[PATCH v4 4/4] OvmfPkg/PlatformDxe: Add support for SEV live migration.

["Ashish Kalra" <ashish.kalra@amd.com>]

From: Ashish Kalra <ashish.kalra@amd.com>

Detect for KVM hypervisor and check for SEV live migration
feature support via KVM_FEATURE_CPUID, if detected setup a new
UEFI enviroment variable to indicate OVMF support for SEV
live migration.

Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
---
 OvmfPkg/Include/Guid/MemEncryptLib.h |  20 ++++
 OvmfPkg/OvmfPkg.dec                  |   1 +
 OvmfPkg/PlatformDxe/AmdSev.c         | 108 ++++++++++++++++++++
 OvmfPkg/PlatformDxe/Platform.c       |   5 +
 OvmfPkg/PlatformDxe/Platform.inf     |   2 +
 OvmfPkg/PlatformDxe/PlatformConfig.h |   5 +
 6 files changed, 141 insertions(+)

diff --git a/OvmfPkg/Include/Guid/MemEncryptLib.h b/OvmfPkg/Include/Guid/MemEncryptLib.h
new file mode 100644
index 0000000000..4c046ba439
--- /dev/null
+++ b/OvmfPkg/Include/Guid/MemEncryptLib.h
@@ -0,0 +1,20 @@
+/** @file
+
+  AMD Memory Encryption GUID, define a new GUID for defining
+  new UEFI enviroment variables assocaiated with SEV Memory Encryption.
+
+  Copyright (c) 2020, AMD Inc. All rights reserved.<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef __MEMENCRYPT_LIB_H__
+#define __MEMENCRYPT_LIB_H__
+
+#define MEMENCRYPT_GUID \
+{0x0cf29b71, 0x9e51, 0x433a, {0xa3, 0xb7, 0x81, 0xf3, 0xab, 0x16, 0xb8, 0x75}}
+
+extern EFI_GUID gMemEncryptGuid;
+
+#endif
diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
index 6ae733f6e3..e452dc8494 100644
--- a/OvmfPkg/OvmfPkg.dec
+++ b/OvmfPkg/OvmfPkg.dec
@@ -122,6 +122,7 @@
   gQemuKernelLoaderFsMediaGuid          = {0x1428f772, 0xb64a, 0x441e, {0xb8, 0xc3, 0x9e, 0xbd, 0xd7, 0xf8, 0x93, 0xc7}}
   gGrubFileGuid                         = {0xb5ae312c, 0xbc8a, 0x43b1, {0x9c, 0x62, 0xeb, 0xb8, 0x26, 0xdd, 0x5d, 0x07}}
   gConfidentialComputingSecretGuid      = {0xadf956ad, 0xe98c, 0x484c, {0xae, 0x11, 0xb5, 0x1c, 0x7d, 0x33, 0x64, 0x47}}
+  gMemEncryptGuid                       = {0x0cf29b71, 0x9e51, 0x433a, {0xa3, 0xb7, 0x81, 0xf3, 0xab, 0x16, 0xb8, 0x75}}
 
 [Ppis]
   # PPI whose presence in the PPI database signals that the TPM base address
diff --git a/OvmfPkg/PlatformDxe/AmdSev.c b/OvmfPkg/PlatformDxe/AmdSev.c
new file mode 100644
index 0000000000..3dbf17a8cd
--- /dev/null
+++ b/OvmfPkg/PlatformDxe/AmdSev.c
@@ -0,0 +1,108 @@
+/**@file
+  Detect KVM hypervisor support for SEV live migration and if
+  detected, setup a new UEFI enviroment variable indicating
+  OVMF support for SEV live migration.
+
+  Copyright (c) 2020, Advanced Micro Devices. All rights reserved.<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+//
+// The package level header files this module uses
+//
+
+#include <Library/BaseLib.h>
+#include <Library/BaseMemoryLib.h>
+#include <Library/DebugLib.h>
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiRuntimeServicesTableLib.h>
+#include <Guid/MemEncryptLib.h>
+
+#define KVM_FEATURE_MIGRATION_CONTROL   17
+
+/**
+  Figures out if we are running inside KVM HVM and
+  KVM HVM supports SEV Live Migration feature.
+
+  @retval TRUE   KVM was detected and Live Migration supported
+  @retval FALSE  KVM was not detected or Live Migration not supported
+
+**/
+BOOLEAN
+KvmDetectSevLiveMigrationFeature(
+  VOID
+  )
+{
+  UINT8 Signature[13];
+  UINT32 mKvmLeaf = 0;
+  UINT32 RegEax, RegEbx, RegEcx, RegEdx;
+
+  Signature[12] = '\0';
+  for (mKvmLeaf = 0x40000000; mKvmLeaf < 0x40010000; mKvmLeaf += 0x100) {
+    AsmCpuid (mKvmLeaf,
+              NULL,
+              (UINT32 *) &Signature[0],
+              (UINT32 *) &Signature[4],
+              (UINT32 *) &Signature[8]);
+
+    if (!AsciiStrCmp ((CHAR8 *) Signature, "KVMKVMKVM\0\0\0")) {
+      DEBUG ((
+        DEBUG_ERROR,
+        "%a: KVM Detected, signature = %s\n",
+        __FUNCTION__,
+        Signature
+        ));
+
+      RegEax = 0x40000001;
+      RegEcx = 0;
+      AsmCpuid (0x40000001, &RegEax, &RegEbx, &RegEcx, &RegEdx);
+      if (RegEax & (1 << KVM_FEATURE_MIGRATION_CONTROL)) {
+        DEBUG ((
+          DEBUG_ERROR,
+          "%a: Live Migration feature supported\n",
+          __FUNCTION__
+          ));
+        return TRUE;
+      }
+    }
+  }
+
+  return FALSE;
+}
+
+/**
+
+  Function checks if SEV Live Migration support is available, if present then it sets
+  a UEFI enviroment variable to be queried later using Runtime services.
+
+  **/
+VOID
+AmdSevSetConfig(
+  VOID
+  )
+{
+  EFI_STATUS Status;
+  BOOLEAN SevLiveMigrationEnabled;
+
+  SevLiveMigrationEnabled = KvmDetectSevLiveMigrationFeature();
+
+  if (SevLiveMigrationEnabled) {
+   Status = gRT->SetVariable (
+                L"SevLiveMigrationEnabled",
+                &gMemEncryptGuid,
+                EFI_VARIABLE_NON_VOLATILE |
+                EFI_VARIABLE_BOOTSERVICE_ACCESS |
+                EFI_VARIABLE_RUNTIME_ACCESS,
+                sizeof (BOOLEAN),
+                &SevLiveMigrationEnabled
+               );
+
+   DEBUG ((
+    DEBUG_ERROR,
+    "%a: Setting SevLiveMigrationEnabled variable, status = %lx\n",
+    __FUNCTION__,
+    Status
+    ));
+  }
+}
diff --git a/OvmfPkg/PlatformDxe/Platform.c b/OvmfPkg/PlatformDxe/Platform.c
index f2e51960ce..f61302d98b 100644
--- a/OvmfPkg/PlatformDxe/Platform.c
+++ b/OvmfPkg/PlatformDxe/Platform.c
@@ -763,6 +763,11 @@ PlatformInit (
 {
   EFI_STATUS Status;
 
+  //
+  // Set Amd Sev configuation
+  //
+  AmdSevSetConfig();
+
   ExecutePlatformConfig ();
 
   mConfigAccess.ExtractConfig = &ExtractConfig;
diff --git a/OvmfPkg/PlatformDxe/Platform.inf b/OvmfPkg/PlatformDxe/Platform.inf
index 14727c1220..2896f0a1d1 100644
--- a/OvmfPkg/PlatformDxe/Platform.inf
+++ b/OvmfPkg/PlatformDxe/Platform.inf
@@ -24,6 +24,7 @@
   PlatformConfig.c
   PlatformConfig.h
   PlatformForms.vfr
+  AmdSev.c
 
 [Packages]
   MdePkg/MdePkg.dec
@@ -56,6 +57,7 @@
 [Guids]
   gEfiIfrTianoGuid
   gOvmfPlatformConfigGuid
+  gMemEncryptGuid
 
 [Depex]
   gEfiHiiConfigRoutingProtocolGuid  AND
diff --git a/OvmfPkg/PlatformDxe/PlatformConfig.h b/OvmfPkg/PlatformDxe/PlatformConfig.h
index 716514da21..4f662aafa4 100644
--- a/OvmfPkg/PlatformDxe/PlatformConfig.h
+++ b/OvmfPkg/PlatformDxe/PlatformConfig.h
@@ -44,6 +44,11 @@ PlatformConfigLoad (
   OUT UINT64          *OptionalElements
   );
 
+VOID
+AmdSevSetConfig(
+  VOID
+  );
+
 //
 // Feature flags for OptionalElements.
 //
-- 
2.17.1