On 09/07/20 11:55, Mohammed Gamal wrote: >> Ideally we would simply outlaw (3), but it's hard for backward >> compatibility reasons. Second best solution is a flag somewhere >> (msr, cpuid, ...) telling the guest firmware "you can use >> GUEST_MAXPHYADDR, we guarantee it is <= HOST_MAXPHYADDR". > Problem is GUEST_MAXPHYADDR > HOST_MAXPHYADDR is actually a supported > configuration on some setups. Namely when memory encryption is enabled > on AMD CPUs[1]. > It's not that bad since there's two MAXPHYADDRs, the one in CPUID and the one computed internally by the kernel. GUEST_MAXPHYADDR greater than the host CPUID maxphyaddr is never supported. Paolo
