[Xen-devel] [PATCH v3 27/35] OvmfPkg/XenPlatformLib: Cache result for XenDetected

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

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@xxxxxxxxxx>
---

Notes:
    v3:
    - new patch

 .../Library/XenPlatformLib/XenPlatformLib.c    | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/OvmfPkg/Library/XenPlatformLib/XenPlatformLib.c 
b/OvmfPkg/Library/XenPlatformLib/XenPlatformLib.c
index 6f27cbffa8..b5257b0c97 100644
--- a/OvmfPkg/Library/XenPlatformLib/XenPlatformLib.c
+++ b/OvmfPkg/Library/XenPlatformLib/XenPlatformLib.c
@@ -26,13 +26,25 @@ XenGetInfoHOB (
   )
 {
   EFI_HOB_GUID_TYPE  *GuidHob;
+  STATIC BOOLEAN     Cached = FALSE;
+  STATIC EFI_XEN_INFO *XenInfo;
+
+  //
+  // Return the cached result for the benefit of XenDetected that can be
+  // called many times.
+  //
+  if (Cached) {
+    return XenInfo;
+  }
 
   GuidHob = GetFirstGuidHob (&gEfiXenInfoGuid);
   if (GuidHob == NULL) {
-    return NULL;
+    XenInfo = NULL;
+  } else {
+    XenInfo = (EFI_XEN_INFO *) GET_GUID_HOB_DATA (GuidHob);
   }
-
-  return (EFI_XEN_INFO *) GET_GUID_HOB_DATA (GuidHob);
+  Cached = TRUE;
+  return XenInfo;
 }
 
 /**
-- 
Anthony PERARD


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