OvmfPkg/QemuFwCfgLib: remove mQemuFwCfgSupported + mQemuFwCfgDmaSupported

Remove global variables, store the state in PlatformInfoHob instead.
Probing for fw_cfg happens on first use, at library initialization
time the Hob might not be present yet.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>

OvmfPkg/Include/Library/PlatformInitLib.h

@@ -50,6 +50,10 @@ typedef struct {
   UINT32               S3AcpiReservedMemorySize;
 
   UINT64               FeatureControlValue;
+
+  BOOLEAN              QemuFwCfgChecked;
+  BOOLEAN              QemuFwCfgSupported;
+  BOOLEAN              QemuFwCfgDmaSupported;
 } EFI_HOB_PLATFORM_INFO;
 #pragma pack()
 

OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPei.c

@@ -9,17 +9,17 @@
   SPDX-License-Identifier: BSD-2-Clause-Patent
 **/
 
+#include <PiPei.h>
 #include <Library/BaseLib.h>
-#include <Library/IoLib.h>
 #include <Library/DebugLib.h>
+#include <Library/HobLib.h>
+#include <Library/IoLib.h>
+#include <Library/PlatformInitLib.h>
 #include <Library/QemuFwCfgLib.h>
 #include <WorkArea.h>
 
 #include "QemuFwCfgLibInternal.h"
 
-STATIC BOOLEAN  mQemuFwCfgSupported = FALSE;
-STATIC BOOLEAN  mQemuFwCfgDmaSupported;
-
 /**
   Check if it is Tdx guest
 
@@ -93,13 +93,39 @@ QemuFwCfgProbe (
     ));
 }
 
+STATIC
+EFI_HOB_PLATFORM_INFO *
+QemuFwCfgGetPlatformInfo (
+  VOID
+  )
+{
+  EFI_HOB_PLATFORM_INFO  *PlatformInfoHob;
+  EFI_HOB_GUID_TYPE      *GuidHob;
+
+  GuidHob = GetFirstGuidHob (&gUefiOvmfPkgPlatformInfoGuid);
+  if (GuidHob == NULL) {
+    return NULL;
+  }
+
+  PlatformInfoHob = (EFI_HOB_PLATFORM_INFO *)GET_GUID_HOB_DATA (GuidHob);
+
+  if (!PlatformInfoHob->QemuFwCfgChecked) {
+    QemuFwCfgProbe (
+      &PlatformInfoHob->QemuFwCfgSupported,
+      &PlatformInfoHob->QemuFwCfgDmaSupported
+      );
+    PlatformInfoHob->QemuFwCfgChecked = TRUE;
+  }
+
+  return PlatformInfoHob;
+}
+
 RETURN_STATUS
 EFIAPI
 QemuFwCfgInitialize (
   VOID
   )
 {
-  QemuFwCfgProbe (&mQemuFwCfgSupported, &mQemuFwCfgDmaSupported);
   return RETURN_SUCCESS;
 }
 
@@ -117,7 +143,9 @@ InternalQemuFwCfgIsAvailable (
   VOID
   )
 {
-  return mQemuFwCfgSupported;
+  EFI_HOB_PLATFORM_INFO  *PlatformInfoHob = QemuFwCfgGetPlatformInfo ();
+
+  return PlatformInfoHob->QemuFwCfgSupported;
 }
 
 /**
@@ -132,7 +160,9 @@ InternalQemuFwCfgDmaIsAvailable (
   VOID
   )
 {
-  return mQemuFwCfgDmaSupported;
+  EFI_HOB_PLATFORM_INFO  *PlatformInfoHob = QemuFwCfgGetPlatformInfo ();
+
+  return PlatformInfoHob->QemuFwCfgDmaSupported;
 }
 
 /**

OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPeiLib.inf

@@ -39,8 +39,12 @@
   BaseLib
   BaseMemoryLib
   DebugLib
+  HobLib
   IoLib
   MemoryAllocationLib
 
+[Guids]
+  gUefiOvmfPkgPlatformInfoGuid
+
 [Pcd]
   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfWorkAreaBase