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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT 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 53B19C43387 for ; Mon, 7 Jan 2019 21:53:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2AFA72089F for ; Mon, 7 Jan 2019 21:53:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727174AbfAGVxX (ORCPT ); Mon, 7 Jan 2019 16:53:23 -0500 Received: from mail-qk1-f193.google.com ([209.85.222.193]:37440 "EHLO mail-qk1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726821AbfAGVxX (ORCPT ); Mon, 7 Jan 2019 16:53:23 -0500 Received: by mail-qk1-f193.google.com with SMTP id g125so1209013qke.4 for ; Mon, 07 Jan 2019 13:53:22 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=XscXXsUqMIUZrTmARrC5SmhRBALRJ2JqQUFxn6IIhQM=; b=m96Bmp1GVIgJOo6oH2ZA/SP4v4JVOtuFgAmfA25TrcX9mVtWQ48WUYUV9ZAzegfVfV 1djf6t4TTMRWBo7VTY0+nwibnMF7BQOcgmjRuk168xISgplW/qtgiSxdFLbtTWFtDKfg bbUlPfVI3DplCCLdEClYe8Lgk5uhUSoiMQASD4g8LQZzS79ApY45FqksOyVWGQcKiCxn h4C9ra+9T5mDqu6MU6JD8uQlKmufG/6tRUC2TUgz+TRMiqCUGdjyNzzgLrJ/wPNnmuTA Dx9Yc77+R6iZCVT5zdHIZKTDgCBg6lqqSs+nFMa9gUlZ/kUoHNLpdhoarjeWKhwj/lpb QE5w== X-Gm-Message-State: AJcUukdZLbbP2PzD/2i61IBGQDaaDLdxK+8aKVHpseARtsQxe0MMVc2v UT8MB1qUgAPenCBH5i17R0Yvmw== X-Google-Smtp-Source: ALg8bN6/GEK0em4Dh5XroXwGuSDYTw865EVky9OyUaJcRwPM62t8IVGhBAX5zQpwQkS+CbRDH3K2yA== X-Received: by 2002:a37:8006:: with SMTP id b6mr20686649qkd.19.1546898001920; Mon, 07 Jan 2019 13:53:21 -0800 (PST) Received: from trogon.sfo.coreos.systems ([2604:2000:80c5:4400:140c:73de:b623:c90]) by smtp.gmail.com with ESMTPSA id w52sm38537702qtc.51.2019.01.07.13.53.20 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 07 Jan 2019 13:53:21 -0800 (PST) Date: Mon, 7 Jan 2019 16:53:18 -0500 From: Benjamin Gilbert To: Wei Huang Cc: "Kirill A. Shutemov" , x86@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, linux-kernel@vger.kernel.org, linux-x86_64@vger.kernel.org Subject: Re: [PATCH 1/1] x86/boot/compressed/64: Set EFER.LME=1 in 32-bit trampoline code before returning to long mode Message-ID: <20190107215318.GA22396@trogon.sfo.coreos.systems> References: <20190104054411.12489-1-wei@redhat.com> <20190107082512.w5gkbebsypionyey@black.fi.intel.com> <6899e645-9579-f599-922a-eb26fc56e8ab@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6899e645-9579-f599-922a-eb26fc56e8ab@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 07, 2019 at 02:03:15PM -0600, Wei Huang wrote: > On 1/7/19 2:25 AM, Kirill A. Shutemov wrote: > > On Fri, Jan 04, 2019 at 05:44:11AM +0000, Wei Huang wrote: > >> In some old AMD KVM implementation, guest's EFER.LME bit is cleared by KVM > >> when the hypervsior detects guest sets CR0.PG to 0. This causes guest OS > >> to reboot when it tries to return from 32-bit trampoline code because CPU > >> is in incorrect state: CR4.PAE=1, CR0.PG=1, CS.L=1, but EFER.LME=0. > >> As a precaution, this patch sets EFER.LME=1 as part of long mode > >> activation procedure. This extra step won't cause any harm when Linux is > >> booting on bare-metal machine. > >> > >> Signed-off-by: Wei Huang > > > > Thanks for tracking this down. > > BTW I think this patch _might_ be related the recent reboot issue > reported in https://lkml.org/lkml/2018/7/1/836 since the symptoms are > exactly the same. The problem in that case turned out to be https://lkml.org/lkml/2018/7/4/723 which was fixed by d503ac531a. --Benjamin Gilbert