I just ran into this. I have a Lenovo ThinkPad L430 with USB controllers 00:14.0, 00:1a.0, and 00:1d.0, all of which share an RMRR at d9cd8000 according to the Xen logs I got when I assigned them to VMs. But before assuming it was safe to attach these three controllers as a group to an untrusted VM, I wanted to confirm that they don't share an RMRR with any other
devices. Maybe it's common sense to hardware folks that they wouldn't, but I didn't know. I didn't want to actually attach all of the other devices to VMs to check for Xen log messages, so the best method I came up with was:
- In dom0: sudo qubes-dom0-update acpica-tools && acpidump >dump && acpixtract -s RMAD dump
(To all appearances, this is the DMAR table; I don't know why the name is RMAD here. Some strange byte order?)
- Open rmad.dat in a hex editor and decode it manually according to the definitions in http://www.intel.com/content/dam/www/public/us/en/documents/product-specifications/vt-directed-io-spec.pdf
sections 8.1 and 8.4.
I guess no one yet saw a need to write user-friendly tools to view DMAR/RMRR information. :(
And indeed, the RMRR at d9cd8000 is not shared with any other devices, and there are no other shared RMRRs; my "VGA compatible controller", 00:02.0, has a unique RMRR at db800000. I suppose I could submit this information to the HCL, but I don't want to spend any more time right now.