Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1752674AbdCPURR (ORCPT <rfc822;w@1wt.eu>);
        Thu, 16 Mar 2017 16:17:17 -0400
Received: from mail-qt0-f194.google.com ([209.85.216.194]:34143 "EHLO
        mail-qt0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1751531AbdCPURP (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Thu, 16 Mar 2017 16:17:15 -0400
Date: Thu, 16 Mar 2017 16:17:11 -0400
From: "Gabriel L. Somlo" <gsomlo@gmail.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        linux-kernel@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
        Jonathan Corbet <corbet@lwn.net>, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
        x86@kernel.org, Joerg Roedel <joro@8bytes.org>, kvm@vger.kernel.org,
        linux-doc@vger.kernel.org
Subject: Re: [PATCH v5 untested] kvm: better MWAIT emulation for guests
Message-ID: <20170316201710.GN4085@HEDWIG.INI.CMU.EDU>
References: <20170316155550-mutt-send-email-mst@kernel.org>
 <20170316145819.GC4085@HEDWIG.INI.CMU.EDU>
 <20170316153517.GL14081@potion>
 <20170316160157.GN14081@potion>
 <20170316164749.GG4085@HEDWIG.INI.CMU.EDU>
 <20170316192622-mutt-send-email-mst@kernel.org>
 <20170316174149.GK4085@HEDWIG.INI.CMU.EDU>
 <20170316202024-mutt-send-email-mst@kernel.org>
 <20170316192440.GL4085@HEDWIG.INI.CMU.EDU>
 <20170316212635-mutt-send-email-mst@kernel.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20170316212635-mutt-send-email-mst@kernel.org>
X-Clacks-Overhead: GNU Terry Pratchett
User-Agent: Mutt/1.7.1 (2016-10-04)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 1433
Lines: 45

On Thu, Mar 16, 2017 at 09:27:56PM +0200, Michael S. Tsirkin wrote:
> On Thu, Mar 16, 2017 at 03:24:41PM -0400, Gabriel L. Somlo wrote:
> > On Thu, Mar 16, 2017 at 08:29:32PM +0200, Michael S. Tsirkin wrote:
> > > Let's take a step back and try to figure out how is
> > > mwait called. How about dumping code of VCPUs
> > > around mwait?  gdb disa command will do this.
> > 
> > Started guest with '-s', tried to attach from gdb with
> > "target remote localhost:1234", got
> > "remote 'g' packet reply is too long: <lengthy string of numbers>"
> 
> Try
> 
> set arch x86-64:x86-64

'set architecture i386:x86-64:intel' is what worked for me;

Been rooting around for a while, can't find mwait or monitor :(

Guess I'll have to recompile KVM to actually issue an invalid opcode,
so OS X will print a panic message with the exact address :)

Stay tuned...
 
> 
> > Tried typing 'cont' in the qemu monitor, got os x to crash:
> > 
> > panic (cpu 1 caller 0xffffff7f813ff488): pmLock: waited too long, held
> > by 0xffffff7f813eff65
> > 
> > Hmm, maybe that's where it keeps its monitor/mwait idle loop.
> > Restarted the guest, tried this from monitor:
> > 
> > 	dump-guest-memory foobar 0xffffff7f813e0000 0x20000
> > 
> > Got "'dump-guest-memory' has failed: integer is for 32-bit values"
> > 
> > Hmmm... I have no idea what I'm doing anymore at this point... :)
> > 
> > --G
> 
> I think 0xffffff7f813ff488 is a PC.
> 
> -- 
> MST