Ashish,


On 08/07/2021 17:09, Ashish Kalra wrote:

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

Check for SEV live migration feature support, if detected
setup a new UEFI enviroment variable to indicate OVMF
support for SEV live migration.

The new runtime UEFI environment variable is set via the
notification function registered for the
EFI_END_OF_DXE_EVENT_GROUP_GUID event in AmdSevDxe driver.

Why is this indirect notification needed? Why not simply call
gRT->SetVariable in AmdSevDxeEntryPoint (instead of calling CreateEventEx)?

If this is needed, please add a clarification (in the commit message and
before the CreateEventEx call).

Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
---
OvmfPkg/AmdSevDxe/AmdSevDxe.c | 59 ++++++++++++++++++++
OvmfPkg/AmdSevDxe/AmdSevDxe.inf | 4 ++
OvmfPkg/Include/Guid/MemEncryptLib.h | 20 +++++++
OvmfPkg/OvmfPkg.dec | 1 +
4 files changed, 84 insertions(+)

diff --git a/OvmfPkg/AmdSevDxe/AmdSevDxe.c b/OvmfPkg/AmdSevDxe/AmdSevDxe.c
index c66c4e9b92..45adf3249c 100644
--- a/OvmfPkg/AmdSevDxe/AmdSevDxe.c
+++ b/OvmfPkg/AmdSevDxe/AmdSevDxe.c
@@ -15,10 +15,49 @@
#include <Library/BaseMemoryLib.h>
#include <Library/DebugLib.h>
#include <Library/DxeServicesTableLib.h>
+#include <Library/UefiRuntimeServicesTableLib.h>
+#include <Library/UefiBootServicesTableLib.h>
#include <Library/MemEncryptSevLib.h>
#include <Library/MemoryAllocationLib.h>
+#include <Guid/MemEncryptLib.h>
+#include <Guid/EventGroup.h>
#include <Library/PcdLib.h>

+STATIC
+VOID
+EFIAPI
+AmdSevDxeOnEndOfDxe (
+ IN EFI_EVENT Event,
+ IN VOID *EventToSignal
+ )
+{
+ EFI_STATUS Status;
+ BOOLEAN SevLiveMigrationEnabled;
+
+ SevLiveMigrationEnabled = MemEncryptSevLiveMigrationIsEnabled();
+
+ if (SevLiveMigrationEnabled) {
+ Status = gRT->SetVariable (
+ L"SevLiveMigrationEnabled",
+ &gMemEncryptGuid,
+ EFI_VARIABLE_NON_VOLATILE |
+ EFI_VARIABLE_BOOTSERVICE_ACCESS |
+ EFI_VARIABLE_RUNTIME_ACCESS,
+ sizeof (BOOLEAN),

Should be:

sizeof SevLiveMigrationEnabled,

+ &SevLiveMigrationEnabled
+ );
+
+ DEBUG ((
+ DEBUG_INFO,
+ "%a: Setting SevLiveMigrationEnabled variable, status = %lx\n",
+ __FUNCTION__,
+ Status
+ ));
+ }
+
+ DEBUG ((DEBUG_VERBOSE, "%a\n", __FUNCTION__));

Remove debug print.

+}
+
EFI_STATUS
EFIAPI
AmdSevDxeEntryPoint (
@@ -30,6 +69,7 @@ AmdSevDxeEntryPoint (
EFI_GCD_MEMORY_SPACE_DESCRIPTOR *AllDescMap;
UINTN NumEntries;
UINTN Index;
+ EFI_EVENT Event;

//
// Do nothing when SEV is not enabled
@@ -130,5 +170,24 @@ AmdSevDxeEntryPoint (
}
}

+ //
+ // Register EFI_END_OF_DXE_EVENT_GROUP_GUID event.
+ // The notification function sets the runtime variable indicating OVMF
+ // support for SEV live migration.
+ //
+ Status = gBS->CreateEventEx (
+ EVT_NOTIFY_SIGNAL,
+ TPL_CALLBACK,
+ AmdSevDxeOnEndOfDxe,
+ NULL,
+ &gEfiEndOfDxeEventGroupGuid,
+ &Event
+ );
+
+ if (EFI_ERROR (Status)) {
+ DEBUG ((DEBUG_INFO, "%a: CreateEventEx(): %r\n",
+ __FUNCTION__, Status));
+ }
+
return EFI_SUCCESS;
}
diff --git a/OvmfPkg/AmdSevDxe/AmdSevDxe.inf b/OvmfPkg/AmdSevDxe/AmdSevDxe.inf
index 0676fcc5b6..f4e40ff412 100644
--- a/OvmfPkg/AmdSevDxe/AmdSevDxe.inf
+++ b/OvmfPkg/AmdSevDxe/AmdSevDxe.inf
@@ -45,3 +45,7 @@

[Pcd]
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfHostBridgePciDevId
+
+[Guids]
+ gMemEncryptGuid
+ gEfiEndOfDxeEventGroupGuid ## CONSUMES ## Event
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

Should the filename, GUID #define name, and global var name include
"AMD" or "SEV" in them? (and similarly in the corresponding Linux patch)

Or: maybe the new "SevLiveMigrationEnabled" variable can be set in the
confidential computing GUID? (not sure what are the guidelines for
creating or reusing GUIDs).

@@ -0,0 +1,20 @@
+/** @file
+
+ AMD Memory Encryption GUID, define a new GUID for defining
+ new UEFI enviroment variables assocaiated with SEV Memory Encryption.

typos: environment, associated

+
+ 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

-Dov