On 3/30/22 01:04, Dov Murik wrote:
On 30/03/2022 8:20, Gerd Hoffmann wrote:
Hi,
Check if that page is defined; if it is, skip it in the metadata list.
In such case, VMM should fill the page with the hashes content, or
explicitly update it as a zero page (if kernel hashes are not used).
Is it an option to just skip the page unconditionally?
I think in the OvmfPkgX64 build the page is not used, so it probably
doesn't matter whenever it is included or not, and it would make things
a bit less confusing ...
Brijesh,
What would happen if we change this:
%define SNP_SEC_MEM_BASE_DESC_3 (CPUID_BASE + CPUID_SIZE)
to:
%define SNP_SEC_MEM_BASE_DESC_3 (FixedPcdGet32 (PcdOvmfSecPeiTempRamBase))
in OvmfPkg/ResetVector/ResetVector.nasmb ?
It means that the page starting at MEMFD_BASE_ADDRESS+0x00F000 (that is, the
page
that follows the SNP CPUID page) will not be pre-validated by QEMU.
Lets look at the OvmfPkgX64.fdf is
...
0x00E000|0x001000
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCpuidBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCpuidSize
0x010000|0x010000
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamSize
0x020000|0x0E0000
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfPeiMemFvBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfPeiMemFvSize
...
If you change SNP_SEC_MEM_BASE_DESC_3 to start from PcdOvmfPeiMemFvBase
then who will validate the range for PcdOvmfSecPeiTempRamBase -
PcdOvmfPeiMemFvBase ? The SEC phase (Sec/X64/SecEntry.nasm) uses the
PcdOvmfSecPeiTempRamBase. If the memory is not validated prior to use
then it will result in #VC (page-not-validated) and crash the guest BIOS
boot.
-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#88268): https://edk2.groups.io/g/devel/message/88268
Mute This Topic: https://groups.io/mt/90092199/21656
Group Owner: devel+ow...@edk2.groups.io
Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com]
-=-=-=-=-=-=-=-=-=-=-=-
