[RFC PATCH 08/28] MdePkg/BaseLib: Implement the VMGEXIT support

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

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

VMGEXIT is a new instruction used for Hypervisor/Guest communication when
running as an SEV-ES guest. A VMGEXIT will cause an automatic exit (AE)
to occur, resulting in a #VMEXIT with an exit code value of 0x403.

To support VMGEXIT, define the VMGEXIT assember routine to issue the
instruction (rep; vmmcall), the GHCB structure and some helper functions
for communicating register information to and from the hypervisor and the
guest.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 MdePkg/Library/BaseLib/BaseLib.inf      |   1 +
 MdePkg/Include/Library/BaseLib.h        |  14 ++
 UefiCpuPkg/Include/Register/Amd/Ghcb.h  | 197 ++++++++++++++++++++++++
 MdePkg/Library/BaseLib/X64/GccInline.c  |  17 ++
 MdePkg/Library/BaseLib/X64/VmgExit.nasm |  38 +++++
 5 files changed, 267 insertions(+)
 create mode 100644 UefiCpuPkg/Include/Register/Amd/Ghcb.h
 create mode 100644 MdePkg/Library/BaseLib/X64/VmgExit.nasm

diff --git a/MdePkg/Library/BaseLib/BaseLib.inf b/MdePkg/Library/BaseLib/BaseLib.inf
index 3586beb0ab5c..a41401340f95 100644
--- a/MdePkg/Library/BaseLib/BaseLib.inf
+++ b/MdePkg/Library/BaseLib/BaseLib.inf
@@ -286,6 +286,7 @@ [Sources.X64]
   X64/ReadCr2.nasm| MSFT
   X64/ReadCr0.nasm| MSFT
   X64/ReadEflags.nasm| MSFT
+  X64/VmgExit.nasm | MSFT
 
 
   X64/Non-existing.c
diff --git a/MdePkg/Include/Library/BaseLib.h b/MdePkg/Include/Library/BaseLib.h
index 2a75bc023f56..80bd5cf57a72 100644
--- a/MdePkg/Include/Library/BaseLib.h
+++ b/MdePkg/Include/Library/BaseLib.h
@@ -7880,6 +7880,20 @@ AsmLfence (
   VOID
   );
 
+/**
+  Executes a VMGEXIT instruction (VMMCALL with a REP prefix)
+
+  Executes a VMGEXIT instruction. This function is only available on IA-32 and
+  x64.
+
+**/
+VOID
+EFIAPI
+AsmVmgExit (
+  VOID
+  );
+
+
 /**
   Patch the immediate operand of an IA32 or X64 instruction such that the byte,
   word, dword or qword operand is encoded at the end of the instruction's
diff --git a/UefiCpuPkg/Include/Register/Amd/Ghcb.h b/UefiCpuPkg/Include/Register/Amd/Ghcb.h
new file mode 100644
index 000000000000..e9fd116fac25
--- /dev/null
+++ b/UefiCpuPkg/Include/Register/Amd/Ghcb.h
@@ -0,0 +1,197 @@
+
+#ifndef __GHCB_H__
+#define __GHCB_H__
+
+#include <Protocol/DebugSupport.h>
+#include <Library/BaseLib.h>
+#include <Library/DebugLib.h>
+
+#define UD_EXCEPTION  6
+#define GP_EXCEPTION 13
+
+#define GHCB_VERSION_MIN     1
+#define GHCB_VERSION_MAX     1
+
+#define GHCB_STANDARD_USAGE  0
+
+typedef enum {
+  SvmExitDr7Read       = 0x27,
+  SvmExitDr7Write      = 0x37,
+  SvmExitRdtsc         = 0x6E,
+  SvmExitRdpmc,
+  SvmExitCpuid         = 0x72,
+  SvmExitInvd          = 0x76,
+  SvmExitIoioProt      = 0x7B,
+  SvmExitMsr,
+  SvmExitVmmCall       = 0x81,
+  SvmExitRdtscp        = 0x87,
+  SvmExitWbinvd        = 0x89,
+  SvmExitMonitor,
+  SvmExitMwait,
+  SvmExitNpf           = 0x400,
+
+  // VMG special exits
+  SvmExitMmioRead      = 0x80000001,
+  SvmExitMmioWrite,
+  SvmExitNmiComplete,
+  SvmExitApResetHold,
+
+  SvmExitUnsupported   = 0x8000FFFF,
+} SVM_EXITCODE;
+
+typedef enum {
+  GhcbCpl              = 25,
+  GhcbRflags           = 46,
+  GhcbRip,
+  GhcbRsp              = 59,
+  GhcbRax              = 63,
+  GhcbRcx              = 97,
+  GhcbRdx,
+  GhcbRbx,
+  GhcbRbp              = 101,
+  GhcbRsi,
+  GhcbRdi,
+  GhcbR8,
+  GhcbR9,
+  GhcbR10,
+  GhcbR11,
+  GhcbR12,
+  GhcbR13,
+  GhcbR14,
+  GhcbR15,
+  GhcbXCr0             = 125,
+} GHCB_REGISTER;
+
+typedef struct {
+  UINT8                  Reserved1[203];
+  UINT8                  Cpl;
+  UINT8                  Reserved2[148];
+  UINT64                 Dr7;
+  UINT8                  Reserved3[144];
+  UINT64                 Rax;
+  UINT8                  Reserved4[264];
+  UINT64                 Rcx;
+  UINT64                 Rdx;
+  UINT64                 Rbx;
+  UINT8                  Reserved5[112];
+  UINT64                 SwExitCode;
+  UINT64                 SwExitInfo1;
+  UINT64                 SwExitInfo2;
+  UINT64                 SwScratch;
+  UINT8                  Reserved6[56];
+  UINT64                 XCr0;
+  UINT8                  ValidBitmap[16];
+  UINT64                 X87StateGpa;
+  UINT8                  Reserved7[1016];
+} __attribute__ ((__packed__)) GHCB_SAVE_AREA;
+
+typedef struct {
+  GHCB_SAVE_AREA         SaveArea;
+  UINT8                  SharedBuffer[2032];
+  UINT8                  Reserved1[10];
+  UINT16                 ProtocolVersion;
+  UINT32                 GhcbUsage;
+} __attribute__ ((__packed__)) __attribute__ ((aligned(SIZE_4KB))) GHCB;
+
+typedef union {
+  struct {
+    UINT32  Lower32Bits;
+    UINT32  Upper32Bits;
+  } Elements;
+
+  UINT64    Uint64;
+} GHCB_EXIT_INFO;
+
+static inline
+BOOLEAN
+GhcbIsRegValid(
+  GHCB                   *Ghcb,
+  GHCB_REGISTER          Reg
+  )
+{
+  UINT32  RegIndex = Reg / 8;
+  UINT32  RegBit   = Reg & 0x07;
+
+  return (Ghcb->SaveArea.ValidBitmap[RegIndex] & (1 << RegBit));
+}
+
+static inline
+VOID
+GhcbSetRegValid(
+  GHCB                   *Ghcb,
+  GHCB_REGISTER          Reg
+  )
+{
+  UINT32  RegIndex = Reg / 8;
+  UINT32  RegBit   = Reg & 0x07;
+
+  Ghcb->SaveArea.ValidBitmap[RegIndex] |= (1 << RegBit);
+}
+
+static inline
+VOID
+VmgException(
+  UINTN                  Exception
+  )
+{
+  switch (Exception) {
+  case UD_EXCEPTION:
+  case GP_EXCEPTION:
+    break;
+  default:
+    ASSERT (0);
+  }
+}
+
+static inline
+UINTN
+VmgExit(
+  GHCB                   *Ghcb,
+  UINT64                 ExitCode,
+  UINT64                 ExitInfo1,
+  UINT64                 ExitInfo2
+  )
+{
+  GHCB_EXIT_INFO   ExitInfo;
+  UINTN            Reason, Action;
+
+  Ghcb->SaveArea.SwExitCode = ExitCode;
+  Ghcb->SaveArea.SwExitInfo1 = ExitInfo1;
+  Ghcb->SaveArea.SwExitInfo2 = ExitInfo2;
+  AsmVmgExit ();
+
+  if (!Ghcb->SaveArea.SwExitInfo1) {
+    return 0;
+  }
+
+  ExitInfo.Uint64 = Ghcb->SaveArea.SwExitInfo1;
+  Reason = ExitInfo.Elements.Upper32Bits;
+  Action = ExitInfo.Elements.Lower32Bits;
+  switch (Action) {
+  case 1:
+    VmgException (Reason);
+    break;
+  default:
+    ASSERT (0);
+  }
+
+  return Reason;
+}
+
+static inline
+VOID
+VmgInit(
+  GHCB                   *Ghcb
+  )
+{
+  SetMem (&Ghcb->SaveArea, sizeof (Ghcb->SaveArea), 0);
+}
+
+static inline
+VOID
+VmgDone(
+  GHCB                   *Ghcb
+  )
+{
+}
+#endif
diff --git a/MdePkg/Library/BaseLib/X64/GccInline.c b/MdePkg/Library/BaseLib/X64/GccInline.c
index 154ce1f57e92..17539caa0798 100644
--- a/MdePkg/Library/BaseLib/X64/GccInline.c
+++ b/MdePkg/Library/BaseLib/X64/GccInline.c
@@ -1798,3 +1798,20 @@ AsmFlushCacheLine (
 }
 
 
+/**
+  Executes a VMGEXIT instruction.
+
+  Executes a VMGEXIT instruction. This function is only available on IA-32 and
+  X64.
+
+**/
+VOID
+EFIAPI
+AsmVmgExit (
+  VOID
+  )
+{
+  __asm__ __volatile__ ("rep; vmmcall":::"memory");
+}
+
+
diff --git a/MdePkg/Library/BaseLib/X64/VmgExit.nasm b/MdePkg/Library/BaseLib/X64/VmgExit.nasm
new file mode 100644
index 000000000000..b673bb94b60d
--- /dev/null
+++ b/MdePkg/Library/BaseLib/X64/VmgExit.nasm
@@ -0,0 +1,38 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (c) 2019, Advanced Micro Device, Inc. All rights reserved.<BR>
+; This program and the accompanying materials
+; are licensed and made available under the terms and conditions of the BSD License
+; which accompanies this distribution.  The full text of the license may be found at
+; http://opensource.org/licenses/bsd-license.php.
+;
+; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+;
+; Module Name:
+;
+;   VmgExit.Asm
+;
+; Abstract:
+;
+;   AsmVmgExit function
+;
+; Notes:
+;
+;------------------------------------------------------------------------------
+
+    DEFAULT REL
+    SECTION .text
+
+;------------------------------------------------------------------------------
+; VOID
+; EFIAPI
+; AsmVmgExit (
+;   VOID
+;   );
+;------------------------------------------------------------------------------
+global ASM_PFX(AsmVmgExit)
+ASM_PFX(AsmVmgExit):
+    rep; vmmcall
+    ret
+
-- 
2.17.1