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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 D19CDC43441 for ; Fri, 12 Oct 2018 09:22:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8FFFB20868 for ; Fri, 12 Oct 2018 09:22:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8FFFB20868 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=dei.uc.pt Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728273AbeJLQxc (ORCPT ); Fri, 12 Oct 2018 12:53:32 -0400 Received: from smtp.dei.uc.pt ([193.137.203.253]:60426 "EHLO smtp.dei.uc.pt" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728021AbeJLQxc (ORCPT ); Fri, 12 Oct 2018 12:53:32 -0400 Received: from mail-ed1-f53.google.com (mail-ed1-f53.google.com [209.85.208.53]) (user=sneves mech=PLAIN bits=0) by smtp.dei.uc.pt (8.15.2/8.15.2) with ESMTPSA id w9C9L1Et023524 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Fri, 12 Oct 2018 10:21:07 +0100 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp.dei.uc.pt w9C9L1Et023524 Received: by mail-ed1-f53.google.com with SMTP id x31-v6so10846958edd.8 for ; Fri, 12 Oct 2018 02:21:07 -0700 (PDT) X-Gm-Message-State: ABuFfoh49TJs6Rd56p++gnyZa2vatwaiuRqnO3/L/Sw1IqsfgeJCUwZO dCfzBQYu+SAuT58qQSuDBEiC/G3Fiwvwn+6+RpQ= X-Google-Smtp-Source: ACcGV62HPqByDX0nYOogBLQMoYGOlgjx/h/Gmbl0k+n2Igu+70VQWfyVcnJoQJRb8Rcb4H1o9+Eklc/Fn/QU3C6tnqE= X-Received: by 2002:a17:906:e1ce:: with SMTP id gp14-v6mr6335446ejb.221.1539336061564; Fri, 12 Oct 2018 02:21:01 -0700 (PDT) MIME-Version: 1.0 References: <20181011185458.10186-1-kristen@linux.intel.com> In-Reply-To: From: Samuel Neves Date: Fri, 12 Oct 2018 10:20:25 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] x86: entry: flush the cache if syscall error To: Andy Lutomirski Cc: kristen@linux.intel.com, Kernel Hardening , Thomas Gleixner , Ingo Molnar , bp@alien8.de, "H. Peter Anvin" , "the arch/x86 maintainers" , linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-FCTUC-DEI-SIC-MailScanner-Information: Please contact helpdesk@dei.uc.pt for more information X-FCTUC-DEI-SIC-MailScanner-ID: w9C9L1Et023524 X-FCTUC-DEI-SIC-MailScanner: Found to be clean X-FCTUC-DEI-SIC-MailScanner-SpamCheck: not spam, SpamAssassin (not cached, score=-60.1, required 3.252, autolearn=not spam, ALL_TRUSTED -10.00, BAYES_00 -0.10, L_SMTP_AUTH -50.00) X-FCTUC-DEI-SIC-MailScanner-From: sneves@dei.uc.pt Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 11, 2018 at 8:25 PM Andy Lutomirski wrote: > What exactly is this trying to protect against? And how many cycles > should we expect L1D_FLUSH to take? As far as I could measure, I got 1660 cycles per wrmsr 0x10b, 0x1 on a Skylake chip, and 1220 cycles on a Skylake-SP.