[$] Seeking an acceptable unaccepted memory policy

Operating systems have traditionally used all of the memory that thehardware provides to them. The advent of virtualization and confidentialcomputing is changing this picture somewhat, though; the system can now bemore picky about which memory it will use. Patches to add support forexplicit memory acceptance when running under AMD's Secure EncryptedVirtualization and Secure Nested Paging (SEV-SNP), though, have runinto some turbulence over how to handle a backward-compatibility issue.