NMI vs #PF clash

[Avi Kivity]

The recent changes to NMI allow exceptions to take place in NMI
handlers, but I think that a #PF (say, due to access to vmalloc space)
is still problematic.  Consider the sequence

  #PF  (cr2 set by processor)
    NMI
      ...
      #PF (cr2 clobbered)
        do_page_fault()
        IRET
      ...
      IRET
    do_page_fault()
      address = read_cr2()
 
The last line reads the overwritten cr2 value.

I vaguely remember some discussion about this back in the day, but I
can't find anything in the code to save/restore cr2 in the NMI handler. 
Did I miss it?  Or perhaps the page fault handler ignores the incorrect
cr2 and IRETs, to fault back immediately?

-- 
error compiling committee.c: too many arguments to function

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