On 4/20/21 5:54 PM, Lendacky, Thomas via groups.io wrote: > From: Tom Lendacky <thomas.lenda...@amd.com> > > BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3345 > > The TPM support in OVMF performs MMIO accesses during the PEI phase. At > this point, MMIO ranges have not been marked un-encyrpted, so an SEV-ES > guest will fail attempting to perform MMIO to an encrypted address. > > Read the PcdTpmBaseAddress and mark the specification defined range > (0x5000 in length) as un-encrypted, to allow an SEV-ES guest to process > the MMIO requests. > > Cc: Laszlo Ersek <ler...@redhat.com> > Cc: Ard Biesheuvel <ardb+tianoc...@kernel.org> > Cc: Jordan Justen <jordan.l.jus...@intel.com> > Cc: Brijesh Singh <brijesh.si...@amd.com> > Cc: James Bottomley <j...@linux.ibm.com> > Cc: Jiewen Yao <jiewen....@intel.com> > Cc: Min Xu <min.m...@intel.com> > Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com> > --- > OvmfPkg/PlatformPei/PlatformPei.inf | 1 + > OvmfPkg/PlatformPei/AmdSev.c | 19 +++++++++++++++++++ > 2 files changed, 20 insertions(+) > > diff --git a/OvmfPkg/PlatformPei/PlatformPei.inf > b/OvmfPkg/PlatformPei/PlatformPei.inf > index 6ef77ba7bb21..de60332e9390 100644 > --- a/OvmfPkg/PlatformPei/PlatformPei.inf > +++ b/OvmfPkg/PlatformPei/PlatformPei.inf > @@ -113,6 +113,7 @@ [Pcd] > > [FixedPcd] > gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress > + gEfiSecurityPkgTokenSpaceGuid.PcdTpmBaseAddress > gEmbeddedTokenSpaceGuid.PcdMemoryTypeEfiACPIMemoryNVS > gEmbeddedTokenSpaceGuid.PcdMemoryTypeEfiACPIReclaimMemory > gEmbeddedTokenSpaceGuid.PcdMemoryTypeEfiReservedMemoryType > diff --git a/OvmfPkg/PlatformPei/AmdSev.c b/OvmfPkg/PlatformPei/AmdSev.c > index dddffdebda4b..d524929f9e10 100644 > --- a/OvmfPkg/PlatformPei/AmdSev.c > +++ b/OvmfPkg/PlatformPei/AmdSev.c > @@ -141,6 +141,7 @@ AmdSevInitialize ( > ) > { > UINT64 EncryptionMask; > + UINT64 TpmBaseAddress; > RETURN_STATUS PcdStatus; > > // > @@ -206,6 +207,24 @@ AmdSevInitialize ( > } > } > > + // > + // PEI TPM support will perform MMIO accesses, be sure this range is not > + // marked encrypted. > + // > + TpmBaseAddress = PcdGet64 (PcdTpmBaseAddress); > + if (TpmBaseAddress != 0) { > + RETURN_STATUS DecryptStatus; > + > + DecryptStatus = MemEncryptSevClearPageEncMask ( > + 0, > + TpmBaseAddress, > + EFI_SIZE_TO_PAGES (0x5000), > + FALSE > + ); > + > + ASSERT_RETURN_ERROR (DecryptStatus); > + } > +
Laszlo, I'm not sure if this is the best way to approach this. It is simple and straight forward and the TCG/TPM support is one of the few (only?) pieces of code that does actual MMIO during PEI that is bitten by not having the address marked as shared/unencrypted. I was also thinking of just marking everything above the highest system memory address below 4GB and up to the PcdOvmfFdBaseAddress as unencrypted. That also works. Once DXE starts it takes care of all this and there isn't an issue in DXE. This is just for PEI. Thoughts? Other suggestions? Thanks, Tom > // > // Check and perform SEV-ES initialization if required. > // > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#74312): https://edk2.groups.io/g/devel/message/74312 Mute This Topic: https://groups.io/mt/82248382/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
