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SubjectRe: OMAP and MSM IOMMU driver misbehavior
On 1/23/2012 6:03 AM, Joerg Roedel wrote:
> Hi,
> while reviewing another IOMMU driver again I came across a problem in
> the IOMMU drivers for OMAP and MSM platforms. In both drivers the
> 'domain_destroy with devices attached' case isn't handled correctly.
> OMAP driver seems not to track the devices attached to a domain at all.
> So when a domain is destroyed it can happen that the hardware still
> references old (and already freed) page-table pointers.
> MSM tracks devices in a domain, but does not automatically remove the
> devices from a domain that is about to be destroyed.
> Please tell me when I mis-read the code, otherwise please fix this in
> your drivers so that we can get consistent behavior for IOMMU-API
> users :-)
> Thanks,
> Joerg


I believe your analysis is correct, and it is a legitimate problem. The
driver does keep a list of devices attached to a domain, so it should
not be too hard to detach them. However, I have been quite occupied with
other things lately, but I can try to get to it when I have some free
time. Calling detach_dev on each element is what needs to happen in
theory, but I feel like the main detach_dev code will need to be broken
out to handle the locking properly. Still, it does not sound
particularly difficult.


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