From: "Xu, Like" <like.xu@intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
eranian@google.com, kvm@vger.kernel.org,
Ingo Molnar <mingo@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Andi Kleen <andi@firstfloor.org>,
Kan Liang <kan.liang@linux.intel.com>,
wei.w.wang@intel.com, luwei.kang@intel.com,
linux-kernel@vger.kernel.org, Like Xu <like.xu@linux.intel.com>
Subject: Re: [PATCH v3 05/17] KVM: x86/pmu: Reprogram guest PEBS event to emulate guest PEBS counter
Date: Fri, 15 Jan 2021 21:53:22 +0800 [thread overview]
Message-ID: <38e774f5-81d6-4853-cbb9-d4b7811e65db@intel.com> (raw)
In-Reply-To: <YAF9mulfhGCIyNz+@hirez.programming.kicks-ass.net>
On 2021/1/15 19:33, Peter Zijlstra wrote:
> On Mon, Jan 04, 2021 at 09:15:30PM +0800, Like Xu wrote:
>> When a guest counter is configured as a PEBS counter through
>> IA32_PEBS_ENABLE, a guest PEBS event will be reprogrammed by
>> configuring a non-zero precision level in the perf_event_attr.
>>
>> The guest PEBS overflow PMI bit would be set in the guest
>> GLOBAL_STATUS MSR when PEBS facility generates a PEBS
>> overflow PMI based on guest IA32_DS_AREA MSR.
>>
>> The attr.precise_ip would be adjusted to a special precision
>> level when the new PEBS-PDIR feature is supported later which
>> would affect the host counters scheduling.
> This seems like a random collection of changes, all required, but
> loosely related.
Yes, these changes are made in the KVM context, and
they are all necessary to emulate basic PEBS hw behavior.
>
>> The guest PEBS event would not be reused for non-PEBS
>> guest event even with the same guest counter index.
Let me add more KVM context here,
we would create a perf_event for a normal non-PEBS counter
and we reuse the same perf_event from time to time as much as possible
instead of "create + destroy" new perf_event.
So when a normal counter is configured for PEBS,
the original perf_event would not be reused and
a new PEBS perf_event is created, vice verse.
> /me rolls eyes at the whole destroy+create nonsense...
I absolutely agree that cross-domain development
may make maintainers' eyes uncomfortable.
My on-demand explanation is always online
if you fire more questions on this patch set.
next prev parent reply other threads:[~2021-01-15 13:54 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-04 13:15 [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS Like Xu
2021-01-04 13:15 ` [PATCH v3 01/17] KVM: x86/pmu: Set MSR_IA32_MISC_ENABLE_EMON bit when vPMU is enabled Like Xu
2021-01-04 13:15 ` [PATCH v3 02/17] KVM: x86/pmu: Use IA32_PERF_CAPABILITIES to adjust features visibility Like Xu
2021-01-04 13:15 ` [PATCH v3 03/17] KVM: x86/pmu: Introduce the ctrl_mask value for fixed counter Like Xu
2021-01-13 18:06 ` Peter Zijlstra
2021-01-14 1:58 ` Xu, Like
2021-01-04 13:15 ` [PATCH v3 04/17] perf: x86/ds: Handle guest PEBS overflow PMI and inject it to guest Like Xu
2021-01-13 18:22 ` Peter Zijlstra
2021-01-13 18:27 ` Peter Zijlstra
2021-01-14 3:39 ` Xu, Like
2021-01-15 12:01 ` Peter Zijlstra
2021-01-15 14:30 ` Xu, Like
2021-01-15 14:44 ` Peter Zijlstra
2021-01-15 15:12 ` Xu, Like
2021-01-25 8:26 ` Like Xu
2021-01-25 11:47 ` Peter Zijlstra
2021-02-02 6:31 ` Xu, Like
2021-01-14 18:55 ` Sean Christopherson
2021-01-15 2:49 ` Xu, Like
2021-01-15 17:42 ` Sean Christopherson
2021-01-22 5:30 ` Like Xu
2021-01-04 13:15 ` [PATCH v3 05/17] KVM: x86/pmu: Reprogram guest PEBS event to emulate guest PEBS counter Like Xu
2021-01-15 11:33 ` Peter Zijlstra
2021-01-15 13:53 ` Xu, Like [this message]
2021-01-04 13:15 ` [PATCH v3 06/17] KVM: x86/pmu: Add IA32_PEBS_ENABLE MSR emulation for extended PEBS Like Xu
2021-01-05 21:11 ` Sean Christopherson
2021-01-07 12:38 ` Xu, Like
2021-01-15 14:46 ` Peter Zijlstra
2021-01-15 15:29 ` Xu, Like
2021-01-04 13:15 ` [PATCH v3 07/17] KVM: x86/pmu: Add IA32_DS_AREA MSR emulation to manage guest DS buffer Like Xu
2021-01-05 21:16 ` Sean Christopherson
2021-01-08 3:05 ` Xu, Like
2021-01-04 13:15 ` [PATCH v3 08/17] KVM: x86/pmu: Add PEBS_DATA_CFG MSR emulation to support adaptive PEBS Like Xu
2021-01-04 13:15 ` [PATCH v3 09/17] KVM: x86: Set PEBS_UNAVAIL in IA32_MISC_ENABLE when PEBS is enabled Like Xu
2021-01-04 13:15 ` [PATCH v3 10/17] KVM: x86/pmu: Expose CPUIDs feature bits PDCM, DS, DTES64 Like Xu
2021-01-04 13:15 ` [PATCH v3 11/17] KVM: x86/pmu: Adjust precise_ip to emulate Ice Lake guest PDIR counter Like Xu
2021-01-04 13:15 ` [PATCH v3 12/17] KVM: x86/pmu: Disable guest PEBS when counters are cross-mapped Like Xu
2021-01-04 13:15 ` [PATCH v3 13/17] KVM: x86/pmu: Add hook to emulate pebs for cross-mapped counters Like Xu
2021-01-04 13:15 ` [PATCH v3 14/17] KVM: vmx/pmu: Limit pebs_interrupt_threshold in the guest DS area Like Xu
2021-01-04 13:15 ` [PATCH v3 15/17] KVM: vmx/pmu: Rewrite applicable_counters field in guest PEBS records Like Xu
2021-01-04 13:15 ` [PATCH v3 16/17] KVM: x86/pmu: Save guest pebs reset values when pebs is configured Like Xu
2021-01-04 13:15 ` [PATCH v3 17/17] KVM: x86/pmu: Adjust guest pebs reset values for crpss-mapped counters Like Xu
2021-01-14 19:10 ` [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS Sean Christopherson
2021-01-15 2:02 ` Xu, Like
2021-01-15 17:57 ` Sean Christopherson
2021-01-15 18:27 ` Andi Kleen
2021-01-15 18:51 ` Sean Christopherson
2021-01-15 19:11 ` Andi Kleen
2021-01-22 9:56 ` Peter Zijlstra
2021-01-25 8:08 ` Like Xu
2021-01-25 11:13 ` Peter Zijlstra
2021-01-25 12:07 ` Xu, Like
2021-01-25 12:18 ` Peter Zijlstra
2021-01-25 12:53 ` Xu, Like
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