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Subject: Re: [PATCH v5 0/7] Convert the intel iommu driver to the dma-iommu api
From:   Chris Wilson <chris@chris-wilson.co.uk>
Cc:     Ashok Raj <ashok.raj@intel.com>,
        Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
        iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
        Lu Baolu <baolu.lu@linux.intel.com>
To:     Christoph Hellwig <hch@infradead.org>,
        David Woodhouse <dwmw2@infradead.org>,
        Joerg Roedel <joro@8bytes.org>,
        Lu Baolu <baolu.lu@linux.intel.com>,
        Tom Murphy <murphyt7@tcd.ie>, Will Deacon <will@kernel.org>
Date:   Fri, 20 Nov 2020 12:24:01 +0000
Message-ID: <160587504147.19364.17448380121292539865@build.alporthouse.com>
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Quoting Lu Baolu (2020-11-20 10:17:12)
> Lu Baolu (3):
>   iommu: Add quirk for Intel graphic devices in map_sg
>   iommu/vt-d: Update domain geometry in iommu_ops.at(de)tach_dev
>   iommu/vt-d: Cleanup after converting to dma-iommu ops
> 
> Tom Murphy (4):
>   iommu: Handle freelists when using deferred flushing in iommu drivers
>   iommu: Add iommu_dma_free_cpu_cached_iovas()
>   iommu: Allow the dma-iommu api to use bounce buffers
>   iommu/vt-d: Convert intel iommu driver to the iommu ops

Something that may be of interest is that we encounter problems with
using intel-iommu across a PCI remove event. All HW generations fail
with faults like:

DMAR: DRHD: handling fault status reg 3
DMAR: [DMA Write] Request device [00:02.0] PASID ffffffff fault addr 4b822000 [fault reason 02] Present bit in context entry is clear

i.e. they all report missing present bit after re-adding the device to the
iommu group. Forcing an identity map (or disabling iommu) works fine.

I applied this series just on the off-chance it changed the symptoms; it
does not. If you have any ideas on how to chase down this fault, that
would be very useful. We have a few other DMAR faults visible on many
platforms, all "[fault reason 07] Next page table ptr is invalid" that
are again not affected by this series, that we also need to resolve.
-Chris