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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 B675AC433E0 for ; Wed, 24 Jun 2020 14:10:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8B3D720823 for ; Wed, 24 Jun 2020 14:10:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Yi/4vpjM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391158AbgFXOKd (ORCPT ); Wed, 24 Jun 2020 10:10:33 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:22329 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2388395AbgFXOKc (ORCPT ); Wed, 24 Jun 2020 10:10:32 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1593007831; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=X/ddPMKFK52O0i/xE6u6isLskFjJDspQUCwUmvG2q9g=; b=Yi/4vpjMgCr1W5Z45yA8bEkKOhAl0wsaGxDWHWXOxYI0a+kBLUI24pzusFh7aeWSF3uFRm 3lUVyzbwAkmQWGdBbsEQiS2tKaNbm/dg40UW9Q/iG5mx/Io5GB8WZGTG/KmPFQsLBOpmga 27Bt34u/CJ53lpda/7frLigraWqseo0= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-164-VDuRhBDzMYCcPZpopP3tlA-1; Wed, 24 Jun 2020 10:10:21 -0400 X-MC-Unique: VDuRhBDzMYCcPZpopP3tlA-1 Received: by mail-wm1-f71.google.com with SMTP id o13so2891798wmh.9 for ; Wed, 24 Jun 2020 07:10:21 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=X/ddPMKFK52O0i/xE6u6isLskFjJDspQUCwUmvG2q9g=; b=HqaOo7w/fqlARFiIRd065YpXPQIfpr63kQcVu9BrTAZKIJKchBzsA3nfIWiTMNxhzY Rj9sOI0P0TBZFS2ZjTBWcxiMvDHGrygbcCoTYH7kmkcM+Uq4nARaYs31vC/upC+p0814 DuaivjehkY49dZ7T+NNwLFQsq9siSgISqOOaqzgHMer/977Iueq/iGDoHT0KbweUdJHU D8QbsdVkTZaKMNJDgiEfDKhfCbTpS89GYKrV91L5noeyesIECVfBLGrAdVIrf/Thv2vF 2/eyMRWdrZBngWsv/eyTY6sSjDYIV2mpuiVPvEnjqiZhMSahHelSAEGiusS2+lYjLtL/ BymA== X-Gm-Message-State: AOAM533tfIxOLTIeG3pV4DV2p6Qne4O5r2Bmg2BQtfohXb9Ug8G0y4ai ngr+N1LVcagUyB2fSloXqnJQFysaNYNvogpBUx28sEreULBH8h6xGarm19fpIHTRBRInGbpSFDf yBMhx4n0ufoZq X-Received: by 2002:a1c:8117:: with SMTP id c23mr22480899wmd.157.1593007820406; Wed, 24 Jun 2020 07:10:20 -0700 (PDT) X-Google-Smtp-Source: ABdhPJy/zjFESCjivTfraJHy6CuthLgkns0Gis7vTXveb2snbUkcIjEeC+OYOh1JiPSt+Zp/40iz8g== X-Received: by 2002:a1c:8117:: with SMTP id c23mr22480790wmd.157.1593007819254; Wed, 24 Jun 2020 07:10:19 -0700 (PDT) Received: from [192.168.178.58] ([151.20.253.55]) by smtp.gmail.com with ESMTPSA id r12sm27031305wrc.22.2020.06.24.07.10.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 24 Jun 2020 07:10:18 -0700 (PDT) Subject: Re: [kvm-unit-tests PATCH] x86: Initialize segment selectors To: Thomas Huth , Nadav Amit Cc: kvm@vger.kernel.org References: <20200623084132.36213-1-namit@vmware.com> <40203296-7f31-16c7-bebb-e1f1cd478a19@redhat.com> From: Paolo Bonzini Message-ID: Date: Wed, 24 Jun 2020 16:10:16 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <40203296-7f31-16c7-bebb-e1f1cd478a19@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 24/06/20 14:52, Thomas Huth wrote: > On 23/06/2020 10.41, Nadav Amit wrote: >> Currently, the BSP's segment selectors are not initialized in 32-bit >> (cstart.S). As a result the tests implicitly rely on the segment >> selector values that are set by the BIOS. If this assumption is not >> kept, the task-switch test fails. >> >> Fix it by initializing them. >> >> Signed-off-by: Nadav Amit >> --- >>   x86/cstart.S | 17 +++++++++++------ >>   1 file changed, 11 insertions(+), 6 deletions(-) > > I'm sorry to be the bearer of bad news again, but this commit broke > another set of tests in the Travis CI: > >  https://travis-ci.com/github/huth/kvm-unit-tests/jobs/353103187#L796 > > smptest, smptest3, kvmclock_test, hyperv_synic and hyperv_stimer are > failing now in the 32-bit kvm-unit-tests :-( And that's just bad testing (both Nadav's and mine). Writing to %gs clobbers the PERCPU area. The fix is as simple as this: diff --git a/x86/cstart.S b/x86/cstart.S index 5ad70b5..77dc34d 100644 --- a/x86/cstart.S +++ b/x86/cstart.S @@ -106,6 +106,7 @@ MSR_GS_BASE = 0xc0000101 .globl start start: mov $stacktop, %esp + setup_segments push %ebx call setup_multiboot call setup_libcflat @@ -118,7 +119,6 @@ start: prepare_32: lgdtl gdt32_descr - setup_segments mov %cr4, %eax bts $4, %eax // pse