linux-kernel - Re: [PATCH] arch/x86/kernel/cpu/microcode/intel: don't store initrd's start

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Message-ID: <20160725123643.GE4901@nazgul.tnic>
Date:	Mon, 25 Jul 2016 14:36:43 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Nicolai Stange <nicstange@...il.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arch/x86/kernel/cpu/microcode/intel: don't store
 initrd's start

On Mon, Jul 25, 2016 at 11:24:31AM +0200, Nicolai Stange wrote:
> I tested on linux-next-20160722 (I wrote this below the '---' marker).

Ok, thanks.

So let's try something simpler first. That works in my kvm guest here,
can you test it on your box too please?

---
diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index 6515c802346a..b98e016ba5fc 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -793,10 +793,10 @@ void __init load_ucode_intel_bsp(void)
 void load_ucode_intel_ap(void)
 {
 	struct ucode_blobs *blobs_p;
+	unsigned long *ptrs, start;
 	struct mc_saved_data *mcs;
 	struct ucode_cpu_info uci;
 	enum ucode_state ret;
-	unsigned long *ptrs;
 
 #ifdef CONFIG_X86_32
 	mcs	= (struct mc_saved_data *)__pa_nodebug(&mc_saved_data);
@@ -815,8 +815,14 @@ void load_ucode_intel_ap(void)
 	if (!mcs->num_saved)
 		return;
 
+	/*
+	 * Pay attention to CONFIG_RANDOMIZE_MEMORY as it shuffles physmem
+	 * mapping too.
+	 */
+	start = blobs_p->start + (PAGE_OFFSET - __PAGE_OFFSET_BASE);
+
 	collect_cpu_info_early(&uci);
-	ret = load_microcode(mcs, ptrs, blobs_p->start, &uci);
+	ret = load_microcode(mcs, ptrs, start, &uci);
 	if (ret != UCODE_OK)
 		return;
 
---

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
--