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.d...@intel.com>
Cc: Ray Ni <ray...@intel.com>
Cc: Laszlo Ersek <ler...@redhat.com>
Acked-by: Laszlo Ersek <ler...@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com>
---
UefiCpuPkg/UefiCpuPkg.dec | 3 +
UefiCpuPkg/UefiCpuPkg.dsc | 2 +
UefiCpuPkg/Library/VmgExitLib/VmgExitLib.inf | 33 +++
UefiCpuPkg/Include/Library/VmgExitLib.h | 111 +++++++++
UefiCpuPkg/Library/VmgExitLib/VmgExitLib.c | 243 +++++++++++++++++++
UefiCpuPkg/Library/VmgExitLib/VmgExitLib.uni | 15 ++
6 files changed, 407 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 2f30bf89615f..795d1c8dedba 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..997840452218 100644
--- a/UefiCpuPkg/UefiCpuPkg.dsc
+++ b/UefiCpuPkg/UefiCpuPkg.dsc
@@ -56,6 +56,7 @@ [LibraryClasses]
PeCoffGetEntryPointLib|MdePkg/Library/BasePeCoffGetEntryPointLib/BasePeCoffGetEntryPointLib.inf
PeCoffExtraActionLib|MdePkg/Library/BasePeCoffExtraActionLibNull/BasePeCoffExtraActionLibNull.inf
TpmMeasurementLib|MdeModulePkg/Library/TpmMeasurementLibNull/TpmMeasurementLibNull.inf
+ VmgExitLib|UefiCpuPkg/Library/VmgExitLib/VmgExitLib.inf
[LibraryClasses.common.SEC]
PlatformSecLib|UefiCpuPkg/Library/PlatformSecLibNull/PlatformSecLibNull.inf
@@ -136,6 +137,7 @@ [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..6afff51ad06b
--- /dev/null
+++ b/UefiCpuPkg/Library/VmgExitLib/VmgExitLib.c
@@ -0,0 +1,243 @@
+/** @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;
+}
+
+/**
+ 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.
+
+**/
+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);
+}
+
+/**
+ 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
+ )
+{
+ SetMem (&Ghcb->SaveArea, sizeof (Ghcb->SaveArea), 0);
+}
+
+/**
+ 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
+ )
+{
+}
+
+STATIC
+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;
+}
+
+/**
+ 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
+ )
+{
+ VmgMmio (Dest, Src, Bytes, TRUE);
+}
+
+/**
+ 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
+ )
+{
+ 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
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