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Date:   Mon, 19 Mar 2018 16:55:51 +0000
From:   Will Deacon <will.deacon@arm.com>
To:     Christoph Hellwig <hch@lst.de>
Cc:     Robin Murphy <robin.murphy@arm.com>, x86@kernel.org,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        linux-kernel@vger.kernel.org, Muli Ben-Yehuda <mulix@mulix.org>,
        iommu@lists.linux-foundation.org,
        David Woodhouse <dwmw2@infradead.org>,
        Catalin Marinas <catalin.marinas@arm.com>
Subject: Re: [PATCH 12/14] dma-direct: handle the memory encryption bit in
 common code
Message-ID: <20180319165551.GE14916@arm.com>
References: <20180319103826.12853-1-hch@lst.de>
 <20180319103826.12853-13-hch@lst.de>
 <dd05dd14-9969-7985-826e-f440c3fc4c08@arm.com>
 <20180319152442.GA27915@lst.de>
 <5316b479-7e75-d62f-6b17-b6bece55187c@arm.com>
 <20180319154832.GD14916@arm.com>
 <20180319160343.GA29002@lst.de>
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On Mon, Mar 19, 2018 at 05:03:43PM +0100, Christoph Hellwig wrote:
> On Mon, Mar 19, 2018 at 03:48:33PM +0000, Will Deacon wrote:
> > Why can't we just resolve the conflict by adding the underscores?
> 
> We can solve the conflict easily that way.  But that's not the point.
> 
> The point is that I've been fighting hard to consolidate dma code
> given that the behavior really is common and not arch specific.  And
> this one is another case like that:  the fact that the non-coherent
> dma boundary is bigger than the exposed size is something that can
> easily happen elsewhere, so there is no need to duplicate a lot
> of code for that.

Fair enough, although I wouldn't say it's a *lot* of code being duplicated.
Are there other architectures working around this issue too? I couldn't
see anything in the other dma-direct.h headers.

> Nevermind that the commit should at least be three different patches:
> 
>  (1) revert the broken original commit
>  (2) increase the dma min alignment
>  (3) put the swiotlb workaround in place

I'd agree with you if this wasn't already queued and sitting in -next.
Reverting what we currently have seems a bit OTT now. Catalin?

Will