The base VmgExitLib library provides a default limited interface. As it
does not provide full support, create an OVMF version of this library to
begin the process of providing full support of SEV-ES within OVMF.
SEV-ES support is only provided for X64 builds, so only OvmfPkgX64.dsc is
updated to make use of the OvmfPkg version of the library.
Cc: Jordan Justen <jordan.l.jus...@intel.com>
Cc: Laszlo Ersek <ler...@redhat.com>
Cc: Ard Biesheuvel <ard.biesheu...@arm.com>
Acked-by: Laszlo Ersek <ler...@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com>
---
OvmfPkg/OvmfPkgX64.dsc | 2 +-
OvmfPkg/Library/VmgExitLib/VmgExitLib.inf | 36 +++++
OvmfPkg/Library/VmgExitLib/VmgExitLib.c | 159 ++++++++++++++++++++
OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c | 81 ++++++++++
4 files changed, 277 insertions(+), 1 deletion(-)
diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc
index 0b9189ab1e38..b5f3859420d0 100644
--- a/OvmfPkg/OvmfPkgX64.dsc
+++ b/OvmfPkg/OvmfPkgX64.dsc
@@ -232,7 +232,7 @@ [LibraryClasses]
[LibraryClasses.common]
BaseCryptLib|CryptoPkg/Library/BaseCryptLib/BaseCryptLib.inf
- VmgExitLib|UefiCpuPkg/Library/VmgExitLibNull/VmgExitLibNull.inf
+ VmgExitLib|OvmfPkg/Library/VmgExitLib/VmgExitLib.inf
[LibraryClasses.common.SEC]
TimerLib|OvmfPkg/Library/AcpiTimerLib/BaseRomAcpiTimerLib.inf
diff --git a/OvmfPkg/Library/VmgExitLib/VmgExitLib.inf
b/OvmfPkg/Library/VmgExitLib/VmgExitLib.inf
new file mode 100644
index 000000000000..8acdee2349b4
--- /dev/null
+++ b/OvmfPkg/Library/VmgExitLib/VmgExitLib.inf
@@ -0,0 +1,36 @@
+## @file
+# VMGEXIT Support Library.
+#
+# Copyright (C) 2020, Advanced Micro Devices, Inc. All rights reserved.<BR>
+# SPDX-License-Identifier: BSD-2-Clause-Patent
+#
+##
+
+[Defines]
+ INF_VERSION = 0x00010005
+ BASE_NAME = VmgExitLib
+ FILE_GUID = 0e923c25-13cd-430b-8714-ffe85652a97b
+ 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 = X64
+#
+
+[Sources.common]
+ VmgExitLib.c
+ VmgExitVcHandler.c
+
+[Packages]
+ MdePkg/MdePkg.dec
+ UefiCpuPkg/UefiCpuPkg.dec
+ OvmfPkg/OvmfPkg.dec
+
+[LibraryClasses]
+ BaseLib
+ DebugLib
+ BaseMemoryLib
+
diff --git a/OvmfPkg/Library/VmgExitLib/VmgExitLib.c
b/OvmfPkg/Library/VmgExitLib/VmgExitLib.c
new file mode 100644
index 000000000000..0ca164a33eb4
--- /dev/null
+++ b/OvmfPkg/Library/VmgExitLib/VmgExitLib.c
@@ -0,0 +1,159 @@
+/** @file
+ VMGEXIT Support Library.
+
+ Copyright (C) 2020, 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 <Library/VmgExitLib.h>
+#include <Register/Amd/Msr.h>
+
+/**
+ Check for VMGEXIT error
+
+ Check if the hypervisor has returned an error after completion of the VMGEXIT
+ by examining the SwExitInfo1 field of the GHCB.
+
+ @param[in] Ghcb A pointer to the GHCB
+
+ @return 0 VMGEXIT succeeded.
+ @return Others VMGEXIT processing did not succeed. Exception number
to
+ be propagated.
+
+**/
+STATIC
+UINT64
+VmgExitErrorCheck (
+ IN 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 GpEvent;
+
+ GpEvent.Uint64 = 0;
+ GpEvent.Elements.Vector = GP_EXCEPTION;
+ GpEvent.Elements.Type = GHCB_EVENT_INJECTION_TYPE_EXCEPTION;
+ GpEvent.Elements.Valid = 1;
+
+ Status = GpEvent.Uint64;
+ }
+
+ return Status;
+}
+
+/**
+ Perform VMGEXIT.
+
+ Sets the necessary fields of the GHCB, invokes the VMGEXIT instruction and
+ then handles the return actions.
+
+ @param[in, out] 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.
+
+ @return 0 VMGEXIT succeeded.
+ @return Others VMGEXIT processing did not succeed. Exception
+ event to be propagated.
+
+**/
+UINT64
+EFIAPI
+VmgExit (
+ IN OUT GHCB *Ghcb,
+ IN UINT64 ExitCode,
+ IN UINT64 ExitInfo1,
+ IN 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. Must be
+ called before setting any fields within the GHCB.
+
+ @param[in, out] Ghcb A pointer to the GHCB
+
+**/
+VOID
+EFIAPI
+VmgInit (
+ IN OUT GHCB *Ghcb
+ )
+{
+ SetMem (&Ghcb->SaveArea, sizeof (Ghcb->SaveArea), 0);
+}
+
+/**
+ Perform post-VMGEXIT cleanup.
+
+ Performs the necessary steps to cleanup after invoking VMGEXIT. Must be
+ called after obtaining needed fields within the GHCB.
+
+ @param[in, out] Ghcb A pointer to the GHCB
+
+**/
+VOID
+EFIAPI
+VmgDone (
+ IN OUT GHCB *Ghcb
+ )
+{
+}
+
diff --git a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
new file mode 100644
index 000000000000..b6a955ed8088
--- /dev/null
+++ b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
@@ -0,0 +1,81 @@
+/** @file
+ X64 #VC Exception Handler functon.
+
+ Copyright (C) 2020, 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 <Library/VmgExitLib.h>
+#include <Register/Amd/Msr.h>
+
+/**
+ Handle a #VC exception.
+
+ Performs the necessary processing to handle a #VC exception.
+
+ @param[in, out] ExceptionType Pointer to an EFI_EXCEPTION_TYPE to be set
+ as value to use on error.
+ @param[in, out] SystemContext Pointer to EFI_SYSTEM_CONTEXT
+
+ @retval EFI_SUCCESS Exception handled
+ @retval EFI_UNSUPPORTED #VC not supported, (new) exception value to
+ propagate provided
+ @retval EFI_PROTOCOL_ERROR #VC handling failed, (new) exception value to
+ propagate provided
+
+**/
+EFI_STATUS
+EFIAPI
+VmgExitHandleVc (
+ IN OUT EFI_EXCEPTION_TYPE *ExceptionType,
+ IN OUT EFI_SYSTEM_CONTEXT SystemContext
+ )
+{
+ MSR_SEV_ES_GHCB_REGISTER Msr;
+ EFI_SYSTEM_CONTEXT_X64 *Regs;
+ GHCB *Ghcb;
+ UINT64 ExitCode, Status;
+ EFI_STATUS VcRet;
+
+ VcRet = EFI_SUCCESS;
+
+ Msr.GhcbPhysicalAddress = AsmReadMsr64 (MSR_SEV_ES_GHCB);
+ ASSERT (Msr.GhcbInfo.Function == 0);
+ ASSERT (Msr.Ghcb != 0);
+
+ Regs = SystemContext.SystemContextX64;
+ Ghcb = Msr.Ghcb;
+
+ VmgInit (Ghcb);
+
+ ExitCode = Regs->ExceptionData;
+ switch (ExitCode) {
+ default:
+ Status = VmgExit (Ghcb, SVM_EXIT_UNSUPPORTED, ExitCode, 0);
+ if (Status == 0) {
+ Regs->ExceptionData = 0;
+ *ExceptionType = GP_EXCEPTION;
+ } else {
+ GHCB_EVENT_INJECTION Event;
+
+ 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;
+ }
+
+ VmgDone (Ghcb);
+
+ return VcRet;
+}
--
2.27.0
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