From: Christoph Hellwig <hch@infradead.org>
To: Robin Murphy <robin.murphy@arm.com>
Cc: maz@kernel.org, joro@8bytes.org,
Christoph Hellwig <hch@infradead.org>,
iommu@lists.linux-foundation.org,
Andre Przywara <andre.przywara@arm.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] iommu/dma: Handle MSI mappings separately
Date: Tue, 30 Jul 2019 08:06:24 -0700 [thread overview]
Message-ID: <20190730150624.GA27573@infradead.org> (raw)
In-Reply-To: <90566814-ed36-2eb9-49e2-98a4a949c9f6@arm.com>
On Tue, Jul 30, 2019 at 11:43:25AM +0100, Robin Murphy wrote:
> > Hmm. I remember proposing this patch and you didn't like it because
> > we could also have msis for a !IOMMU_DMA_IOVA_COOKIE cookie type.
> > Or did we talk past each other?
>
> Do you have a pointer? That sparks the vaguest of memories, but I can't seem
> to turn anything up in my inbox. If that was my objection, though, it sounds
> like your patch was probably trying to go a step or two further than this
> one.
I can't find anything either. This must have been a git tree I passed
around to you before posting it.
> > Note that if this change turns out to be valid we should also
> > clean up the iommu_dma_free_iova() side.
>
> We're not touching the iommu_dma_{alloc,free}_iova() path here; those are
> designed to cope with both types of cookie, and I think that's a reasonable
> abstraction to keep. This is just getting rid of the asymmetry - and now bug
> - caused by trying to keep the MSI page flow going through a special case in
> __iommu_dma_map() despite that having evolved into a more specific DMA
> domain fastpath (there's no corresponding unmap special case since MSI
> mappings just persist and get recycled until the domain is destroyed).
Ok, that might have been the issue with my earlier patch..
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next prev parent reply other threads:[~2019-07-30 15:07 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-29 15:32 [PATCH] iommu/dma: Handle MSI mappings separately Robin Murphy
2019-07-29 16:03 ` Marc Zyngier
2019-07-29 16:15 ` Andre Przywara
2019-07-29 16:47 ` Shameerali Kolothum Thodi
2019-07-30 6:28 ` Christoph Hellwig
2019-07-30 10:43 ` Robin Murphy
2019-07-30 15:06 ` Christoph Hellwig [this message]
2019-08-06 15:23 ` Joerg Roedel
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