From: Peter Zijlstra <peterz@infradead.org>
To: "Xu, Like" <like.xu@intel.com>
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 02/16] perf/x86/intel: Handle guest PEBS overflow PMI for KVM guest
Date: Tue, 18 May 2021 10:37:46 +0200 [thread overview]
Message-ID: <YKN82utjfLEX9ZJh@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <bd684011-b83d-5c83-bdfb-926d6bc4595a@intel.com>
On Tue, May 18, 2021 at 03:38:52PM +0800, Xu, Like wrote:
> > I'm thinking you have your conditions in the wrong order; would it not
> > be much cheaper to first check: '!x86_pmu.pebs_active || !guest_pebs_idx'
> > than to do that horrible indirect ->is_in_guest() call?
> >
> > After all, if the guest doesn't have PEBS enabled, who cares if we're
> > currently in a guest or not.
>
> Yes, it makes sense. How about:
>
> @@ -2833,6 +2867,10 @@ static int handle_pmi_common(struct pt_regs *regs,
> u64 status)
> u64 pebs_enabled = cpuc->pebs_enabled;
>
> handled++;
> + if (x86_pmu.pebs_vmx && x86_pmu.pebs_active &&
> + (cpuc->pebs_enabled & ~cpuc->intel_ctrl_host_mask) &&
> + (static_call(x86_guest_state)() & PERF_GUEST_ACTIVE))
> + x86_pmu_handle_guest_pebs(regs, &data);
This is terruble, just call x86_pmu_handle_guest_pebs() unconditionally
and put all the ugly inside it.
> x86_pmu.drain_pebs(regs, &data);
> status &= intel_ctrl | GLOBAL_STATUS_TRACE_TOPAPMI;
>
> >
> > Also, something like the below perhaps (arm64 and xen need fixing up at
> > the very least) could make all that perf_guest_cbs stuff suck less.
>
> How about the commit message for your below patch:
>
> From: "Peter Zijlstra (Intel)" <peterz@infradead.org>
>
> x86/core: Use static_call to rewrite perf_guest_info_callbacks
>
> The two fields named "is_in_guest" and "is_user_mode" in
> perf_guest_info_callbacks are replaced with a new multiplexed member
> named "state", and the "get_guest_ip" field will be renamed to "get_ip".
>
> The application of DEFINE_STATIC_CALL_RET0 (arm64 and xen need fixing
> up at the very least) could make all that perf_guest_cbs stuff suck less.
> For KVM, these callbacks will be updated in the kvm_arch_init().
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Well, you *do* need to fix up arm64 and xen, we can't very well break
their builds can we now.
> ----
>
> I'm not sue if you have a strong reason to violate the check-patch rule:
>
> ERROR: Using weak declarations can have unintended link defects
> #238: FILE: include/linux/perf_event.h:1242:
> +extern void __weak arch_perf_update_guest_cbs(void);
Copy/paste fail I think. I didn't really put much effort into the patch,
only made sure defconfig+kvm_guest.config compiled.
next prev parent reply other threads:[~2021-05-18 8:39 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 [this message]
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
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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