BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3974

CcProbeLib once was designed to probe the Confidential Computing guest
type by checking the PcdOvmfWorkArea. But this memory is allocated with
either EfiACPIMemoryNVS or EfiBootServicesData. It cannot be accessed
after ExitBootService. Please see the detailed analysis in BZ#3974.

To fix this issue, CcProbeLib is re-designed as 2 implementation:
 - SecPeiCcProbeLib
 - CcProbeLib

In SecPeiCcProbeLib we still check the CC guest type by reading the
PcdOvmfWorkArea. Because it is used in SEC / PEI and we don't worry about
the issues in BZ#3974.

In CcProbeLib we call TdIsEnabled() to check if it is of Tdx guest. To
improve the efficiency the result is cached in a global variable. In
current stage only the Tdx related code is added in CcProbeLib. SEV code
may be added in the future.

The reason why we probe CC guest type in 2 different ways is the global
varialbe. Global variable cannot be used in SEC/PEI and CcProbe is called
very frequently.

Code: https://github.com/mxu9/edk2/tree/CcProbeLib.BZ3974.v1

Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Yuan Yu <yuanyu@google.com>
Signed-off-by: Min Xu <min.m.xu@intel.com>

Min M Xu (2):
  OvmfPkg: Add SecPeiCcProbeLib
  OvmfPkg: Update CcProbeLib

 OvmfPkg/IntelTdx/IntelTdxX64.dsc              |  1 +
 OvmfPkg/Library/CcProbeLib/CcProbeLib.c       | 24 +++++++++++---
 OvmfPkg/Library/CcProbeLib/CcProbeLib.inf     |  5 +--
 OvmfPkg/Library/CcProbeLib/SecPeiCcProbeLib.c | 31 +++++++++++++++++++
 .../Library/CcProbeLib/SecPeiCcProbeLib.inf   | 25 +++++++++++++++
 OvmfPkg/OvmfPkgX64.dsc                        |  3 ++
 6 files changed, 81 insertions(+), 8 deletions(-)
 create mode 100644 OvmfPkg/Library/CcProbeLib/SecPeiCcProbeLib.c
 create mode 100644 OvmfPkg/Library/CcProbeLib/SecPeiCcProbeLib.inf

-- 
2.29.2.windows.2



-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#91132): https://edk2.groups.io/g/devel/message/91132
Mute This Topic: https://groups.io/mt/92223431/1787277
Group Owner: devel+owner@edk2.groups.io
Unsubscribe: https://edk2.groups.io/g/devel/unsub [importer@patchew.org]
-=-=-=-=-=-=-=-=-=-=-=-