Messages in this thread | | | Subject | Re: [RFC PATCH V3 0/5] Hi: | From | Jason Wang <> | Date | Tue, 8 Jan 2019 18:12:38 +0800 |
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On 2019/1/7 下午10:47, Michael S. Tsirkin wrote: > On Mon, Jan 07, 2019 at 02:58:08PM +0800, Jason Wang wrote: >> On 2019/1/5 上午5:41, Michael S. Tsirkin wrote: >>> On Sat, Dec 29, 2018 at 08:46:51PM +0800, Jason Wang wrote: >>>> This series tries to access virtqueue metadata through kernel virtual >>>> address instead of copy_user() friends since they had too much >>>> overheads like checks, spec barriers or even hardware feature >>>> toggling. >>> I think it's a reasonable approach. >>> However I need to look at whether and which mmu notifiers are invoked before >>> writeback. Do you know? >> >> I don't know but just looking at the MMU notifier ops definition, there's no >> such callback if my understanding is correct. >> >> Thanks > In that case how are you making sure used ring updates are written back? > If they aren't guest will crash ...
I think this is the writeback issue you mentioned early. I don't do a followup on the pointer but it looks to me some work is ongoing to fix the issue.
I can investigate it more, but it's not something new, consider the case of VFIO.
Thanks
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