Re: [PATCH v2 0/3] Fix task switches into/out of VM86

[Gleb Natapov <gleb@redhat.com>]

On Mon, Jan 30, 2012 at 10:55:41AM +0200, Gleb Natapov wrote:
> On Mon, Jan 30, 2012 at 09:48:33AM +0100, Kevin Wolf wrote:
> > Am 27.01.2012 20:52, schrieb Gleb Natapov:
> > > On Fri, Jan 27, 2012 at 08:23:33PM +0100, Kevin Wolf wrote:
> > >> I believe this should work with both VMX and SVM now. Gleb, Jörg, can one of
> > >> you test this with SVM? I did some testing on my buggy processor and it looks
> > >> as good as it gets, but it would be better if you could confirm.
> > >>
> > > You forgot to set cpl to 3 in vmcb in svm_set_rflags() when vm86 is enabled, no?
> > 
> > SVM updates the CPL when the segment selector for CS is loaded. From a
> > svm.c POV, segment selectors are updated immediately after set_rflags,
> > so it wouldn't really make a difference to do it twice.
> > 
> It is too subtle to rely on that. The fact is that checking cpl after
> set_rflags provides incorrect value. This better be fixed. BTW does
> load_state_from_tss16() need the same fix?
> 
Probably not since you can't switch to vm86 this way. But may be for
other reasons.

--
			Gleb.