From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1753983Ab2LYPwo (ORCPT <rfc822;w@1wt.eu>);
	Tue, 25 Dec 2012 10:52:44 -0500
Received: from terminus.zytor.com ([198.137.202.10]:40000 "EHLO mail.zytor.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1752812Ab2LYPwm (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Tue, 25 Dec 2012 10:52:42 -0500
User-Agent: K-9 Mail for Android
In-Reply-To: <20121225115226.GD7720@liondog.tnic>
References: <1355814959-10573-1-git-send-email-yinghai@kernel.org> <20121222024225.GG3468@phenom.dumpdata.com> <eee81bb9-f11b-4ff8-8a84-72f122766fd8@email.android.com> <20121222132419.GB2936@phenom.dumpdata.com> <50D8FBF9.6050509@zytor.com> <20121225115226.GD7720@liondog.tnic>
MIME-Version: 1.0
Content-Type: text/plain;
 charset=UTF-8
Content-Transfer-Encoding: 8bit
Subject: Re: [PATCH v7 00/27] x86, boot, 64bit: Add support for loading ramdisk and bzImage above 4G
From: "H. Peter Anvin" <hpa@zytor.com>
Date: Tue, 25 Dec 2012 07:51:54 -0800
To: Borislav Petkov <bp@alien8.de>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        Yinghai Lu <yinghai@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@elte.hu>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org
Message-ID: <e91771a5-0d4e-457b-a3da-f8e855a1baa0@email.android.com>
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Right, it's the ljmpq issue.

Borislav Petkov <bp@alien8.de> wrote:

>On Mon, Dec 24, 2012 at 05:06:01PM -0800, H. Peter Anvin wrote:
>> Could this be the ljmpq problem that Borislav reported
>> (Intel implemented ljmpq, AMD didn't, and I was tempted by a
>> micro-optimization which broke AMD which made it into the patchset)?
>
>It has to be. Just booted Yinghai's -v8 in kvm on an AMD host and it
>worked fine.
>
>With the change below it keeps rebooting like I reported earlier. I'd
>go
>out on a limb here and guess that the guest is triple-faulting due to
>an
>unhandled #GP caused by an invalid opcode or similar.
>
>---
>diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
>index d94f6d68be2a..1842d30c96a2 100644
>--- a/arch/x86/kernel/head_64.S
>+++ b/arch/x86/kernel/head_64.S
>@@ -279,11 +279,8 @@ ENTRY(secondary_startup_64)
>         *      REX.W + FF /5 JMP m16:64 Jump far, absolute indirect,
>         *              address given in m16:64.
>         */
>-       movq    initial_code(%rip),%rax
>        pushq   $0              # fake return address to stop unwinder
>-       pushq   $__KERNEL_CS    # set correct cs
>-       pushq   %rax            # target address in negative space
>-       lretq
>+       rex64 ljmp *initial_code(%rip)
> 
> #ifdef CONFIG_HOTPLUG_CPU
> /*

-- 
Sent from my mobile phone. Please excuse brevity and lack of formatting.