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

From: Ian Campbell
Date: Sun Jan 10 2010 - 09:11:26 EST


On Sun, 2010-01-10 at 16:49 +0300, Cyrill Gorcunov wrote:
> On Sun, Jan 10, 2010 at 04:36:28PM +0300, Cyrill Gorcunov wrote:
> ...
> > >
> > > With just the CS RPL fix below I see a GPF at kernel_thread_helper with
> > > SS=3 (hence my hypothesis about NULL selectors and non-zero RPL above).
> > > With both the SS and CS fixes things work fine.
> >
> > any of CS,SS loaded with NULL descriptor should lead to #GP
> >
>
> though SS with RPL=0 is allowed to be NULL descriptor in 64bit mode

yes, that's what I meant.

Ian.

--
Ian Campbell

Tussman's Law:
Nothing is as inevitable as a mistake whose time has come.

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