OvmfPkg: Update Sec to support Tdx

RFC: https://bugzilla.tianocore.org/show_bug.cgi?id=3429

There are below major changes in this commit.

1. SecEntry.nasm
In TDX BSP and APs goes to the same entry point in SecEntry.nasm.

BSP initialize the temporary stack and then jumps to SecMain, just as
legacy Ovmf does.

APs spin in a modified mailbox loop using initial mailbox structure.
Its structure defition is in OvmfPkg/Include/IndustryStandard/IntelTdx.h.
APs wait for command to see if the command is for me. If so execute the
command.

2. Sec/SecMain.c
When host VMM create the Td guest, the system memory informations are
stored in TdHob, which is a memory region described in Tdx metadata.
The system memory region in TdHob should be accepted before it can be
accessed. So the major task of this patch is to process the TdHobList
to accept the memory. After that TDVF follow the standard OVMF flow
and jump to PEI phase.

PcdUse1GPageTable is set to FALSE by default in OvmfPkgX64.dsc. It gives
no chance for Intel TDX to support 1G page table. To support 1G page
table this PCD is set to TRUE in OvmfPkgX64.dsc.

TDX_GUEST_SUPPORTED is defined in OvmfPkgX64.dsc. This macro wraps the
Tdx specific code.

TDX only works on X64, so the code is only valid in X64 arch.

Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Signed-off-by: Min Xu <min.m.xu@intel.com>

3 files changed, 112 insertions, 2 deletions

diff --git a/OvmfPkg/Sec/SecMain.c b/OvmfPkg/Sec/SecMain.c
index 02520e2..ca9717a 100644
--- a/OvmfPkg/Sec/SecMain.c
+++ b/OvmfPkg/Sec/SecMain.c
@@ -26,9 +26,8 @@
 #include <Library/ExtractGuidedSectionLib.h>

 #include <Library/LocalApicLib.h>

 #include <Library/CpuExceptionHandlerLib.h>

-

 #include <Ppi/TemporaryRamSupport.h>

-

+#include <Library/PlatformInitLib.h>

 #include "AmdSev.h"

 

 #define SEC_IDT_ENTRY_COUNT  34

@@ -738,6 +737,20 @@ SecCoreStartupWithStack (
   UINT32                Index;

   volatile UINT8        *Table;

 

+ #if defined (TDX_GUEST_SUPPORTED)

+  if (TdIsEnabled ()) {

+    //

+    // For Td guests, the memory map info is in TdHobLib. It should be processed

+    // first so that the memory is accepted. Otherwise access to the unaccepted

+    // memory will trigger tripple fault.

+    //

+    if (ProcessTdxHobList () != EFI_SUCCESS) {

+      CpuDeadLoop ();

+    }

+  }

+

+ #endif

+

   //

   // To ensure SMM can't be compromised on S3 resume, we must force re-init of

   // the BaseExtractGuidedSectionLib. Since this is before library contructors

@@ -756,6 +769,7 @@ SecCoreStartupWithStack (
   // we use a loop rather than CopyMem.

   //

   IdtTableInStack.PeiService = NULL;

+

   for (Index = 0; Index < SEC_IDT_ENTRY_COUNT; Index++) {

     //

     // Declare the local variables that actually move the data elements as

@@ -813,6 +827,17 @@ SecCoreStartupWithStack (
     AsmEnableCache ();

   }

 

+ #if defined (TDX_GUEST_SUPPORTED)

+  if (TdIsEnabled ()) {

+    //

+    // InitializeCpuExceptionHandlers () should be called in Td guests so that

+    // #VE exceptions can be handled correctly.

+    //

+    InitializeCpuExceptionHandlers (NULL);

+  }

+

+ #endif

+

   DEBUG ((

     DEBUG_INFO,

     "SecCoreStartupWithStack(0x%x, 0x%x)\n",

diff --git a/OvmfPkg/Sec/SecMain.inf b/OvmfPkg/Sec/SecMain.inf
index 95cf002..4b5b089 100644
--- a/OvmfPkg/Sec/SecMain.inf
+++ b/OvmfPkg/Sec/SecMain.inf
@@ -77,6 +77,9 @@
   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfWorkAreaBase

   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecValidatedStart

   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecValidatedEnd

+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbBackupBase

+  gUefiOvmfPkgTokenSpaceGuid.PcdTdxAcceptPageSize

+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfWorkAreaBase

 

 [FeaturePcd]

   gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire

diff --git a/OvmfPkg/Sec/X64/SecEntry.nasm b/OvmfPkg/Sec/X64/SecEntry.nasm
index 1cc680a..4528fec 100644
--- a/OvmfPkg/Sec/X64/SecEntry.nasm
+++ b/OvmfPkg/Sec/X64/SecEntry.nasm
@@ -10,12 +10,17 @@
 ;------------------------------------------------------------------------------

 

 #include <Base.h>

+%include "TdxCommondefs.inc"

 

 DEFAULT REL

 SECTION .text

 

 extern ASM_PFX(SecCoreStartupWithStack)

 

+%macro  tdcall  0

+  db  0x66, 0x0f, 0x01, 0xcc

+%endmacro

+

 ;

 ; SecCore Entry Point

 ;

@@ -36,6 +41,32 @@ global ASM_PFX(_ModuleEntryPoint)
 ASM_PFX(_ModuleEntryPoint):

 

     ;

+    ; Guest type is stored in OVMF_WORK_AREA

+    ;

+    %define OVMF_WORK_AREA        FixedPcdGet32 (PcdOvmfWorkAreaBase)

+    %define VM_GUEST_TYPE_TDX     2

+    mov     eax, OVMF_WORK_AREA

+    cmp     byte[eax], VM_GUEST_TYPE_TDX

+    jne     InitStack

+

+    mov     rax, TDCALL_TDINFO

+    tdcall

+

+    ;

+    ; R8  [31:0]  NUM_VCPUS

+    ;     [63:32] MAX_VCPUS

+    ; R9  [31:0]  VCPU_INDEX

+    ; Td Guest set the VCPU0 as the BSP, others are the APs

+    ; APs jump to spinloop and get released by DXE's MpInitLib

+    ;

+    mov     rax, r9

+    and     rax, 0xffff

+    test    rax, rax

+    jne     ParkAp

+

+InitStack:

+

+    ;

     ; Fill the temporary RAM with the initial stack value.

     ; The loop below will seed the heap as well, but that's harmless.

     ;

@@ -67,3 +98,54 @@ ASM_PFX(_ModuleEntryPoint):
     sub     rsp, 0x20

     call    ASM_PFX(SecCoreStartupWithStack)

 

+    ;

+    ; Note: BSP never gets here. APs will be unblocked by DXE

+    ;

+    ; R8  [31:0]  NUM_VCPUS

+    ;     [63:32] MAX_VCPUS

+    ; R9  [31:0]  VCPU_INDEX

+    ;

+ParkAp:

+

+    mov     rbp,  r9

+

+.do_wait_loop:

+    mov     rsp, FixedPcdGet32 (PcdOvmfSecGhcbBackupBase)

+

+    ;

+    ; register itself in [rsp + CpuArrivalOffset]

+    ;

+    mov       rax, 1

+    lock xadd dword [rsp + CpuArrivalOffset], eax

+    inc       eax

+

+.check_arrival_cnt:

+    cmp       eax, r8d

+    je        .check_command

+    mov       eax, dword[rsp + CpuArrivalOffset]

+    jmp       .check_arrival_cnt

+

+.check_command:

+    mov     eax, dword[rsp + CommandOffset]

+    cmp     eax, MpProtectedModeWakeupCommandNoop

+    je      .check_command

+

+    cmp     eax, MpProtectedModeWakeupCommandWakeup

+    je      .do_wakeup

+

+    ; Don't support this command, so ignore

+    jmp     .check_command

+

+.do_wakeup:

+    ;

+    ; BSP sets these variables before unblocking APs

+    ;   RAX:  WakeupVectorOffset

+    ;   RBX:  Relocated mailbox address

+    ;   RBP:  vCpuId

+    ;

+    mov     rax, 0

+    mov     eax, dword[rsp + WakeupVectorOffset]

+    mov     rbx, [rsp + WakeupArgsRelocatedMailBox]

+    nop

+    jmp     rax

+    jmp     $