From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x227en/7gdrZ3fLr2gPu5XbMIxkGlYdHUC3tZrBg2HZXaGcx8zwMWUQDBcVfknDZeCb66k1qp ARC-Seal: i=1; a=rsa-sha256; t=1519772414; cv=none; d=google.com; s=arc-20160816; b=ePJ+eMqviEF4HVs70JWSBLcEgdfECeDfgC9iY4mIJK2YEjNpftIM6getkGXWleClqN kWjXzTB/dxJcr68zpFVmf6hl+M8lINdSu3RE7iqTIYPP8vmBsIetrfBRpVAwG0gL61H0 7+Z3CUgYMd4MpGUNwM4Y1f1hYi7GbWT+ctEY1lEwYX+H+Jk4l36M4Od2bwUWNwbvOYpr h8cbRZldDbuJmuxNaNkZZ+XIs13+vkcY/Yv1CAm7cafJBbjzcInRQLcfKpzZ8Sytir4N i491NNojHdmjTpRgARDsSRoNmnTni3APlYuW5HuOrwOW4h594kG9tWrD6fU+jn49SJQt OkKQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:user-agent:in-reply-to :content-disposition:mime-version:references:message-id:subject:cc :to:from:date:dkim-signature:arc-authentication-results; bh=Em+jJfvDYtWrXqDLbYwnw38CyHkeIaTVOi+KfPUDZu8=; b=p1AC0PIifpRlsOeVlRTjvIqUbNIHT5hFMenG3btufP13ty3oANw8mbmtbeVvxk0lz4 NdKZ02nRfkUqunRBBrvlIoLVOb9NPGP6aA2M2xVP37ibNpUsEh4PN3HEukNnYtXPtXdF ehWCSCzE9jsS/3q4ODwaN4HYExbuVamkI1M9kT4DCNhARe+qg+RlHSZ9cJEWlztV9hES QGLlXDgPcAhmoWvKtfZaYQChbaVzFERYtS2LiN6N2yip/q7YR+veglKoAjJgW/bFdrVm /yaMlqaTnSsKP0R2EsB9nQWDwBpNh7fW/vuZgH2pnqsTry0jZbXWSmyOYj/raNz6qFrE Y3TQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=neutral (body hash did not verify) header.i=@linaro.org header.s=google header.b=gJ8kjJbW; spf=pass (google.com: best guess record for domain of linux-kselftest-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kselftest-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=linaro.org Authentication-Results: mx.google.com; dkim=neutral (body hash did not verify) header.i=@linaro.org header.s=google header.b=gJ8kjJbW; spf=pass (google.com: best guess record for domain of linux-kselftest-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kselftest-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751960AbeB0XAB (ORCPT ); Tue, 27 Feb 2018 18:00:01 -0500 Received: from mail-io0-f181.google.com ([209.85.223.181]:39718 "EHLO mail-io0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751906AbeB0W75 (ORCPT ); Tue, 27 Feb 2018 17:59:57 -0500 Date: Tue, 27 Feb 2018 16:59:55 -0600 From: Dan Rue To: "H. Peter Anvin" Cc: Andy Lutomirski , Andy Lutomirski , Borislav Petkov , Shuah Khan , Ingo Molnar , Dmitry Safonov , "open list:KERNEL SELFTEST FRAMEWORK" , LKML Subject: Re: selftests/x86/fsgsbase_64 test problem Message-ID: <20180227225955.s2vs4g7oc7tdi72i@xps> References: <46328204-e363-e517-f30c-c8c94ac1442c@zytor.com> <624b9e67-14ee-6882-e55e-f337ec2471d3@zytor.com> <0b0a3cea-d951-d3be-16de-a0e9d50cb2ba@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0b0a3cea-d951-d3be-16de-a0e9d50cb2ba@zytor.com> User-Agent: NeoMutt/20171215 Sender: linux-kselftest-owner@vger.kernel.org X-Mailing-List: linux-kselftest@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1590669876861238825?= X-GMAIL-MSGID: =?utf-8?q?1593596878883771098?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Mon, Jan 29, 2018 at 10:30:05AM -0800, H. Peter Anvin wrote: > On 01/29/18 10:26, Andy Lutomirski wrote: > >>> > >>> That will utterly suck on non-UMIP machines that have > >>> hypervisor-provided UMIP emulation. > >> > >> Is that a valid thing to optimize for, especially given that paranoid > >> entries aren't the most common anyway? > > > > A bunch of people seem to care about NMI performance for perf. > > > > That wasn't really the question... > > > And the current patch set works without this trick. > > But I believe the tricks it uses are fragile. > > > FWIW, if we switch all entries to the entry text trampoline, we get direct percpu access for free. > > That might be a better option. Has there been any conclusion to this thread? I can still reproduce the issue on mainline and next. Thanks, Dan