From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 91106C432BE for ; Fri, 27 Aug 2021 07:34:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 74F1760F92 for ; Fri, 27 Aug 2021 07:34:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244400AbhH0HfT (ORCPT ); Fri, 27 Aug 2021 03:35:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38410 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231345AbhH0HfR (ORCPT ); Fri, 27 Aug 2021 03:35:17 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8042DC061757; Fri, 27 Aug 2021 00:34:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=pX/U+rVEPbfrs2KxIK3fTT5zek69Vi8l41Blp4tBLok=; b=Yc/w61MYBYU/2XovOdaG/1LI+3 ofvXZY72T/bqQpEDQIopTT41ymuCj9LCYB3YpGsaZsw8I7lr88Q2nTCRx2MpWUAJi2+3qnashJI4R pq0hm4wrqjtQzjgnu14Y0Hv71MTmXVlwUtR00yaCrR+u7hNfiDC4NQgkVvvO74M9TS46PVdKtznHr cI35oR72a6g4a2mZG68PMOuldBKtE8eyE5BYPjhe0gvPrNhQPT9HfquqIFtVn1+9kmnU1uaROxDf6 T9v8X9G4zCE0HsYiDhrr3Coe9vaArCNE5m8ZWnIbYQ2Ri33yjkJEKLCpR695YXtWTkmMXBqMBOcvc uj1qfSCA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mJWJz-00EFo3-0q; Fri, 27 Aug 2021 07:30:56 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 0C6F23005AD; Fri, 27 Aug 2021 09:30:37 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id E07822C6670E9; Fri, 27 Aug 2021 09:30:36 +0200 (CEST) Date: Fri, 27 Aug 2021 09:30:36 +0200 From: Peter Zijlstra To: Sean Christopherson Cc: Will Deacon , Mark Rutland , Ingo Molnar , Arnaldo Carvalho de Melo , Catalin Marinas , Marc Zyngier , Guo Ren , Nick Hu , Greentime Hu , Vincent Chen , Paul Walmsley , Palmer Dabbelt , Albert Ou , Thomas Gleixner , Borislav Petkov , x86@kernel.org, Paolo Bonzini , Boris Ostrovsky , Juergen Gross , Alexander Shishkin , Jiri Olsa , Namhyung Kim , James Morse , Alexandru Elisei , Suzuki K Poulose , "H. Peter Anvin" , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Stefano Stabellini , 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 , Like Xu , Zhu Lingshan Subject: Re: [PATCH 07/15] KVM: Use dedicated flag to track if KVM is handling an NMI from guest Message-ID: References: <20210827005718.585190-1-seanjc@google.com> <20210827005718.585190-8-seanjc@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210827005718.585190-8-seanjc@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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?