Messages in this thread | | | Date | Mon, 09 Apr 2012 17:25:19 +0300 | From | Avi Kivity <> | Subject | Re: [PATCH 00/13] KVM: MMU: fast page fault |
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On 04/09/2012 04:55 PM, Xiao Guangrong wrote: > > Okay, let's simplify it as possible: > > - let it only fix the page fault with PFEC.P == 1 && PFEC.W = 0, that means > unlock set_spte path can be dropped > > - let it just fixes the page fault caused by dirty-log that means we always > skip the spte which write-protected by shadow page protection. > > Then, things should be fair simper: > > In set_spte path, if the spte can be writable, we set ALLOW_WRITE bit > In rmap_write_protect: > if (spte.PT_WRITABLE_MASK) { > WARN_ON(!(spte & ALLOW_WRITE)); > spte &= ~PT_WRITABLE_MASK; > spte |= WRITE_PROTECT; > } > > in fast page fault: > > if (spte & PT_WRITABLE_MASK) > return_go_guest; > > if ((spte & ALLOW_WRITE) && !(spte & WRITE_PROTECT)) > cmpxchg spte + PT_WRITABLE_MASK > > The information all we needed comes from spte it is independence from other path, > and no barriers. > > > Hmm, how about this one? >
I like it. WRITE_PROTECT is better than my ALLOW_WRITES, the meaning is clearer.
-- error compiling committee.c: too many arguments to function
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