From: Robin Murphy <robin.murphy@arm.com>
To: Tom Murphy <murphyt7@tcd.ie>, iommu@lists.linux-foundation.org
Cc: Heiko Stuebner <heiko@sntech.de>,
kvm@vger.kernel.org, David Airlie <airlied@linux.ie>,
Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
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Cornelia Huck <cohuck@redhat.com>,
linux-kernel@vger.kernel.org, Kukjin Kim <kgene@kernel.org>,
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David Woodhouse <dwmw2@infradead.org>
Subject: Re: [PATCH 0/8] Convert the intel iommu driver to the dma-iommu api
Date: Wed, 26 Aug 2020 19:14:28 +0100 [thread overview]
Message-ID: <03caf286-09e8-a072-8d3a-b6bcca991516@arm.com> (raw)
In-Reply-To: <20191221150402.13868-1-murphyt7@tcd.ie>
Hi Tom,
On 2019-12-21 15:03, Tom Murphy wrote:
> This patchset converts the intel iommu driver to the dma-iommu api.
>
> While converting the driver I exposed a bug in the intel i915 driver which causes a huge amount of artifacts on the screen of my laptop. You can see a picture of it here:
> https://github.com/pippy360/kernelPatches/blob/master/IMG_20191219_225922.jpg
>
> This issue is most likely in the i915 driver and is most likely caused by the driver not respecting the return value of the dma_map_ops::map_sg function. You can see the driver ignoring the return value here:
> https://github.com/torvalds/linux/blob/7e0165b2f1a912a06e381e91f0f4e495f4ac3736/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c#L51
>
> Previously this didn’t cause issues because the intel map_sg always returned the same number of elements as the input scatter gather list but with the change to this dma-iommu api this is no longer the case. I wasn’t able to track the bug down to a specific line of code unfortunately.
>
> Could someone from the intel team look at this?
>
>
> I have been testing on a lenovo x1 carbon 5th generation. Let me know if there’s any more information you need.
>
> To allow my patch set to be tested I have added a patch (patch 8/8) in this series to disable combining sg segments in the dma-iommu api which fixes the bug but it doesn't fix the actual problem.
>
> As part of this patch series I copied the intel bounce buffer code to the dma-iommu path. The addition of the bounce buffer code took me by surprise. I did most of my development on this patch series before the bounce buffer code was added and my reimplementation in the dma-iommu path is very rushed and not properly tested but I’m running out of time to work on this patch set.
>
> On top of that I also didn’t port over the intel tracing code from this commit:
> https://github.com/torvalds/linux/commit/3b53034c268d550d9e8522e613a14ab53b8840d8#diff-6b3e7c4993f05e76331e463ab1fc87e1
> So all the work in that commit is now wasted. The code will need to be removed and reimplemented in the dma-iommu path. I would like to take the time to do this but I really don’t have the time at the moment and I want to get these changes out before the iommu code changes any more.
Further to what we just discussed at LPC, I've realised that tracepoints
are actually something I could do with *right now* for debugging my Arm
DMA ops series, so if I'm going to hack something up anyway I may as
well take responsibility for polishing it into a proper patch as well :)
Robin.
>
> Tom Murphy (8):
> iommu/vt-d: clean up 32bit si_domain assignment
> iommu/vt-d: Use default dma_direct_* mapping functions for direct
> mapped devices
> iommu/vt-d: Remove IOVA handling code from non-dma_ops path
> iommu: Handle freelists when using deferred flushing in iommu drivers
> iommu: Add iommu_dma_free_cpu_cached_iovas function
> iommu: allow the dma-iommu api to use bounce buffers
> iommu/vt-d: Convert intel iommu driver to the iommu ops
> DO NOT MERGE: iommu: disable list appending in dma-iommu
>
> drivers/iommu/Kconfig | 1 +
> drivers/iommu/amd_iommu.c | 14 +-
> drivers/iommu/arm-smmu-v3.c | 3 +-
> drivers/iommu/arm-smmu.c | 3 +-
> drivers/iommu/dma-iommu.c | 183 +++++--
> drivers/iommu/exynos-iommu.c | 3 +-
> drivers/iommu/intel-iommu.c | 936 ++++----------------------------
> drivers/iommu/iommu.c | 39 +-
> drivers/iommu/ipmmu-vmsa.c | 3 +-
> drivers/iommu/msm_iommu.c | 3 +-
> drivers/iommu/mtk_iommu.c | 3 +-
> drivers/iommu/mtk_iommu_v1.c | 3 +-
> drivers/iommu/omap-iommu.c | 3 +-
> drivers/iommu/qcom_iommu.c | 3 +-
> drivers/iommu/rockchip-iommu.c | 3 +-
> drivers/iommu/s390-iommu.c | 3 +-
> drivers/iommu/tegra-gart.c | 3 +-
> drivers/iommu/tegra-smmu.c | 3 +-
> drivers/iommu/virtio-iommu.c | 3 +-
> drivers/vfio/vfio_iommu_type1.c | 2 +-
> include/linux/dma-iommu.h | 3 +
> include/linux/intel-iommu.h | 1 -
> include/linux/iommu.h | 32 +-
> 23 files changed, 345 insertions(+), 908 deletions(-)
>
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iommu@lists.linux-foundation.org
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next prev parent reply other threads:[~2020-08-26 18:14 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-21 15:03 [PATCH 0/8] Convert the intel iommu driver to the dma-iommu api Tom Murphy
2019-12-21 15:03 ` [PATCH 1/8] iommu/vt-d: clean up 32bit si_domain assignment Tom Murphy
2019-12-21 23:46 ` Arvind Sankar
2019-12-23 3:00 ` Lu Baolu
2019-12-21 15:03 ` [PATCH 2/8] iommu/vt-d: Use default dma_direct_* mapping functions for direct mapped devices Tom Murphy
2019-12-21 15:03 ` [PATCH 3/8] iommu/vt-d: Remove IOVA handling code from non-dma_ops path Tom Murphy
2020-03-20 6:30 ` Tom Murphy
2020-03-20 7:06 ` Lu Baolu
2019-12-21 15:03 ` [PATCH 4/8] iommu: Handle freelists when using deferred flushing in iommu drivers Tom Murphy
2019-12-21 15:03 ` [PATCH 5/8] iommu: Add iommu_dma_free_cpu_cached_iovas function Tom Murphy
2019-12-21 15:03 ` [PATCH 6/8] iommu: allow the dma-iommu api to use bounce buffers Tom Murphy
2019-12-24 10:20 ` kbuild test robot
2019-12-21 15:03 ` [PATCH 7/8] iommu/vt-d: Convert intel iommu driver to the iommu ops Tom Murphy
2019-12-21 15:04 ` [PATCH 8/8] DO NOT MERGE: iommu: disable list appending in dma-iommu Tom Murphy
2019-12-23 10:37 ` [PATCH 0/8] Convert the intel iommu driver to the dma-iommu api Jani Nikula
2019-12-23 11:29 ` Robin Murphy
2019-12-23 11:41 ` Jani Nikula
2020-03-20 6:28 ` Tom Murphy
2020-05-29 0:00 ` Logan Gunthorpe
2020-05-29 12:45 ` Christoph Hellwig
2020-05-29 19:05 ` Logan Gunthorpe
2020-05-29 21:11 ` Marek Szyprowski
2020-05-29 21:21 ` Logan Gunthorpe
2020-08-24 0:04 ` Tom Murphy
2020-08-26 18:26 ` Alex Deucher
2020-08-27 21:36 ` Logan Gunthorpe
2020-08-27 23:34 ` Tom Murphy
2020-09-03 20:26 ` Tom Murphy
2020-09-08 15:28 ` [Intel-gfx] " Tvrtko Ursulin
2020-09-08 15:44 ` Logan Gunthorpe
2020-09-08 15:56 ` Tvrtko Ursulin
2020-09-08 22:43 ` Tom Murphy
2020-09-09 9:16 ` Tvrtko Ursulin
2020-09-09 12:55 ` Tvrtko Ursulin
2020-09-10 13:33 ` Tom Murphy
2020-09-10 13:34 ` Tom Murphy
2020-08-26 18:14 ` Robin Murphy [this message]
2020-08-26 18:23 ` Tom Murphy
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