Re: 2.6.33-rc2: Xen/Guest switching to user mode with no user pagetables

From: Christian Kujau
Date: Fri Jan 15 2010 - 03:38:12 EST

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@xxxxxxxxxxxxxxx>

Thanks so much for your efforts to everyone involved!

BOFH excuse #436:

Daemon escaped from pentagram
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