[RFC PATCH 06/14] OvmfPkg/AmdSev: Setup Migration Handler Mailbox

["Tobin Feldman-Fitzthum" <tobin@linux.ibm.com>]

The migration handler communicates with the hypervisor using a
special mailbox, a page of shared memory where pending commands
can be written. Another shared page is used to pass the incoming
or outgoing guest memory pages. These pages are set aside in MEMFD,
which this patch expands, and reserved as runtime memory in
ConfidentialMigrationPei, which this patch introduces.

Signed-off-by: Tobin Feldman-Fitzthum <tobin@linux.ibm.com>
---
 OvmfPkg/OvmfPkg.dec                           |  5 +++
 OvmfPkg/AmdSev/AmdSevX64.dsc                  |  1 +
 OvmfPkg/AmdSev/AmdSevX64.fdf                  | 12 ++++---
 .../ConfidentialMigrationPei.inf              | 35 +++++++++++++++++++
 .../ConfidentialMigrationPei.c                | 25 +++++++++++++
 5 files changed, 74 insertions(+), 4 deletions(-)
 create mode 100644 OvmfPkg/AmdSev/ConfidentialMigration/ConfidentialMigrationPei.inf
 create mode 100644 OvmfPkg/AmdSev/ConfidentialMigration/ConfidentialMigrationPei.c

diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
index 402c3b61fa..5c55e3c7c9 100644
--- a/OvmfPkg/OvmfPkg.dec
+++ b/OvmfPkg/OvmfPkg.dec
@@ -318,6 +318,11 @@
   gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretBase|0x0|UINT32|0x42
   gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretSize|0x0|UINT32|0x43
 
+  ## Area used by the confidential migration handler to communicate with
+  # the hypervisor.
+  gUefiOvmfPkgTokenSpaceGuid.PcdConfidentialMigrationMailboxBase|0x0|UINT32|0x48
+  gUefiOvmfPkgTokenSpaceGuid.PcdConfidentialMigrationMailboxSize|0x0|UINT32|0x49
+
 [PcdsDynamic, PcdsDynamicEx]
   gUefiOvmfPkgTokenSpaceGuid.PcdEmuVariableEvent|0|UINT64|2
   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfFlashVariablesEnable|FALSE|BOOLEAN|0x10
diff --git a/OvmfPkg/AmdSev/AmdSevX64.dsc b/OvmfPkg/AmdSev/AmdSevX64.dsc
index fa68143663..4f748a0015 100644
--- a/OvmfPkg/AmdSev/AmdSevX64.dsc
+++ b/OvmfPkg/AmdSev/AmdSevX64.dsc
@@ -620,6 +620,7 @@
   UefiCpuPkg/Universal/Acpi/S3Resume2Pei/S3Resume2Pei.inf
   UefiCpuPkg/CpuMpPei/CpuMpPei.inf
   OvmfPkg/AmdSev/SecretPei/SecretPei.inf
+  OvmfPkg/AmdSev/ConfidentialMigration/ConfidentialMigrationPei.inf
 
 !if $(TPM_ENABLE) == TRUE
   OvmfPkg/Tcg/Tcg2Config/Tcg2ConfigPei.inf
diff --git a/OvmfPkg/AmdSev/AmdSevX64.fdf b/OvmfPkg/AmdSev/AmdSevX64.fdf
index 6ef6dc89f2..94468f2ca0 100644
--- a/OvmfPkg/AmdSev/AmdSevX64.fdf
+++ b/OvmfPkg/AmdSev/AmdSevX64.fdf
@@ -36,10 +36,10 @@ FV = SECFV
 
 [FD.MEMFD]
 BaseAddress   = $(MEMFD_BASE_ADDRESS)
-Size          = 0xD00000
+Size          = 0xE00000
 ErasePolarity = 1
 BlockSize     = 0x10000
-NumBlocks     = 0xD0
+NumBlocks     = 0xE0
 
 0x000000|0x006000
 gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesSize
@@ -68,11 +68,14 @@ gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbBackupBase|gUefiOvmfPkgTokenSpaceGuid.P
 0x010000|0x010000
 gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamSize
 
-0x020000|0x0E0000
+0x020000|0x003000
+gUefiOvmfPkgTokenSpaceGuid.PcdConfidentialMigrationMailboxBase|gUefiOvmfPkgTokenSpaceGuid.PcdConfidentialMigrationMailboxSize
+
+0x120000|0x0E0000
 gUefiOvmfPkgTokenSpaceGuid.PcdOvmfPeiMemFvBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfPeiMemFvSize
 FV = PEIFV
 
-0x100000|0xC00000
+0x200000|0xC00000
 gUefiOvmfPkgTokenSpaceGuid.PcdOvmfDxeMemFvBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfDxeMemFvSize
 FV = DXEFV
 
@@ -145,6 +148,7 @@ INF  MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf
 INF  UefiCpuPkg/Universal/Acpi/S3Resume2Pei/S3Resume2Pei.inf
 INF  UefiCpuPkg/CpuMpPei/CpuMpPei.inf
 INF  OvmfPkg/AmdSev/SecretPei/SecretPei.inf
+INF  OvmfPkg/AmdSev/ConfidentialMigration/ConfidentialMigrationPei.inf
 
 !if $(TPM_ENABLE) == TRUE
 INF  OvmfPkg/Tcg/Tcg2Config/Tcg2ConfigPei.inf
diff --git a/OvmfPkg/AmdSev/ConfidentialMigration/ConfidentialMigrationPei.inf b/OvmfPkg/AmdSev/ConfidentialMigration/ConfidentialMigrationPei.inf
new file mode 100644
index 0000000000..918cf22abd
--- /dev/null
+++ b/OvmfPkg/AmdSev/ConfidentialMigration/ConfidentialMigrationPei.inf
@@ -0,0 +1,35 @@
+## @file
+#  PEI support for confidential migration.
+#
+#  Copyright (C) 2021 IBM Corporation.
+#
+#  SPDX-License-Identifier: BSD-2-Clause-Patent
+#
+##
+
+[Defines]
+  INF_VERSION                    = 0x00010005
+  BASE_NAME                      = ConfidentialMigration
+  FILE_GUID                      = a747792e-71a1-4c24-84a9-a76a0a279878
+  MODULE_TYPE                    = PEIM
+  VERSION_STRING                 = 1.0
+  ENTRY_POINT                    = InitializeConfidentialMigrationPei
+
+[Sources]
+  ConfidentialMigrationPei.c
+
+[Packages]
+  OvmfPkg/OvmfPkg.dec
+  MdePkg/MdePkg.dec
+
+[LibraryClasses]
+  HobLib
+  PeimEntryPoint
+  PcdLib
+
+[FixedPcd]
+  gUefiOvmfPkgTokenSpaceGuid.PcdConfidentialMigrationMailboxBase
+  gUefiOvmfPkgTokenSpaceGuid.PcdConfidentialMigrationMailboxSize
+
+[Depex]
+  TRUE
diff --git a/OvmfPkg/AmdSev/ConfidentialMigration/ConfidentialMigrationPei.c b/OvmfPkg/AmdSev/ConfidentialMigration/ConfidentialMigrationPei.c
new file mode 100644
index 0000000000..ce304bc07b
--- /dev/null
+++ b/OvmfPkg/AmdSev/ConfidentialMigration/ConfidentialMigrationPei.c
@@ -0,0 +1,25 @@
+/** @file
+  Reserve memory for confidential migration handler.
+
+  Copyright (C) 2020 IBM Corporation.
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+#include <PiPei.h>
+#include <Library/HobLib.h>
+#include <Library/PcdLib.h>
+
+EFI_STATUS
+EFIAPI
+InitializeConfidentialMigrationPei (
+  IN       EFI_PEI_FILE_HANDLE  FileHandle,
+  IN CONST EFI_PEI_SERVICES     **PeiServices
+  )
+{
+  BuildMemoryAllocationHob (
+    PcdGet32 (PcdConfidentialMigrationMailboxBase),
+    PcdGet32 (PcdConfidentialMigrationMailboxSize),
+    EfiRuntimeServicesData
+    );
+
+  return EFI_SUCCESS;
+}
-- 
2.20.1