linux-kernel - Re: 2.6.33-rc2: Xen/Guest switching to user mode with no user page tables

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Message-ID: <20100115120031.GA5412@lenovo>
Date:	Fri, 15 Jan 2010 15:00:31 +0300
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	Christian Kujau <lists@...dbynature.de>
Cc:	Ian Campbell <ijc@...lion.org.uk>, Brian Gerst <brgerst@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: 2.6.33-rc2: Xen/Guest switching to user mode with no user page
	tables

On Fri, Jan 15, 2010 at 12:36:42AM -0800, Christian Kujau wrote:
> On Sun, 10 Jan 2010 at 12:59, Ian Campbell wrote:
> > The correct fix is for the Xen backend to declare kernel RPL == 0 for 64
> > bit guests -- the hyervisor already takes care of all the necessary
> > squashing to ring 3 transparently (because making the guest worry about
> > it would break the very common assumption that you can distinguish user
> > from kernel CS by RPL).
> 
> Yes' it's a 64bit guest, I should have mentioned this from the beginning. 
> With the 2 patches from Ian and Cyrill applied, the DomU is now booting 
> fine again (currently running mainline -git).
> 
> Cyrill: with your patch alone (for arch/x86/kernel/process.c), the DomU
> is still not booting, Dom0 "xm dmesg" reporting the same error. As it's
> working with both patches applied, should I try to test with only Ian's
> patch (for arch/x86/xen/enlighten.c) applied?
> 
> In any case, feel free to add:
> 
>    Tested-by: Christian Kujau <lists@...dbynature.de>
> 
> Thanks so much for your efforts to everyone involved!
> 
> Christian.
> -- 
> BOFH excuse #436:
> 
> Daemon escaped from pentagram
> 

Well, I think the Ian's patch is a key here and mine should be
droppped then. Thanks for testing!

	-- Cyrill
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