From: will.deacon@arm•com (Will Deacon)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 0/5] Implement SMMU passthrough using the default domain
Date: Thu, 2 Feb 2017 15:12:42 +0000 [thread overview]
Message-ID: <20170202151241.GE13839@arm.com> (raw)
In-Reply-To: <CAF6AEGtfrrwVZ_W86_HqVsiqfcM=XFa+g2LECFYQJmvv7-JSqQ@mail.gmail.com>
On Thu, Feb 02, 2017 at 10:02:50AM -0500, Rob Clark wrote:
> On Thu, Jan 26, 2017 at 12:18 PM, Joerg Roedel <joro@8bytes•org> wrote:
> > On Tue, Jan 24, 2017 at 08:42:23PM +0530, Sricharan wrote:
> >> Thanks for this series. We had a case with the GPU.
> >> The GPU's iommu was setup by kernel and the GPU
> >> also does dynamic updates for on-the-fly switching between
> >> process pagetables. GPU driver was not using DMA domain and
> >> the GPU's firmware was always expecting to run out of contextbank
> >> '0' (although not correct) , which was not the case after the DMA domain
> >> was made default as '0' was getting allocated for DMA domain and
> >> there were concerns about reusing the DMA domain as well.
> >> Now with this series, looks there is an way out of that that can be tried.
> >>
> >> So should the default domain not be per device specific selectable ?
> >
> > Note that iommu-drivers can request direct-mapping for any given device
> > on its initializtion. This is used on x86 for devices that need a 1-1
> > mapping for some reason.
> >
> > Also device drivers can use the iommu-api and assign their own domain to
> > a device, which allows them to manage the dma address space on their
> > own.
>
> Part of the problem is that dev->archdata.dma_ops gets wired up to
> iommu_dma_ops. Which isn't so bad on it's own, except that cache ops
> are not exposed to drivers, forcing us to use dma-mapping API
> (dma_map_sg, etc) for cache operations.
>
> Possibly we should just expose cache op's to drivers bypass this abuse
> of dma-mapping.
>
> btw, Will, we definitely want this to *not* rely on kcmdline for the
> gpu with it's own private iommu case..
I still need to understand the unmanaged domain case, but I don't really
see why that's related to this series to be honest.
Will
next prev parent reply other threads:[~2017-02-02 15:12 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-19 18:19 [PATCH 0/5] Implement SMMU passthrough using the default domain Will Deacon
2017-01-19 18:19 ` [PATCH 1/5] iommu/arm-smmu: Restrict domain attributes to UNMANAGED domains Will Deacon
2017-01-19 18:41 ` Robin Murphy
2017-01-26 17:06 ` Joerg Roedel
2017-01-26 17:03 ` Joerg Roedel
2017-01-26 17:57 ` Will Deacon
2017-01-19 18:19 ` [PATCH 2/5] iommu/arm-smmu: Install bypass S2CRs for IOMMU_DOMAIN_IDENTITY domains Will Deacon
2017-01-19 18:50 ` Robin Murphy
2017-01-19 18:19 ` [PATCH 3/5] iommu/arm-smmu-v3: Install bypass STEs " Will Deacon
2017-01-19 18:56 ` Robin Murphy
2017-01-19 18:19 ` [PATCH 4/5] arm64: dma-mapping: Only swizzle DMA ops for IOMMU_DOMAIN_DMA Will Deacon
2017-01-19 19:00 ` Robin Murphy
2017-01-26 17:57 ` Will Deacon
2017-01-19 18:19 ` [PATCH 5/5] iommu: Allow default domain type to be set on the kernel command line Will Deacon
2017-01-26 17:15 ` Joerg Roedel
2017-01-26 17:26 ` Robin Murphy
2017-01-26 17:48 ` Will Deacon
2017-01-24 15:12 ` [PATCH 0/5] Implement SMMU passthrough using the default domain Sricharan
2017-01-26 17:18 ` Joerg Roedel
2017-02-02 15:02 ` Rob Clark
2017-02-02 15:12 ` Will Deacon [this message]
2017-02-03 12:20 ` Rob Clark
2017-02-02 15:45 ` Sricharan
2017-02-02 16:10 ` Will Deacon
2017-02-03 16:33 ` Sricharan
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