From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ot1-x336.google.com (mail-ot1-x336.google.com [IPv6:2607:f8b0:4864:20::336]) by sourceware.org (Postfix) with ESMTPS id 40862385801A; Sat, 27 Mar 2021 19:58:22 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 40862385801A Received: by mail-ot1-x336.google.com with SMTP id 91-20020a9d08640000b0290237d9c40382so8475254oty.12; Sat, 27 Mar 2021 12:58:22 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=cT9vftvSDZvxU0Rf2aMOp1UD0PXoHd2C3C+Tf0qOtv0=; b=VVUa/3iqlS1WJaAfNbwE5YgCQ8UwGf1DDWXcGrK1tmwC5jD+ktXovmTGBZZRA/+Agd QlP2ggYh+CNDBizy9Dy12Elu4SlOmhKd6T7KkeiOLWYkn1tSCk10VXeq/229JhJDqaad DwtGf4azot9itFlY44H/nxemxeCP2EeYd3n2T+JqpA+GWhPOsyLHYdr3AsbB6c7NJAxx +EChbYpaKdJ8dWBmql/aYigWu+0oL6UJVcr0oIl4E5Y4qppUz7Ry3OZ+6MyPr3mrZOGY IPYzAoE5N8FZEsf9R5NrycQVLhKENhAXRCA5X3P/dEhd/lXQ9yxyLPOm6pdHAVzQSpRN Kxnw== X-Gm-Message-State: AOAM531cQKuPjd7XtqJlSeXh04ktsbOUzTnt7jAWlmdZxMNiWW1CAj49 K3XnWK8C6hM1XK1b9NWD4RVtp/VkLrV5K0TWLx9ZDq3EdAw= X-Google-Smtp-Source: ABdhPJywuE5Yoqlm1ejMENZ1Z7uZ/n60h0QDv0O/AB+NdlDSlF9SeUgh2w7ipiDCUZgS2d0DsGpfzF6BidhCzXWfpWo= X-Received: by 2002:a05:6830:1515:: with SMTP id k21mr16927916otp.269.1616875100854; Sat, 27 Mar 2021 12:58:20 -0700 (PDT) MIME-Version: 1.0 References: <20210327183417.3390361-1-hjl.tools@gmail.com> <87mtuo76i6.fsf@mid.deneb.enyo.de> In-Reply-To: <87mtuo76i6.fsf@mid.deneb.enyo.de> From: "H.J. Lu" Date: Sat, 27 Mar 2021 12:57:44 -0700 Message-ID: Subject: Re: [PATCH] x86: Disable RTM on Skylake [BZ #27398] To: Florian Weimer Cc: "H.J. Lu via Libc-alpha" , Siddhesh Poyarekar Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-3035.5 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 27 Mar 2021 19:58:24 -0000 On Sat, Mar 27, 2021 at 12:15 PM Florian Weimer wrote: > > * H. J. Lu via Libc-alpha: > > > Disable RTM explicitly on Skylake since CPUID may incorrectly report RTM > > feature. > > --- > > sysdeps/x86/cpu-features.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c > > index d7248cbb45..3641a48407 100644 > > --- a/sysdeps/x86/cpu-features.c > > +++ b/sysdeps/x86/cpu-features.c > > @@ -518,6 +518,10 @@ init_cpu_features (struct cpu_features *cpu_features) > > with stepping >= 4) to avoid TSX on kernels that weren't > > updated with the latest microcode package (which disables > > broken feature by default). */ > > + case 0x8e: > > + case 0x9e: > > + /* Disable RTM explicitly on Skylake since CPUID may report > > + RTM feature incorrectly [BZ #27398]. */ > > CPU_FEATURE_UNSET (cpu_features, RTM); > > break; > > } > > Won't this affect the server parts as well? I'm not sure if that's > what our users want. No since Xeon has a different model number (0x55). > We need to report the kernel bug properly, it got stalled because we > initially suspected it might be a security bug. -- H.J.