[edk2-devel] [PATCH 21/23] OvmfPkg: Add PcdUse1GPageTable support for TDX

[Min Xu]

RFC： https://bugzilla.tianocore.org/show_bug.cgi?id=3429

Intel TDX uses 1G page table. But PcdUse1GPageTable is set to FALSE
by default in OvmfPkgX64.dsc. It gives no chance to support 1G page
table. To support 1G page table in TDX this PCD is set to TRUE in
OvmfPkgX64.dsc.

>From the code in VirtualMemory.c (MdeModulePkg\Core\DxeIplPeim\X64),
even PcdUse1GPageTable is TRUE, Page1GSupport is FALSE until more
checking is done. So setting PcdUse1GPageTable to TRUE is to give a
chance to check if 1G page table is supported.
  Page1GSupport = FALSE;
  if (PcdGetBool(PcdUse1GPageTable)) {
    AsmCpuid (0x80000000, &RegEax, NULL, NULL, NULL);
    if (RegEax >= 0x80000001) {
      AsmCpuid (0x80000001, NULL, NULL, NULL, &RegEdx);
      if ((RegEdx & BIT26) != 0) {
        Page1GSupport = TRUE;
      }
    }
  }

Cc: Ard Biesheuvel <ardb+tianocore at kernel.org>
Cc: Jordan Justen <jordan.l.justen at intel.com>
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>
Signed-off-by: Min Xu <min.m.xu at intel.com>
---
 OvmfPkg/OvmfPkgX64.dsc | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc
index b2e07233ebd6..97c923423d3f 100644
--- a/OvmfPkg/OvmfPkgX64.dsc
+++ b/OvmfPkg/OvmfPkgX64.dsc
@@ -576,6 +576,10 @@
   gEmbeddedTokenSpaceGuid.PcdMemoryTypeEfiRuntimeServicesCode|0x100
   gEmbeddedTokenSpaceGuid.PcdMemoryTypeEfiRuntimeServicesData|0x100
 
+  #
+  # TDX need 1G PageTable support
+  gEfiMdeModulePkgTokenSpaceGuid.PcdUse1GPageTable|TRUE
+
   #
   # Network Pcds
   #
-- 
2.29.2.windows.2



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