[coreboot-gerrit] Change in coreboot[master]: cpu/intel/microcode: Add caching layer around intel_microcode_find

[Patrick Rudolph (Code Review)]

Attention is currently required from: Patrick Rudolph.
Patrick Rudolph has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/49896 )

Change subject: cpu/intel/microcode: Add caching layer around intel_microcode_find
......................................................................

cpu/intel/microcode: Add caching layer around intel_microcode_find

Change-Id: Ic40d57964600f8f20ddb26c7d1691b043fd89f29
Signed-off-by: Patrick Rudolph 
---
M src/cpu/intel/microcode/microcode.c
M src/include/cpu/intel/microcode.h
2 files changed, 25 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/96/49896/1

diff --git a/src/cpu/intel/microcode/microcode.c b/src/cpu/intel/microcode/microcode.c
index 0f362d4..843fc91 100644
--- a/src/cpu/intel/microcode/microcode.c
+++ b/src/cpu/intel/microcode/microcode.c
@@ -176,9 +176,26 @@
    return NULL;
 }

+const void *intel_microcode_find_cached(void)
+{
+#if ENV_STAGE_HAS_DATA_SECTION
+	static bool checked;
+	static void *cached;
+
+	if (checked)
+		return cached;
+
+	cached = intel_microcode_find();
+	checked = 1;
+	return cached;
+#else
+	return intel_microcode_find();
+#endif
+}
+
 void intel_update_microcode_from_cbfs(void)
 {
-	const void *patch = intel_microcode_find();
+	const void *patch = intel_microcode_find_cached();

spin_lock(&microcode_lock);

diff --git a/src/include/cpu/intel/microcode.h b/src/include/cpu/intel/microcode.h
index f1a8601..4b5223c 100644
--- a/src/include/cpu/intel/microcode.h
+++ b/src/include/cpu/intel/microcode.h
@@ -8,6 +8,13 @@
 /* Find a microcode that matches the revision and platform family returning
  * NULL if none found. */
 const void *intel_microcode_find(void);
+
+/*
+ * Returns the microcode patch found in CBFS (if any), using caching if possible.
+ * In early stages this is as slow as intel_microcode_find().
+ */
+const void *intel_microcode_find_cached(void);
+
 /* It is up to the caller to determine if parallel loading is possible as
  * well as ensuring the microcode matches the family and revision (i.e. with
  * intel_microcode_find()). */