Comment by devttyeu
2 hours ago
Yeah, just started looking at this with my team (we run a cloud with VM instance offering on AMD so this very much caught our eye)
So far seems this is about right:
1. You need platform register access, so seems can't KVM-escape with just this
2. Big question is what about breaking Confidential SEV-SNP guests from the host?
Ok, on 2. and in general this exploit only works on pre-Zen AMD platforms as the repo states in not-so-clear terms.
Zen changed DTC (DRAM Controller) to UMC (Unified Memory Controller), UMC is programmed at boot, and one would hope they figured that locking access to it makes sense when they were adding confidential compute support; Not clear though because there is no public documentation on it, so best we can hope for is some statement from AMD/3rd party researcher saying "this won't work on Zen because X/Y/Z"