From: Wei Wang <wei.w.wang@intel.com>
To: Andi Kleen <ak@linux.intel.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"pbonzini@redhat.com" <pbonzini@redhat.com>,
"Liang, Kan" <kan.liang@intel.com>,
"peterz@infradead.org" <peterz@infradead.org>,
"mingo@redhat.com" <mingo@redhat.com>,
"rkrcmar@redhat.com" <rkrcmar@redhat.com>,
"Xu, Like" <like.xu@intel.com>
Subject: Re: [PATCH v2 1/8] perf/x86: add a function to get the lbr stack
Date: Fri, 07 Sep 2018 14:45:24 +0800 [thread overview]
Message-ID: <5B921E84.4010008@intel.com> (raw)
In-Reply-To: <20180907032811.GO27886@tassilo.jf.intel.com>
On 09/07/2018 11:28 AM, Andi Kleen wrote:
>> +int perf_get_lbr_stack(struct perf_lbr_stack *stack)
>> +{
>> + stack->lbr_nr = x86_pmu.lbr_nr;
>> + stack->lbr_tos = x86_pmu.lbr_tos;
>> + stack->lbr_from = x86_pmu.lbr_from;
>> + stack->lbr_to = x86_pmu.lbr_to;
>> +
>> + if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_INFO)
>> + stack->lbr_info = MSR_LBR_INFO_0;
>> + else
>> + stack->lbr_info = 0;
> Seems weird to export the enum value if the enum isn't exported.
> How can it be used?
>
I'm not sure about the issue. The caller gets the value of
MSR_LBR_INFO_0 (not the enum, LBR_FORMAT_INFO) only when the hardware
supports it. If hardware doesn't support it, just sets it to 0, and
there will be no lbr info msr to be passed through.
Best,
Wei
next prev parent reply other threads:[~2018-09-07 6:40 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-06 11:30 [PATCH v2 0/8] Guest LBR Enabling Wei Wang
2018-09-06 11:30 ` [PATCH v2 1/8] perf/x86: add a function to get the lbr stack Wei Wang
2018-09-07 3:28 ` Andi Kleen
2018-09-07 6:45 ` Wei Wang [this message]
2018-09-06 11:30 ` [PATCH v2 2/8] KVM/x86: KVM_CAP_X86_GUEST_LBR Wei Wang
2018-09-06 11:30 ` [PATCH v2 3/8] KVM/vmx: Pass through the lbr stack to a guest Wei Wang
2018-09-06 11:30 ` [PATCH v2 4/8] KVM/x86: expose MSR_IA32_PERF_CAPABILITIES to the guest Wei Wang
2018-09-06 11:30 ` [PATCH v2 5/8] KVM/x86: enable the guest to access the debugctl msr Wei Wang
2018-09-06 11:30 ` [PATCH v2 6/8] perf/x86/intel/lbr: guest requesting KVM for lbr stack save/restore Wei Wang
2018-09-07 3:27 ` Andi Kleen
2018-09-07 5:24 ` Wei Wang
2018-09-07 14:10 ` Andi Kleen
2018-09-07 15:20 ` Wang, Wei W
2018-09-07 20:05 ` Andi Kleen
2018-09-08 1:34 ` Wang, Wei W
2018-09-06 11:30 ` [PATCH v2 7/8] KVM: PMU: support to save/restore the guest lbr stack on vCPU switching Wei Wang
2018-09-07 14:36 ` Jann Horn
2018-09-07 15:21 ` Wang, Wei W
2018-09-18 0:58 ` Gonglei (Arei)
2018-09-18 2:56 ` Andi Kleen
2018-09-18 9:57 ` Wei Wang
2018-09-18 10:34 ` Gonglei (Arei)
2018-09-06 11:30 ` [PATCH v2 8/8] perf/x86/intel/lbr: add the guest_lbr boolean to cpuc Wei Wang
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