Messages in this thread | | | From | David Matlack <> | Date | Mon, 18 Aug 2014 22:00:33 -0700 | Subject | Re: [PATCH 1/2] KVM: fix cache stale memslot info with correct mmio generation number |
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On Mon, Aug 18, 2014 at 9:41 PM, Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> wrote: > On 08/19/2014 12:31 PM, David Matlack wrote: >> But it looks like you basically said the same thing earlier, so I think >> we're on the same page. >> > > Yes, that is what i try to explain in previous mails. :(
I'm glad we understand each other now! Sorry again for my confusion.
>> The single line patch I suggested was only intended to fix the "forever >> incorrectly exit mmio". > > My patch also fixes this case and that does not doubly increase the > number. I think this is the better one.
I prefer doubly increasing the generation for this reason: the updated boolean requires extra code on the "client-side" to check if there's an update in progress. And that makes it easy to get wrong. In fact, your patch forgot to check the updated bit in mark_mmio_spte(). Doubly increasing the generation requires no "client-side" code to work.
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