[edk2-devel] [PATCH V2 3/4] UefiCpuPkg/ResetVector: Add Main32 entry point in Main.asm

[Min Xu]

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

In Tdx all CPUs "reset" to run on 32-bit protected mode with flat
descriptor (paging disabled). Main32 entry point is added in
UefiCpuPkg/ResetVector/Vtf0/Main.asm so that Main.asm can support
the 32-bit protected mode.

Init32.asm is the 32-bit initialization code. It is a null stub in
UefiCpuPkg. The actual initialization can be implemented in the platform
(OvmfPkg/ResetVector/Ia32/Init32.asm is the example.)

Cc: Eric Dong <eric.dong at intel.com>
Cc: Ray Ni <ray.ni at intel.com>
Cc: Jiewen Yao <jiewen.yao at intel.com>
Signed-off-by: Min Xu <min.m.xu at intel.com>
---
 UefiCpuPkg/ResetVector/Vtf0/Ia32/Init32.asm | 13 +++++++++++++
 UefiCpuPkg/ResetVector/Vtf0/Main.asm        | 14 ++++++++++++++
 UefiCpuPkg/ResetVector/Vtf0/Vtf0.nasmb      |  2 +-
 3 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 UefiCpuPkg/ResetVector/Vtf0/Ia32/Init32.asm

diff --git a/UefiCpuPkg/ResetVector/Vtf0/Ia32/Init32.asm b/UefiCpuPkg/ResetVector/Vtf0/Ia32/Init32.asm
new file mode 100644
index 000000000000..0cdae4a4a84a
--- /dev/null
+++ b/UefiCpuPkg/ResetVector/Vtf0/Ia32/Init32.asm
@@ -0,0 +1,13 @@
+;------------------------------------------------------------------------------
+; @file
+;   32-bit initialization code.
+; Copyright (c) 2021, Intel Corporation. All rights reserved.<BR>
+; SPDX-License-Identifier: BSD-2-Clause-Patent
+;
+;------------------------------------------------------------------------------
+
+BITS 32
+
+Init32:
+    nop
+    OneTimeCallRet Init32
diff --git a/UefiCpuPkg/ResetVector/Vtf0/Main.asm b/UefiCpuPkg/ResetVector/Vtf0/Main.asm
index 19d08482f831..4920c6937e1b 100644
--- a/UefiCpuPkg/ResetVector/Vtf0/Main.asm
+++ b/UefiCpuPkg/ResetVector/Vtf0/Main.asm
@@ -36,6 +36,20 @@ Main16:
 
 BITS    32
 
+%ifdef ARCH_X64
+
+    jmp SearchBfv
+
+;
+; Entry point of Main32
+;
+Main32:
+
+    OneTimeCall Init32
+
+%endif
+
+SearchBfv:
     ;
     ; Search for the Boot Firmware Volume (BFV)
     ;
diff --git a/UefiCpuPkg/ResetVector/Vtf0/Vtf0.nasmb b/UefiCpuPkg/ResetVector/Vtf0/Vtf0.nasmb
index 493738c79c1c..6493b9863c48 100644
--- a/UefiCpuPkg/ResetVector/Vtf0/Vtf0.nasmb
+++ b/UefiCpuPkg/ResetVector/Vtf0/Vtf0.nasmb
@@ -51,7 +51,7 @@
 %include "Ia32/SearchForSecEntry.asm"
 
 %ifdef ARCH_X64
-%include "Ia32/Flat32ToFlat64.asm"
+%include "Ia32/Init32.asm"
 %include "Ia32/PageTables64.asm"
 %endif
 
-- 
2.29.2.windows.2



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