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From: Joerg Roedel <joro@8bytes.org>
To: Jean-Philippe Brucker <jean-philippe@linaro.org>
Cc: robin.murphy@arm.com, iommu@lists.linux-foundation.org, will@kernel.org
Subject: Re: [PATCH] iommu/amd: Clear DMA ops when switching domain
Date: Tue, 18 May 2021 11:19:13 +0200	[thread overview]
Message-ID: <YKOGkY7BpXJeU+Xc@8bytes.org> (raw)
In-Reply-To: <20210422094216.2282097-1-jean-philippe@linaro.org>

On Thu, Apr 22, 2021 at 11:42:19AM +0200, Jean-Philippe Brucker wrote:
> Since commit 08a27c1c3ecf ("iommu: Add support to change default domain
> of an iommu group") a user can switch a device between IOMMU and direct
> DMA through sysfs. This doesn't work for AMD IOMMU at the moment because
> dev->dma_ops is not cleared when switching from a DMA to an identity
> IOMMU domain. The DMA layer thus attempts to use the dma-iommu ops on an
> identity domain, causing an oops:
> 
>   # echo 0000:00:05.0 > /sys/sys/bus/pci/drivers/e1000e/unbind
>   # echo identity > /sys/bus/pci/devices/0000:00:05.0/iommu_group/type
>   # echo 0000:00:05.0 > /sys/sys/bus/pci/drivers/e1000e/bind
>    ...
>   BUG: kernel NULL pointer dereference, address: 0000000000000028
>    ...
>    Call Trace:
>     iommu_dma_alloc
>     e1000e_setup_tx_resources
>     e1000e_open
> 
> Since iommu_change_dev_def_domain() calls probe_finalize() again, clear
> the dma_ops there like Vt-d does.
> 
> Fixes: 08a27c1c3ecf ("iommu: Add support to change default domain of an iommu group")
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>

Applied for v5.13, thanks Jean-Philippe.
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      reply	other threads:[~2021-05-18  9:19 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-22  9:42 [PATCH] iommu/amd: Clear DMA ops when switching domain Jean-Philippe Brucker
2021-05-18  9:19 ` Joerg Roedel [this message]

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