RFC: https://bugzilla.tianocore.org/show_bug.cgi?id=3429
In TDX IA32_ERER is RO to host VMM. It could not be changed.
PcdIa32EferChangeAllowed is added in MdeModulePkg.dec and it is
to be set to FALSE in Tdx guest.
Cc: Jian J Wang <jian.j.w...@intel.com>
Cc: Hao A Wu <hao.a...@intel.com>
Cc: Brijesh Singh <brijesh.si...@amd.com>
Cc: Erdem Aktas <erdemak...@google.com>
Cc: James Bottomley <j...@linux.ibm.com>
Cc: Jiewen Yao <jiewen....@intel.com>
Cc: Tom Lendacky <thomas.lenda...@amd.com>
Cc: Gerd Hoffmann <kra...@redhat.com>
Acked-by: Gerd Hoffmann <kra...@redhat.com>
Signed-off-by: Min Xu <min.m...@intel.com>
---
MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf | 1 +
MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c | 7 +++++++
MdeModulePkg/MdeModulePkg.dec | 5 +++++
3 files changed, 13 insertions(+)
diff --git a/MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf
b/MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf
index 19b8a4c8aefa..106b679b6bd0 100644
--- a/MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf
+++ b/MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf
@@ -117,6 +117,7 @@
gEfiMdeModulePkgTokenSpaceGuid.PcdUse5LevelPageTable ##
SOMETIMES_CONSUMES
gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbBase ##
CONSUMES
gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbSize ##
CONSUMES
+ gEfiMdeModulePkgTokenSpaceGuid.PcdIa32EferChangeAllowed ##
CONSUMES
[Pcd.IA32,Pcd.X64,Pcd.ARM,Pcd.AARCH64]
gEfiMdeModulePkgTokenSpaceGuid.PcdSetNxForStack ##
SOMETIMES_CONSUMES
diff --git a/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c
b/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c
index 0700f310b203..5c647c74e773 100644
--- a/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c
+++ b/MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c
@@ -159,6 +159,13 @@ IsEnableNonExecNeeded (
return FALSE;
}
+ //
+ // Intel TDX sets this flag to FALSE.
+ //
+ if (!PcdGetBool (PcdIa32EferChangeAllowed)) {
+ return FALSE;
+ }
+
//
// XD flag (BIT63) in page table entry is only valid if IA32_EFER.NXE is set.
// Features controlled by Following PCDs need this feature to be enabled.
diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec
index 463e889e9a68..453f2a74b11d 100644
--- a/MdeModulePkg/MdeModulePkg.dec
+++ b/MdeModulePkg/MdeModulePkg.dec
@@ -2138,6 +2138,11 @@
# @Prompt GHCB Pool Size
gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbSize|0|UINT64|0x00030008
+ ## This dynamic PCD indicates if IA32_EFER can be changed. The default value
is TRUE but in
+ # Intel TDX change of IA32_EFER is not allowed.
+ # @Prompt The flag which indicates if IA32_EFER is allowed to be changed.
+
gEfiMdeModulePkgTokenSpaceGuid.PcdIa32EferChangeAllowed|TRUE|BOOLEAN|0x00030009
+
[PcdsDynamicEx]
## This dynamic PCD enables the default variable setting.
# Its value is the default store ID value. The default value is zero as
Standard default.
--
2.29.2.windows.2
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