Re: [PATCH v2 3/3] KVM: x86 emulator: Allow PM/VM86 switch during task switch

[Gleb Natapov]

On Mon, Jan 30, 2012 at 04:26:06PM +0100, Kevin Wolf wrote:
> >> Would that be enough or would we have to avoid clearing it in all other
> >> places as well? Where would it be initialised if it's not enough?
> > 
> > Maybe vmx_vcpu_reset().
> 
> Do all CPL changes go through set_cr0/segment/rflags/cpl? I guess yes,
> so initialising on reset and keeping it valid all the time should be
> possible indeed.
> 
CPL can be changed while guest is running. SVM saves it for us in cpl
field. VMX does not, so we either will have to update cpl on each exit
(cpl = cs & 3) or somehow mark it not up-to-date and recalculate on
access. Can VMX exit while cpl != cs & 3 or can this happen only during
emulation? If it can we cannot know real cpl after exit.
  
--
                        Gleb.
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