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    SubjectRe: [PATCH v4 01/16] perf/x86/intel: Add x86_pmu.pebs_vmx for Ice Lake Servers
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    Do you have any comments or ideas about it ?

    https://lore.kernel.org/kvm/606E5EF6.2060402@huawei.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.
    >
    >>
    >>
    >> 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
    >

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