diff options
Diffstat (limited to 'OvmfPkg/Library/VmgExitLib/VmgExitLib.c')
| -rw-r--r-- | OvmfPkg/Library/VmgExitLib/VmgExitLib.c | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/OvmfPkg/Library/VmgExitLib/VmgExitLib.c b/OvmfPkg/Library/VmgExitLib/VmgExitLib.c new file mode 100644 index 0000000000..53040cc6f6 --- /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
+
+ @retval 0 VMGEXIT succeeded.
+ @return Exception number to be propagated, VMGEXIT processing
+ did not succeed.
+
+**/
+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.
+
+ @retval 0 VMGEXIT succeeded.
+ @return Exception number to be propagated, VMGEXIT
+ processing did not succeed.
+
+**/
+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
+ )
+{
+}
+
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