OvmfPkg/XenPlatformLib: Cache result for XenDetected

We are going to replace XenDetected() implementation in
PlatformBootManagerLib by the one in XenPlatformLib.
PlatformBootManagerLib's implementation does cache the result of
GetFirstGuidHob(), so we do something similar in XenPlatformLib.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1689
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20190813113119.14804-27-anthony.perard@citrix.com>

diff --git a/OvmfPkg/Library/XenPlatformLib/XenPlatformLib.c b/OvmfPkg/Library/XenPlatformLib/XenPlatformLib.c
index 974a0e73f189a8988f0b0319c777d9070a612466..8f20ae2d456ee329233d2253cc32661859ca78d3 100644 (file)
--- a/OvmfPkg/Library/XenPlatformLib/XenPlatformLib.c
+++ b/OvmfPkg/Library/XenPlatformLib/XenPlatformLib.c
@@ -25,14 +25,26 @@ XenGetInfoHOB (
   VOID\r
   )\r
 {\r
-  EFI_HOB_GUID_TYPE  *GuidHob;\r
+  EFI_HOB_GUID_TYPE   *GuidHob;\r
+  STATIC BOOLEAN      Cached = FALSE;\r
+  STATIC EFI_XEN_INFO *XenInfo;\r
+\r
+  //\r
+  // Return the cached result for the benefit of XenDetected that can be\r
+  // called many times.\r
+  //\r
+  if (Cached) {\r
+    return XenInfo;\r
+  }\r
 \r
   GuidHob = GetFirstGuidHob (&gEfiXenInfoGuid);\r
   if (GuidHob == NULL) {\r
-    return NULL;\r
+    XenInfo = NULL;\r
+  } else {\r
+    XenInfo = (EFI_XEN_INFO *) GET_GUID_HOB_DATA (GuidHob);\r
   }\r
-\r
-  return (EFI_XEN_INFO *) GET_GUID_HOB_DATA (GuidHob);\r
+  Cached = TRUE;\r
+  return XenInfo;\r
 }\r
 \r
 /**\r