Re: [edk2-devel] [PATCH v4 07/40] UefiCpuPkg: Implement library support for VMGEXIT

["Dong, Eric" <eric.dong@intel.com>]

Hi Tom,

For this patch, I found the function implementations not have function header comments for them. This is not follow edk2 coding style, please update them.

Thanks,
Eric

-----Original Message-----
From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Lendacky, Thomas
Sent: Wednesday, February 5, 2020 7:01 AM
To: devel@edk2.groups.io
Cc: Justen, Jordan L <jordan.l.justen@intel.com>; Laszlo Ersek <lersek@redhat.com>; Ard Biesheuvel <ard.biesheuvel@linaro.org>; Kinney, Michael D <michael.d.kinney@intel.com>; Gao, Liming <liming.gao@intel.com>; Dong, Eric <eric.dong@intel.com>; Ni, Ray <ray.ni@intel.com>; Brijesh Singh <brijesh.singh@amd.com>
Subject: [edk2-devel] [PATCH v4 07/40] UefiCpuPkg: Implement library support for VMGEXIT

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198

To support issuing a VMGEXIT instruction, create a library that can be used to perform GHCB and VMGEXIT related operations and to issue the actual VMGEXIT instruction when using the GHCB.

Additionally, two VMGEXIT / MMIO related functions are created to support flash emulation. Flash emulation currently is done by marking the flash area as read-only and taking a nested page fault to perform the emulation of the instruction. However, emulation cannot be performed because there is no instruction decode assist support when SEV-ES is enabled. Provide routines to initiate an MMIO request to perform actual writes to flash.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 UefiCpuPkg/UefiCpuPkg.dec                    |   3 +
 UefiCpuPkg/UefiCpuPkg.dsc                    |   5 +
 UefiCpuPkg/Library/VmgExitLib/VmgExitLib.inf |  33 ++++
 UefiCpuPkg/Include/Library/VmgExitLib.h      | 111 +++++++++++
 UefiCpuPkg/Library/VmgExitLib/VmgExitLib.c   | 187 +++++++++++++++++++
 UefiCpuPkg/Library/VmgExitLib/VmgExitLib.uni |  15 ++
 6 files changed, 354 insertions(+)
 create mode 100644 UefiCpuPkg/Library/VmgExitLib/VmgExitLib.inf
 create mode 100644 UefiCpuPkg/Include/Library/VmgExitLib.h
 create mode 100644 UefiCpuPkg/Library/VmgExitLib/VmgExitLib.c
 create mode 100644 UefiCpuPkg/Library/VmgExitLib/VmgExitLib.uni

diff --git a/UefiCpuPkg/UefiCpuPkg.dec b/UefiCpuPkg/UefiCpuPkg.dec index 005703d8a3e7..893d2d06b0f2 100644
--- a/UefiCpuPkg/UefiCpuPkg.dec
+++ b/UefiCpuPkg/UefiCpuPkg.dec
@@ -53,6 +53,9 @@ [LibraryClasses.IA32, LibraryClasses.X64]
   ##
   MpInitLib|Include/Library/MpInitLib.h
 
+  ##  @libraryclass  Provides function to support VMGEXIT processing.
+  VmgExitLib|Include/Library/VmgExitLib.h
+
 [Guids]
   gUefiCpuPkgTokenSpaceGuid      = { 0xac05bf33, 0x995a, 0x4ed4, { 0xaa, 0xb8, 0xef, 0x7a, 0xe8, 0xf, 0x5c, 0xb0 }}
   gMsegSmramGuid                 = { 0x5802bce4, 0xeeee, 0x4e33, { 0xa1, 0x30, 0xeb, 0xad, 0x27, 0xf0, 0xe4, 0x39 }}
diff --git a/UefiCpuPkg/UefiCpuPkg.dsc b/UefiCpuPkg/UefiCpuPkg.dsc index d28cb5cccb52..5ab7e423e8ab 100644
--- a/UefiCpuPkg/UefiCpuPkg.dsc
+++ b/UefiCpuPkg/UefiCpuPkg.dsc
@@ -63,6 +63,7 @@ [LibraryClasses.common.SEC]
   HobLib|MdePkg/Library/PeiHobLib/PeiHobLib.inf
   PeiServicesTablePointerLib|MdePkg/Library/PeiServicesTablePointerLibIdt/PeiServicesTablePointerLibIdt.inf
   MemoryAllocationLib|MdePkg/Library/PeiMemoryAllocationLib/PeiMemoryAllocationLib.inf
+  VmgExitLib|UefiCpuPkg/Library/VmgExitLib/VmgExitLib.inf
 
 [LibraryClasses.common.PEIM]
   MemoryAllocationLib|MdePkg/Library/PeiMemoryAllocationLib/PeiMemoryAllocationLib.inf
@@ -74,6 +75,7 @@ [LibraryClasses.common.PEIM]  [LibraryClasses.IA32.PEIM, LibraryClasses.X64.PEIM]
   PeiServicesTablePointerLib|MdePkg/Library/PeiServicesTablePointerLibIdt/PeiServicesTablePointerLibIdt.inf
   CpuExceptionHandlerLib|UefiCpuPkg/Library/CpuExceptionHandlerLib/PeiCpuExceptionHandlerLib.inf
+  VmgExitLib|UefiCpuPkg/Library/VmgExitLib/VmgExitLib.inf
 
 [LibraryClasses.common.DXE_DRIVER]
   MemoryAllocationLib|MdePkg/Library/UefiMemoryAllocationLib/UefiMemoryAllocationLib.inf
@@ -81,12 +83,14 @@ [LibraryClasses.common.DXE_DRIVER]
   CpuExceptionHandlerLib|UefiCpuPkg/Library/CpuExceptionHandlerLib/DxeCpuExceptionHandlerLib.inf
   MpInitLib|UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
   RegisterCpuFeaturesLib|UefiCpuPkg/Library/RegisterCpuFeaturesLib/DxeRegisterCpuFeaturesLib.inf
+  VmgExitLib|UefiCpuPkg/Library/VmgExitLib/VmgExitLib.inf
 
 [LibraryClasses.common.DXE_SMM_DRIVER]
   SmmServicesTableLib|MdePkg/Library/SmmServicesTableLib/SmmServicesTableLib.inf
   MemoryAllocationLib|MdePkg/Library/SmmMemoryAllocationLib/SmmMemoryAllocationLib.inf
   HobLib|MdePkg/Library/DxeHobLib/DxeHobLib.inf
   CpuExceptionHandlerLib|UefiCpuPkg/Library/CpuExceptionHandlerLib/SmmCpuExceptionHandlerLib.inf
+  VmgExitLib|UefiCpuPkg/Library/VmgExitLib/VmgExitLib.inf
 
 [LibraryClasses.common.UEFI_APPLICATION]
   UefiApplicationEntryPoint|MdePkg/Library/UefiApplicationEntryPoint/UefiApplicationEntryPoint.inf
@@ -136,6 +140,7 @@ [Components.IA32, Components.X64]
   UefiCpuPkg/Library/SmmCpuPlatformHookLibNull/SmmCpuPlatformHookLibNull.inf
   UefiCpuPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.inf
   UefiCpuPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLibStm.inf
+  UefiCpuPkg/Library/VmgExitLib/VmgExitLib.inf
   UefiCpuPkg/PiSmmCommunication/PiSmmCommunicationPei.inf
   UefiCpuPkg/PiSmmCommunication/PiSmmCommunicationSmm.inf
   UefiCpuPkg/SecCore/SecCore.inf
diff --git a/UefiCpuPkg/Library/VmgExitLib/VmgExitLib.inf b/UefiCpuPkg/Library/VmgExitLib/VmgExitLib.inf
new file mode 100644
index 000000000000..6acfa779e75a
--- /dev/null
+++ b/UefiCpuPkg/Library/VmgExitLib/VmgExitLib.inf
@@ -0,0 +1,33 @@
+## @file
+#  VMGEXIT Support Library.
+#
+#  Copyright (c) 2019, Advanced Micro Devices, Inc. All rights 
+reserved.<BR> #  SPDX-License-Identifier: BSD-2-Clause-Patent # ##
+
+[Defines]
+  INF_VERSION                    = 0x00010005
+  BASE_NAME                      = VmgExitLib
+  MODULE_UNI_FILE                = VmgExitLib.uni
+  FILE_GUID                      = 3cd7368f-ef9b-4a9b-9571-2ed93813677e
+  MODULE_TYPE                    = BASE
+  VERSION_STRING                 = 1.0
+  LIBRARY_CLASS                  = VmgExitLib
+
+#
+# The following information is for reference only and not required by the build tools.
+#
+#  VALID_ARCHITECTURES           = IA32 X64
+#
+
+[Sources]
+  VmgExitLib.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+  UefiCpuPkg/UefiCpuPkg.dec
+
+[LibraryClasses]
+  BaseLib
+
diff --git a/UefiCpuPkg/Include/Library/VmgExitLib.h b/UefiCpuPkg/Include/Library/VmgExitLib.h
new file mode 100644
index 000000000000..602b213f1f63
--- /dev/null
+++ b/UefiCpuPkg/Include/Library/VmgExitLib.h
@@ -0,0 +1,111 @@
+/** @file
+  Public header file for the VMGEXIT Support library class.
+
+  This library class defines some routines used when invoking the 
+ VMGEXIT  instruction in support of SEV-ES.
+
+  Copyright (c) 2019, Advanced Micro Devices, Inc. All rights 
+ reserved.<BR>
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef __VMG_EXIT_LIB_H__
+#define __VMG_EXIT_LIB_H__
+
+#include <Register/Amd/Ghcb.h>
+
+
+/**
+  Perform VMGEXIT.
+
+  Sets the necessary fields of the GHCB, invokes the VMGEXIT 
+ instruction and  then handles the return actions.
+
+  @param[in]  GHCB       A pointer to the GHCB
+  @param[in]  ExitCode   VMGEXIT code to be assigned to the SwExitCode field of
+                         the GHCB.
+  @param[in]  ExitInfo1  VMGEXIT information to be assigned to the SwExitInfo1
+                         field of the GHCB.
+  @param[in]  ExitInfo2  VMGEXIT information to be assigned to the SwExitInfo2
+                         field of the GHCB.
+
+  @retval  0       VMGEXIT succeeded.
+  @retval  Others  VMGEXIT processing did not succeed. Exception number to
+                   be issued.
+
+**/
+UINTN
+EFIAPI
+VmgExit (
+  GHCB                *Ghcb,
+  UINT64              ExitCode,
+  UINT64              ExitInfo1,
+  UINT64              ExitInfo2
+  );
+
+/**
+  Perform pre-VMGEXIT initialization/preparation.
+
+  Performs the necessary steps in preparation for invoking VMGEXIT.
+
+  @param[in]  GHCB       A pointer to the GHCB
+
+**/
+VOID
+EFIAPI
+VmgInit (
+  GHCB                *Ghcb
+  );
+
+/**
+  Perform post-VMGEXIT cleanup.
+
+  Performs the necessary steps to cleanup after invoking VMGEXIT.
+
+  @param[in]  GHCB       A pointer to the GHCB
+
+**/
+VOID
+EFIAPI
+VmgDone (
+  GHCB                *Ghcb
+  );
+
+#define VMGMMIO_READ   False
+#define VMGMMIO_WRITE  True
+
+/**
+  Perform MMIO write of a buffer to a non-MMIO marked range.
+
+  Performs an MMIO write without taking a #VC. This is useful  for 
+ Flash devices, which are marked read-only.
+
+  @param[in]  UINT8      A pointer to the destination buffer
+  @param[in]  UINTN      The immediate value to write
+  @param[in]  UINTN      Number of bytes to write
+
+**/
+VOID
+EFIAPI
+VmgMmioWrite (
+  UINT8               *Dest,
+  UINT8               *Src,
+  UINTN                Bytes
+  );
+
+/**
+  Issue the GHCB set AP Jump Table VMGEXIT.
+
+  Performs a VMGEXIT using the GHCB AP Jump Table exit code to save the
+ AP Jump Table address with the hypervisor for retrieval at a later time.
+
+  @param[in]  EFI_PHYSICAL_ADDRESS  Physical address of the AP Jump 
+ Table
+
+**/
+UINTN
+EFIAPI
+VmgExitSetAPJumpTable (
+  EFI_PHYSICAL_ADDRESS  Address
+  );
+
+#endif
diff --git a/UefiCpuPkg/Library/VmgExitLib/VmgExitLib.c b/UefiCpuPkg/Library/VmgExitLib/VmgExitLib.c
new file mode 100644
index 000000000000..4e7315a58202
--- /dev/null
+++ b/UefiCpuPkg/Library/VmgExitLib/VmgExitLib.c
@@ -0,0 +1,187 @@
+/** @file
+  VMGEXIT Support Library.
+
+  Copyright (c) 2019, Advanced Micro Devices, Inc. All rights 
+ reserved.<BR>
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <Base.h>
+#include <Uefi.h>
+#include <Library/BaseMemoryLib.h>
+#include <Register/Amd/Ghcb.h>
+#include <Register/Amd/Msr.h>
+
+STATIC
+UINT64
+VmgExitErrorCheck (
+  GHCB                *Ghcb
+  )
+{
+  GHCB_EVENT_INJECTION  Event;
+  GHCB_EXIT_INFO        ExitInfo;
+  UINT64                Status;
+
+  ExitInfo.Uint64 = Ghcb->SaveArea.SwExitInfo1;  ASSERT 
+ ((ExitInfo.Elements.Lower32Bits == 0) ||
+          (ExitInfo.Elements.Lower32Bits == 1));
+
+  Status = 0;
+  if (ExitInfo.Elements.Lower32Bits == 0) {
+    return Status;
+  }
+
+  if (ExitInfo.Elements.Lower32Bits == 1) {
+    ASSERT (Ghcb->SaveArea.SwExitInfo2 != 0);
+
+    // Check that the return event is valid
+    Event.Uint64 = Ghcb->SaveArea.SwExitInfo2;
+    if (Event.Elements.Valid &&
+        Event.Elements.Type == GHCB_EVENT_INJECTION_TYPE_EXCEPTION) {
+      switch (Event.Elements.Vector) {
+      case GP_EXCEPTION:
+      case UD_EXCEPTION:
+        // Use returned event as return code
+        Status = Event.Uint64;
+      }
+    }
+  }
+
+  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;
+}
+
+UINT64
+EFIAPI
+VmgExit (
+  GHCB                *Ghcb,
+  UINT64              ExitCode,
+  UINT64              ExitInfo1,
+  UINT64              ExitInfo2
+  )
+{
+  Ghcb->SaveArea.SwExitCode = ExitCode;
+  Ghcb->SaveArea.SwExitInfo1 = ExitInfo1;
+  Ghcb->SaveArea.SwExitInfo2 = ExitInfo2;
+
+  //
+  // Guest memory is used for the guest-hypervisor communication, so 
+ fence  // the invocation of the VMGEXIT instruction to ensure GHCB 
+ accesses are  // synchronized properly.
+  //
+  MemoryFence ();
+  AsmVmgExit ();
+  MemoryFence ();
+
+  return VmgExitErrorCheck (Ghcb);
+}
+
+VOID
+EFIAPI
+VmgInit (
+  GHCB                *Ghcb
+  )
+{
+  SetMem (&Ghcb->SaveArea, sizeof (Ghcb->SaveArea), 0); }
+
+VOID
+EFIAPI
+VmgDone (
+  GHCB                *Ghcb
+  )
+{
+}
+
+UINTN
+EFIAPI
+VmgMmio (
+  UINT8               *MmioAddress,
+  UINT8               *Buffer,
+  UINTN               Bytes,
+  BOOLEAN             Write
+  )
+{
+  UINT64                    MmioOp, ExitInfo1, ExitInfo2, Status;
+  GHCB                      *Ghcb;
+  MSR_SEV_ES_GHCB_REGISTER  Msr;
+
+  Msr.GhcbPhysicalAddress = AsmReadMsr64 (MSR_SEV_ES_GHCB);  Ghcb = 
+ Msr.Ghcb;
+
+  VmgInit (Ghcb);
+
+  if (Write) {
+    MmioOp = SvmExitMmioWrite;
+  } else {
+    MmioOp = SvmExitMmioRead;
+  }
+
+  ExitInfo1 = (UINT64) (UINTN) MmioAddress;
+  ExitInfo2 = Bytes;
+
+  if (Write) {
+    CopyMem (Ghcb->SharedBuffer, Buffer, Bytes);  }
+
+  Ghcb->SaveArea.SwScratch = (UINT64) (UINTN) Ghcb->SharedBuffer;
+ Status = VmgExit (Ghcb, MmioOp, ExitInfo1, ExitInfo2);  if (Status != 
+ 0) {
+    return Status;
+  }
+
+  if (!Write) {
+    CopyMem (Buffer, Ghcb->SharedBuffer, Bytes);  }
+
+  VmgDone (Ghcb);
+
+  return 0;
+}
+
+VOID
+EFIAPI
+VmgMmioWrite (
+  UINT8               *Dest,
+  UINT8               *Src,
+  UINTN                Bytes
+  )
+{
+  VmgMmio (Dest, Src, Bytes, TRUE);
+}
+
+UINTN
+EFIAPI
+VmgExitSetAPJumpTable (
+  EFI_PHYSICAL_ADDRESS  Address
+  )
+{
+  UINT64                    ExitInfo1, ExitInfo2, Status;
+  GHCB                      *Ghcb;
+  MSR_SEV_ES_GHCB_REGISTER  Msr;
+
+  Msr.GhcbPhysicalAddress = AsmReadMsr64 (MSR_SEV_ES_GHCB);  Ghcb = 
+ Msr.Ghcb;
+
+  VmgInit (Ghcb);
+
+  ExitInfo1 = 0;
+  ExitInfo2 = (UINT64) (UINTN) Address;
+
+  Status = VmgExit (Ghcb, SvmExitApJumpTable, ExitInfo1, ExitInfo2);
+
+  VmgDone (Ghcb);
+
+  return Status;
+}
+
diff --git a/UefiCpuPkg/Library/VmgExitLib/VmgExitLib.uni b/UefiCpuPkg/Library/VmgExitLib/VmgExitLib.uni
new file mode 100644
index 000000000000..e8656aae4726
--- /dev/null
+++ b/UefiCpuPkg/Library/VmgExitLib/VmgExitLib.uni
@@ -0,0 +1,15 @@
+// /** @file
+// VMGEXIT support library instance.
+//
+// VMGEXIT support library instance.
+//
+// Copyright (c) 2019, Advanced Micro Devices, Inc. All rights 
+reserved.<BR> // SPDX-License-Identifier: BSD-2-Clause-Patent // // **/
+
+
+#string STR_MODULE_ABSTRACT             #language en-US "VMGEXIT Support Library."
+
+#string STR_MODULE_DESCRIPTION          #language en-US "VMGEXIT Support Library."
+
--
2.17.1