Re: [PATCH 11/11] KVM: MMU: improve write flooding detected

From: Avi Kivity
Date: Wed Jul 27 2011 - 07:08:40 EST


On 07/27/2011 01:20 PM, Xiao Guangrong wrote:
>> }
>
> I think this is a little dangerous. A guest kernel may be instantiating multiple gptes on a page fault, but guest userspace hits only one of them (the one which caused the page fault) - I think Windows does this, but I'm not sure.
>

I think this case is not bad: if the guest kernel need to write multiple gptes (>=3),
it will cause many page fault, we do better zap the shadow page and let it become writable as
soon as possible.
(And, we have pte-fetch, it can quickly establish the mapping for a new shadow page)

Actually, what should save us is unsync pages. Why are we hitting this path at all?

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

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