On Thu, Feb 22, 2024 at 5:13 PM Paolo Bonzini <pbonz...@redhat.com> wrote: > Also, to clarify the hardware behavior, if hCR4.LA57=0 and host > PhysAddrSize==52, then will guest physical addresses above 2^48 > > 1) cause a reserved #PF in the guest, or > > 2) cause a non-present NPF exit in the hypervisor? > > I remember that several years ago we had a discussion on hCR4.LA57=0 > reducing the address space compared to MAXPHYADDR, but I cannot find the > emails and also at the time I didn't notice GuestPhysAddrSize.
Found them! They say that "according to the design document, CPU will report #NPF if the guest references a PA that is greater than 48 bits while the hypervisor is in 4-level nested paging mode". That's nice, because it's the same behavior as the affected Intel processors. Paolo > Anyhow, basically we would like GuestPhysAddrSize to be "redefined" as > > Maximum usable physical address size in bits. Physical addresses > above this size should not be used, but will not produce a "reserved" > page fault. When this field is zero, all bits up to PhysAddrSize are > usable. This field is expected to be nonzero only on guests where > the hypervisor is using nested paging. -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#115859): https://edk2.groups.io/g/devel/message/115859 Mute This Topic: https://groups.io/mt/104510523/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
