[PATCH v3 2/2] OvmfPkg/ResetVector: Depend on PCD values of the page tables.

[Laszlo Ersek <lersek@redhat.com>]

From: Marvin Häuser <Marvin.Haeuser@outlook.com>

Currently, the values of the page tables' address and size are
hard-coded in the ResetVector. This patch replaces this with a PCD
dependency for the NASM Reset Vector.

Checks for the size have been added to alert the developer to rewrite
the ASM according to the new size, if it has been changed.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Marvin Haeuser <Marvin.Haeuser@outlook.com>
[lersek@redhat.com: simplify patch]
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Marvin Häuser <Marvin.Haeuser@outlook.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
---
 OvmfPkg/ResetVector/ResetVector.inf       |  5 +++++
 OvmfPkg/ResetVector/Ia32/PageTables64.asm | 22 +++++++++-----------
 OvmfPkg/ResetVector/ResetVector.nasmb     | 12 +++++++++--
 3 files changed, 25 insertions(+), 14 deletions(-)

diff --git a/OvmfPkg/ResetVector/ResetVector.inf b/OvmfPkg/ResetVector/ResetVector.inf
index 46610d243ecf..82df438db0dc 100644
--- a/OvmfPkg/ResetVector/ResetVector.inf
+++ b/OvmfPkg/ResetVector/ResetVector.inf
@@ -30,8 +30,13 @@ [Sources]
 
 [Packages]
   MdePkg/MdePkg.dec
+  OvmfPkg/OvmfPkg.dec
   UefiCpuPkg/UefiCpuPkg.dec
 
 [BuildOptions]
    *_*_IA32_NASMB_FLAGS = -I$(WORKSPACE)/UefiCpuPkg/ResetVector/Vtf0/
    *_*_X64_NASMB_FLAGS = -I$(WORKSPACE)/UefiCpuPkg/ResetVector/Vtf0/
+
+[FixedPcd]
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesBase ## CONSUMES
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesSize ## CONSUMES
diff --git a/OvmfPkg/ResetVector/Ia32/PageTables64.asm b/OvmfPkg/ResetVector/Ia32/PageTables64.asm
index b5a4cf8d7187..25c9ebd5f73e 100644
--- a/OvmfPkg/ResetVector/Ia32/PageTables64.asm
+++ b/OvmfPkg/ResetVector/Ia32/PageTables64.asm
@@ -44,10 +44,8 @@ BITS    32
 SetCr3ForPageTables64:
 
     ;
-    ; For OVMF, build some initial page tables at 0x800000-0x806000.
-    ;
-    ; This range should match with PcdOvmfSecPageTablesBase and
-    ; PcdOvmfSecPageTablesSize which are declared in the FDF files.
+    ; For OVMF, build some initial page tables at
+    ; PT_ADDR (0) .. PT_ADDR (0x6000).
     ;
     ; At the end of PEI, the pages tables will be rebuilt into a
     ; more permanent location by DxeIpl.
@@ -56,21 +54,21 @@ SetCr3ForPageTables64:
     mov     ecx, 6 * 0x1000 / 4
     xor     eax, eax
 clearPageTablesMemoryLoop:
-    mov     dword[ecx * 4 + 0x800000 - 4], eax
+    mov     dword[ecx * 4 + PT_ADDR (0) - 4], eax
     loop    clearPageTablesMemoryLoop
 
     ;
     ; Top level Page Directory Pointers (1 * 512GB entry)
     ;
-    mov     dword[0x800000], 0x801000 + PAGE_PDP_ATTR
+    mov     dword[PT_ADDR (0)], PT_ADDR (0x1000) + PAGE_PDP_ATTR
 
     ;
     ; Next level Page Directory Pointers (4 * 1GB entries => 4GB)
     ;
-    mov     dword[0x801000], 0x802000 + PAGE_PDP_ATTR
-    mov     dword[0x801008], 0x803000 + PAGE_PDP_ATTR
-    mov     dword[0x801010], 0x804000 + PAGE_PDP_ATTR
-    mov     dword[0x801018], 0x805000 + PAGE_PDP_ATTR
+    mov     dword[PT_ADDR (0x1000)], PT_ADDR (0x2000) + PAGE_PDP_ATTR
+    mov     dword[PT_ADDR (0x1008)], PT_ADDR (0x3000) + PAGE_PDP_ATTR
+    mov     dword[PT_ADDR (0x1010)], PT_ADDR (0x4000) + PAGE_PDP_ATTR
+    mov     dword[PT_ADDR (0x1018)], PT_ADDR (0x5000) + PAGE_PDP_ATTR
 
     ;
     ; Page Table Entries (2048 * 2MB entries => 4GB)
@@ -81,13 +79,13 @@ pageTableEntriesLoop:
     dec     eax
     shl     eax, 21
     add     eax, PAGE_2M_PDE_ATTR
-    mov     [ecx * 8 + 0x802000 - 8], eax
+    mov     [ecx * 8 + PT_ADDR (0x2000) - 8], eax
     loop    pageTableEntriesLoop
 
     ;
     ; Set CR3 now that the paging structures are available
     ;
-    mov     eax, 0x800000
+    mov     eax, PT_ADDR (0)
     mov     cr3, eax
 
     OneTimeCallRet SetCr3ForPageTables64
diff --git a/OvmfPkg/ResetVector/ResetVector.nasmb b/OvmfPkg/ResetVector/ResetVector.nasmb
index 31ac06ae4a8c..65f39a7d2d52 100644
--- a/OvmfPkg/ResetVector/ResetVector.nasmb
+++ b/OvmfPkg/ResetVector/ResetVector.nasmb
@@ -53,8 +53,16 @@
 %include "Ia32/SearchForSecEntry.asm"
 
 %ifdef ARCH_X64
-%include "Ia32/Flat32ToFlat64.asm"
-%include "Ia32/PageTables64.asm"
+  #include <AutoGen.h>
+
+  %if (FixedPcdGet32 (PcdOvmfSecPageTablesSize) != 0x6000)
+    %error "This implementation inherently depends on PcdOvmfSecPageTablesSize"
+  %endif
+
+  %define PT_ADDR(Offset) (FixedPcdGet32 (PcdOvmfSecPageTablesBase) + (Offset))
+
+  %include "Ia32/Flat32ToFlat64.asm"
+  %include "Ia32/PageTables64.asm"
 %endif
 
 %include "Ia16/Real16ToFlat32.asm"
-- 
2.9.2