OvmfPkg/Sec: Build identity mapped pages in RAM for X64

This is based on MdeModulePkg/Core/DxeIplPeim/X64/VirtualMemory.c.

Previously we would run using page tables built into the
firmware device.

If a flash memory is available, it is unsafe for the page
tables to be stored in memory since the processor may try
to write to the page table data structures.

Additionally, when KVM ROM support is enabled for the
firmware device, then PEI fails to boot when the page
tables are in the firmware device.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@14494 6f19259b-4bc3-4df7-8a09-765794883524

1 files changed, 142 insertions, 2 deletions

diff --git a/OvmfPkg/Sec/SecMain.c b/OvmfPkg/Sec/SecMain.c
index 3882dadd63..56081c9b44 100644
--- a/OvmfPkg/Sec/SecMain.c
+++ b/OvmfPkg/Sec/SecMain.c
@@ -1,7 +1,7 @@
 /** @file
   Main SEC phase code.  Transitions to PEI.
 
-  Copyright (c) 2008 - 2011, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2008 - 2013, Intel Corporation. All rights reserved.<BR>
 
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD License
@@ -31,6 +31,8 @@
 
 #include <Ppi/TemporaryRamSupport.h>
 
+#include <IndustryStandard/X64Paging.h>
+
 #define SEC_IDT_ENTRY_COUNT  34
 
 typedef struct _SEC_IDT_TABLE {
@@ -523,6 +525,137 @@ FindImageBase (
   }
 }
 
+#if defined (MDE_CPU_X64)
+/**
+  Allocates and fills in the Page Directory and Page Table Entries to
+  establish a 1:1 Virtual to Physical mapping.
+
+  @param  Location   Memory to build the page tables in
+
+**/
+VOID
+Create4GbIdentityMappingPageTables (
+  VOID *Location
+  )
+{
+  UINT32                                        RegEax;
+  UINT32                                        RegEdx;
+  EFI_PHYSICAL_ADDRESS                          PageAddress;
+  UINTN                                         IndexOfPml4Entries;
+  UINTN                                         IndexOfPdpEntries;
+  UINTN                                         IndexOfPageDirectoryEntries;
+  UINT32                                        NumberOfPml4EntriesNeeded;
+  UINT32                                        NumberOfPdpEntriesNeeded;
+  X64_PAGE_MAP_AND_DIRECTORY_POINTER            *PageMapLevel4Entry;
+  X64_PAGE_MAP_AND_DIRECTORY_POINTER            *PageMap;
+  X64_PAGE_MAP_AND_DIRECTORY_POINTER            *PageDirectoryPointerEntry;
+  X64_PAGE_TABLE_ENTRY                          *PageDirectoryEntry;
+  UINTN                                         NextAllocAddress;
+  BOOLEAN                                       Page1GSupport;
+  X64_PAGE_TABLE_1G_ENTRY                       *PageDirectory1GEntry;
+
+  Page1GSupport = FALSE;
+  AsmCpuid (0x80000000, &RegEax, NULL, NULL, NULL);
+  if (RegEax >= 0x80000001) {
+    AsmCpuid (0x80000001, NULL, NULL, NULL, &RegEdx);
+    if ((RegEdx & BIT26) != 0) {
+      Page1GSupport = TRUE;
+    }
+  }
+
+  //
+  // Only build entries for the first 4GB at this stage.
+  //
+  NumberOfPml4EntriesNeeded = 1;
+  NumberOfPdpEntriesNeeded = 4;
+
+  NextAllocAddress = (UINTN) Location;
+
+  //
+  // By architecture only one PageMapLevel4 exists - so lets allocate storage for it.
+  //
+  PageMap         = (VOID *) NextAllocAddress;
+  NextAllocAddress += SIZE_4KB;
+
+  PageMapLevel4Entry = PageMap;
+  PageAddress        = 0;
+  for (IndexOfPml4Entries = 0; IndexOfPml4Entries < NumberOfPml4EntriesNeeded; IndexOfPml4Entries++, PageMapLevel4Entry++) {
+    //
+    // Each PML4 entry points to a page of Page Directory Pointer entires.
+    // So lets allocate space for them and fill them in in the IndexOfPdpEntries loop.
+    //
+    PageDirectoryPointerEntry = (VOID *) NextAllocAddress;
+    NextAllocAddress += SIZE_4KB;
+
+    //
+    // Make a PML4 Entry
+    //
+    PageMapLevel4Entry->Uint64 = (UINT64)(UINTN)PageDirectoryPointerEntry;
+    PageMapLevel4Entry->Bits.ReadWrite = 1;
+    PageMapLevel4Entry->Bits.Present = 1;
+
+    if (Page1GSupport) {
+      PageDirectory1GEntry = (VOID *) PageDirectoryPointerEntry;
+
+      for (IndexOfPageDirectoryEntries = 0; IndexOfPageDirectoryEntries < 512; IndexOfPageDirectoryEntries++, PageDirectory1GEntry++, PageAddress += SIZE_1GB) {
+        //
+        // Fill in the Page Directory entries
+        //
+        PageDirectory1GEntry->Uint64 = (UINT64)PageAddress;
+        PageDirectory1GEntry->Bits.ReadWrite = 1;
+        PageDirectory1GEntry->Bits.Present = 1;
+        PageDirectory1GEntry->Bits.MustBe1 = 1;
+      }
+    } else {
+      for (IndexOfPdpEntries = 0; IndexOfPdpEntries < NumberOfPdpEntriesNeeded; IndexOfPdpEntries++, PageDirectoryPointerEntry++) {
+        //
+        // Each Directory Pointer entries points to a page of Page Directory entires.
+        // So allocate space for them and fill them in in the IndexOfPageDirectoryEntries loop.
+        //
+        PageDirectoryEntry = (VOID *) NextAllocAddress;
+        NextAllocAddress += SIZE_4KB;
+
+        //
+        // Fill in a Page Directory Pointer Entries
+        //
+        PageDirectoryPointerEntry->Uint64 = (UINT64)(UINTN)PageDirectoryEntry;
+        PageDirectoryPointerEntry->Bits.ReadWrite = 1;
+        PageDirectoryPointerEntry->Bits.Present = 1;
+
+        for (IndexOfPageDirectoryEntries = 0; IndexOfPageDirectoryEntries < 512; IndexOfPageDirectoryEntries++, PageDirectoryEntry++, PageAddress += SIZE_2MB) {
+          //
+          // Fill in the Page Directory entries
+          //
+          PageDirectoryEntry->Uint64 = (UINT64)PageAddress;
+          PageDirectoryEntry->Bits.ReadWrite = 1;
+          PageDirectoryEntry->Bits.Present = 1;
+          PageDirectoryEntry->Bits.MustBe1 = 1;
+        }
+      }
+
+      for (; IndexOfPdpEntries < 512; IndexOfPdpEntries++, PageDirectoryPointerEntry++) {
+        ZeroMem (
+          PageDirectoryPointerEntry,
+          sizeof(X64_PAGE_MAP_AND_DIRECTORY_POINTER)
+          );
+      }
+    }
+  }
+
+  //
+  // For the PML4 entries we are not using fill in a null entry.
+  //
+  for (; IndexOfPml4Entries < 512; IndexOfPml4Entries++, PageMapLevel4Entry++) {
+    ZeroMem (
+      PageMapLevel4Entry,
+      sizeof (X64_PAGE_MAP_AND_DIRECTORY_POINTER)
+      );
+  }
+
+  AsmWriteCr3 ((UINTN) PageMap);
+}
+#endif
+
 /*
   Find and return Pei Core entry point.
 
@@ -645,7 +778,14 @@ SecCoreStartupWithStack (
   //
   IoWrite8 (0x21, 0xff);
   IoWrite8 (0xA1, 0xff);
-  
+
+#if defined (MDE_CPU_X64)
+  //
+  // Create Identity Mapped Pages in RAM
+  //
+  Create4GbIdentityMappingPageTables (TopOfCurrentStack);
+#endif
+
   //
   // Initialize Debug Agent to support source level debug in SEC/PEI phases before memory ready.
   //