intel microcode: split up microcode loading stages

This patch only applies to CONFIG_MICROCODE_IN_CBFS. The intel microcode
update routine would always walk the CBFS for the microcode file. Then
it would loop through the whole file looking for a match then load the
microcode. This process was maintained for intel_update_microcode_from_cbfs(),
however 2 new functions were exported:
	1.  const void *intel_microcode_find(void)
	2.  void intel_microcode_load_unlocked(const void *microcode_patch)

The first locates a matching microcode while the second loads that
mircocode. These new functions can then be used to cache the found
microcode blob w/o having to re-walk the CBFS.

Booted baskingridge board to Linux and noted that all microcode
revisions match on all the CPUs.

Change-Id: Ifde3f3e5c100911c4f984dd56d36664a8acdf7d5
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/2778
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/cpu/intel/microcode/microcode.c

@@ -82,8 +82,117 @@ static inline u32 read_microcode_rev(void)
 }
 
 #if CONFIG_CPU_MICROCODE_IN_CBFS
-static
+
+#define MICROCODE_CBFS_FILE "cpu_microcode_blob.bin"
+
+void intel_microcode_load_unlocked(const void *microcode_patch)
+{
+	u32 current_rev;
+	msr_t msr;
+	const struct microcode *m = microcode_patch;
+
+	if (!m)
+		return;
+
+	current_rev = read_microcode_rev();
+
+	/* No use loading the same revision. */
+	if (current_rev == m->rev)
+		return;
+
+	msr.lo = (unsigned long)m + sizeof(struct microcode);
+	msr.hi = 0;
+	wrmsr(0x79, msr);
+
+#if !defined(__ROMCC__)
+	printk(BIOS_DEBUG, "microcode: updated to revision "
+		    "0x%x date=%04x-%02x-%02x\n", read_microcode_rev(),
+		    m->date & 0xffff, (m->date >> 24) & 0xff,
+		    (m->date >> 16) & 0xff);
 #endif
+}
+
+const void *intel_microcode_find(void)
+{
+	void *microcode_updates;
+	u32 eax;
+	u32 pf, rev, sig;
+	unsigned int x86_model, x86_family;
+	const struct microcode *m;
+	const char *c;
+	msr_t msr;
+
+#ifdef __PRE_RAM__
+	microcode_updates = walkcbfs((char *) MICROCODE_CBFS_FILE);
+#else
+	microcode_updates = cbfs_get_file_content(CBFS_DEFAULT_MEDIA,
+					       MICROCODE_CBFS_FILE,
+					       CBFS_TYPE_MICROCODE);
+#endif
+
+	if (!microcode_updates)
+		return microcode_updates;
+
+	/* CPUID sets MSR 0x8B iff a microcode update has been loaded. */
+	msr.lo = 0;
+	msr.hi = 0;
+	wrmsr(0x8B, msr);
+	eax = cpuid_eax(1);
+	msr = rdmsr(0x8B);
+	rev = msr.hi;
+	x86_model = (eax >>4) & 0x0f;
+	x86_family = (eax >>8) & 0x0f;
+	sig = eax;
+
+	pf = 0;
+	if ((x86_model >= 5)||(x86_family>6)) {
+		msr = rdmsr(0x17);
+		pf = 1 << ((msr.hi >> 18) & 7);
+	}
+#if !defined(__ROMCC__)
+	/* If this code is compiled with ROMCC we're probably in
+	 * the bootblock and don't have console output yet.
+	 */
+	printk(BIOS_DEBUG, "microcode: sig=0x%x pf=0x%x revision=0x%x\n",
+			sig, pf, rev);
+#endif
+
+	m = microcode_updates;
+	for(c = microcode_updates; m->hdrver; m = (const struct microcode *)c) {
+		if ((m->sig == sig) && (m->pf & pf))
+			return m;
+
+		if (m->total_size) {
+			c += m->total_size;
+		} else {
+#if !defined(__ROMCC__)
+			printk(BIOS_WARNING, "Microcode has no valid size field!\n");
+#endif
+			c += 2048;
+		}
+	}
+
+	/* ROMCC doesn't like NULL. */
+	return (void *)0;
+}
+
+void intel_update_microcode_from_cbfs(void)
+{
+	const void *patch = intel_microcode_find();
+
+#if !defined(__ROMCC__) && !defined(__PRE_RAM__)
+	spin_lock(&microcode_lock);
+#endif
+
+	intel_microcode_load_unlocked(patch);
+
+#if !defined(__ROMCC__) && !defined(__PRE_RAM__)
+	spin_unlock(&microcode_lock);
+#endif
+}
+
+#else /* !CONFIG_CPU_MICROCODE_IN_CBFS */
+
 void intel_update_microcode(const void *microcode_updates)
 {
 	u32 eax;
@@ -155,21 +264,4 @@ void intel_update_microcode(const void *microcode_updates)
 #endif
 }
 
-#if CONFIG_CPU_MICROCODE_IN_CBFS
-
-#define MICROCODE_CBFS_FILE "cpu_microcode_blob.bin"
-
-void intel_update_microcode_from_cbfs(void)
-{
-	void *microcode_blob;
-
-#ifdef __PRE_RAM__
-	microcode_blob = walkcbfs((char *) MICROCODE_CBFS_FILE);
-#else
-	microcode_blob = cbfs_get_file_content(CBFS_DEFAULT_MEDIA,
-					       MICROCODE_CBFS_FILE,
-					       CBFS_TYPE_MICROCODE);
-#endif
-	intel_update_microcode(microcode_blob);
-}
 #endif

src/include/cpu/intel/microcode.h

@@ -23,6 +23,13 @@
 #ifndef __PRE_RAM__
 #if CONFIG_CPU_MICROCODE_IN_CBFS
 void intel_update_microcode_from_cbfs(void);
+/* Find a microcode that matches the revision and platform family returning
+ * NULL if none found. */
+const void *intel_microcode_find(void);
+/* It is up to the caller to determine if parallel loading is possible as
+ * well as ensuring the micrcode matches the family and revision (i.e. with
+ * intel_microcode_find()). */
+void intel_microcode_load_unlocked(const void *microcode_patch);
 #else
 void intel_update_microcode(const void *microcode_updates);
 #endif