linux-kernel - Re: Builtin microcode does nothing..

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Message-ID: <20160526100353.GA30784@pd.tnic>
Date:	Thu, 26 May 2016 12:03:53 +0200
From:	Borislav Petkov <bp@...e.de>
To:	Gabriel C <nix.or.die@...il.com>
Cc:	Jim Bos <jim876@...all.nl>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: Builtin microcode does nothing..

On Thu, May 26, 2016 at 01:36:51AM +0200, Gabriel C wrote:
>  Hangs on the second box too also..

Ok, please try the diff below ontop to see if it fixes your issue.

Looks like I'd need to rewrite the figuring out where the microcode data
is. Currently, it is ugly and error prone.

Thanks.

---
diff --git a/arch/x86/include/asm/microcode.h b/arch/x86/include/asm/microcode.h
index 01c2d14ec05f..4bee5bdbaf2c 100644
--- a/arch/x86/include/asm/microcode.h
+++ b/arch/x86/include/asm/microcode.h
@@ -143,8 +143,13 @@ static inline bool
 get_builtin_firmware(struct cpio_data *cd, const char *name)	{ return false; }
 #endif
 
+static bool initrd_valid;
+
 static inline unsigned long get_initrd_start(void)
 {
+	if (!initrd_valid)
+		return 0;
+
 #ifdef CONFIG_BLK_DEV_INITRD
 	return initrd_start;
 #else
@@ -154,6 +159,9 @@ static inline unsigned long get_initrd_start(void)
 
 static inline unsigned long get_initrd_start_addr(void)
 {
+	if (!initrd_valid)
+		return 0;
+
 #ifdef CONFIG_BLK_DEV_INITRD
 #ifdef CONFIG_X86_32
 	unsigned long *initrd_start_p = (unsigned long *)__pa_nodebug(&initrd_start);
diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index 43f7caff4749..7ed06c397e2b 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -55,6 +55,8 @@ static struct mc_saved_data {
 	struct microcode_intel **mc_saved;
 } mc_saved_data;
 
+static bool initrd_valid;
+
 /* Go through saved patches and find the one suitable for the current CPU. */
 static enum ucode_state
 find_microcode_patch(struct microcode_intel **saved,
@@ -533,12 +535,10 @@ static bool __init load_builtin_intel_microcode(struct cpio_data *cp)
 
 static __init enum ucode_state
 scan_microcode(struct mc_saved_data *mcs, unsigned long *mc_ptrs,
-	       unsigned long *start, unsigned long size,
+	       unsigned long start, unsigned long size,
 	       struct ucode_cpu_info *uci)
 {
-	struct cpio_data cd;
-	cd.data = NULL;
-	cd.size = 0;
+	struct cpio_data cd = { NULL, 0, "" };
 
 	/* try built-in microcode first */
 	if (load_builtin_intel_microcode(&cd))
@@ -547,21 +547,23 @@ scan_microcode(struct mc_saved_data *mcs, unsigned long *mc_ptrs,
 		 * the boot loader, by mistake or simply forgotten there. That's
 		 * fine, we ignore it since we've found builtin microcode.
 		 */
-		*start = 0;
+		initrd_valid = false;
 	else {
 #ifdef CONFIG_BLK_DEV_INITRD
 		static __initdata char ucode_name[] = "kernel/x86/microcode/GenuineIntel.bin";
 		char *p = IS_ENABLED(CONFIG_X86_32) ? (char *)__pa_nodebug(ucode_name)
 						    : ucode_name;
 
-		cd = find_cpio_data(p, (void *)*start, size, NULL);
-		if (!cd.data)
+		cd = find_cpio_data(p, (void *)start, size, NULL);
+		if (cd.data)
+			initrd_valid = true;
+		else
 #endif
 			return UCODE_ERROR;
 	}
 
-	return get_matching_model_microcode(*start, cd.data, cd.size,
-					    mcs, mc_ptrs, uci);
+	return get_matching_model_microcode(initrd_valid ? start : 0,
+					    cd.data, cd.size, mcs, mc_ptrs, uci);
 }
 
 /*
@@ -703,20 +705,16 @@ static void __init
 _load_ucode_intel_bsp(struct mc_saved_data *mcs, unsigned long *mc_ptrs,
 		      unsigned long start, unsigned long size)
 {
-	unsigned long _start = start;
 	struct ucode_cpu_info uci;
 	enum ucode_state ret;
 
 	collect_cpu_info_early(&uci);
 
-	ret = scan_microcode(mcs, mc_ptrs, &_start, size, &uci);
+	ret = scan_microcode(mcs, mc_ptrs, start, size, &uci);
 	if (ret != UCODE_OK)
 		return;
 
-	/* Pass updated starting address of blobs to the next routine.  */
-	start = _start;
-
-	ret = load_microcode(mcs, mc_ptrs, start, &uci);
+	ret = load_microcode(mcs, mc_ptrs, initrd_valid ? start : 0, &uci);
 	if (ret != UCODE_OK)
 		return;
 


-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--