linux-kernel - [PATCH] x86/microcode: Disable builtin microcode loading on 32-bit for now

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Date:	Thu, 4 Jun 2015 11:21:33 +0200
From:	Borislav Petkov <bp@...e.de>
To:	"Shevchenko, Andriy" <andriy.shevchenko@...el.com>
Cc:	"andy.shevchenko@...il.com" <andy.shevchenko@...il.com>,
	"mingo@...nel.org" <mingo@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"mika.westerberg@...ux.intel.com" <mika.westerberg@...ux.intel.com>
Subject: [PATCH] x86/microcode: Disable builtin microcode loading on 32-bit
 for now

Ok, here's an actual patch. I'm very sorry for the confusion and big
thanks guys for catching it on time, before it hits the merge window!

Much appreciated. :-D

---
From: Borislav Petkov <bp@...e.de>
Date: Thu, 4 Jun 2015 09:52:37 +0200
Subject: [PATCH] x86/microcode: Disable builtin microcode loading on 32-bit for now

Andy Shevchenko reported machine freezes when booting latest tip on
x32 setups. Problem is, the builtin microcode handling cannot really
work that early, when we haven't even enabled paging. A proper fix
would involve handling that case specially as every other early 32-bit
boot case in the microcode loader and would require much more involved
changes for which it is too late now, more than a week before the
upcoming merge window.

So, disable the builtin microcode loading only on 32-bit for now.

Reported-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc: <x86@...nel.org>
Link: http://lkml.kernel.org/r/1433257003-159485-1-git-send-email-andriy.shevchenko@linux.intel.com
Signed-off-by: 
---
 arch/x86/kernel/cpu/microcode/amd_early.c   | 4 ++++
 arch/x86/kernel/cpu/microcode/intel_early.c | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/arch/x86/kernel/cpu/microcode/amd_early.c b/arch/x86/kernel/cpu/microcode/amd_early.c
index 9208a36d0f03..9243cd839829 100644
--- a/arch/x86/kernel/cpu/microcode/amd_early.c
+++ b/arch/x86/kernel/cpu/microcode/amd_early.c
@@ -230,6 +230,7 @@ static void apply_ucode_in_initrd(void *ucode, size_t size, bool save_patch)
 
 static bool __init load_builtin_amd_microcode(struct cpio_data *cp, int family)
 {
+#ifdef CONFIG_X86_64
 	char fw_name[36] = "amd-ucode/microcode_amd.bin";
 
 	if (family >= 0x15)
@@ -237,6 +238,9 @@ static bool __init load_builtin_amd_microcode(struct cpio_data *cp, int family)
 			 "amd-ucode/microcode_amd_fam%.2xh.bin", family);
 
 	return get_builtin_firmware(cp, fw_name);
+#else
+	return false;
+#endif
 }
 
 void __init load_ucode_amd_bsp(int family)
diff --git a/arch/x86/kernel/cpu/microcode/intel_early.c b/arch/x86/kernel/cpu/microcode/intel_early.c
index 10dff3f3f686..b4858d892592 100644
--- a/arch/x86/kernel/cpu/microcode/intel_early.c
+++ b/arch/x86/kernel/cpu/microcode/intel_early.c
@@ -523,6 +523,7 @@ EXPORT_SYMBOL_GPL(save_mc_for_early);
 
 static bool __init load_builtin_intel_microcode(struct cpio_data *cp)
 {
+#ifdef CONFIG_X86_64
 	u32 eax = 0x00000001, ebx, ecx = 0, edx;
 	int family, model, stepping;
 	char name[30];
@@ -536,6 +537,9 @@ static bool __init load_builtin_intel_microcode(struct cpio_data *cp)
 	sprintf(name, "intel-ucode/%02x-%02x-%02x", family, model, stepping);
 
 	return get_builtin_firmware(cp, name);
+#else
+	return false;
+#endif
 }
 
 static __initdata char ucode_name[] = "kernel/x86/microcode/GenuineIntel.bin";
-- 
2.3.5


-- 
Regards/Gruss,
    Boris.

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