From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mga09.intel.com (mga09.intel.com [134.134.136.24])
 by mx.groups.io with SMTP id smtpd.web08.7471.1627364568393799384
 for <devel@edk2.groups.io>;
 Mon, 26 Jul 2021 22:43:03 -0700
Authentication-Results: mx.groups.io;
 dkim=missing; spf=pass (domain: intel.com, ip: 134.134.136.24, mailfrom: min.m.xu@intel.com)
X-IronPort-AV: E=McAfee;i="6200,9189,10057"; a="212361192"
X-IronPort-AV: E=Sophos;i="5.84,272,1620716400"; 
   d="scan'208";a="212361192"
Received: from fmsmga003.fm.intel.com ([10.253.24.29])
  by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Jul 2021 22:43:03 -0700
X-IronPort-AV: E=Sophos;i="5.84,272,1620716400"; 
   d="scan'208";a="505347646"
Received: from mxu9-mobl1.ccr.corp.intel.com ([10.238.4.4])
  by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Jul 2021 22:43:01 -0700
From: "Min Xu" <min.m.xu@intel.com>
To: devel@edk2.groups.io
Cc: Min Xu <min.m.xu@intel.com>,
	Ard Biesheuvel <ardb+tianocore@kernel.org>,
	Jordan Justen <jordan.l.justen@intel.com>,
	Brijesh Singh <brijesh.singh@amd.com>,
	Erdem Aktas <erdemaktas@google.com>,
	James Bottomley <jejb@linux.ibm.com>,
	Jiewen Yao <jiewen.yao@intel.com>,
	Tom Lendacky <thomas.lendacky@amd.com>
Subject: [PATCH V3 07/10] OvmfPkg: Add ReloadFlat32
Date: Tue, 27 Jul 2021 13:42:24 +0800
Message-Id: <9010c96e45fc8b2b7fe5d3bb5baaa9b39c0949cf.1627364333.git.min.m.xu@intel.com>
X-Mailer: git-send-email 2.29.2.windows.2
In-Reply-To: <cover.1627364332.git.min.m.xu@intel.com>
References: <cover.1627364332.git.min.m.xu@intel.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

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

Load the GDT and set the CR0, then jump to Flat 32 protected mode. After
that CR4 is set.

Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Min Xu <min.m.xu@intel.com>
---
 OvmfPkg/ResetVector/Ia32/ReloadFlat32.asm | 44 +++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 OvmfPkg/ResetVector/Ia32/ReloadFlat32.asm

diff --git a/OvmfPkg/ResetVector/Ia32/ReloadFlat32.asm b/OvmfPkg/ResetVector/Ia32/ReloadFlat32.asm
new file mode 100644
index 000000000000..cfcea06fbd11
--- /dev/null
+++ b/OvmfPkg/ResetVector/Ia32/ReloadFlat32.asm
@@ -0,0 +1,44 @@
+;------------------------------------------------------------------------------
+; @file
+;   Load the GDT and set the CR0, then jump to Flat 32 protected mode.
+;
+; Copyright (c) 2021, Intel Corporation. All rights reserved.<BR>
+; SPDX-License-Identifier: BSD-2-Clause-Patent
+;
+;------------------------------------------------------------------------------
+
+%define SEC_DEFAULT_CR0  0x00000023
+%define SEC_DEFAULT_CR4  0x640
+
+BITS    32
+
+;
+; Modified:  EAX, EBX, CR0, CR4, DS, ES, FS, GS, SS
+;
+ReloadFlat32:
+
+    cli
+    mov     ebx, ADDR_OF(gdtr)
+    lgdt    [ebx]
+
+    mov     eax, SEC_DEFAULT_CR0
+    mov     cr0, eax
+
+    jmp     LINEAR_CODE_SEL:dword ADDR_OF(jumpToFlat32BitAndLandHere)
+BITS    32
+jumpToFlat32BitAndLandHere:
+
+    mov     eax, SEC_DEFAULT_CR4
+    mov     cr4, eax
+
+    debugShowPostCode POSTCODE_32BIT_MODE
+
+    mov     ax, LINEAR_SEL
+    mov     ds, ax
+    mov     es, ax
+    mov     fs, ax
+    mov     gs, ax
+    mov     ss, ax
+
+    OneTimeCallRet ReloadFlat32
+
-- 
2.29.2.windows.2