From fb040cced3b68f6a5ea88ec9881b362346d71c22 Mon Sep 17 00:00:00 2001 From: Tom Lendacky Date: Wed, 12 Aug 2020 15:21:37 -0500 Subject: OvmfPkg/VmgExitLib: Add support for IOIO_PROT NAE events BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198 Under SEV-ES, a IOIO_PROT intercept generates a #VC exception. VMGEXIT must be used to allow the hypervisor to handle this intercept. Add support to construct the required GHCB values to support a IOIO_PROT NAE event. Parse the instruction that generated the #VC exception, setting the required register values in the GHCB and creating the proper SW_EXITINFO1 value in the GHCB. Cc: Jordan Justen Cc: Laszlo Ersek Cc: Ard Biesheuvel Acked-by: Laszlo Ersek Signed-off-by: Tom Lendacky Regression-tested-by: Laszlo Ersek --- OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c | 558 +++++++++++++++++++++++++- 1 file changed, 545 insertions(+), 13 deletions(-) (limited to 'OvmfPkg/Library') diff --git a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c index b6a955ed80..04e8b8aebf 100644 --- a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c +++ b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c @@ -11,6 +11,529 @@ #include #include #include +#include + +// +// Instruction execution mode definition +// +typedef enum { + LongMode64Bit = 0, + LongModeCompat32Bit, + LongModeCompat16Bit, +} SEV_ES_INSTRUCTION_MODE; + +// +// Instruction size definition (for operand and address) +// +typedef enum { + Size8Bits = 0, + Size16Bits, + Size32Bits, + Size64Bits, +} SEV_ES_INSTRUCTION_SIZE; + +// +// Intruction segment definition +// +typedef enum { + SegmentEs = 0, + SegmentCs, + SegmentSs, + SegmentDs, + SegmentFs, + SegmentGs, +} SEV_ES_INSTRUCTION_SEGMENT; + +// +// Instruction rep function definition +// +typedef enum { + RepNone = 0, + RepZ, + RepNZ, +} SEV_ES_INSTRUCTION_REP; + +typedef struct { + UINT8 Rm; + UINT8 Reg; + UINT8 Mod; +} SEV_ES_INSTRUCTION_MODRM_EXT; + +typedef struct { + UINT8 Base; + UINT8 Index; + UINT8 Scale; +} SEV_ES_INSTRUCTION_SIB_EXT; + +// +// Instruction opcode definition +// +typedef struct { + SEV_ES_INSTRUCTION_MODRM_EXT ModRm; + + SEV_ES_INSTRUCTION_SIB_EXT Sib; + + UINTN RegData; + UINTN RmData; +} SEV_ES_INSTRUCTION_OPCODE_EXT; + +// +// Instruction parsing context definition +// +typedef struct { + GHCB *Ghcb; + + SEV_ES_INSTRUCTION_MODE Mode; + SEV_ES_INSTRUCTION_SIZE DataSize; + SEV_ES_INSTRUCTION_SIZE AddrSize; + BOOLEAN SegmentSpecified; + SEV_ES_INSTRUCTION_SEGMENT Segment; + SEV_ES_INSTRUCTION_REP RepMode; + + UINT8 *Begin; + UINT8 *End; + + UINT8 *Prefixes; + UINT8 *OpCodes; + UINT8 *Displacement; + UINT8 *Immediate; + + INSTRUCTION_REX_PREFIX RexPrefix; + + BOOLEAN ModRmPresent; + INSTRUCTION_MODRM ModRm; + + BOOLEAN SibPresent; + INSTRUCTION_SIB Sib; + + UINTN PrefixSize; + UINTN OpCodeSize; + UINTN DisplacementSize; + UINTN ImmediateSize; + + SEV_ES_INSTRUCTION_OPCODE_EXT Ext; +} SEV_ES_INSTRUCTION_DATA; + +// +// Non-automatic Exit function prototype +// +typedef +UINT64 +(*NAE_EXIT) ( + GHCB *Ghcb, + EFI_SYSTEM_CONTEXT_X64 *Regs, + SEV_ES_INSTRUCTION_DATA *InstructionData + ); + + +/** + Checks the GHCB to determine if the specified register has been marked valid. + + The ValidBitmap area represents the areas of the GHCB that have been marked + valid. Return an indication of whether the area of the GHCB that holds the + specified register has been marked valid. + + @param[in] Ghcb Pointer to the Guest-Hypervisor Communication Block + @param[in] Reg Offset in the GHCB of the register to check + + @retval TRUE Register has been marked vald in the GHCB + @retval FALSE Register has not been marked valid in the GHCB + +**/ +STATIC +BOOLEAN +GhcbIsRegValid ( + IN GHCB *Ghcb, + IN GHCB_REGISTER Reg + ) +{ + UINT32 RegIndex; + UINT32 RegBit; + + RegIndex = Reg / 8; + RegBit = Reg & 0x07; + + return ((Ghcb->SaveArea.ValidBitmap[RegIndex] & (1 << RegBit)) != 0); +} + +/** + Marks a register as valid in the GHCB. + + The ValidBitmap area represents the areas of the GHCB that have been marked + valid. Set the area of the GHCB that holds the specified register as valid. + + @param[in, out] Ghcb Pointer to the Guest-Hypervisor Communication Block + @param[in] Reg Offset in the GHCB of the register to mark valid + +**/ +STATIC +VOID +GhcbSetRegValid ( + IN OUT GHCB *Ghcb, + IN GHCB_REGISTER Reg + ) +{ + UINT32 RegIndex; + UINT32 RegBit; + + RegIndex = Reg / 8; + RegBit = Reg & 0x07; + + Ghcb->SaveArea.ValidBitmap[RegIndex] |= (1 << RegBit); +} + +/** + Decode instruction prefixes. + + Parse the instruction data to track the instruction prefixes that have + been used. + + @param[in] Regs x64 processor context + @param[in, out] InstructionData Instruction parsing context + +**/ +STATIC +VOID +DecodePrefixes ( + IN EFI_SYSTEM_CONTEXT_X64 *Regs, + IN OUT SEV_ES_INSTRUCTION_DATA *InstructionData + ) +{ + SEV_ES_INSTRUCTION_MODE Mode; + SEV_ES_INSTRUCTION_SIZE ModeDataSize; + SEV_ES_INSTRUCTION_SIZE ModeAddrSize; + UINT8 *Byte; + + // + // Always in 64-bit mode + // + Mode = LongMode64Bit; + ModeDataSize = Size32Bits; + ModeAddrSize = Size64Bits; + + InstructionData->Mode = Mode; + InstructionData->DataSize = ModeDataSize; + InstructionData->AddrSize = ModeAddrSize; + + InstructionData->Prefixes = InstructionData->Begin; + + Byte = InstructionData->Prefixes; + for ( ; ; Byte++, InstructionData->PrefixSize++) { + // + // Check the 0x40 to 0x4F range using an if statement here since some + // compilers don't like the "case 0x40 ... 0x4F:" syntax. This avoids + // 16 case statements below. + // + if ((*Byte >= REX_PREFIX_START) && (*Byte <= REX_PREFIX_STOP)) { + InstructionData->RexPrefix.Uint8 = *Byte; + if ((*Byte & REX_64BIT_OPERAND_SIZE_MASK) != 0) { + InstructionData->DataSize = Size64Bits; + } + continue; + } + + switch (*Byte) { + case OVERRIDE_SEGMENT_CS: + case OVERRIDE_SEGMENT_DS: + case OVERRIDE_SEGMENT_ES: + case OVERRIDE_SEGMENT_SS: + if (Mode != LongMode64Bit) { + InstructionData->SegmentSpecified = TRUE; + InstructionData->Segment = (*Byte >> 3) & 3; + } + break; + + case OVERRIDE_SEGMENT_FS: + case OVERRIDE_SEGMENT_GS: + InstructionData->SegmentSpecified = TRUE; + InstructionData->Segment = *Byte & 7; + break; + + case OVERRIDE_OPERAND_SIZE: + if (InstructionData->RexPrefix.Uint8 == 0) { + InstructionData->DataSize = + (Mode == LongMode64Bit) ? Size16Bits : + (Mode == LongModeCompat32Bit) ? Size16Bits : + (Mode == LongModeCompat16Bit) ? Size32Bits : 0; + } + break; + + case OVERRIDE_ADDRESS_SIZE: + InstructionData->AddrSize = + (Mode == LongMode64Bit) ? Size32Bits : + (Mode == LongModeCompat32Bit) ? Size16Bits : + (Mode == LongModeCompat16Bit) ? Size32Bits : 0; + break; + + case LOCK_PREFIX: + break; + + case REPZ_PREFIX: + InstructionData->RepMode = RepZ; + break; + + case REPNZ_PREFIX: + InstructionData->RepMode = RepNZ; + break; + + default: + InstructionData->OpCodes = Byte; + InstructionData->OpCodeSize = (*Byte == TWO_BYTE_OPCODE_ESCAPE) ? 2 : 1; + + InstructionData->End = Byte + InstructionData->OpCodeSize; + InstructionData->Displacement = InstructionData->End; + InstructionData->Immediate = InstructionData->End; + return; + } + } +} + +/** + Determine instruction length + + Return the total length of the parsed instruction. + + @param[in] InstructionData Instruction parsing context + + @return Length of parsed instruction + +**/ +STATIC +UINT64 +InstructionLength ( + IN SEV_ES_INSTRUCTION_DATA *InstructionData + ) +{ + return (UINT64) (InstructionData->End - InstructionData->Begin); +} + +/** + Initialize the instruction parsing context. + + Initialize the instruction parsing context, which includes decoding the + instruction prefixes. + + @param[in, out] InstructionData Instruction parsing context + @param[in] Ghcb Pointer to the Guest-Hypervisor Communication + Block + @param[in] Regs x64 processor context + +**/ +STATIC +VOID +InitInstructionData ( + IN OUT SEV_ES_INSTRUCTION_DATA *InstructionData, + IN GHCB *Ghcb, + IN EFI_SYSTEM_CONTEXT_X64 *Regs + ) +{ + SetMem (InstructionData, sizeof (*InstructionData), 0); + InstructionData->Ghcb = Ghcb; + InstructionData->Begin = (UINT8 *) Regs->Rip; + InstructionData->End = (UINT8 *) Regs->Rip; + + DecodePrefixes (Regs, InstructionData); +} + +/** + Report an unsupported event to the hypervisor + + Use the VMGEXIT support to report an unsupported event to the hypervisor. + + @param[in] Ghcb Pointer to the Guest-Hypervisor Communication + Block + @param[in] Regs x64 processor context + @param[in] InstructionData Instruction parsing context + + @return New exception value to propagate + +**/ +STATIC +UINT64 +UnsupportedExit ( + IN GHCB *Ghcb, + IN EFI_SYSTEM_CONTEXT_X64 *Regs, + IN SEV_ES_INSTRUCTION_DATA *InstructionData + ) +{ + UINT64 Status; + + Status = VmgExit (Ghcb, SVM_EXIT_UNSUPPORTED, Regs->ExceptionData, 0); + if (Status == 0) { + GHCB_EVENT_INJECTION Event; + + Event.Uint64 = 0; + Event.Elements.Vector = GP_EXCEPTION; + Event.Elements.Type = GHCB_EVENT_INJECTION_TYPE_EXCEPTION; + Event.Elements.Valid = 1; + + Status = Event.Uint64; + } + + return Status; +} + +/** + Build the IOIO event information. + + The IOIO event information identifies the type of IO operation to be performed + by the hypervisor. Build this information based on the instruction data. + + @param[in] Regs x64 processor context + @param[in, out] InstructionData Instruction parsing context + + @return IOIO event information value + +**/ +STATIC +UINT64 +IoioExitInfo ( + IN EFI_SYSTEM_CONTEXT_X64 *Regs, + IN OUT SEV_ES_INSTRUCTION_DATA *InstructionData + ) +{ + UINT64 ExitInfo; + + ExitInfo = 0; + + switch (*(InstructionData->OpCodes)) { + // + // IN immediate opcodes + // + case 0xE4: + case 0xE5: + InstructionData->ImmediateSize = 1; + InstructionData->End++; + ExitInfo |= IOIO_TYPE_IN; + ExitInfo |= ((*(InstructionData->OpCodes + 1)) << 16); + break; + + // + // OUT immediate opcodes + // + case 0xE6: + case 0xE7: + InstructionData->ImmediateSize = 1; + InstructionData->End++; + ExitInfo |= IOIO_TYPE_OUT; + ExitInfo |= ((*(InstructionData->OpCodes + 1)) << 16) | IOIO_TYPE_OUT; + break; + + // + // IN register opcodes + // + case 0xEC: + case 0xED: + ExitInfo |= IOIO_TYPE_IN; + ExitInfo |= ((Regs->Rdx & 0xffff) << 16); + break; + + // + // OUT register opcodes + // + case 0xEE: + case 0xEF: + ExitInfo |= IOIO_TYPE_OUT; + ExitInfo |= ((Regs->Rdx & 0xffff) << 16); + break; + + default: + return 0; + } + + switch (*(InstructionData->OpCodes)) { + // + // Single-byte opcodes + // + case 0xE4: + case 0xE6: + case 0xEC: + case 0xEE: + ExitInfo |= IOIO_DATA_8; + break; + + // + // Length determined by instruction parsing + // + default: + ExitInfo |= (InstructionData->DataSize == Size16Bits) ? IOIO_DATA_16 + : IOIO_DATA_32; + } + + switch (InstructionData->AddrSize) { + case Size16Bits: + ExitInfo |= IOIO_ADDR_16; + break; + + case Size32Bits: + ExitInfo |= IOIO_ADDR_32; + break; + + case Size64Bits: + ExitInfo |= IOIO_ADDR_64; + break; + + default: + break; + } + + if (InstructionData->RepMode != 0) { + ExitInfo |= IOIO_REP; + } + + return ExitInfo; +} + +/** + Handle an IOIO event. + + Use the VMGEXIT instruction to handle an IOIO event. + + @param[in, out] Ghcb Pointer to the Guest-Hypervisor Communication + Block + @param[in, out] Regs x64 processor context + @param[in] InstructionData Instruction parsing context + + @retval 0 Event handled successfully + @return New exception value to propagate + +**/ +STATIC +UINT64 +IoioExit ( + IN OUT GHCB *Ghcb, + IN OUT EFI_SYSTEM_CONTEXT_X64 *Regs, + IN SEV_ES_INSTRUCTION_DATA *InstructionData + ) +{ + UINT64 ExitInfo1, Status; + + ExitInfo1 = IoioExitInfo (Regs, InstructionData); + if (ExitInfo1 == 0) { + return UnsupportedExit (Ghcb, Regs, InstructionData); + } + + if ((ExitInfo1 & IOIO_TYPE_IN) != 0) { + Ghcb->SaveArea.Rax = 0; + } else { + CopyMem (&Ghcb->SaveArea.Rax, &Regs->Rax, IOIO_DATA_BYTES (ExitInfo1)); + } + GhcbSetRegValid (Ghcb, GhcbRax); + + Status = VmgExit (Ghcb, SVM_EXIT_IOIO_PROT, ExitInfo1, 0); + if (Status != 0) { + return Status; + } + + if ((ExitInfo1 & IOIO_TYPE_IN) != 0) { + if (!GhcbIsRegValid (Ghcb, GhcbRax)) { + return UnsupportedExit (Ghcb, Regs, InstructionData); + } + CopyMem (&Regs->Rax, &Ghcb->SaveArea.Rax, IOIO_DATA_BYTES (ExitInfo1)); + } + + return 0; +} /** Handle a #VC exception. @@ -38,6 +561,8 @@ VmgExitHandleVc ( MSR_SEV_ES_GHCB_REGISTER Msr; EFI_SYSTEM_CONTEXT_X64 *Regs; GHCB *Ghcb; + NAE_EXIT NaeExit; + SEV_ES_INSTRUCTION_DATA InstructionData; UINT64 ExitCode, Status; EFI_STATUS VcRet; @@ -54,24 +579,31 @@ VmgExitHandleVc ( ExitCode = Regs->ExceptionData; switch (ExitCode) { + case SVM_EXIT_IOIO_PROT: + NaeExit = IoioExit; + break; + default: - Status = VmgExit (Ghcb, SVM_EXIT_UNSUPPORTED, ExitCode, 0); - if (Status == 0) { - Regs->ExceptionData = 0; - *ExceptionType = GP_EXCEPTION; - } else { - GHCB_EVENT_INJECTION Event; + NaeExit = UnsupportedExit; + } - Event.Uint64 = Status; - if (Event.Elements.ErrorCodeValid != 0) { - Regs->ExceptionData = Event.Elements.ErrorCode; - } else { - Regs->ExceptionData = 0; - } + InitInstructionData (&InstructionData, Ghcb, Regs); + + Status = NaeExit (Ghcb, Regs, &InstructionData); + if (Status == 0) { + Regs->Rip += InstructionLength (&InstructionData); + } else { + GHCB_EVENT_INJECTION Event; - *ExceptionType = Event.Elements.Vector; + Event.Uint64 = Status; + if (Event.Elements.ErrorCodeValid != 0) { + Regs->ExceptionData = Event.Elements.ErrorCode; + } else { + Regs->ExceptionData = 0; } + *ExceptionType = Event.Elements.Vector; + VcRet = EFI_PROTOCOL_ERROR; } -- cgit v1.2.3