From 699a2c30cb6e74a55f0c3f67c376460f99c201ed Mon Sep 17 00:00:00 2001
From: Dandan Bi <dandan.bi@intel.com>
Date: Fri, 23 Mar 2018 11:21:56 +0800
Subject: [PATCH] OvmfPkg:Fix VS2012 build failure

Initialize local variable to suppress warning C4701/C4703:
potentially uninitialized local variable/pointer variable.

1.In VirtualMemory.c:
Read of "PageMapLevel4Entry" in SetMemoryEncDe() is only
reached when "PageMapLevel4Entry" is got correctly.

2.In VirtioBlk.c:
Reads (dereferences) of "BufferMapping" and "BufferDeviceAddress"
in SynchronousRequest() are only reached if "BufferSize > 0" *and*
we map the data buffer successfully.

3.In VirtioScsi.c:
Reads (dereferences) of "InDataMapping" and "InDataDeviceAddress",
in VirtioScsiPassThru() are only reached if
"Packet->InTransferLength > 0" on input, *and* we map the
input buffer successfully. The similar reason for "OutDataMapping"
and "OutDataDeviceAddress".

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Dandan Bi <dandan.bi@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
---
 .../Library/BaseMemEncryptSevLib/X64/VirtualMemory.c  |  7 ++++++-
 OvmfPkg/VirtioBlkDxe/VirtioBlk.c                      |  9 ++++++++-
 OvmfPkg/VirtioScsiDxe/VirtioScsi.c                    | 11 ++++++++++-
 3 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.c
index c1bfa35d7a..5d6289df10 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.c
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.c
@@ -2,7 +2,7 @@
 
   Virtual Memory Management Services to set or clear the memory encryption bit
 
-  Copyright (c) 2006 - 2016, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
   Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
 
   This program and the accompanying materials are licensed and made available
@@ -596,6 +596,11 @@ SetMemoryEncDec (
   BOOLEAN                        IsWpEnabled;
   RETURN_STATUS                  Status;
 
+  //
+  // Set PageMapLevel4Entry to suppress incorrect compiler/analyzer warnings.
+  //
+  PageMapLevel4Entry = NULL;
+
   DEBUG ((
     DEBUG_VERBOSE,
     "%a:%a: Cr3Base=0x%Lx Physical=0x%Lx Length=0x%Lx Mode=%a CacheFlush=%u\n",
diff --git a/OvmfPkg/VirtioBlkDxe/VirtioBlk.c b/OvmfPkg/VirtioBlkDxe/VirtioBlk.c
index 5559884345..95e42ef3dc 100644
--- a/OvmfPkg/VirtioBlkDxe/VirtioBlk.c
+++ b/OvmfPkg/VirtioBlkDxe/VirtioBlk.c
@@ -11,7 +11,7 @@
     synchronous requests and EFI_BLOCK_IO_PROTOCOL for now.
 
   Copyright (C) 2012, Red Hat, Inc.
-  Copyright (c) 2012 - 2016, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2012 - 2018, Intel Corporation. All rights reserved.<BR>
   Copyright (c) 2017, AMD Inc, All rights reserved.<BR>
 
   This program and the accompanying materials are licensed and made available
@@ -264,6 +264,13 @@ SynchronousRequest (
 
   BlockSize = Dev->BlockIoMedia.BlockSize;
 
+  //
+  // Set BufferMapping and BufferDeviceAddress to suppress incorrect
+  // compiler/analyzer warnings.
+  //
+  BufferMapping       = NULL;
+  BufferDeviceAddress = 0;
+
   //
   // ensured by VirtioBlkInit()
   //
diff --git a/OvmfPkg/VirtioScsiDxe/VirtioScsi.c b/OvmfPkg/VirtioScsiDxe/VirtioScsi.c
index 1a68f06210..e773ecf7cc 100644
--- a/OvmfPkg/VirtioScsiDxe/VirtioScsi.c
+++ b/OvmfPkg/VirtioScsiDxe/VirtioScsi.c
@@ -26,7 +26,7 @@
     unreasonable for now.
 
   Copyright (C) 2012, Red Hat, Inc.
-  Copyright (c) 2012 - 2014, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2012 - 2018, Intel Corporation. All rights reserved.<BR>
   Copyright (c) 2017, AMD Inc, All rights reserved.<BR>
 
   This program and the accompanying materials are licensed and made available
@@ -455,6 +455,15 @@ VirtioScsiPassThru (
   UINTN                     InDataNumPages;
   BOOLEAN                   OutDataBufferIsMapped;
 
+  //
+  // Set InDataMapping,OutDataMapping,InDataDeviceAddress and OutDataDeviceAddress to
+  // suppress incorrect compiler/analyzer warnings.
+  //
+  InDataMapping        = NULL;
+  OutDataMapping       = NULL;
+  InDataDeviceAddress  = 0;
+  OutDataDeviceAddress = 0;
+
   ZeroMem ((VOID*) &Request, sizeof (Request));
 
   Dev = VIRTIO_SCSI_FROM_PASS_THRU (This);
-- 
2.39.2