[PATCH v6 06/17] OvmfPkg: Add AmdSevDxe driver

[Brijesh Singh <brijesh.singh@amd.com>]

When SEV is enabled, the MMIO memory range must be mapped as unencrypted
(i.e C-bit cleared).

We need to clear the C-bit for MMIO GCD entries in order to cover the
ranges that were added during the PEI phase (through memory resource
descriptor HOBs). Additionally, the NonExistent ranges are processed
in order to cover, in advance, MMIO ranges added later in the DXE phase
by various device drivers, via the appropriate DXE memory space services.

The approach is not transparent for later addition of system memory ranges
to the GCD memory space map. (Such ranges should be encrypted.) OVMF does
not do such a thing at the moment, so this approach should be OK.

The driver is being added to the APRIORI DXE file so that, we clear the
C-bit from MMIO regions before any driver accesses it.


Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Leo Duran <leo.duran@amd.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Suggested-by: Jiewen Yao <jiewen.yao@intel.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
---
 OvmfPkg/OvmfPkgIa32X64.dsc      |  1 +
 OvmfPkg/OvmfPkgX64.dsc          |  1 +
 OvmfPkg/OvmfPkgIa32X64.fdf      |  2 +
 OvmfPkg/OvmfPkgX64.fdf          |  2 +
 OvmfPkg/AmdSevDxe/AmdSevDxe.inf | 43 +++++++++++
 OvmfPkg/AmdSevDxe/AmdSevDxe.c   | 75 ++++++++++++++++++++
 6 files changed, 124 insertions(+)

diff --git a/OvmfPkg/OvmfPkgIa32X64.dsc b/OvmfPkg/OvmfPkgIa32X64.dsc
index dfc2534fc998..8dd6179893a9 100644
--- a/OvmfPkg/OvmfPkgIa32X64.dsc
+++ b/OvmfPkg/OvmfPkgIa32X64.dsc
@@ -824,6 +824,7 @@ [Components.X64]
 !endif
 
   OvmfPkg/PlatformDxe/Platform.inf
+  OvmfPkg/AmdSevDxe/AmdSevDxe.inf
 
 !if $(SMM_REQUIRE) == TRUE
   OvmfPkg/SmmAccess/SmmAccess2Dxe.inf
diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc
index 60e42794483b..6324941ca2ab 100644
--- a/OvmfPkg/OvmfPkgX64.dsc
+++ b/OvmfPkg/OvmfPkgX64.dsc
@@ -822,6 +822,7 @@ [Components]
 !endif
 
   OvmfPkg/PlatformDxe/Platform.inf
+  OvmfPkg/AmdSevDxe/AmdSevDxe.inf
 
 !if $(SMM_REQUIRE) == TRUE
   OvmfPkg/SmmAccess/SmmAccess2Dxe.inf
diff --git a/OvmfPkg/OvmfPkgIa32X64.fdf b/OvmfPkg/OvmfPkgIa32X64.fdf
index 5233314139bc..12871860d001 100644
--- a/OvmfPkg/OvmfPkgIa32X64.fdf
+++ b/OvmfPkg/OvmfPkgIa32X64.fdf
@@ -190,6 +190,7 @@ [FV.DXEFV]
 APRIORI DXE {
   INF  MdeModulePkg/Universal/DevicePathDxe/DevicePathDxe.inf
   INF  MdeModulePkg/Universal/PCD/Dxe/Pcd.inf
+  INF  OvmfPkg/AmdSevDxe/AmdSevDxe.inf
 !if $(SMM_REQUIRE) == FALSE
   INF  OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FvbServicesRuntimeDxe.inf
 !endif
@@ -351,6 +352,7 @@ [FV.DXEFV]
 INF  OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
 INF  OvmfPkg/VirtioGpuDxe/VirtioGpu.inf
 INF  OvmfPkg/PlatformDxe/Platform.inf
+INF  OvmfPkg/AmdSevDxe/AmdSevDxe.inf
 
 !if $(SMM_REQUIRE) == TRUE
 INF  OvmfPkg/SmmAccess/SmmAccess2Dxe.inf
diff --git a/OvmfPkg/OvmfPkgX64.fdf b/OvmfPkg/OvmfPkgX64.fdf
index 36150101e784..ae6e66a1c08d 100644
--- a/OvmfPkg/OvmfPkgX64.fdf
+++ b/OvmfPkg/OvmfPkgX64.fdf
@@ -190,6 +190,7 @@ [FV.DXEFV]
 APRIORI DXE {
   INF  MdeModulePkg/Universal/DevicePathDxe/DevicePathDxe.inf
   INF  MdeModulePkg/Universal/PCD/Dxe/Pcd.inf
+  INF  OvmfPkg/AmdSevDxe/AmdSevDxe.inf
 !if $(SMM_REQUIRE) == FALSE
   INF  OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FvbServicesRuntimeDxe.inf
 !endif
@@ -351,6 +352,7 @@ [FV.DXEFV]
 INF  OvmfPkg/QemuVideoDxe/QemuVideoDxe.inf
 INF  OvmfPkg/VirtioGpuDxe/VirtioGpu.inf
 INF  OvmfPkg/PlatformDxe/Platform.inf
+INF  OvmfPkg/AmdSevDxe/AmdSevDxe.inf
 
 !if $(SMM_REQUIRE) == TRUE
 INF  OvmfPkg/SmmAccess/SmmAccess2Dxe.inf
diff --git a/OvmfPkg/AmdSevDxe/AmdSevDxe.inf b/OvmfPkg/AmdSevDxe/AmdSevDxe.inf
new file mode 100644
index 000000000000..41635a57a454
--- /dev/null
+++ b/OvmfPkg/AmdSevDxe/AmdSevDxe.inf
@@ -0,0 +1,43 @@
+#/** @file
+#
+#  Driver clears the encryption attribute from MMIO regions when SEV is enabled
+#
+#  Copyright (c) 2017, AMD Inc. All rights reserved.<BR>
+#
+#  This program and the accompanying materials
+#  are licensed and made available under the terms and conditions of the BSD
+#  License which accompanies this distribution.  The full text of the license may
+#  be found at http://opensource.org/licenses/bsd-license.php
+#
+#  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+#
+#**/
+
+[Defines]
+  INF_VERSION                    = 1.25
+  BASE_NAME                      = AmdSevDxe
+  FILE_GUID                      = 2ec9da37-ee35-4de9-86c5-6d9a81dc38a7
+  MODULE_TYPE                    = DXE_DRIVER
+  VERSION_STRING                 = 1.0
+  ENTRY_POINT                    = AmdSevDxeEntryPoint
+
+[Sources]
+  AmdSevDxe.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+  MdeModulePkg/MdeModulePkg.dec
+  OvmfPkg/OvmfPkg.dec
+
+[LibraryClasses]
+  BaseLib
+  UefiLib
+  UefiDriverEntryPoint
+  UefiBootServicesTableLib
+  DxeServicesTableLib
+  DebugLib
+  MemEncryptSevLib
+
+[Depex]
+  TRUE
diff --git a/OvmfPkg/AmdSevDxe/AmdSevDxe.c b/OvmfPkg/AmdSevDxe/AmdSevDxe.c
new file mode 100644
index 000000000000..e472096320ea
--- /dev/null
+++ b/OvmfPkg/AmdSevDxe/AmdSevDxe.c
@@ -0,0 +1,75 @@
+/** @file
+
+  AMD Sev Dxe driver. This driver is dispatched early in DXE, due to being list
+  in APRIORI. It clears C-bit from MMIO and NonExistent Memory space when SEV is
+  enabled.
+
+  Copyright (c) 2017, AMD Inc. All rights reserved.<BR>
+
+  This program and the accompanying materials
+  are licensed and made available under the terms and conditions of the BSD
+  License which accompanies this distribution.  The full text of the license may
+  be found at http://opensource.org/licenses/bsd-license.php
+
+  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+**/
+
+#include <PiDxe.h>
+
+#include <Library/BaseLib.h>
+#include <Library/DebugLib.h>
+#include <Library/BaseMemoryLib.h>
+#include <Library/MemoryAllocationLib.h>
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/DxeServicesTableLib.h>
+#include <Library/MemEncryptSevLib.h>
+
+EFI_STATUS
+EFIAPI
+AmdSevDxeEntryPoint (
+  IN EFI_HANDLE         ImageHandle,
+  IN EFI_SYSTEM_TABLE   *SystemTable
+  )
+{
+  EFI_STATUS                       Status;
+  EFI_GCD_MEMORY_SPACE_DESCRIPTOR  *AllDescMap;
+  UINTN                            NumEntries;
+  UINTN                            Index;
+
+  //
+  // Do nothing when SEV is not enabled
+  //
+  if (!MemEncryptSevIsEnabled ()) {
+    return EFI_UNSUPPORTED;
+  }
+
+  //
+  // Iterate through the GCD map and clear the C-bit from MMIO and NonExistent
+  // memory space. The NonExistent memory space will be used for mapping the MMIO
+  // space added later (eg PciRootBridge). By clearing both known MMIO and
+  // NonExistent memory space can gurantee that current and furture MMIO adds
+  // will have C-bit cleared.
+  //
+  Status = gDS->GetMemorySpaceMap (&NumEntries, &AllDescMap);
+  if (!EFI_ERROR (Status)) {
+    for (Index = 0; Index < NumEntries; Index++) {
+      CONST EFI_GCD_MEMORY_SPACE_DESCRIPTOR *Desc;
+
+      Desc = &AllDescMap[Index];
+      if (Desc->GcdMemoryType == EfiGcdMemoryTypeMemoryMappedIo ||
+          Desc->GcdMemoryType == EfiGcdMemoryTypeNonExistent) {
+        Status = MemEncryptSevClearPageEncMask (0,
+                                                Desc->BaseAddress,
+                                                EFI_SIZE_TO_PAGES(Desc->Length),
+                                                FALSE);
+        ASSERT_EFI_ERROR (Status);
+      }
+    }
+
+    FreePool (AllDescMap);
+  }
+
+  return EFI_SUCCESS;
+}
-- 
2.7.4