From: Yao, Jiewen <jiewen.yao@intel.com>
Date: Tue, 15 Dec 2015 04:27:00 +0000 (+0000)
Subject: Fix >4G issue on IDT not restored correctly.
X-Git-Tag: edk2-stable201903~8295
X-Git-Url: https://git.proxmox.com/?p=mirror_edk2.git;a=commitdiff_plain;h=3b567f08f99df24a31fa06750171b7050e08f966

Fix >4G issue on IDT not restored correctly.

Idtr might be changed inside of FSP. 32bit FSP only knows the <4G address.
If IDTR.Base is >4G, FSP can not handle. So we need save/restore IDTR here.
Interrupt is already disabled here, so it is safety to update IDTR.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: "Yao, Jiewen" <jiewen.yao@intel.com>
Reviewed-by: "Ma, Maurice" <maurice.ma@intel.com>
Reviewed-by: "Mudusuru, Giri P" <giri.p.mudusuru@intel.com>
Reviewed-by: "Yarlagadda, Satya P" <satya.p.yarlagadda@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19246 6f19259b-4bc3-4df7-8a09-765794883524
---

diff --git a/IntelFspWrapperPkg/Library/BaseFspApiLib/X64/DispatchExecute.c b/IntelFspWrapperPkg/Library/BaseFspApiLib/X64/DispatchExecute.c
index e2f4422534..360327ed08 100644
--- a/IntelFspWrapperPkg/Library/BaseFspApiLib/X64/DispatchExecute.c
+++ b/IntelFspWrapperPkg/Library/BaseFspApiLib/X64/DispatchExecute.c
@@ -89,6 +89,18 @@ Execute32BitCode (
   IN UINT64      Param1
   )
 {
-  return AsmExecute32BitCode (Function, Param1, 0, &mGdt);
+  EFI_STATUS       Status;
+  IA32_DESCRIPTOR  Idtr;
+
+  //
+  // Idtr might be changed inside of FSP. 32bit FSP only knows the <4G address.
+  // If IDTR.Base is >4G, FSP can not handle. So we need save/restore IDTR here for X64 only.
+  // Interrupt is already disabled here, so it is safety to update IDTR.
+  //
+  AsmReadIdtr (&Idtr);
+  Status = AsmExecute32BitCode (Function, Param1, 0, &mGdt);
+  AsmWriteIdtr (&Idtr);
+
+  return Status;
 }