linux-kernel - Re: swiotlb/caamjr regression (Was: [GIT PULL] (swiotlb) stable/for-linus-5.12)

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Date:   Fri, 11 Jun 2021 13:59:36 +0300
From:   Horia Geantă <horia.geanta@....com>
To:     Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Christoph Hellwig <hch@....de>,
        Dominique MARTINET <dominique.martinet@...ark-techno.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        jianxiong Gao <jxgao@...gle.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Lukas Hartmann <lukas@...mn.com>,
        Aymen Sghaier <aymen.sghaier@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        Bumyong Lee <bumyong.lee@...sung.com>,
        Chanho Park <chanho61.park@...sung.com>
Subject: Re: swiotlb/caamjr regression (Was: [GIT PULL] (swiotlb)
 stable/for-linus-5.12)

On 6/11/2021 1:35 PM, Konrad Rzeszutek Wilk wrote:
> On Fri, Jun 11, 2021 at 08:21:53AM +0200, Christoph Hellwig wrote:
>> On Thu, Jun 10, 2021 at 05:52:07PM +0300, Horia Geantă wrote:
>>> I've noticed the failure also in v5.10 and v5.11 stable kernels,
>>> since the patch set has been backported.
>>
>> FYI, there has been a patch on the list that should have fixed this
>> for about a month:
>>
>> https://lore.kernel.org/linux-iommu/20210510091816.GA2084@lst.de/T/#m0d0df6490350a08dcc24c9086c8edc165b402d6f
>>
>> but it seems like it never got picked up.
> 
> Yikes!
> 
> Dominique,
> 
> Would you be up to testing the attached (and inline) patch please?
> 
> Linus,
> 
> Would you be terribly offended if I took your code (s/unsigned
> long/unsigned int), and used Chanho's description of the problem (see below)?
> 
Both patches work for my case.

However, there's yet another, possibly significant, difference b/w the two:
	offset = (tlb_addr - mem->start) & (IO_TLB_SIZE - 1);
vs.
	offset = (tlb_addr & (IO_TLB_SIZE - 1)) -
		 swiotlb_align_offset(dev, orig_addr);

I think accounting for the alignment offset (swiotlb_align_offset())
has to be kept.

Horia