[PATCH 16/18] UefiCpuPkg: Disable MTRR programming for UefiPayloadPkg

["Sean Rhodes" <sean@starlabs.systems>]

From: Patrick Rudolph <patrick.rudolph@9elements.com>

The MTRRs have already been programmed by FSB.

Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
---
 UefiCpuPkg/Library/MtrrLib/MtrrLib.c   | 4 ++++
 UefiCpuPkg/Library/MtrrLib/MtrrLib.inf | 2 +-
 UefiCpuPkg/UefiCpuPkg.dec              | 4 ++++
 UefiCpuPkg/UefiCpuPkg.uni              | 8 ++++++--
 UefiPayloadPkg/UefiPayloadPkg.dsc      | 4 ++++
 5 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/UefiCpuPkg/Library/MtrrLib/MtrrLib.c b/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
index e5c862c83d..8734bae2f0 100644
--- a/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
+++ b/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
@@ -2845,6 +2845,10 @@ IsMtrrSupported (
   CPUID_VERSION_INFO_EDX     Edx;
   MSR_IA32_MTRRCAP_REGISTER  MtrrCap;
 
+  if (PcdGetBool (PcdCpuDisableMtrrProgramming)) {
+    return FALSE;
+  }
+
   //
   // Check CPUID(1).EDX[12] for MTRR capability
   //
diff --git a/UefiCpuPkg/Library/MtrrLib/MtrrLib.inf b/UefiCpuPkg/Library/MtrrLib/MtrrLib.inf
index 4c9ea2def3..afc0bcc724 100644
--- a/UefiCpuPkg/Library/MtrrLib/MtrrLib.inf
+++ b/UefiCpuPkg/Library/MtrrLib/MtrrLib.inf
@@ -15,7 +15,6 @@
   VERSION_STRING                 = 1.0
   LIBRARY_CLASS                  = MtrrLib
 
-
 #
 # The following information is for reference only and not required by the build tools.
 #
@@ -37,4 +36,5 @@
 
 [Pcd]
   gUefiCpuPkgTokenSpaceGuid.PcdCpuNumberOfReservedVariableMtrrs   ## SOMETIMES_CONSUMES
+  gUefiCpuPkgTokenSpaceGuid.PcdCpuDisableMtrrProgramming          ## CONSUMES
 
diff --git a/UefiCpuPkg/UefiCpuPkg.dec b/UefiCpuPkg/UefiCpuPkg.dec
index 7de66fde67..a2a4ecc094 100644
--- a/UefiCpuPkg/UefiCpuPkg.dec
+++ b/UefiCpuPkg/UefiCpuPkg.dec
@@ -217,6 +217,10 @@
   # @Prompt SMM Code Access Check.
   gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmCodeAccessCheckEnable|TRUE|BOOLEAN|0x60000013
 
+  ## Disables MTRR programming in case it's already programmed by FSB.
+  # @Prompt Disable MTRR programming.
+  gUefiCpuPkgTokenSpaceGuid.PcdCpuDisableMtrrProgramming|FALSE|BOOLEAN|0x00000017
+
   ## Specifies the number of variable MTRRs reserved for OS use. The default number of
   #  MTRRs reserved for OS use is 2.
   # @Prompt Number of reserved variable MTRRs.
diff --git a/UefiCpuPkg/UefiCpuPkg.uni b/UefiCpuPkg/UefiCpuPkg.uni
index 219c1963bf..3db0063f50 100644
--- a/UefiCpuPkg/UefiCpuPkg.uni
+++ b/UefiCpuPkg/UefiCpuPkg.uni
@@ -140,9 +140,13 @@
 
 #string STR_gUefiCpuPkgTokenSpaceGuid_PcdCpuHotPlugDataAddress_HELP  #language en-US "Contains the pointer to a CPU Hot Plug Data structure if CPU hot-plug is supported."
 
-#string STR_gUefiCpuPkgTokenSpaceGuid_PcdCpuNumberOfReservedVariableMtrrs_PROMPT  #language en-US "Number of reserved variable MTRRs"
+#string STR_gUefiCpuPkgTokenSpaceGuid_PcdCpuDisableMtrrProgramming_PROMPT  #language en-US "Number of reserved variable MTRRs"
 
-#string STR_gUefiCpuPkgTokenSpaceGuid_PcdCpuNumberOfReservedVariableMtrrs_HELP  #language en-US "Specifies the number of variable MTRRs reserved for OS use."
+#string STR_gUefiCpuPkgTokenSpaceGuid_PcdCpuDisableMtrrProgramming_HELP  #language en-US "Specifies the number of variable MTRRs reserved for OS use."
+
+#string STR_gUefiCpuPkgTokenSpaceGuid_PcdCpuNumberOfReservedVariableMtrrs_PROMPT  #language en-US "Disable MTRR programming."
+
+#string STR_gUefiCpuPkgTokenSpaceGuid_PcdCpuNumberOfReservedVariableMtrrs_HELP  #language en-US "Disables MTRR programming in case it's already programmed by FSB."
 
 #string STR_gUefiCpuPkgTokenSpaceGuid_PcdCpuApLoopMode_PROMPT  #language en-US "The AP wait loop state"
 
diff --git a/UefiPayloadPkg/UefiPayloadPkg.dsc b/UefiPayloadPkg/UefiPayloadPkg.dsc
index c8562d592b..afec9109c1 100644
--- a/UefiPayloadPkg/UefiPayloadPkg.dsc
+++ b/UefiPayloadPkg/UefiPayloadPkg.dsc
@@ -37,6 +37,7 @@
   DEFINE BOOT_MANAGER_ESCAPE          = FALSE
   DEFINE BOOTSPLASH_IMAGE             = FALSE
   DEFINE FOLLOW_BGRT_SPEC             = FALSE
+  DEFINE MTRR_PROGRAMMING             = TRUE
   DEFINE PLATFORM_BOOT_TIMEOUT        = 3
   #
   # SBL:      UEFI payload for Slim Bootloader
@@ -412,6 +413,9 @@
 
   gUefiPayloadPkgTokenSpaceGuid.PcdAbove4GMemory|$(ABOVE_4G_MEMORY)
 
+  # Disable MTRR programming
+  gUefiCpuPkgTokenSpaceGuid.PcdCpuDisableMtrrProgramming|$(MTRR_PROGRAMMING)
+
 [PcdsPatchableInModule.X64]
   gPcAtChipsetPkgTokenSpaceGuid.PcdRtcIndexRegister|$(RTC_INDEX_REGISTER)
   gPcAtChipsetPkgTokenSpaceGuid.PcdRtcTargetRegister|$(RTC_TARGET_REGISTER)
-- 
2.32.0