On 05.01.2024 16:32, Jeffrey Hugo wrote: > On 1/5/2024 4:22 AM, Jacek Lawrynowicz wrote: >> From: "Wachowski, Karol" <karol.wachowski@xxxxxxxxx> >> >> It is common need to be able to see IOVA/physical to VPU addresses > > Errant double space between "to" and "see" Sure >> mappings. Especially when debugging different kind of memory related >> issues. Lack of such logs forces user to modify and recompile KMD manually. >> >> This commit adds those logs under MMU debug mask which can be turned on >> dynamically with module param during KMD load. > As far as I understand, the preference is to not expose any kind of raw addresses as it is seen as a security issue, and usually the addresses don't have any real value to someone reading logs, etc. I beleive I picked this up from GregKH. > > However, this commit text suggests there is value, and I see that one needs to be root to enable this which could probably be considered a sufficent gate to avoiding the data getting into the wrong hands. > > Is it possible to provide more details as a justification for this? Perhaps an example of a past issue where this data was necessary for debug? There were multiple occasions were these messages were useful: - Debugging IOMMU issues on pre-production hardware - Enabling DevTLB cache on a functional simulator - Debugging performance issues with fragmented buffers There is always some security tradeoff when enabling debug features but in this case it seems to be worth it.
