2 files changed, 42 insertions, 0 deletions
diff --git a/OvmfPkg/Include/Library/QemuFwCfgLib.h b/OvmfPkg/Include/Library/QemuFwCfgLib.h
index 2519fc297f..8d3b835d43 100644
--- a/OvmfPkg/Include/Library/QemuFwCfgLib.h
+++ b/OvmfPkg/Include/Library/QemuFwCfgLib.h
@@ -214,5 +214,19 @@ InternalQemuFwCfgIsAvailable (
   VOID
   );
 
+
+/**
+  Determine if S3 support is explicitly enabled.
+
+  @retval  TRUE   if S3 support is explicitly enabled.
+           FALSE  otherwise. This includes unavailability of the firmware
+                  configuration interface.
+**/
+BOOLEAN
+EFIAPI
+QemuFwCfgS3Enabled (
+  VOID
+  );
+
 #endif
 
diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c
index 3c5963f31b..92c85c1d3d 100644
--- a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c
+++ b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c
@@ -294,3 +294,31 @@ QemuFwCfgFindFile (
 
   return RETURN_NOT_FOUND;
 }
+
+
+/**
+  Determine if S3 support is explicitly enabled.
+
+  @retval  TRUE   if S3 support is explicitly enabled.
+           FALSE  otherwise. This includes unavailability of the firmware
+                  configuration interface.
+**/
+BOOLEAN
+EFIAPI
+QemuFwCfgS3Enabled (
+  VOID
+  )
+{
+  RETURN_STATUS        Status;
+  FIRMWARE_CONFIG_ITEM FwCfgItem;
+  UINTN                FwCfgSize;
+  UINT8                SystemStates[6];
+
+  Status = QemuFwCfgFindFile ("etc/system-states", &FwCfgItem, &FwCfgSize);
+  if (Status != RETURN_SUCCESS || FwCfgSize != sizeof SystemStates) {
+    return FALSE;
+  }
+  QemuFwCfgSelectItem (FwCfgItem);
+  QemuFwCfgReadBytes (sizeof SystemStates, SystemStates);
+  return (BOOLEAN) (SystemStates[3] & BIT7);
+}