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From: Christoph Hellwig <hch@infradead.org>
To: Robin Murphy <robin.murphy@arm.com>
Cc: maz@kernel.org, iommu@lists.linux-foundation.org,
	linux-arm-kernel@lists.infradead.org,
	Andre Przywara <andre.przywara@arm.com>
Subject: Re: [PATCH] iommu/dma: Handle MSI mappings separately
Date: Mon, 29 Jul 2019 23:28:43 -0700	[thread overview]
Message-ID: <20190730062843.GA1400@infradead.org> (raw)
In-Reply-To: <2b2595de703c60a772ebcffe248d0cf036143e6a.1564414114.git.robin.murphy@arm.com>

On Mon, Jul 29, 2019 at 04:32:38PM +0100, Robin Murphy wrote:
> MSI pages must always be mapped into a device's *current* domain, which
> *might* be the default DMA domain, but might instead be a VFIO domain
> with its own MSI cookie. This subtlety got accidentally lost in the
> streamlining of __iommu_dma_map(), but rather than reintroduce more
> complexity and/or special-casing, it turns out neater to just split this
> path out entirely.
> 
> Since iommu_dma_get_msi_page() already duplicates much of what
> __iommu_dma_map() does, it can easily just make the allocation and
> mapping calls directly as well. That way we can further streamline the
> helper back to exclusively operating on DMA domains.
> 
> Fixes: b61d271e59d7 ("iommu/dma: Move domain lookup into __iommu_dma_{map,unmap}")
> Reported-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> Reported-by: Andre Przywara <andre.przywara@arm.com>
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>

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?

Note that if this change turns out to be valid we should also
clean up the iommu_dma_free_iova() side.
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iommu@lists.linux-foundation.org
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WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@infradead.org>
To: Robin Murphy <robin.murphy@arm.com>
Cc: maz@kernel.org, joro@8bytes.org,
	iommu@lists.linux-foundation.org,
	linux-arm-kernel@lists.infradead.org,
	Andre Przywara <andre.przywara@arm.com>
Subject: Re: [PATCH] iommu/dma: Handle MSI mappings separately
Date: Mon, 29 Jul 2019 23:28:43 -0700	[thread overview]
Message-ID: <20190730062843.GA1400@infradead.org> (raw)
In-Reply-To: <2b2595de703c60a772ebcffe248d0cf036143e6a.1564414114.git.robin.murphy@arm.com>

On Mon, Jul 29, 2019 at 04:32:38PM +0100, Robin Murphy wrote:
> MSI pages must always be mapped into a device's *current* domain, which
> *might* be the default DMA domain, but might instead be a VFIO domain
> with its own MSI cookie. This subtlety got accidentally lost in the
> streamlining of __iommu_dma_map(), but rather than reintroduce more
> complexity and/or special-casing, it turns out neater to just split this
> path out entirely.
> 
> Since iommu_dma_get_msi_page() already duplicates much of what
> __iommu_dma_map() does, it can easily just make the allocation and
> mapping calls directly as well. That way we can further streamline the
> helper back to exclusively operating on DMA domains.
> 
> Fixes: b61d271e59d7 ("iommu/dma: Move domain lookup into __iommu_dma_{map,unmap}")
> Reported-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> Reported-by: Andre Przywara <andre.przywara@arm.com>
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>

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?

Note that if this change turns out to be valid we should also
clean up the iommu_dma_free_iova() side.

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2019-07-30  6:33 UTC|newest]

Thread overview: 16+ 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 15:32 ` Robin Murphy
2019-07-29 16:03 ` Marc Zyngier
2019-07-29 16:03   ` Marc Zyngier
2019-07-29 16:15 ` Andre Przywara
2019-07-29 16:15   ` Andre Przywara
2019-07-29 16:47 ` Shameerali Kolothum Thodi
2019-07-29 16:47   ` Shameerali Kolothum Thodi
2019-07-30  6:28 ` Christoph Hellwig [this message]
2019-07-30  6:28   ` Christoph Hellwig
2019-07-30 10:43   ` Robin Murphy
2019-07-30 10:43     ` Robin Murphy
2019-07-30 15:06     ` Christoph Hellwig
2019-07-30 15:06       ` Christoph Hellwig
2019-08-06 15:23 ` Joerg Roedel
2019-08-06 15:23   ` Joerg Roedel

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