Messages in this thread | | | Subject | Re: [PATCH 0/5] iommu: Some IOVA code reorganisation | From | John Garry <> | Date | Mon, 4 Oct 2021 14:56:49 +0100 |
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On 04/10/2021 12:44, Will Deacon wrote:
> On Fri, Sep 24, 2021 at 06:01:52PM +0800, John Garry wrote: >> The IOVA domain structure is a bit overloaded, holding: >> - IOVA tree management >> - FQ control >> - IOVA rcache memories >> >> Indeed only a couple of IOVA users use the rcache, and only dma-iommu.c >> uses the FQ feature. >> >> This series separates out that structure. In addition, it moves the FQ >> code into dma-iommu.c . This is not strictly necessary, but it does make >> it easier for the FQ domain lookup the rcache domain. >> >> The rcache code stays where it is, as it may be reworked in future, so >> there is not much point in relocating and then discarding. >> >> This topic was initially discussed and suggested (I think) by Robin here: >> https://lore.kernel.org/linux-iommu/1d06eda1-9961-d023-f5e7-fe87e768f067@arm.com/ >
Hi Will,
> It would be useful to have Robin's Ack on patches 2-4. The implementation > looks straightforward to me, but the thread above isn't very clear about > what is being suggested.
Sure, I intentionally didn't add names to patches so avoid possible incorrect attribution.
> > To play devil's advocate: there aren't many direct users of the iovad code: > either they'll die out entirely (and everybody will use the dma-iommu code) > and it's fine having the flush queue code where it is, or we'll get more > users and the likelihood of somebody else wanting flush queues increases. >
I make it 5x direct users (including vdpa).
Anyway, as I mentioned, I'm not totally determined to relocate the FQ code. It's just that dma-iommu is the only user today and co-locating makes the iova rcache domain info lookup easier from the FQ code.
Thanks, John
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