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[35.247.111.240]) by smtp.gmail.com with ESMTPSA id x9sm16309575pfd.66.2021.05.26.10.39.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 May 2021 10:39:01 -0700 (PDT) Date: Wed, 26 May 2021 17:38:57 +0000 From: Sean Christopherson To: Like Xu Cc: Paolo Bonzini , Alexander Shishkin , Peter Zijlstra , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH] KVM: x86/pt: Do not inject TraceToPAPMI when guest PT isn't supported Message-ID: References: <20210514084436.848396-1-like.xu@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210514084436.848396-1-like.xu@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 14, 2021, Like Xu wrote: > When a PT perf user is running in system-wide mode on the host, > the guest (w/ pt_mode=0) will warn about anonymous NMIs from > kvm_handle_intel_pt_intr(): > > [ 18.126444] Uhhuh. NMI received for unknown reason 10 on CPU 0. > [ 18.126447] Do you have a strange power saving mode enabled? > [ 18.126448] Dazed and confused, but trying to continue > > In this case, these PMIs should be handled by the host PT handler(). > When PT is used in guest-only mode, it's harmless to call host handler. > > Fix: 8479e04e7d("KVM: x86: Inject PMI for KVM guest") s/Fix/Fixes > Signed-off-by: Like Xu > --- > arch/x86/events/intel/core.c | 3 +-- > arch/x86/kvm/x86.c | 3 +++ > 2 files changed, 4 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c > index 2521d03de5e0..2f09eb0853de 100644 > --- a/arch/x86/events/intel/core.c > +++ b/arch/x86/events/intel/core.c > @@ -2853,8 +2853,7 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status) > if (unlikely(perf_guest_cbs && perf_guest_cbs->is_in_guest() && > perf_guest_cbs->handle_intel_pt_intr)) > perf_guest_cbs->handle_intel_pt_intr(); > - else > - intel_pt_interrupt(); > + intel_pt_interrupt(); Would it make sense to instead do something like: bool host_pmi = true; ... if (unlikely(perf_guest_cbs && perf_guest_cbs->is_in_guest() && perf_guest_cbs->handle_intel_pt_intr) host_pmi = !perf_guest_cbs->handle_intel_pt_intr(); if (likely(host_pmi)) intel_pt_interrupt(); > } > > /* > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 6529e2023147..6660f3948cea 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -8087,6 +8087,9 @@ static void kvm_handle_intel_pt_intr(void) > { > struct kvm_vcpu *vcpu = __this_cpu_read(current_vcpu); > > + if (!guest_cpuid_has(vcpu, X86_FEATURE_INTEL_PT)) > + return; > + > kvm_make_request(KVM_REQ_PMI, vcpu); > __set_bit(MSR_CORE_PERF_GLOBAL_OVF_CTRL_TRACE_TOPA_PMI_BIT, > (unsigned long *)&vcpu->arch.pmu.global_status); > -- > 2.31.1 >