[edk2-devel] [PATCH V3 1/1] OvmfPkg/OvmfPkgX64: Adjust load sequence of TdxDxe and AmdSevDxe driver

[Min Xu]

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3904

TdxDxe driver is introduced for Intel TDX feature. Unfortunately, this
driver also breaks boot process in SEV-ES guest. The root cause is in
the PciLib which is imported by TdxDxe driver.

In a SEV-ES guest the AmdSevDxe driver performs a
MemEncryptSevClearMmioPageEncMask() call against the
PcdPciExpressBaseAddress range to mark it shared/unencrypted. However,
the TdxDxe driver is loaded before the AmdSevDxe driver, and the PciLib
in TdxDxe is DxePciLibI440FxQ35 which will access the
PcdPciExpressBaseAddress range. Since the range has not been marked
shared/unencrypted, the #VC handler terminates the guest for trying to
do MMIO to an encrypted region.

Adjusting the load sequence of TdxDxe and AmdSevDxe can fix the issue.

Cc: Brijesh Singh <brijesh.singh at amd.com>
Cc: Erdem Aktas <erdemaktas at google.com>
Cc: James Bottomley <jejb at linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao at intel.com>
Cc: Tom Lendacky <thomas.lendacky at amd.com>
SEV-Tested-by: Tom Lendacky <thomas.lendacky at amd.com>
TDX-Tested-by: Min Xu <min.m.xu at intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao at intel.com>
Signed-off-by: Min Xu <min.m.xu at intel.com>
---
 OvmfPkg/OvmfPkgX64.fdf | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/OvmfPkg/OvmfPkgX64.fdf b/OvmfPkg/OvmfPkgX64.fdf
index 71df28705ea8..6e72cdf3453e 100644
--- a/OvmfPkg/OvmfPkgX64.fdf
+++ b/OvmfPkg/OvmfPkgX64.fdf
@@ -214,8 +214,13 @@ READ_LOCK_STATUS   = TRUE
 APRIORI DXE {
   INF  MdeModulePkg/Universal/DevicePathDxe/DevicePathDxe.inf
   INF  MdeModulePkg/Universal/PCD/Dxe/Pcd.inf
-  INF  OvmfPkg/TdxDxe/TdxDxe.inf
+  # AmdSevDxe must be loaded before TdxDxe. Because in SEV guest AmdSevDxe
+  # driver performs a MemEncryptSevClearMmioPageEncMask() call against the
+  # PcdPciExpressBaseAddress range to mark it shared/unencrypted.
+  # Otherwise #VC handler terminates the guest for trying to do MMIO to an
+  # encrypted region (Since the range has not been marked shared/unencrypted).
   INF  OvmfPkg/AmdSevDxe/AmdSevDxe.inf
+  INF  OvmfPkg/TdxDxe/TdxDxe.inf
 !if $(SMM_REQUIRE) == FALSE
   INF  OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FvbServicesRuntimeDxe.inf
 !endif
-- 
2.29.2.windows.2



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