Re: [Xen-devel] [PATCH] [SVM]: Make 32bit legacy guests boot again

[Christoph Egger <Christoph.Egger@xxxxxxx>]

Tnx. I will check as soon as it appears in the public staging tree.

Christoph


On Saturday 27 June 2009 11:35:20 Keir Fraser wrote:
> Changeset 19856 is a cleaned up and streamlined version of this patch.
> Please take a look. It also fixes a couple of largely theoretical issues:
>  * Should depend on EFER.LMA not EFER.LME
>  * Should handle the LMA 1->0 transition (i.e., return to legacy mode).
>
>  -- Keir
>
> On 26/06/2009 16:19, "Christoph Egger" <Christoph.Egger@xxxxxxx> wrote:
> > Hi!
> >
> > Attached patch fixes a bug introduced in c/s 19648.
> >
> > 32bit legacy guests have the sysenter/sysexit instructions available.
> > Therefore, we have to disable intercepts for the sysenter MSRs or the
> > guest stucks in an infinite loop of #GPs, otherwise.
> >
> > For guests in 64bit mode and 32bit compat mode, sysenter/sysexit
> > instructions aren't available. The sysenter MSRs have to be intercepted
> > to make the instruction emulation working.
> >
> > Attach patch first assumes the guest is in 32bit legacy mode and
> > therefore disables the sysenter MSRs in construct_vmcb().
> > Access to the MSR_EFER is intercepted. When the guest enables longmode,
> > then enable interception of the sysenter MSRs.
> >
> > Signed-off-by: Christoph Egger <Christoph.Egger@xxxxxxx>



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