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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 A4A12C433E0 for ; Fri, 15 May 2020 05:25:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7980B2075F for ; Fri, 15 May 2020 05:25:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589520300; bh=0p4MU9sh09UIkFcUSyxNYENjUyCA8wdnYR5djowsWds=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=eu3/2WuDLBldzHvezbP9Y8MDZMUQLKsiaBvB+ZADLGzWDUCveUUASfMb3nzNSlIAC VvJn0Gpg/ugGXYL/7u7DbbX0FFgE+3b9xjzkIDV3xKjOGN1yzM2asxhoYAvvY9gjL9 flVPPi0VUVhHcyX7MeiKFIY748kJOu6EIhmT/gG0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726407AbgEOFY7 (ORCPT ); Fri, 15 May 2020 01:24:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:33086 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726139AbgEOFY7 (ORCPT ); Fri, 15 May 2020 01:24:59 -0400 Received: from mail-wm1-f43.google.com (mail-wm1-f43.google.com [209.85.128.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A9798207CB for ; Fri, 15 May 2020 05:24:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589520298; bh=0p4MU9sh09UIkFcUSyxNYENjUyCA8wdnYR5djowsWds=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=ikwtUa/gDF6fJgChKS0y0UollW3L4h//gNNj6zLIgUyaQylRw/Hb/4m/YJfpyRXjY ftWzMFVS0cyZ3hU+wPi9BmpQ8SBEDsUr0zY1EJy8UfAbNNBeZFTkMcc4ykAPvAl06V vw8ZGi74SHtKSkhugFP9sUu452R4gY0Yt4g8Slc8= Received: by mail-wm1-f43.google.com with SMTP id f13so906442wmc.5 for ; Thu, 14 May 2020 22:24:58 -0700 (PDT) X-Gm-Message-State: AOAM531Dq/haussTaZCACVB7Wjk/KRSITOemoSjDtqYu0LDdD4+rNHg6 Pmk9keMLdNF15qGic5NcbPHX3E574pyesZhP31Wj0A== X-Google-Smtp-Source: ABdhPJwEqHdowY9NniUCQHeBVoG3ZlWxFICr2MtxsYmj4V8ZPbATgegyODakKp4Ov6wnJ/I4JqmkRmafHJCXi/2wkoc= X-Received: by 2002:a1c:8141:: with SMTP id c62mr1024333wmd.21.1589520297084; Thu, 14 May 2020 22:24:57 -0700 (PDT) MIME-Version: 1.0 References: <20200505134926.578885807@linutronix.de> <20200505135314.426347351@linutronix.de> In-Reply-To: <20200505135314.426347351@linutronix.de> From: Andy Lutomirski Date: Thu, 14 May 2020 22:24:45 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [patch V4 part 4 11/24] x86/mce: Use untraced rd/wrmsr in the MCE offline/crash check To: Thomas Gleixner Cc: LKML , X86 ML , "Paul E. McKenney" , Andy Lutomirski , Alexandre Chartre , Frederic Weisbecker , Paolo Bonzini , Sean Christopherson , Masami Hiramatsu , Petr Mladek , Steven Rostedt , Joel Fernandes , Boris Ostrovsky , Juergen Gross , Brian Gerst , Mathieu Desnoyers , Josh Poimboeuf , Will Deacon Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 5, 2020 at 7:16 AM Thomas Gleixner wrote: > > mce_check_crashing_cpu() is called right at the entry of the MCE > handler. It uses mce_rdmsr() and mce_wrmsr() which are wrappers around > rdmsr() and wrmsr() to handle the MCE error injection mechanism, which is > pointless in this context, i.e. when the MCE hits an offline CPU or the > system is already marked crashing. > > The MSR access can also be traced, so use the untraceable variants. This > is also safe vs. XEN paravirt as these MSRs are not affected by XEN PV > modifications. Acked-by: Andy Lutomirski