On Thu, Jun 24, 2021, Tom Lendacky wrote: > > > > Here's an explanation of the physical address reduction for bare-metal and > > guest. > > > > With MSR 0xC001_0010[SMEE] = 0: > > No reduction in host or guest max physical address. > > > > With MSR 0xC001_0010[SMEE] = 1: > > - Reduction in the host is enumerated by CPUID 0x8000_001F_EBX[11:6], > > regardless of whether SME is enabled in the host or not. So, for example > > on EPYC generation 2 (Rome) you would see a reduction from 48 to 43. > > - There is no reduction in physical address in a legacy guest (non-SEV > > guest), so the guest can use a 48-bit physical address So the behavior I'm seeing is either a CPU bug or user error. Can you verify the unexpected #PF behavior to make sure I'm not doing something stupid? Thanks! > > - There is a reduction of only the encryption bit in an SEV guest, so > > the guest can use up to a 47-bit physical address. This is why the > > Qemu command line sev-guest option uses a value of 1 for the > > "reduced-phys-bits" parameter. > > > > The guest statements all assume that NPT is enabled. > > Thanks, > Tom
