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OvmfPkg: Add the ResetVector in TDX MailBox
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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 <cepingx.sun@intel.com>
reviewed-by: Min Xu <min.m.xu@intel.com>
tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
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@sunceping @mxu9
sunceping authored and mxu9 committed Jan 5, 2024
1 parent 912c70b commit aaac8f2
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Showing 5 changed files with 162 additions and 5 deletions.
1 change: 1 addition & 0 deletions OvmfPkg/Include/IndustryStandard/IntelTdx.h
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Original file line number Diff line number Diff line change
Expand Up @@ -61,6 +61,7 @@ typedef struct {
typedef struct {
UINT8 *RelocateApLoopFuncAddress;
UINTN RelocateApLoopFuncSize;
UINT8 *RelocateApResetVector;
} MP_RELOCATION_MAP;

#pragma pack()
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58 changes: 55 additions & 3 deletions OvmfPkg/TdxDxe/TdxAcpiTable.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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;
Expand Down Expand Up @@ -92,6 +134,7 @@ RelocateMailbox (
ApLoopFunc
));

SetMailboxResetVectorGDT();
//
// Initialize mailbox
//
Expand All @@ -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;
}

Expand Down Expand Up @@ -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;

Expand All @@ -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"));
Expand Down Expand Up @@ -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)) {
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4 changes: 3 additions & 1 deletion OvmfPkg/TdxDxe/TdxAcpiTable.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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>

Expand All @@ -41,7 +43,7 @@ AsmGetRelocationMap (
EFI_PHYSICAL_ADDRESS
EFIAPI
RelocateMailbox (
VOID
EFI_PHYSICAL_ADDRESS *ResetVector
);

/**
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4 changes: 4 additions & 0 deletions OvmfPkg/TdxDxe/TdxDxe.inf
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Original file line number Diff line number Diff line change
Expand Up @@ -71,3 +71,7 @@
gEfiMdeModulePkgTokenSpaceGuid.PcdSetNxForStack
gEfiMdeModulePkgTokenSpaceGuid.PcdEmuVariableNvStoreReserved
gUefiOvmfPkgTokenSpaceGuid.PcdTdxAcceptPageSize
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfWorkAreaBase
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfWorkAreaSize
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesBase
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesSize
100 changes: 99 additions & 1 deletion OvmfPkg/TdxDxe/X64/ApRunLoop.nasm
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down Expand Up @@ -49,6 +59,7 @@ AsmRelocateApMailBoxLoopStart:
test r10, r10
jnz Panic
mov r8, r15
mov qword[rel mailbox_address], rbx

MailBoxLoop:
; Spin until command set
Expand Down Expand Up @@ -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:

Expand All @@ -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

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