linux-kernel - Re: [PATCH] iommu/of: Handle PCI aliases properly

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Date:   Wed, 26 Jul 2017 11:12:25 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Robin Murphy <robin.murphy@....com>
Cc:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iommu/of: Handle PCI aliases properly

On Wed, May 31, 2017 at 06:52:29PM +0100, Robin Murphy wrote:
> When a PCI device has DMA quirks, we need to ensure that an upstream
> IOMMU knows about all possible aliases, since the presence of a DMA
> quirk does not preclude the device still also emitting transactions
> (e.g. MSIs) on its 'real' RID. Similarly, the rules for bridge aliasing
> are relatively complex, and some bridges may only take ownership of
> transactions under particular transient circumstances, leading again to
> multiple RIDs potentially being seen at the IOMMU for the given device.
> 
> Take all this into account in the OF code by translating every RID
> produced by the alias walk, not just whichever one comes out last.
> Happily, this also makes things tidy enough that we can reduce the
> number of both total lines of code, and confusing levels of indirection,
> by pulling the "iommus"/"iommu-map" parsing helpers back in-line again.
> 
> Signed-off-by: Robin Murphy <robin.murphy@....com>
> ---
> 
> This applies on top of the fix currently queued in the IOMMU tree:
> "iommu/of: Ignore all errors except EPROBE_DEFER"
> 
>  drivers/iommu/of_iommu.c | 104 +++++++++++++++++++++--------------------------
>  1 file changed, 47 insertions(+), 57 deletions(-)

Applied, thanks.