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Date:   Tue, 22 Jun 2021 16:48:24 +0900
From:   'Dominique MARTINET' <dominique.martinet@atmark-techno.com>
To:     Konrad Rzeszutek Wilk <konrad@darnok.org>
Cc:     Chanho Park <chanho61.park@samsung.com>,
        'Jianxiong Gao' <jxgao@google.com>,
        'Christoph Hellwig' <hch@lst.de>,
        'Konrad Rzeszutek Wilk' <konrad.wilk@oracle.com>,
        'Linus Torvalds' <torvalds@linux-foundation.org>,
        'Horia =?utf-8?Q?Geant=C4=83'?= <horia.geanta@nxp.com>,
        linux-kernel@vger.kernel.org, 'Lukas Hartmann' <lukas@mntmn.com>,
        'Aymen Sghaier' <aymen.sghaier@nxp.com>,
        'Herbert Xu' <herbert@gondor.apana.org.au>,
        "'David S. Miller'" <davem@davemloft.net>,
        linux-crypto@vger.kernel.org, iommu@lists.linux-foundation.org,
        'Marc Orr' <marcorr@google.com>,
        'Erdem Aktas' <erdemaktas@google.com>,
        'Peter Gonda' <pgonda@google.com>,
        'Bumyong Lee' <bumyong.lee@samsung.com>
Subject: Re: swiotlb/caamjr regression (Was: [GIT PULL] (swiotlb)
 stable/for-linus-5.12)
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Konrad Rzeszutek Wilk wrote on Mon, Jun 21, 2021 at 09:16:43AM -0400:
> The beaty of 'devel' and 'linux-next' is that they can be reshuffled and
> mangled. I pushed them original patch from Bumyong there and will let
> it sit for a day and then create a stable branch and give it to Linus.

Thanks, that should be good.

Do you want me to send a follow-up patch with the two extra checks
(tlb_addr & (IO_TLB_SIZE -1)) > swiotlb_align_offset(dev, orig_addr)
tlb_offset < alloc_size

or are we certain this can't ever happen?
(I didn't see any hit in dmesg when I ran with these, but my opinion is
better safe than sorry...)


> Then I need to expand the test-regression bucket so that this does not
> happen again. Dominique, how easy would it be to purchase one of those
> devices?

My company is making such a device, but it's not on the market yet
(was planned for august, with some delay in approvisionning it'll
probably be a bit late), and would mean buying from Japan so I'm not
sure how convenient that would be...

These are originally NXP devices so I assume Horia would have better
suggestions, if you would?


> I was originally thinking to create a crypto device in QEMU to simulate
> this but that may take longer to write than just getting the real thing.
> 
> Or I could create some fake devices with weird offsets and write a driver
> for it to exercise this.. like this one I had done some time ago that
> needs some brushing off.

Just a fake device with fake offsets as a test is probably good enough,
ideally would need to exerce both failures we've seen (offset in
dma_sync_single_for_device like caam does and in the original mapping (I
assume?) like the NVMe driver does), but that sounds possible :)


Thanks again!
-- 
Dominique