Re: [PATCH 4/4] KVM: MMU: Reinstate pte prefetch on invlpg

[Avi Kivity <avi@redhat.com>]

On 02/15/2010 02:48 PM, Avi Kivity wrote:
> Commit fb341f57 removed the pte prefetch on guest invlpg, citing guest races.
> However, the SDM is adamant that prefetch is allowed:
>
>    "The processor may create entries in paging-structure caches for
>     translations required for prefetches and for accesses that are a
>     result of speculative execution that would never actually occur
>     in the executed code path."
>
> And, in fact, there was a race in the prefetch code: we picked up the pte
> without the mmu lock held, so an older invlpg could install the pte over
> a newer invlpg.
>
> Reinstate the prefetch logic, but this time note whether another invlpg has
> executed using a counter.  If a race occured, do not install the pte.
>
>    

This patch is broken (UP windows XP won't start), I'm debugging it.

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