From: Sean Christopherson <seanjc@google.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Marc Zyngier <maz@kernel.org>, Guo Ren <guoren@kernel.org>,
Nick Hu <nickhu@andestech.com>, Greentime Hu <green.hu@gmail.com>,
Vincent Chen <deanbo422@gmail.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@alien8.de>,
x86@kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Juergen Gross <jgross@suse.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Stefano Stabellini <sstabellini@kernel.org>,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, linux-csky@vger.kernel.org,
linux-riscv@lists.infradead.org, kvm@vger.kernel.org,
xen-devel@lists.xenproject.org,
Artem Kashkanov <artem.kashkanov@intel.com>,
Like Xu <like.xu.linux@gmail.com>,
Zhu Lingshan <lingshan.zhu@intel.com>
Subject: Re: [PATCH 07/15] KVM: Use dedicated flag to track if KVM is handling an NMI from guest
Date: Fri, 27 Aug 2021 14:58:35 +0000 [thread overview]
Message-ID: <YSj9mz4F2NDSKaas@google.com> (raw)
In-Reply-To: <YSiUnDbi/aZ3nunT@hirez.programming.kicks-ass.net>
On Fri, Aug 27, 2021, Peter Zijlstra wrote:
> On Thu, Aug 26, 2021 at 05:57:10PM -0700, Sean Christopherson wrote:
> > diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
> > index 5cedc0e8a5d5..4c5ba4128b38 100644
> > --- a/arch/x86/kvm/x86.h
> > +++ b/arch/x86/kvm/x86.h
> > @@ -395,9 +395,10 @@ static inline void kvm_unregister_perf_callbacks(void)
> >
> > DECLARE_PER_CPU(struct kvm_vcpu *, current_vcpu);
> >
> > -static inline void kvm_before_interrupt(struct kvm_vcpu *vcpu)
> > +static inline void kvm_before_interrupt(struct kvm_vcpu *vcpu, bool is_nmi)
> > {
> > __this_cpu_write(current_vcpu, vcpu);
> > + WRITE_ONCE(vcpu->arch.handling_nmi_from_guest, is_nmi);
> >
> > kvm_register_perf_callbacks();
> > }
> > @@ -406,6 +407,7 @@ static inline void kvm_after_interrupt(struct kvm_vcpu *vcpu)
> > {
> > kvm_unregister_perf_callbacks();
> >
> > + WRITE_ONCE(vcpu->arch.handling_nmi_from_guest, false);
> > __this_cpu_write(current_vcpu, NULL);
> > }
>
> Does this rely on kvm_{,un}register_perf_callback() being a function
> call and thus implying a sequence point to order the stores?
No, I'm just terrible at remembering which macros provide what ordering guarantees,
i.e. I was thinking WRITE_ONCE provided guarantees against compiler reordering.
next prev parent reply other threads:[~2021-08-27 14:58 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-27 0:57 [PATCH 00/15] perf: KVM: Fix, optimize, and clean up callbacks Sean Christopherson
2021-08-27 0:57 ` [PATCH 01/15] KVM: x86: Register perf callbacks after calling vendor's hardware_setup() Sean Christopherson
2021-08-27 0:57 ` [PATCH 02/15] KVM: x86: Register Processor Trace interrupt hook iff PT enabled in guest Sean Christopherson
2021-08-27 0:57 ` [PATCH 03/15] perf: Stop pretending that perf can handle multiple guest callbacks Sean Christopherson
2021-08-27 0:57 ` [PATCH 04/15] perf: Force architectures to opt-in to " Sean Christopherson
2021-08-27 0:57 ` [PATCH 05/15] perf: Track guest callbacks on a per-CPU basis Sean Christopherson
2021-08-27 7:15 ` Peter Zijlstra
2021-08-27 14:49 ` Sean Christopherson
2021-08-27 14:56 ` Peter Zijlstra
2021-08-27 15:22 ` Sean Christopherson
2021-08-27 0:57 ` [PATCH 06/15] KVM: x86: Register perf callbacks only when actively handling interrupt Sean Christopherson
2021-08-27 7:21 ` Peter Zijlstra
2021-08-27 0:57 ` [PATCH 07/15] KVM: Use dedicated flag to track if KVM is handling an NMI from guest Sean Christopherson
2021-08-27 7:30 ` Peter Zijlstra
2021-08-27 14:58 ` Sean Christopherson [this message]
2021-08-27 0:57 ` [PATCH 08/15] KVM: x86: Drop current_vcpu in favor of kvm_running_vcpu Sean Christopherson
2021-08-27 0:57 ` [PATCH 09/15] KVM: arm64: Register/unregister perf callbacks at vcpu load/put Sean Christopherson
2021-08-27 0:57 ` [PATCH 10/15] KVM: Move x86's perf guest info callbacks to generic KVM Sean Christopherson
2021-08-27 0:57 ` [PATCH 11/15] KVM: x86: Move Intel Processor Trace interrupt handler to vmx.c Sean Christopherson
2021-08-27 7:34 ` Peter Zijlstra
2021-08-27 0:57 ` [PATCH 12/15] KVM: arm64: Convert to the generic perf callbacks Sean Christopherson
2021-08-27 0:57 ` [PATCH 13/15] KVM: arm64: Drop perf.c and fold its tiny bit of code into pmu.c Sean Christopherson
2021-08-27 0:57 ` [PATCH 14/15] perf: Disallow bulk unregistering of guest callbacks and do cleanup Sean Christopherson
2021-08-27 0:57 ` [PATCH 15/15] perf: KVM: Indicate "in guest" via NULL ->is_in_guest callback Sean Christopherson
2021-08-27 6:52 ` [PATCH 00/15] perf: KVM: Fix, optimize, and clean up callbacks Like Xu
2021-08-27 7:44 ` Peter Zijlstra
2021-08-27 8:01 ` Like Xu
2021-08-27 10:47 ` Peter Zijlstra
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