[PATCH 4/4] kvmppc: convert wrteei to wrtee as kvm guest optimization

[Scott Wood]

On Fri, Aug 22, 2008 at 09:56:16AM -0400, Jimi Xenidis wrote:
> Sorry, I have not really been following this, I assume you are  
> replacing SPR accesses with load/stores that do not trap.
> I believe thats fine for reading any SPR, but not true for modifying  
> some SPRs, particularly MSR.
> IMHO you must trap on any instruction that modifies the MSR.
> So you should prolly not rewrite mtmsr or wrtee* but let them trap.

You only need to trap when changing MSR[EE] if there's a pending
interrupt.  The hypervisor can change the mapping of the shared page when
it is unable to deliver an interrupt due to the virtual EE value being
zero.

-Scott