Re: [kvm-devel] [PATCH 2/3] Refactor hypercall infrastructure (v3)

[Anthony Liguori]

Avi Kivity wrote:
> Avi Kivity wrote:
>   
> > Avi Kivity wrote:
> >     
> > > Anthony Liguori wrote:
> > >  
> > >       
> > > > This patch refactors the current hypercall infrastructure to better 
> > > > support live
> > > > migration and SMP.  It eliminates the hypercall page by trapping the UD
> > > > exception that would occur if you used the wrong hypercall 
> > > > instruction for the
> > > > underlying architecture and replacing it with the right one lazily.
> > > >
> > > > It also introduces the infrastructure to probe for hypercall 
> > > > available via
> > > > CPUID leaves 0x40000000.  CPUID leaf 0x40000001 should be filled out by
> > > > userspace.
> > > >
> > > > A fall-out of this patch is that the unhandled hypercalls no longer 
> > > > trap to
> > > > userspace.  There is very little reason though to use a hypercall to 
> > > > communicate
> > > > with userspace as PIO or MMIO can be used.  There is no code in tree 
> > > > that uses
> > > > userspace hypercalls.
> > > >
> > > >       
> > > >         
> > > Surprisingly, this patch kills Windows XP (ACPI HAL).  I'll try to 
> > > find out why.
> > >
> > >   
> > >       
> > Not trapping #UD brings things back to normal.  So, Windows likes to 
> > execute undefined instructions, and we don'd handle these well.
> >
> >     
> Okay, vmx_inject_ud() was broken.  Fixed now.
>   

Yeah, I was just about to send the patch for that.  Sorry about that, I 
didn't even think to test Windows...

Regards,

Anthony Liguori

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