OvmfPkg: Add the ResetVector in TDX MailBox

sunceping · mxu9 · commit aaac8f2de726 · 2024-01-04T20:07:50.000-05:00
Refer to the ACPI 6.6 changed, MADT table needs to
provide the ResetVector address to OS and it should
can make the AP to entry a state to check the mailbox.

Signed-off-by: Ceping Sun &lt;cepingx.sun@intel.com&gt;
reviewed-by: Min Xu &lt;min.m.xu@intel.com&gt;
tested-by: Kirill A. Shutemov &lt;kirill.shutemov@linux.intel.com&gt;
diff --git a/OvmfPkg/Include/IndustryStandard/IntelTdx.h b/OvmfPkg/Include/IndustryStandard/IntelTdx.h
@@ -61,6 +61,7 @@ typedef struct {
 typedef struct {
   UINT8    *RelocateApLoopFuncAddress;
   UINTN    RelocateApLoopFuncSize;
+  UINT8    *RelocateApResetVector;
 } MP_RELOCATION_MAP;
 
 #pragma pack()
diff --git a/OvmfPkg/TdxDxe/TdxAcpiTable.c b/OvmfPkg/TdxDxe/TdxAcpiTable.c
@@ -28,6 +28,46 @@
 #include <Uefi.h>
 #include <TdxAcpiTable.h>
 
+
+ IA32_GDT  mGdtEntries[] = {
+  {
+    { 0,      0, 0, 0,   0, 0, 0, 0,   0, 0, 0, 0, 0 }
+  },                                                            /* 0x0:  reserve */
+  {
+    { 0xFFFF, 0, 0, 0xB, 1, 0, 1, 0xF, 0, 0, 1, 1, 0 }
+  },                                                            /* 0x8:  compatibility mode */
+  {
+    { 0xFFFF, 0, 0, 0xB, 1, 0, 1, 0xF, 0, 1, 0, 1, 0 }
+  },                                                            /* 0x10: for long mode */
+  {
+    { 0xFFFF, 0, 0, 0x3, 1, 0, 1, 0xF, 0, 0, 1, 1, 0 }
+  },                                                            /* 0x18: data */
+  {
+    { 0,      0, 0, 0,   0, 0, 0, 0,   0, 0, 0, 0, 0 }
+  },                                                            /* 0x20: reserve */
+};
+
+
+/**
+  At the beginning of ResetVector in OS, the GDT needs to be reloaded.
+**/
+VOID
+SetMailboxResetVectorGDT (
+ VOID
+ )
+{
+  TDX_WORK_AREA  *TdxWorkArea;
+
+  TdxWorkArea = (TDX_WORK_AREA *)(UINTN)FixedPcdGet32 (PcdOvmfWorkAreaBase);
+  ASSERT (TdxWorkArea != NULL);
+  ZeroMem ((VOID *)TdxWorkArea->MailboxGdt.Data, sizeof (TdxWorkArea->MailboxGdt.Data));
+
+  CopyMem((VOID *)TdxWorkArea->MailboxGdt.Data, (VOID *)mGdtEntries, sizeof(mGdtEntries));
+  TdxWorkArea->MailboxGdt.Gdtr.Base = (UINTN)TdxWorkArea->MailboxGdt.Data;
+  TdxWorkArea->MailboxGdt.Gdtr.Limit  = sizeof (mGdtEntries) - 1;
+}
+
+
 /**
   At the beginning of system boot, a 4K-aligned, 4K-size memory (Td mailbox) is
   pre-allocated by host VMM. BSP & APs do the page accept together in that memory
@@ -37,12 +77,14 @@
   memory block which is allocated in the ACPI Nvs memory. APs are waken up and
   spin around the relocated mailbox for further command.
 
+  @param[in, out]  ResetVector      Pointer to the ResetVector
+
   @return   EFI_PHYSICAL_ADDRESS    Address of the relocated mailbox
 **/
 EFI_PHYSICAL_ADDRESS
 EFIAPI
 RelocateMailbox (
-  VOID
+  EFI_PHYSICAL_ADDRESS *ResetVector
   )
 {
   EFI_PHYSICAL_ADDRESS  Address;
@@ -92,6 +134,7 @@ RelocateMailbox (
     ApLoopFunc
     ));
 
+  SetMailboxResetVectorGDT();
   //
   // Initialize mailbox
   //
@@ -115,6 +158,13 @@ RelocateMailbox (
     0
     );
 
+  *ResetVector = (UINT64)ApLoopFunc + (RelocationMap.RelocateApResetVector -
+				       RelocationMap.RelocateApLoopFuncAddress);
+  DEBUG ((
+    DEBUG_INFO,
+    "Ap Relocation: reset_vector %llx\n",
+    *ResetVector
+    ));
   return Address;
 }
 
@@ -142,6 +192,7 @@ AlterAcpiTable (
   UINT8                                                *NewMadtTable;
   UINTN                                                NewMadtTableLength;
   EFI_PHYSICAL_ADDRESS                                 RelocateMailboxAddress;
+  EFI_PHYSICAL_ADDRESS                                 RelocateResetVector;
   EFI_ACPI_6_4_MULTIPROCESSOR_WAKEUP_STRUCTURE         *MadtMpWk;
   EFI_ACPI_1_0_MULTIPLE_APIC_DESCRIPTION_TABLE_HEADER  *MadtHeader;
 
@@ -155,7 +206,7 @@ AlterAcpiTable (
     return;
   }
 
-  RelocateMailboxAddress = RelocateMailbox ();
+  RelocateMailboxAddress = RelocateMailbox (&RelocateResetVector);
   if (RelocateMailboxAddress == 0) {
     ASSERT (FALSE);
     DEBUG ((DEBUG_ERROR, "Failed to relocate Td mailbox\n"));
@@ -186,9 +237,10 @@ AlterAcpiTable (
       MadtMpWk                 = (EFI_ACPI_6_4_MULTIPROCESSOR_WAKEUP_STRUCTURE *)(NewMadtTable + Table->Length);
       MadtMpWk->Type           = EFI_ACPI_6_4_MULTIPROCESSOR_WAKEUP;
       MadtMpWk->Length         = sizeof (EFI_ACPI_6_4_MULTIPROCESSOR_WAKEUP_STRUCTURE);
-      MadtMpWk->MailBoxVersion = 0;
+      MadtMpWk->MailBoxVersion = 1;
       MadtMpWk->Reserved       = 0;
       MadtMpWk->MailBoxAddress = RelocateMailboxAddress;
+      MadtMpWk->ResetVector    = RelocateResetVector;
 
       Status = AcpiTableProtocol->InstallAcpiTable (AcpiTableProtocol, NewMadtTable, NewMadtTableLength, &NewTableKey);
       if (EFI_ERROR (Status)) {
diff --git a/OvmfPkg/TdxDxe/TdxAcpiTable.h b/OvmfPkg/TdxDxe/TdxAcpiTable.h
@@ -18,6 +18,8 @@
 #include <Library/UefiBootServicesTableLib.h>
 #include <Library/DebugLib.h>
 #include <Library/PcdLib.h>
+#include <WorkArea.h>
+
 #include <IndustryStandard/IntelTdx.h>
 #include <IndustryStandard/Acpi.h>
 
@@ -41,7 +43,7 @@ AsmGetRelocationMap (
 EFI_PHYSICAL_ADDRESS
 EFIAPI
 RelocateMailbox (
-  VOID
+  EFI_PHYSICAL_ADDRESS *ResetVector
   );
 
 /**
diff --git a/OvmfPkg/TdxDxe/TdxDxe.inf b/OvmfPkg/TdxDxe/TdxDxe.inf
@@ -71,3 +71,7 @@
   gEfiMdeModulePkgTokenSpaceGuid.PcdSetNxForStack
   gEfiMdeModulePkgTokenSpaceGuid.PcdEmuVariableNvStoreReserved
   gUefiOvmfPkgTokenSpaceGuid.PcdTdxAcceptPageSize
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfWorkAreaBase
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfWorkAreaSize
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesBase
+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesSize
diff --git a/OvmfPkg/TdxDxe/X64/ApRunLoop.nasm b/OvmfPkg/TdxDxe/X64/ApRunLoop.nasm
@@ -16,8 +16,18 @@
 
 DEFAULT REL
 
+SECTION .bss
+global STACK_BASE
+STACK_BASE:
+ resb 1024
+STACK_TOP:
+
 SECTION .text
 
+%define TDX_WORK_AREA_MAILBOX_GDTR   (FixedPcdGet32 (PcdOvmfWorkAreaBase) + 128)
+
+%define PT_ADDR(Offset)                 (FixedPcdGet32 (PcdOvmfSecPageTablesBase) + (Offset))
+
 BITS 64
 
 %define TDVMCALL_EXPOSE_REGS_MASK       0xffec
@@ -49,6 +59,7 @@ AsmRelocateApMailBoxLoopStart:
     test        r10, r10
     jnz         Panic
     mov         r8, r15
+    mov         qword[rel mailbox_address], rbx
 
 MailBoxLoop:
     ; Spin until command set
@@ -81,6 +92,91 @@ MailBoxSleep:
     jmp       $
 Panic:
     ud2
+
+AsmRelocateApResetVector:
+
+.prepareStack:
+    ; The stack can then be used to switch from long mode to compatibility mode
+    mov rsp, STACK_TOP
+
+.loadGDT:
+    cli
+    mov      rax, TDX_WORK_AREA_MAILBOX_GDTR
+    lgdt     [rax]
+
+.loadSwicthModeCode:
+    mov     rcx, dword 0x10    ; load long mode selector
+    shl     rcx, 32
+    lea     rdx, [LongMode]    ; assume address < 4G
+    or      rcx, rdx
+    push    rcx 
+
+    mov     rcx, dword 0x08     ; load compatible mode selector
+    shl     rcx, 32
+    lea     rdx, [Compatible]  ; assume address < 4G
+    or      rcx, rdx
+    push    rcx
+    retf
+
+BITS 32
+Compatible:
+    mov     eax, dword 0x18
+;     ; reload DS/ES/SS to make sure they are correct referred to current GDT
+    mov     ds, ax
+    mov     es, ax
+    mov     ss, ax
+    ; reload the fs and gs
+    mov     fs, ax
+    mov     gs, ax
+
+    ; Must clear the CR4.PCIDE before clearing paging
+    mov     ecx, cr4
+    btc     ecx, 17
+    mov     cr4, ecx
+    ;
+    ; Disable paging
+    ;
+    mov     ecx, cr0
+    btc     ecx, 31
+    mov     cr0, ecx
+    ;
+RestoreCr0:
+    ; Only enable  PE(bit 0), NE(bit 5), ET(bit 4) 0x31
+    mov    eax, dword 0x31
+    mov    cr0, eax
+
+
+    ; Only Enable MCE(bit 6), VMXE(bit 13) 0x2040
+    ; TDX enforeced the VMXE = 1 and mask it in VMM, so not set it.
+RestoreCr4:
+    mov     eax, 0x40
+    mov     cr4, eax
+SetCr3:
+    ;
+    ; Can use the boot page tables since it's reserved
+
+    mov     eax, PT_ADDR (0)
+    mov     cr3, eax
+
+EnablePAE:
+    mov     eax, cr4
+    bts     eax, 5
+    mov     cr4, eax
+
+EnablePaging:
+    mov     eax, cr0
+    bts     eax, 31                     ; set PG
+    mov     cr0, eax                    ; enable paging
+    ; return to LongMode
+    retf
+
+BITS  64
+LongMode:
+    mov      rbx, qword[rel mailbox_address]
+    jmp      AsmRelocateApMailBoxLoopStart
+align 16
+mailbox_address:
+    dq 0
 BITS 64
 AsmRelocateApMailBoxLoopEnd:
 
@@ -89,8 +185,10 @@ AsmRelocateApMailBoxLoopEnd:
 ;-------------------------------------------------------------------------------------
 global ASM_PFX(AsmGetRelocationMap)
 ASM_PFX(AsmGetRelocationMap):
+    ; mov        byte[TDX_WORK_AREA_MB_PGTBL_READY], 0
     lea        rax, [AsmRelocateApMailBoxLoopStart]
     mov        qword [rcx], rax
     mov        qword [rcx +  8h], AsmRelocateApMailBoxLoopEnd - AsmRelocateApMailBoxLoopStart
+    lea        rax, [AsmRelocateApResetVector]
+    mov        qword [rcx + 10h], rax
     ret
-
