My understanding of the Xilinx ultra scale secure boot process is that the CSU validates the SPK with the PPK. If the SPK is authenticated, the CSU checks to see if the SPK ID that’s associated with the SPK in the boot header is the same as the most recent one burned in eFUSES. How does this ID add security? What is stopping an adversary from loading a compromised SPK with a different ID? Admins and the system would think everything is ok, since the ID rolled over, but it’s in fact the same SPK that’s been compromised.
