Service Product Dept.)"  <liuxiangdong5@huawei.com>
To: "Xu, Like" <like.xu@intel.com>
Cc: <andi@firstfloor.org>, "Fangyi (Eric)" <eric.fangyi@huawei.com>,
	Xiexiangyou <xiexiangyou@huawei.com>, <kan.liang@linux.intel.com>,
	<kvm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<wei.w.wang@intel.com>, <x86@kernel.org>
Subject: Re: [PATCH v4 01/16] perf/x86/intel: Add x86_pmu.pebs_vmx for Ice Lake Servers
Date: Thu, 8 Apr 2021 09:40:06 +0800	[thread overview]
Message-ID: <606E5EF6.2060402@huawei.com> (raw)
In-Reply-To: <18597e2b-3719-8d0d-9043-e9dbe39496a2@intel.com>



On 2021/4/6 13:14, Xu, Like wrote:
> Hi Xiangdong,
>
> On 2021/4/6 11:24, Liuxiangdong (Aven, Cloud Infrastructure Service 
> Product Dept.) wrote:
>> Hi，like.
>> Some questions about this new pebs patches set：
>> https://lore.kernel.org/kvm/20210329054137.120994-2-like.xu@linux.intel.com/ 
>>
>>
>> The new hardware facility supporting guest PEBS is only available
>> on Intel Ice Lake Server platforms for now.
>
> Yes, we have documented this "EPT-friendly PEBS" capability in the SDM
> 18.3.10.1 Processor Event Based Sampling (PEBS) Facility
>
> And again, this patch set doesn't officially support guest PEBS on the 
> Skylake.
>
>>
>>
>> AFAIK， Icelake supports adaptive PEBS and extended PEBS which 
>> Skylake doesn't.
>> But we can still use IA32_PEBS_ENABLE MSR to indicate general-purpose 
>> counter in Skylake.
>
> For Skylake, only the PMC0-PMC3 are valid for PEBS and you may
> mask the other unsupported bits in the pmu->pebs_enable_mask.
>
>> Is there anything else that only Icelake supports in this patches set?
>
> The PDIR counter on the Ice Lake is the fixed counter 0
> while the PDIR counter on the Sky Lake is the gp counter 1.
>
> You may also expose x86_pmu.pebs_vmx for Skylake in the 1st patch.
>

Yes. In fact, I have tried using this patch set in Skylake after these 
modifications:
1.  Expose x86_pmu.pebs_vmx for Skylake.
2.  Use PMC0-PMC3 for pebs
     2.1 Replace "INTEL_PMC_IDX_FIXED + x86_pmu.num_counters_fixed" with 
"x86_pmu.max_pebs_events" in "x86_pmu_handle_guest_pebs"
     2.2 Unmask other unsupported bits in the pmu->pebs_enable_mask. 
IA32_PERF_CAPABILITIES.PEBS_BASELINE [bit 14]
           is always 0 in Skylake, so pmu->pebs_enable_mask equals 
`((1ull << pmu->nr_arch_gp_counters)-1).
     2.3  Replace "pmc->idx == 32 " with "pmc->idx == 1" because the 
PDIR counter on the Skylake is the gp counter 1.
3.  Shield patch-09 because Skylake does not support adaptive pebs.
4.  Shield all cpu check code in this patch set just for test.


But, unfortunately, guest will record only a few seconds and then host 
will certainly soft lockup .
Is there anything wrong?

>>
>>
>> Besides, we have tried this patches set in Icelake.  We can use 
>> pebs(eg: "perf record -e cycles:pp")
>> when guest is kernel-5.11, but can't when kernel-4.18.  Is there a 
>> minimum guest kernel version requirement?
>
> The Ice Lake CPU model has been added since v5.4.
>
> You may double check whether the stable tree(s) code has
> INTEL_FAM6_ICELAKE in the arch/x86/include/asm/intel-family.h.
>
>>
>>
>> Thanks,
>> Xiangdong Liu
>


  reply	other threads:[~2021-04-08  1:40 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-29  5:41 [PATCH v4 00/16] KVM: x86/pmu: Add basic support to enable Guest PEBS via DS Like Xu
2021-03-29  5:41 ` [PATCH v4 01/16] perf/x86/intel: Add x86_pmu.pebs_vmx for Ice Lake Servers Like Xu
2021-04-06  3:24   ` Liuxiangdong (Aven, Cloud Infrastructure Service Product Dept.)
2021-04-06  5:14     ` Xu, Like
2021-04-08  1:40       ` Liuxiangdong (Aven, Cloud Infrastructure Service Product Dept.) [this message]
2021-04-09  8:33       ` Liuxiangdong (Aven, Cloud Infrastructure Service Product Dept.)
2021-04-09  8:46         ` Like Xu
2021-04-12 11:26           ` Liuxiangdong (Aven, Cloud Infrastructure Service Product Dept.)
2021-04-12 15:25             ` Andi Kleen
2021-04-14 14:10               ` Liuxiangdong
2021-04-14 14:49           ` Liuxiangdong
2021-04-15  1:38             ` Xu, Like
2021-04-15  2:49               ` Liuxiangdong
2021-04-15  3:23                 ` Like Xu
2021-04-06 12:47     ` Andi Kleen
2021-04-07  3:05       ` Liuxiangdong (Aven, Cloud Infrastructure Service Product Dept.)
2021-04-07 14:32         ` Andi Kleen
2021-03-29  5:41 ` [PATCH v4 02/16] perf/x86/intel: Handle guest PEBS overflow PMI for KVM guest Like Xu
2021-04-06 16:22   ` Peter Zijlstra
2021-04-07  0:47     ` Xu, Like
2021-03-29  5:41 ` [PATCH v4 03/16] perf/x86/core: Pass "struct kvm_pmu *" to determine the guest values Like Xu
2021-03-29  5:41 ` [PATCH v4 04/16] KVM: x86/pmu: Set MSR_IA32_MISC_ENABLE_EMON bit when vPMU is enabled Like Xu
2021-03-29  5:41 ` [PATCH v4 05/16] KVM: x86/pmu: Introduce the ctrl_mask value for fixed counter Like Xu
2021-03-29  5:41 ` [PATCH v4 06/16] KVM: x86/pmu: Reprogram guest PEBS event to emulate guest PEBS counter Like Xu
2021-04-07  8:40   ` Peter Zijlstra
2021-03-29  5:41 ` [PATCH v4 07/16] KVM: x86/pmu: Add IA32_PEBS_ENABLE MSR emulation for extended PEBS Like Xu
2021-04-07  8:56   ` Peter Zijlstra
2021-04-07 15:25   ` Peter Zijlstra
2021-03-29  5:41 ` [PATCH v4 08/16] KVM: x86/pmu: Add IA32_DS_AREA MSR emulation to manage guest DS buffer Like Xu
2021-04-07 15:39   ` Peter Zijlstra
2021-04-08  5:39     ` Xu, Like
2021-04-08  7:52       ` Peter Zijlstra
2021-04-08  8:44         ` Xu, Like
2021-04-09  7:07         ` Xu, Like
2021-04-09  7:59           ` Peter Zijlstra
2021-04-09  8:30             ` Xu, Like
2021-03-29  5:41 ` [PATCH v4 09/16] KVM: x86/pmu: Add PEBS_DATA_CFG MSR emulation to support adaptive PEBS Like Xu
2021-04-07 15:40   ` Peter Zijlstra
2021-03-29  5:41 ` [PATCH v4 10/16] KVM: x86: Set PEBS_UNAVAIL in IA32_MISC_ENABLE when PEBS is enabled Like Xu
2021-03-29  5:41 ` [PATCH v4 11/16] KVM: x86/pmu: Adjust precise_ip to emulate Ice Lake guest PDIR counter Like Xu
2021-03-29  5:41 ` [PATCH v4 12/16] KVM: x86/pmu: Move pmc_speculative_in_use() to arch/x86/kvm/pmu.h Like Xu
2021-03-29  5:41 ` [PATCH v4 13/16] KVM: x86/pmu: Disable guest PEBS before vm-entry in two cases Like Xu
2021-03-29  5:41 ` [PATCH v4 14/16] KVM: x86/pmu: Add kvm_pmu_cap to optimize perf_get_x86_pmu_capability Like Xu
2021-03-29  5:41 ` [PATCH v4 15/16] KVM: x86/cpuid: Refactor host/guest CPU model consistency check Like Xu
2021-03-29  5:41 ` [PATCH v4 16/16] KVM: x86/pmu: Expose CPUIDs feature bits PDCM, DS, DTES64 Like Xu
2021-04-06  3:19 ` [PATCH v4 00/16] KVM: x86/pmu: Add basic support to enable Guest PEBS via DS Xu, Like

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