From 506740982bba199f12e75f6cfda510c30aa4e7c6 Mon Sep 17 00:00:00 2001
From: Gerd Hoffmann <kraxel@redhat.com>
Date: Mon, 22 Apr 2024 12:47:28 +0200
Subject: [PATCH] OvmfPkg/VirtHstiDxe: add code flash check

Detects qemu config issue: code pflash is writable.
Checked for both PC and Q35.

Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Konstantin Kostiuk <kkostiuk@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Jiewen Yao <Jiewen.yao@intel.com>
---
 OvmfPkg/VirtHstiDxe/QemuCommon.c    | 36 +++++++++++++++++++++++++++++
 OvmfPkg/VirtHstiDxe/VirtHstiDxe.c   |  4 ++++
 OvmfPkg/VirtHstiDxe/VirtHstiDxe.h   | 13 +++++++++++
 OvmfPkg/VirtHstiDxe/VirtHstiDxe.inf |  2 ++
 4 files changed, 55 insertions(+)
 create mode 100644 OvmfPkg/VirtHstiDxe/QemuCommon.c

diff --git a/OvmfPkg/VirtHstiDxe/QemuCommon.c b/OvmfPkg/VirtHstiDxe/QemuCommon.c
new file mode 100644
index 0000000000..4ab3fe2d6e
--- /dev/null
+++ b/OvmfPkg/VirtHstiDxe/QemuCommon.c
@@ -0,0 +1,36 @@
+/** @file
+
+SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <Library/BaseLib.h>
+#include <Library/DebugLib.h>
+
+#include "VirtHstiDxe.h"
+
+VOID
+VirtHstiQemuCommonInit (
+  VIRT_ADAPTER_INFO_PLATFORM_SECURITY  *VirtHsti
+  )
+{
+  VirtHstiSetSupported (VirtHsti, 0, VIRT_HSTI_BYTE0_READONLY_CODE_FLASH);
+}
+
+VOID
+VirtHstiQemuCommonVerify (
+  VOID
+  )
+{
+  CHAR16  *ErrorMsg;
+
+  switch (VirtHstiQemuFirmwareFlashCheck (PcdGet32 (PcdBfvBase))) {
+    case QEMU_FIRMWARE_FLASH_WRITABLE:
+      ErrorMsg = L"qemu code pflash is writable";
+      break;
+    default:
+      ErrorMsg = NULL;
+  }
+
+  VirtHstiTestResult (ErrorMsg, 0, VIRT_HSTI_BYTE0_READONLY_CODE_FLASH);
+}
diff --git a/OvmfPkg/VirtHstiDxe/VirtHstiDxe.c b/OvmfPkg/VirtHstiDxe/VirtHstiDxe.c
index 74e5e6bd9d..b6e53a1219 100644
--- a/OvmfPkg/VirtHstiDxe/VirtHstiDxe.c
+++ b/OvmfPkg/VirtHstiDxe/VirtHstiDxe.c
@@ -104,9 +104,11 @@ VirtHstiOnReadyToBoot (
   switch (VirtHstiGetHostBridgeDevId ()) {
     case INTEL_82441_DEVICE_ID:
       VirtHstiQemuPCVerify ();
+      VirtHstiQemuCommonVerify ();
       break;
     case INTEL_Q35_MCH_DEVICE_ID:
       VirtHstiQemuQ35Verify ();
+      VirtHstiQemuCommonVerify ();
       break;
     default:
       ASSERT (FALSE);
@@ -142,9 +144,11 @@ VirtHstiDxeEntrypoint (
   switch (DevId) {
     case INTEL_82441_DEVICE_ID:
       VirtHsti = VirtHstiQemuPCInit ();
+      VirtHstiQemuCommonInit (VirtHsti);
       break;
     case INTEL_Q35_MCH_DEVICE_ID:
       VirtHsti = VirtHstiQemuQ35Init ();
+      VirtHstiQemuCommonInit (VirtHsti);
       break;
     default:
       DEBUG ((DEBUG_INFO, "%a: unknown platform (0x%x)\n", __func__, DevId));
diff --git a/OvmfPkg/VirtHstiDxe/VirtHstiDxe.h b/OvmfPkg/VirtHstiDxe/VirtHstiDxe.h
index ceff41c037..f8bdcfe8f2 100644
--- a/OvmfPkg/VirtHstiDxe/VirtHstiDxe.h
+++ b/OvmfPkg/VirtHstiDxe/VirtHstiDxe.h
@@ -8,6 +8,7 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 
 #define VIRT_HSTI_BYTE0_SMM_SMRAM_LOCK         BIT0
 #define VIRT_HSTI_BYTE0_SMM_SECURE_VARS_FLASH  BIT1
+#define VIRT_HSTI_BYTE0_READONLY_CODE_FLASH    BIT2
 
 typedef struct {
   // ADAPTER_INFO_PLATFORM_SECURITY
@@ -67,6 +68,18 @@ VirtHstiQemuPCVerify (
   VOID
   );
 
+/* QemuCommon.c */
+
+VOID
+VirtHstiQemuCommonInit (
+  VIRT_ADAPTER_INFO_PLATFORM_SECURITY  *VirtHsti
+  );
+
+VOID
+VirtHstiQemuCommonVerify (
+  VOID
+  );
+
 /* Flash.c */
 
 #define QEMU_FIRMWARE_FLASH_UNKNOWN    0
diff --git a/OvmfPkg/VirtHstiDxe/VirtHstiDxe.inf b/OvmfPkg/VirtHstiDxe/VirtHstiDxe.inf
index b6bdd1f22e..9514933011 100644
--- a/OvmfPkg/VirtHstiDxe/VirtHstiDxe.inf
+++ b/OvmfPkg/VirtHstiDxe/VirtHstiDxe.inf
@@ -22,6 +22,7 @@
   VirtHstiDxe.c
   QemuPC.c
   QemuQ35.c
+  QemuCommon.c
   Flash.c
 
 [Packages]
@@ -48,6 +49,7 @@
   gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire
 
 [Pcd]
+  gUefiOvmfPkgTokenSpaceGuid.PcdBfvBase
   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfFlashNvStorageVariableBase
 
 [Depex]