[edk2-devel] [PATCH V10 06/47] OvmfPkg: Extend VmgExitLib to handle #VE exception
Min Xu
min.m.xu at intel.com
Thu Mar 24 00:09:52 UTC 2022
RFC： https://bugzilla.tianocore.org/show_bug.cgi?id=3429
The base VmgExitLib library provides a default limited interface to
handle #VE exception. To provide full support, the OVMF version of
VmgExitLib is extended to provide full support of #VE handler.
Cc: Ard Biesheuvel <ardb+tianocore at kernel.org>
Cc: Jiewen Yao <jiewen.yao at intel.com>
Cc: Jordan Justen <jordan.l.justen at intel.com>
Cc: Brijesh Singh <brijesh.singh at amd.com>
Cc: Erdem Aktas <erdemaktas at google.com>
Cc: James Bottomley <jejb at linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao at intel.com>
Cc: Tom Lendacky <thomas.lendacky at amd.com>
Cc: Gerd Hoffmann <kraxel at redhat.com>
Acked-by: Gerd Hoffmann <kraxel at redhat.com>
Signed-off-by: Min Xu <min.m.xu at intel.com>
---
OvmfPkg/Library/VmgExitLib/SecVmgExitLib.inf | 3 +-
OvmfPkg/Library/VmgExitLib/VmTdExitHandler.h | 32 +
.../Library/VmgExitLib/VmTdExitVeHandler.c | 559 ++++++++++++++++++
OvmfPkg/Library/VmgExitLib/VmgExitLib.inf | 2 +
.../Library/VmgExitLib/X64/TdVmcallCpuid.nasm | 146 +++++
5 files changed, 741 insertions(+), 1 deletion(-)
create mode 100644 OvmfPkg/Library/VmgExitLib/VmTdExitHandler.h
create mode 100644 OvmfPkg/Library/VmgExitLib/VmTdExitVeHandler.c
create mode 100644 OvmfPkg/Library/VmgExitLib/X64/TdVmcallCpuid.nasm
diff --git a/OvmfPkg/Library/VmgExitLib/SecVmgExitLib.inf b/OvmfPkg/Library/VmgExitLib/SecVmgExitLib.inf
index 78207fa0f9c9..f9bd4974f6dc 100644
--- a/OvmfPkg/Library/VmgExitLib/SecVmgExitLib.inf
+++ b/OvmfPkg/Library/VmgExitLib/SecVmgExitLib.inf
@@ -25,6 +25,8 @@
VmgExitVcHandler.c
VmgExitVcHandler.h
SecVmgExitVcHandler.c
+ VmTdExitVeHandler.c
+ X64/TdVmcallCpuid.nasm
[Packages]
MdePkg/MdePkg.dec
@@ -44,4 +46,3 @@
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbBackupSize
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCpuidBase
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCpuidSize
-
diff --git a/OvmfPkg/Library/VmgExitLib/VmTdExitHandler.h b/OvmfPkg/Library/VmgExitLib/VmTdExitHandler.h
new file mode 100644
index 000000000000..7eacd0872f46
--- /dev/null
+++ b/OvmfPkg/Library/VmgExitLib/VmTdExitHandler.h
@@ -0,0 +1,32 @@
+/** @file
+
+ Copyright (c) 2020 - 2021, Intel Corporation. All rights reserved.<BR>
+ SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef VMTD_EXIT_HANDLER_H_
+#define VMTD_EXIT_HANDLER_H_
+
+#include <Base.h>
+#include <Uefi.h>
+
+/**
+ This function enable the TD guest to request the VMM to emulate CPUID
+ operation, especially for non-architectural, CPUID leaves.
+
+ @param[in] Eax Main leaf of the CPUID
+ @param[in] Ecx Sub-leaf of the CPUID
+ @param[out] Results Returned result of CPUID operation
+
+ @return EFI_SUCCESS
+**/
+EFI_STATUS
+EFIAPI
+TdVmCallCpuid (
+ IN UINT64 Eax,
+ IN UINT64 Ecx,
+ OUT VOID *Results
+ );
+
+#endif
diff --git a/OvmfPkg/Library/VmgExitLib/VmTdExitVeHandler.c b/OvmfPkg/Library/VmgExitLib/VmTdExitVeHandler.c
new file mode 100644
index 000000000000..b73e877c093b
--- /dev/null
+++ b/OvmfPkg/Library/VmgExitLib/VmTdExitVeHandler.c
@@ -0,0 +1,559 @@
+/** @file
+
+ Copyright (c) 2021, Intel Corporation. All rights reserved.<BR>
+
+ SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <Library/BaseLib.h>
+#include <Library/DebugLib.h>
+#include "VmTdExitHandler.h"
+#include <Library/VmgExitLib.h>
+#include <Library/BaseMemoryLib.h>
+#include <IndustryStandard/Tdx.h>
+#include <IndustryStandard/InstructionParsing.h>
+
+typedef union {
+ struct {
+ UINT32 Eax;
+ UINT32 Edx;
+ } Regs;
+ UINT64 Val;
+} MSR_DATA;
+
+typedef union {
+ UINT8 Val;
+ struct {
+ UINT8 B : 1;
+ UINT8 X : 1;
+ UINT8 R : 1;
+ UINT8 W : 1;
+ } Bits;
+} REX;
+
+typedef union {
+ UINT8 Val;
+ struct {
+ UINT8 Rm : 3;
+ UINT8 Reg : 3;
+ UINT8 Mod : 2;
+ } Bits;
+} MODRM;
+
+typedef struct {
+ UINT64 Regs[4];
+} CPUID_DATA;
+
+/**
+ Handle an CPUID event.
+
+ Use the TDVMCALL instruction to handle cpuid #ve
+
+ @param[in, out] Regs x64 processor context
+ @param[in] Veinfo VE Info
+
+ @retval 0 Event handled successfully
+ @return New exception value to propagate
+**/
+STATIC
+UINT64
+EFIAPI
+CpuIdExit (
+ IN EFI_SYSTEM_CONTEXT_X64 *Regs,
+ IN TDCALL_VEINFO_RETURN_DATA *Veinfo
+ )
+{
+ CPUID_DATA CpuIdData;
+ UINT64 Status;
+
+ Status = TdVmCallCpuid (Regs->Rax, Regs->Rcx, &CpuIdData);
+
+ if (Status == 0) {
+ Regs->Rax = CpuIdData.Regs[0];
+ Regs->Rbx = CpuIdData.Regs[1];
+ Regs->Rcx = CpuIdData.Regs[2];
+ Regs->Rdx = CpuIdData.Regs[3];
+ }
+
+ return Status;
+}
+
+/**
+ Handle an IO event.
+
+ Use the TDVMCALL instruction to handle either an IO read or an IO write.
+
+ @param[in, out] Regs x64 processor context
+ @param[in] Veinfo VE Info
+
+ @retval 0 Event handled successfully
+ @return New exception value to propagate
+**/
+STATIC
+UINT64
+EFIAPI
+IoExit (
+ IN OUT EFI_SYSTEM_CONTEXT_X64 *Regs,
+ IN TDCALL_VEINFO_RETURN_DATA *Veinfo
+ )
+{
+ BOOLEAN Write;
+ UINTN Size;
+ UINTN Port;
+ UINT64 Val;
+ UINT64 RepCnt;
+ UINT64 Status;
+
+ Val = 0;
+ Write = Veinfo->ExitQualification.Io.Direction ? FALSE : TRUE;
+ Size = Veinfo->ExitQualification.Io.Size + 1;
+ Port = Veinfo->ExitQualification.Io.Port;
+
+ if (Veinfo->ExitQualification.Io.String) {
+ //
+ // If REP is set, get rep-cnt from Rcx
+ //
+ RepCnt = Veinfo->ExitQualification.Io.Rep ? Regs->Rcx : 1;
+
+ while (RepCnt) {
+ Val = 0;
+ if (Write == TRUE) {
+ CopyMem (&Val, (VOID *)Regs->Rsi, Size);
+ Regs->Rsi += Size;
+ }
+
+ Status = TdVmCall (EXIT_REASON_IO_INSTRUCTION, Size, Write, Port, Val, (Write ? NULL : &Val));
+ if (Status != 0) {
+ break;
+ }
+
+ if (Write == FALSE) {
+ CopyMem ((VOID *)Regs->Rdi, &Val, Size);
+ Regs->Rdi += Size;
+ }
+
+ if (Veinfo->ExitQualification.Io.Rep) {
+ Regs->Rcx -= 1;
+ }
+
+ RepCnt -= 1;
+ }
+ } else {
+ if (Write == TRUE) {
+ CopyMem (&Val, (VOID *)&Regs->Rax, Size);
+ }
+
+ Status = TdVmCall (EXIT_REASON_IO_INSTRUCTION, Size, Write, Port, Val, (Write ? NULL : &Val));
+ if ((Status == 0) && (Write == FALSE)) {
+ CopyMem ((VOID *)&Regs->Rax, &Val, Size);
+ }
+ }
+
+ return Status;
+}
+
+/**
+ Handle an READ MSR event.
+
+ Use the TDVMCALL instruction to handle msr read
+
+ @param[in, out] Regs x64 processor context
+ @param[in] Veinfo VE Info
+
+ @retval 0 Event handled successfully
+ @return New exception value to propagate
+**/
+STATIC
+UINT64
+ReadMsrExit (
+ IN OUT EFI_SYSTEM_CONTEXT_X64 *Regs,
+ IN TDCALL_VEINFO_RETURN_DATA *Veinfo
+ )
+{
+ MSR_DATA Data;
+ UINT64 Status;
+
+ Status = TdVmCall (EXIT_REASON_MSR_READ, Regs->Rcx, 0, 0, 0, &Data);
+ if (Status == 0) {
+ Regs->Rax = Data.Regs.Eax;
+ Regs->Rdx = Data.Regs.Edx;
+ }
+
+ return Status;
+}
+
+/**
+ Handle an WRITE MSR event.
+
+ Use the TDVMCALL instruction to handle msr write
+
+ @param[in, out] Regs x64 processor context
+ @param[in] Veinfo VE Info
+
+ @retval 0 Event handled successfully
+ @return New exception value to propagate
+**/
+STATIC
+UINT64
+WriteMsrExit (
+ IN OUT EFI_SYSTEM_CONTEXT_X64 *Regs,
+ IN TDCALL_VEINFO_RETURN_DATA *Veinfo
+ )
+{
+ UINT64 Status;
+ MSR_DATA Data;
+
+ Data.Regs.Eax = (UINT32)Regs->Rax;
+ Data.Regs.Edx = (UINT32)Regs->Rdx;
+
+ Status = TdVmCall (EXIT_REASON_MSR_WRITE, Regs->Rcx, Data.Val, 0, 0, NULL);
+
+ return Status;
+}
+
+STATIC
+VOID
+EFIAPI
+TdxDecodeInstruction (
+ IN UINT8 *Rip
+ )
+{
+ UINTN i;
+
+ DEBUG ((DEBUG_INFO, "TDX: #TD[EPT] instruction (%p):", Rip));
+ for (i = 0; i < 15; i++) {
+ DEBUG ((DEBUG_INFO, "%02x:", Rip[i]));
+ }
+
+ DEBUG ((DEBUG_INFO, "\n"));
+}
+
+#define TDX_DECODER_BUG_ON(x) \
+ if ((x)) { \
+ TdxDecodeInstruction(Rip); \
+ TdVmCall(TDVMCALL_HALT, 0, 0, 0, 0, 0); \
+ }
+
+STATIC
+UINT64 *
+EFIAPI
+GetRegFromContext (
+ IN EFI_SYSTEM_CONTEXT_X64 *Regs,
+ IN UINTN RegIndex
+ )
+{
+ switch (RegIndex) {
+ case 0: return &Regs->Rax;
+ break;
+ case 1: return &Regs->Rcx;
+ break;
+ case 2: return &Regs->Rdx;
+ break;
+ case 3: return &Regs->Rbx;
+ break;
+ case 4: return &Regs->Rsp;
+ break;
+ case 5: return &Regs->Rbp;
+ break;
+ case 6: return &Regs->Rsi;
+ break;
+ case 7: return &Regs->Rdi;
+ break;
+ case 8: return &Regs->R8;
+ break;
+ case 9: return &Regs->R9;
+ break;
+ case 10: return &Regs->R10;
+ break;
+ case 11: return &Regs->R11;
+ break;
+ case 12: return &Regs->R12;
+ break;
+ case 13: return &Regs->R13;
+ break;
+ case 14: return &Regs->R14;
+ break;
+ case 15: return &Regs->R15;
+ break;
+ }
+
+ return NULL;
+}
+
+/**
+ Handle an MMIO event.
+
+ Use the TDVMCALL instruction to handle either an mmio read or an mmio write.
+
+ @param[in, out] Regs x64 processor context
+ @param[in] Veinfo VE Info
+
+ @retval 0 Event handled successfully
+ @return New exception value to propagate
+**/
+STATIC
+INTN
+EFIAPI
+MmioExit (
+ IN OUT EFI_SYSTEM_CONTEXT_X64 *Regs,
+ IN TDCALL_VEINFO_RETURN_DATA *Veinfo
+ )
+{
+ UINT64 Status;
+ UINT32 MmioSize;
+ UINT32 RegSize;
+ UINT8 OpCode;
+ BOOLEAN SeenRex;
+ UINT64 *Reg;
+ UINT8 *Rip;
+ UINT64 Val;
+ UINT32 OpSize;
+ MODRM ModRm;
+ REX Rex;
+
+ Rip = (UINT8 *)Regs->Rip;
+ Val = 0;
+ Rex.Val = 0;
+ SeenRex = FALSE;
+
+ //
+ // Default to 32bit transfer
+ //
+ OpSize = 4;
+
+ do {
+ OpCode = *Rip++;
+ if (OpCode == 0x66) {
+ OpSize = 2;
+ } else if ((OpCode == 0x64) || (OpCode == 0x65) || (OpCode == 0x67)) {
+ continue;
+ } else if ((OpCode >= 0x40) && (OpCode <= 0x4f)) {
+ SeenRex = TRUE;
+ Rex.Val = OpCode;
+ } else {
+ break;
+ }
+ } while (TRUE);
+
+ //
+ // We need to have at least 2 more bytes for this instruction
+ //
+ TDX_DECODER_BUG_ON (((UINT64)Rip - Regs->Rip) > 13);
+
+ OpCode = *Rip++;
+ //
+ // Two-byte opecode, get next byte
+ //
+ if (OpCode == 0x0F) {
+ OpCode = *Rip++;
+ }
+
+ switch (OpCode) {
+ case 0x88:
+ case 0x8A:
+ case 0xB6:
+ MmioSize = 1;
+ break;
+ case 0xB7:
+ MmioSize = 2;
+ break;
+ default:
+ MmioSize = Rex.Bits.W ? 8 : OpSize;
+ break;
+ }
+
+ /* Punt on AH/BH/CH/DH unless it shows up. */
+ ModRm.Val = *Rip++;
+ TDX_DECODER_BUG_ON (MmioSize == 1 && ModRm.Bits.Reg > 4 && !SeenRex && OpCode != 0xB6);
+ Reg = GetRegFromContext (Regs, ModRm.Bits.Reg | ((int)Rex.Bits.R << 3));
+ TDX_DECODER_BUG_ON (!Reg);
+
+ if (ModRm.Bits.Rm == 4) {
+ ++Rip; /* SIB byte */
+ }
+
+ if ((ModRm.Bits.Mod == 2) || ((ModRm.Bits.Mod == 0) && (ModRm.Bits.Rm == 5))) {
+ Rip += 4; /* DISP32 */
+ } else if (ModRm.Bits.Mod == 1) {
+ ++Rip; /* DISP8 */
+ }
+
+ switch (OpCode) {
+ case 0x88:
+ case 0x89:
+ CopyMem ((void *)&Val, Reg, MmioSize);
+ Status = TdVmCall (TDVMCALL_MMIO, MmioSize, 1, Veinfo->GuestPA, Val, 0);
+ break;
+ case 0xC7:
+ CopyMem ((void *)&Val, Rip, OpSize);
+ Status = TdVmCall (TDVMCALL_MMIO, MmioSize, 1, Veinfo->GuestPA, Val, 0);
+ Rip += OpSize;
+ default:
+ //
+ // 32-bit write registers are zero extended to the full register
+ // Hence 'MOVZX r[32/64], r/m16' is
+ // hardcoded to reg size 8, and the straight MOV case has a reg
+ // size of 8 in the 32-bit read case.
+ //
+ switch (OpCode) {
+ case 0xB6:
+ RegSize = Rex.Bits.W ? 8 : OpSize;
+ break;
+ case 0xB7:
+ RegSize = 8;
+ break;
+ default:
+ RegSize = MmioSize == 4 ? 8 : MmioSize;
+ break;
+ }
+
+ Status = TdVmCall (TDVMCALL_MMIO, MmioSize, 0, Veinfo->GuestPA, 0, &Val);
+ if (Status == 0) {
+ ZeroMem (Reg, RegSize);
+ CopyMem (Reg, (void *)&Val, MmioSize);
+ }
+ }
+
+ if (Status == 0) {
+ TDX_DECODER_BUG_ON (((UINT64)Rip - Regs->Rip) > 15);
+
+ //
+ // We change instruction length to reflect true size so handler can
+ // bump rip
+ //
+ Veinfo->ExitInstructionLength = (UINT32)((UINT64)Rip - Regs->Rip);
+ }
+
+ return Status;
+}
+
+/**
+ Handle a #VE exception.
+
+ Performs the necessary processing to handle a #VE exception.
+
+ @param[in, out] ExceptionType Pointer to an EFI_EXCEPTION_TYPE to be set
+ as value to use on error.
+ @param[in, out] SystemContext Pointer to EFI_SYSTEM_CONTEXT
+
+ @retval EFI_SUCCESS Exception handled
+ @retval EFI_UNSUPPORTED #VE not supported, (new) exception value to
+ propagate provided
+ @retval EFI_PROTOCOL_ERROR #VE handling failed, (new) exception value to
+ propagate provided
+
+**/
+EFI_STATUS
+EFIAPI
+VmTdExitHandleVe (
+ IN OUT EFI_EXCEPTION_TYPE *ExceptionType,
+ IN OUT EFI_SYSTEM_CONTEXT SystemContext
+ )
+{
+ UINT64 Status;
+ TD_RETURN_DATA ReturnData;
+ EFI_SYSTEM_CONTEXT_X64 *Regs;
+
+ Regs = SystemContext.SystemContextX64;
+ Status = TdCall (TDCALL_TDGETVEINFO, 0, 0, 0, &ReturnData);
+ ASSERT (Status == 0);
+ if (Status != 0) {
+ DEBUG ((DEBUG_ERROR, "#VE happened. TDGETVEINFO failed with Status = 0x%llx\n", Status));
+ TdVmCall (TDVMCALL_HALT, 0, 0, 0, 0, 0);
+ }
+
+ switch (ReturnData.VeInfo.ExitReason) {
+ case EXIT_REASON_CPUID:
+ Status = CpuIdExit (Regs, &ReturnData.VeInfo);
+ DEBUG ((
+ DEBUG_VERBOSE,
+ "CPUID #VE happened, ExitReasion is %d, ExitQualification = 0x%x.\n",
+ ReturnData.VeInfo.ExitReason,
+ ReturnData.VeInfo.ExitQualification.Val
+ ));
+ break;
+
+ case EXIT_REASON_HLT:
+ Status = TdVmCall (EXIT_REASON_HLT, 0, 0, 0, 0, 0);
+ break;
+
+ case EXIT_REASON_IO_INSTRUCTION:
+ Status = IoExit (Regs, &ReturnData.VeInfo);
+ DEBUG ((
+ DEBUG_VERBOSE,
+ "IO_Instruction #VE happened, ExitReasion is %d, ExitQualification = 0x%x.\n",
+ ReturnData.VeInfo.ExitReason,
+ ReturnData.VeInfo.ExitQualification.Val
+ ));
+ break;
+
+ case EXIT_REASON_MSR_READ:
+ Status = ReadMsrExit (Regs, &ReturnData.VeInfo);
+ DEBUG ((
+ DEBUG_VERBOSE,
+ "RDMSR #VE happened, ExitReasion is %d, ExitQualification = 0x%x. Regs->Rcx=0x%llx, Status = 0x%llx\n",
+ ReturnData.VeInfo.ExitReason,
+ ReturnData.VeInfo.ExitQualification.Val,
+ Regs->Rcx,
+ Status
+ ));
+ break;
+
+ case EXIT_REASON_MSR_WRITE:
+ Status = WriteMsrExit (Regs, &ReturnData.VeInfo);
+ DEBUG ((
+ DEBUG_VERBOSE,
+ "WRMSR #VE happened, ExitReasion is %d, ExitQualification = 0x%x. Regs->Rcx=0x%llx, Status = 0x%llx\n",
+ ReturnData.VeInfo.ExitReason,
+ ReturnData.VeInfo.ExitQualification.Val,
+ Regs->Rcx,
+ Status
+ ));
+ break;
+
+ case EXIT_REASON_EPT_VIOLATION:
+ Status = MmioExit (Regs, &ReturnData.VeInfo);
+ DEBUG ((
+ DEBUG_VERBOSE,
+ "MMIO #VE happened, ExitReasion is %d, ExitQualification = 0x%x.\n",
+ ReturnData.VeInfo.ExitReason,
+ ReturnData.VeInfo.ExitQualification.Val
+ ));
+ break;
+
+ case EXIT_REASON_VMCALL:
+ case EXIT_REASON_MWAIT_INSTRUCTION:
+ case EXIT_REASON_MONITOR_INSTRUCTION:
+ case EXIT_REASON_WBINVD:
+ case EXIT_REASON_RDPMC:
+ /* Handle as nops. */
+ break;
+
+ default:
+ DEBUG ((
+ DEBUG_ERROR,
+ "Unsupported #VE happened, ExitReason is %d, ExitQualification = 0x%x.\n",
+ ReturnData.VeInfo.ExitReason,
+ ReturnData.VeInfo.ExitQualification.Val
+ ));
+
+ ASSERT (FALSE);
+ CpuDeadLoop ();
+ }
+
+ if (Status) {
+ DEBUG ((
+ DEBUG_ERROR,
+ "#VE Error (0x%llx) returned from host, ExitReason is %d, ExitQualification = 0x%x.\n",
+ Status,
+ ReturnData.VeInfo.ExitReason,
+ ReturnData.VeInfo.ExitQualification.Val
+ ));
+
+ TdVmCall (TDVMCALL_HALT, 0, 0, 0, 0, 0);
+ }
+
+ SystemContext.SystemContextX64->Rip += ReturnData.VeInfo.ExitInstructionLength;
+ return EFI_SUCCESS;
+}
diff --git a/OvmfPkg/Library/VmgExitLib/VmgExitLib.inf b/OvmfPkg/Library/VmgExitLib/VmgExitLib.inf
index 7963670e7d30..255b0c1a2f7f 100644
--- a/OvmfPkg/Library/VmgExitLib/VmgExitLib.inf
+++ b/OvmfPkg/Library/VmgExitLib/VmgExitLib.inf
@@ -25,6 +25,8 @@
VmgExitVcHandler.c
VmgExitVcHandler.h
PeiDxeVmgExitVcHandler.c
+ VmTdExitVeHandler.c
+ X64/TdVmcallCpuid.nasm
[Packages]
MdePkg/MdePkg.dec
diff --git a/OvmfPkg/Library/VmgExitLib/X64/TdVmcallCpuid.nasm b/OvmfPkg/Library/VmgExitLib/X64/TdVmcallCpuid.nasm
new file mode 100644
index 000000000000..fa86440904fe
--- /dev/null
+++ b/OvmfPkg/Library/VmgExitLib/X64/TdVmcallCpuid.nasm
@@ -0,0 +1,146 @@
+;------------------------------------------------------------------------------
+;*
+;* Copyright (c) 2020 - 2021, Intel Corporation. All rights reserved.<BR>
+;* SPDX-License-Identifier: BSD-2-Clause-Patent
+;*
+;*
+;------------------------------------------------------------------------------
+
+DEFAULT REL
+SECTION .text
+
+%define TDVMCALL_EXPOSE_REGS_MASK 0xffec
+%define TDVMCALL 0x0
+%define EXIT_REASON_CPUID 0xa
+
+%macro tdcall 0
+ db 0x66,0x0f,0x01,0xcc
+%endmacro
+
+%macro tdcall_push_regs 0
+ push rbp
+ mov rbp, rsp
+ push r15
+ push r14
+ push r13
+ push r12
+ push rbx
+ push rsi
+ push rdi
+%endmacro
+
+%macro tdcall_pop_regs 0
+ pop rdi
+ pop rsi
+ pop rbx
+ pop r12
+ pop r13
+ pop r14
+ pop r15
+ pop rbp
+%endmacro
+
+%define number_of_regs_pushed 8
+%define number_of_parameters 4
+
+;
+; Keep these in sync for push_regs/pop_regs, code below
+; uses them to find 5th or greater parameters
+;
+%define first_variable_on_stack_offset \
+ ((number_of_regs_pushed * 8) + (number_of_parameters * 8) + 8)
+%define second_variable_on_stack_offset \
+ ((first_variable_on_stack_offset) + 8)
+
+%macro tdcall_regs_preamble 2
+ mov rax, %1
+
+ xor rcx, rcx
+ mov ecx, %2
+
+ ; R10 = 0 (standard TDVMCALL)
+
+ xor r10d, r10d
+
+ ; Zero out unused (for standard TDVMCALL) registers to avoid leaking
+ ; secrets to the VMM.
+
+ xor ebx, ebx
+ xor esi, esi
+ xor edi, edi
+
+ xor edx, edx
+ xor ebp, ebp
+ xor r8d, r8d
+ xor r9d, r9d
+ xor r14, r14
+ xor r15, r15
+%endmacro
+
+%macro tdcall_regs_postamble 0
+ xor ebx, ebx
+ xor esi, esi
+ xor edi, edi
+
+ xor ecx, ecx
+ xor edx, edx
+ xor r8d, r8d
+ xor r9d, r9d
+ xor r10d, r10d
+ xor r11d, r11d
+%endmacro
+
+;------------------------------------------------------------------------------
+; 0 => RAX = TDCALL leaf / TDVMCALL
+; M => RCX = TDVMCALL register behavior
+; 0xa => R11 = TDVMCALL function / CPUID
+; RCX => R12 = p1
+; RDX => R13 = p2
+;
+; UINT64
+; EFIAPI
+; TdVmCallCpuid (
+; UINT64 EaxIn, // Rcx
+; UINT64 EcxIn, // Rdx
+; UINT64 *Results // R8
+; )
+global ASM_PFX(TdVmCallCpuid)
+ASM_PFX(TdVmCallCpuid):
+ tdcall_push_regs
+
+ mov r11, EXIT_REASON_CPUID
+ mov r12, rcx
+ mov r13, rdx
+
+ ; Save *results pointers
+ push r8
+
+ tdcall_regs_preamble TDVMCALL, TDVMCALL_EXPOSE_REGS_MASK
+
+ tdcall
+
+ ; ignore return data if TDCALL reports failure.
+ test rax, rax
+ jnz .no_return_data
+
+ ; Propagate TDVMCALL success/failure to return value.
+ mov rax, r10
+ test rax, rax
+ jnz .no_return_data
+
+ ; Retrieve *Results
+ pop r8
+ test r8, r8
+ jz .no_return_data
+ ; Caller pass in buffer so store results r12-r15 contains eax-edx
+ mov [r8 + 0], r12
+ mov [r8 + 8], r13
+ mov [r8 + 16], r14
+ mov [r8 + 24], r15
+
+.no_return_data:
+ tdcall_regs_postamble
+
+ tdcall_pop_regs
+
+ ret
--
2.29.2.windows.2
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