On September 24, 2021 6:58 PM, Brijesh Singh wrote: > Hi Min, > > On 9/21/21 4:05 AM, Min Xu wrote: > > ; > > ; Modified: EAX, EBX, ECX, EDX > > ; > > SetCr3ForPageTables64: > > - > > - ; Clear the WorkArea header. The SEV probe routines will populate the > > - ; work area when detected. > > - mov byte[WORK_AREA_GUEST_TYPE], 0 > > Why you are removing the above block ? The workarea hdr must be initialized > to zero, its not safe to assume that the guest memory is zero'ed in the non- > encrypted case. > Hi, Brijesh Please see below explanation (It is in the commit message) - In Main16 entry point, after TransitionFromReal16To32BitFlat, WORK_AREA_GUEST_TYPE is cleared to 0. WORK_AREA_GUEST_TYPE was previously cleared in SetCr3ForPageTables64 (see commit ab77b60). This doesn't work after TDX is introduced in Ovmf. It is because all TDX CPUs (BSP and APs) start to run from 0xfffffff0. In previous code WORK_AREA_GUEST_TYPE will be cleared multi-times in TDX guest. So for SEV and Legacy guest it is moved to Main16 entry point (after TransitionFromReal16To32BitFlat). For TDX guest WORK_AREA_GUEST_TYPE is cleared and set in InitTdxWorkarea >
Thanks! Min -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#81110): https://edk2.groups.io/g/devel/message/81110 Mute This Topic: https://groups.io/mt/85761661/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
