[edk2-devel] [PATCH 06/10] OvmfPkg/ResetVector: add 5-level paging support

["Gerd Hoffmann" <kraxel@redhat.com>]

Add macros to check for 5-level paging and gigabyte page support.
Enable 5-level paging for the non-confidential-computing case.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 OvmfPkg/ResetVector/ResetVector.inf       |   1 +
 OvmfPkg/ResetVector/Ia32/PageTables64.asm | 105 ++++++++++++++++++++++
 OvmfPkg/ResetVector/ResetVector.nasmb     |   1 +
 3 files changed, 107 insertions(+)

diff --git a/OvmfPkg/ResetVector/ResetVector.inf b/OvmfPkg/ResetVector/ResetVector.inf
index a4154ca90c28..65f71b05a02e 100644
--- a/OvmfPkg/ResetVector/ResetVector.inf
+++ b/OvmfPkg/ResetVector/ResetVector.inf
@@ -64,3 +64,4 @@ [FixedPcd]
   gUefiOvmfPkgTokenSpaceGuid.PcdQemuHashTableSize
   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsBase
   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSnpSecretsSize
+  gEfiMdeModulePkgTokenSpaceGuid.PcdUse5LevelPageTable
diff --git a/OvmfPkg/ResetVector/Ia32/PageTables64.asm b/OvmfPkg/ResetVector/Ia32/PageTables64.asm
index 84a7b4efc019..825589f31193 100644
--- a/OvmfPkg/ResetVector/Ia32/PageTables64.asm
+++ b/OvmfPkg/ResetVector/Ia32/PageTables64.asm
@@ -101,6 +101,97 @@ BITS    32
     loop    .pageTableEntriesLoop4Level
 %endmacro
 
+;
+; Check whenever 5-level paging can ca used
+;
+; Argument: jump label for 4-level paging
+;
+%macro Check5LevelPaging 1
+    ; check for cpuid leaf 0x07
+    mov     eax, 0x00
+    cpuid
+    cmp     eax, 0x07
+    jb      %1
+
+    ; check for la57 (aka 5-level paging)
+    mov     eax, 0x07
+    mov     ecx, 0x00
+    cpuid
+    bt      ecx, 16
+    jnc     %1
+
+    ; check for cpuid leaf 0x80000001
+    mov     eax, 0x80000000
+    cpuid
+    cmp     eax, 0x80000001
+    jb      %1
+
+    ; check for 1g pages
+    mov     eax, 0x80000001
+    cpuid
+    bt      edx, 26
+    jnc     %1
+%endmacro
+
+;
+; Create page tables for 5-level paging with gigabyte pages
+;
+; Argument: upper 32 bits of the page table entries
+;
+; We have 6 pages available for the early page tables,
+; we use four of them:
+;    PT_ADDR(0)      - level 5 directory
+;    PT_ADDR(0x1000) - level 4 directory
+;    PT_ADDR(0x2000) - level 2 directory (0 -> 1GB)
+;    PT_ADDR(0x3000) - level 3 directory
+;
+; The level 2 directory for the first gigabyte has the same
+; physical address in both 4-level and 5-level paging mode,
+; SevClearPageEncMaskForGhcbPage depends on this.
+;
+; The 1 GB -> 4 GB range is mapped using 1G pages in the
+; level 3 directory.
+;
+%macro CreatePageTables5Level 1
+    ; level 5
+    mov     dword[PT_ADDR (0)], PT_ADDR (0x1000) + PAGE_PDE_DIRECTORY_ATTR
+    mov     dword[PT_ADDR (4)], %1
+
+    ; level 4
+    mov     dword[PT_ADDR (0x1000)], PT_ADDR (0x3000) + PAGE_PDE_DIRECTORY_ATTR
+    mov     dword[PT_ADDR (0x1004)], %1
+
+    ; level 3 (1x -> level 2, 3x 1GB)
+    mov     dword[PT_ADDR (0x3000)], PT_ADDR (0x2000) + PAGE_PDE_DIRECTORY_ATTR
+    mov     dword[PT_ADDR (0x3004)], %1
+    mov     dword[PT_ADDR (0x3008)], (1 << 30) + PAGE_PDE_LARGEPAGE_ATTR
+    mov     dword[PT_ADDR (0x300c)], %1
+    mov     dword[PT_ADDR (0x3010)], (2 << 30) + PAGE_PDE_LARGEPAGE_ATTR
+    mov     dword[PT_ADDR (0x3014)], %1
+    mov     dword[PT_ADDR (0x3018)], (3 << 30) + PAGE_PDE_LARGEPAGE_ATTR
+    mov     dword[PT_ADDR (0x301c)], %1
+
+    ;
+    ; level 2 (512 * 2MB entries => 1GB)
+    ;
+    mov     ecx, 0x200
+.pageTableEntriesLoop5Level:
+    mov     eax, ecx
+    dec     eax
+    shl     eax, 21
+    add     eax, PAGE_PDE_LARGEPAGE_ATTR
+    mov     dword[ecx * 8 + PT_ADDR (0x2000 - 8)], eax
+    mov     dword[(ecx * 8 + PT_ADDR (0x2000 - 8)) + 4], %1
+    loop    .pageTableEntriesLoop5Level
+%endmacro
+
+%macro Enable5LevelPaging 0
+    ; set la57 bit in cr4
+    mov     eax, cr4
+    bts     eax, 12
+    mov     cr4, eax
+%endmacro
+
 ;
 ; Modified:  EAX, EBX, ECX, EDX
 ;
@@ -125,6 +216,12 @@ SetCr3ForPageTables64:
     ; normal (non-CoCo) workflow
     ;
     ClearOvmfPageTables
+%if PG_5_LEVEL
+    Check5LevelPaging Paging4Level
+    CreatePageTables5Level 0
+    jmp SetCr3La57
+Paging4Level:
+%endif
     CreatePageTables4Level 0
     jmp SetCr3
 
@@ -151,6 +248,14 @@ TdxBspInit:
     OneTimeCall TdxPostBuildPageTables
     jmp SetCr3
 
+    ;
+    ; common workflow
+    ;
+%if PG_5_LEVEL
+SetCr3La57:
+    Enable5LevelPaging
+%endif
+
 SetCr3:
     ;
     ; Set CR3 now that the paging structures are available
diff --git a/OvmfPkg/ResetVector/ResetVector.nasmb b/OvmfPkg/ResetVector/ResetVector.nasmb
index 366a70fb9992..2bd80149e58b 100644
--- a/OvmfPkg/ResetVector/ResetVector.nasmb
+++ b/OvmfPkg/ResetVector/ResetVector.nasmb
@@ -53,6 +53,7 @@
 
 %define WORK_AREA_GUEST_TYPE          (FixedPcdGet32 (PcdOvmfWorkAreaBase))
 %define PT_ADDR(Offset)               (FixedPcdGet32 (PcdOvmfSecPageTablesBase) + (Offset))
+%define PG_5_LEVEL                    (FixedPcdGetBool (PcdUse5LevelPageTable))
 
 %define GHCB_PT_ADDR                  (FixedPcdGet32 (PcdOvmfSecGhcbPageTableBase))
 %define GHCB_BASE                     (FixedPcdGet32 (PcdOvmfSecGhcbBase))
-- 
2.43.2



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