[RFC PATCH v2 19/44] UefiCpuPkg/CpuExceptionHandler: Add support for IOIO_PROT NAE events

["Lendacky, Thomas" <thomas.lendacky@amd.com>]

From: Tom Lendacky <thomas.lendacky@amd.com>

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: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 .../X64/AMDSevVcCommon.c                      | 434 +++++++++++++++++-
 1 file changed, 433 insertions(+), 1 deletion(-)

diff --git a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/AMDSevVcCommon.c b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/AMDSevVcCommon.c
index a56dcffe1d5d..16091fe38f83 100644
--- a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/AMDSevVcCommon.c
+++ b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/AMDSevVcCommon.c
@@ -4,6 +4,425 @@
 #include <Library/DebugLib.h>
 #include "AMDSevVcCommon.h"
 
+typedef enum {
+  LongMode64Bit        = 0,
+  LongModeCompat32Bit,
+  LongModeCompat16Bit,
+} SEV_ES_INSTRUCTION_MODE;
+
+typedef enum {
+  Size8Bits            = 0,
+  Size16Bits,
+  Size32Bits,
+  Size64Bits,
+} SEV_ES_INSTRUCTION_SIZE;
+
+typedef enum {
+  SegmentEs            = 0,
+  SegmentCs,
+  SegmentSs,
+  SegmentDs,
+  SegmentFs,
+  SegmentGs,
+} SEV_ES_INSTRUCTION_SEGMENT;
+
+typedef enum {
+  RepNone              = 0,
+  RepZ,
+  RepNZ,
+} SEV_ES_INSTRUCTION_REP;
+
+typedef union {
+  struct {
+    UINT8  B:1;
+    UINT8  X:1;
+    UINT8  R:1;
+    UINT8  W:1;
+    UINT8  REX:4;
+  } Bits;
+
+  UINT8  Uint8;
+} SEV_ES_INSTRUCTION_REX_PREFIX;
+
+typedef union {
+  struct {
+    UINT8  Rm:3;
+    UINT8  Reg:3;
+    UINT8  Mod:2;
+  } Bits;
+
+  UINT8  Uint8;
+} SEV_ES_INSTRUCTION_MODRM;
+
+typedef union {
+  struct {
+    UINT8  Base:3;
+    UINT8  Index:3;
+    UINT8  Scale:2;
+  } Bits;
+
+  UINT8  Uint8;
+} SEV_ES_INSTRUCTION_SIB;
+
+typedef struct {
+  struct {
+    UINT8  Rm;
+    UINT8  Reg;
+    UINT8  Mod;
+  } ModRm;
+
+  struct {
+    UINT8  Base;
+    UINT8  Index;
+    UINT8  Scale;
+  } Sib;
+
+  UINTN  RegData;
+  UINTN  RmData;
+} SEV_ES_INSTRUCTION_OPCODE_EXT;
+
+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;
+
+  SEV_ES_INSTRUCTION_REX_PREFIX  RexPrefix;
+
+  BOOLEAN                        ModRmPresent;
+  SEV_ES_INSTRUCTION_MODRM       ModRm;
+
+  BOOLEAN                        SibPresent;
+  SEV_ES_INSTRUCTION_SIB         Sib;
+
+  UINT8                          PrefixSize;
+  UINT8                          OpCodeSize;
+  UINT8                          DisplacementSize;
+  UINT8                          ImmediateSize;
+
+  SEV_ES_INSTRUCTION_OPCODE_EXT  Ext;
+} SEV_ES_INSTRUCTION_DATA;
+
+typedef
+UINTN
+(*NAE_EXIT) (
+  GHCB                     *Ghcb,
+  EFI_SYSTEM_CONTEXT_X64   *Regs,
+  SEV_ES_INSTRUCTION_DATA  *InstructionData
+  );
+
+
+STATIC
+BOOLEAN
+GhcbIsRegValid (
+  GHCB                *Ghcb,
+  GHCB_REGISTER       Reg
+  )
+{
+  UINT32  RegIndex = Reg / 8;
+  UINT32  RegBit   = Reg & 0x07;
+
+  return (Ghcb->SaveArea.ValidBitmap[RegIndex] & (1 << RegBit));
+}
+
+STATIC
+VOID
+GhcbSetRegValid (
+  GHCB                *Ghcb,
+  GHCB_REGISTER       Reg
+  )
+{
+  UINT32  RegIndex = Reg / 8;
+  UINT32  RegBit   = Reg & 0x07;
+
+  Ghcb->SaveArea.ValidBitmap[RegIndex] |= (1 << RegBit);
+}
+
+STATIC
+VOID
+DecodePrefixes (
+  EFI_SYSTEM_CONTEXT_X64   *Regs,
+  SEV_ES_INSTRUCTION_DATA  *InstructionData
+  )
+{
+  SEV_ES_INSTRUCTION_MODE  Mode;
+  SEV_ES_INSTRUCTION_SIZE  ModeDataSize;
+  SEV_ES_INSTRUCTION_SIZE  ModeAddrSize;
+  UINT8                    *Byte;
+
+  /*TODO: Determine current mode - 64-bit for now */
+  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++) {
+    switch (*Byte) {
+    case 0x26:
+    case 0x2E:
+    case 0x36:
+    case 0x3E:
+      if (Mode != LongMode64Bit) {
+        InstructionData->SegmentSpecified = TRUE;
+        InstructionData->Segment = (*Byte >> 3) & 3;
+      }
+      break;
+
+    case 0x40 ... 0x4F:
+      InstructionData->RexPrefix.Uint8 = *Byte;
+      if (*Byte & 0x08)
+        InstructionData->DataSize = Size64Bits;
+      break;
+
+    case 0x64:
+      InstructionData->SegmentSpecified = TRUE;
+      InstructionData->Segment = *Byte & 7;
+      break;
+
+    case 0x66:
+      if (!InstructionData->RexPrefix.Uint8) {
+        InstructionData->DataSize =
+          (Mode == LongMode64Bit)       ? Size16Bits :
+          (Mode == LongModeCompat32Bit) ? Size16Bits :
+          (Mode == LongModeCompat16Bit) ? Size32Bits : 0;
+      }
+      break;
+
+    case 0x67:
+      InstructionData->AddrSize =
+        (Mode == LongMode64Bit)       ? Size32Bits :
+        (Mode == LongModeCompat32Bit) ? Size16Bits :
+        (Mode == LongModeCompat16Bit) ? Size32Bits : 0;
+      break;
+
+    case 0xF0:
+      break;
+
+    case 0xF2:
+      InstructionData->RepMode = RepZ;
+      break;
+
+    case 0xF3:
+      InstructionData->RepMode = RepNZ;
+      break;
+
+    default:
+      InstructionData->OpCodes = Byte;
+      InstructionData->OpCodeSize = (*Byte == 0x0F) ? 2 : 1;
+
+      InstructionData->End = Byte + InstructionData->OpCodeSize;
+      InstructionData->Displacement = InstructionData->End;
+      InstructionData->Immediate = InstructionData->End;
+      return;
+    }
+  }
+}
+
+UINT64
+InstructionLength (
+  SEV_ES_INSTRUCTION_DATA  *InstructionData
+  )
+{
+  return (UINT64) (InstructionData->End - InstructionData->Begin);
+}
+
+STATIC
+VOID
+InitInstructionData (
+  SEV_ES_INSTRUCTION_DATA  *InstructionData,
+  GHCB                     *Ghcb,
+  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);
+}
+
+STATIC
+UINTN
+UnsupportedExit (
+  GHCB                     *Ghcb,
+  EFI_SYSTEM_CONTEXT_X64   *Regs,
+  SEV_ES_INSTRUCTION_DATA  *InstructionData
+  )
+{
+  UINTN  Status;
+
+  Status = VmgExit (Ghcb, SvmExitUnsupported, Regs->ExceptionData, 0);
+  ASSERT (0);
+
+  return Status;
+}
+
+#define IOIO_TYPE_STR  (1 << 2)
+#define IOIO_TYPE_IN   1
+#define IOIO_TYPE_INS  (IOIO_TYPE_IN | IOIO_TYPE_STR)
+#define IOIO_TYPE_OUT  0
+#define IOIO_TYPE_OUTS (IOIO_TYPE_OUT | IOIO_TYPE_STR)
+
+#define IOIO_REP       (1 << 3)
+
+#define IOIO_ADDR_64   (1 << 9)
+#define IOIO_ADDR_32   (1 << 8)
+#define IOIO_ADDR_16   (1 << 7)
+
+#define IOIO_DATA_32   (1 << 6)
+#define IOIO_DATA_16   (1 << 5)
+#define IOIO_DATA_8    (1 << 4)
+
+#define IOIO_SEG_ES    (0 << 10)
+#define IOIO_SEG_DS    (3 << 10)
+
+STATIC
+UINT64
+IoioExitInfo (
+  EFI_SYSTEM_CONTEXT_X64   *Regs,
+  SEV_ES_INSTRUCTION_DATA  *InstructionData
+  )
+{
+  UINT64  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)) {
+  case 0xE4:
+  case 0xE6:
+  case 0xEC:
+  case 0xEE:
+    // Single-byte opcodes
+    ExitInfo |= IOIO_DATA_8;
+    break;
+
+  default:
+    // Length determined by instruction parsing
+    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) {
+    ExitInfo |= IOIO_REP;
+  }
+
+  return ExitInfo;
+}
+
+STATIC
+UINTN
+IoioExit (
+  GHCB                     *Ghcb,
+  EFI_SYSTEM_CONTEXT_X64   *Regs,
+  SEV_ES_INSTRUCTION_DATA  *InstructionData
+  )
+{
+  UINT64  ExitInfo1;
+  UINTN   Status;
+
+  ExitInfo1 = IoioExitInfo (Regs, InstructionData);
+  if (!ExitInfo1) {
+    VmgExit (Ghcb, SvmExitUnsupported, SvmExitIoioProt, 0);
+    ASSERT (0);
+  }
+
+  if (!(ExitInfo1 & IOIO_TYPE_IN)) {
+    Ghcb->SaveArea.Rax = Regs->Rax;
+    GhcbSetRegValid (Ghcb, GhcbRax);
+  }
+
+  //FIXME: This is likely needed for the merging cases (size<32 bits)
+  //       Pass in zero and perform merge here (only for non-string)
+  Ghcb->SaveArea.Rax = Regs->Rax;
+  GhcbSetRegValid (Ghcb, GhcbRax);
+
+  Status = VmgExit (Ghcb, SvmExitIoioProt, ExitInfo1, 0);
+  if (Status) {
+    return Status;
+  }
+
+  if (ExitInfo1 & IOIO_TYPE_IN) {
+    if (!GhcbIsRegValid (Ghcb, GhcbRax)) {
+      VmgExit (Ghcb, SvmExitUnsupported, SvmExitIoioProt, 0);
+      ASSERT (0);
+    }
+    Regs->Rax = Ghcb->SaveArea.Rax;
+  }
+
+  return 0;
+}
+
 UINTN
 DoVcCommon (
   GHCB                *Ghcb,
@@ -11,6 +430,8 @@ DoVcCommon (
   )
 {
   EFI_SYSTEM_CONTEXT_X64   *Regs = Context.SystemContextX64;
+  SEV_ES_INSTRUCTION_DATA  InstructionData;
+  NAE_EXIT                 NaeExit;
   UINTN                    ExitCode;
   UINTN                    Status;
 
@@ -18,8 +439,19 @@ DoVcCommon (
 
   ExitCode = Regs->ExceptionData;
   switch (ExitCode) {
+  case SvmExitIoioProt:
+    NaeExit = IoioExit;
+    break;
+
   default:
-    Status = VmgExit (Ghcb, SvmExitUnsupported, ExitCode, 0);
+    NaeExit = UnsupportedExit;
+  }
+
+  InitInstructionData (&InstructionData, Ghcb, Regs);
+
+  Status = NaeExit (Ghcb, Regs, &InstructionData);
+  if (!Status) {
+    Regs->Rip += InstructionLength(&InstructionData);
   }
 
   VmgDone (Ghcb);
-- 
2.17.1