[Patch V2 0/2] iommu/arm-smmu: Fix races in iommu domain/group creation
Robin Murphy
robin.murphy at arm.com
Mon Aug 2 08:46:37 PDT 2021
On 2021-08-02 16:16, Will Deacon wrote:
> On Fri, Jun 18, 2021 at 02:00:35AM +0530, Ashish Mhetre wrote:
>> Multiple iommu domains and iommu groups are getting created for the devices
>> sharing same SID. It is expected for devices sharing same SID to be in same
>> iommu group and same iommu domain.
>> This is leading to context faults when one device is accessing IOVA from
>> other device which shouldn't be the case for devices sharing same SID.
>> Fix this by protecting iommu domain and iommu group creation with mutexes.
>
> Robin -- any chance you could take a look at these, please? You had some
> comments on the first version which convinced me that they are needed,
> but I couldn't tell whether you wanted to solve this a different way or not.
Sorry, I was lamenting that this came to light due to the
of_iommu_configure() flow being yucky, but that wasn't meant to imply
that there aren't - or couldn't be in future - better reasons for
iommu_probe_device() to be robust against concurrency anyway. I do think
these are legitimate fixes to make in their own right, even if the
current need might get swept back under the rug in future.
I would say, however, that the commit messages seem to focus too much on
the wrong details and aren't overly useful, and patch #2 is missing
Ashish's sign-off.
Thanks,
Robin.
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