Re: [Qemu-devel] i386: EFER vs 32-bit CPU

[Pavel Dovgalyuk]

> From: Peter Xu [mailto:address@hidden
> On Wed, May 29, 2019 at 02:26:39PM +0300, Pavel Dovgalyuk wrote:
> > Hello!
> >
> >
> >
> > I found this while debugging the inconsistent saved/restored state of the 
> > virtual machine.
> >
> >
> >
> > i386 (32 bit) emulation uses this register (in wrmsr and in MMU fault 
> > processing).
> 
> Sorry if this question is elementary, but... why would a 32bit guest
> use IA32_EFER?  From SDM I only see 4 bits defined in this MSR (SCE,
> LME, LMA, NXE) but is there any of them that should be set in a 32bit
> guest?

Ubuntu server 16.04 (32 bit) sets NXE while booting.
NXE affects the MMU fault processing and exception generation.

Pavel Dovgalyuk