linux-kernel - [PATCH 1/2] x86/microcode: Make sure boot_cpu

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Date:   Wed, 1 Aug 2018 17:44:34 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Prarit Bhargava <prarit@...hat.com>
Cc:     linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org,
        sironi@...zon.de, tony.luck@...el.com
Subject: [PATCH 1/2] x86/microcode: Make sure boot_cpu_data.microcode is
 up-to-date

From: Prarit Bhargava <prarit@...hat.com>

The MCE code uses boot_cpu_data.microcode to prepare the MCE record.
However, on systems where late microcode update has occurred, the
microcode revision output in a MCE log record is wrong because
boot_cpu_data.microcode is not updated when the microcode gets updated.

However, the microcode revision saved in boot_cpu_data's microcode
member should be kept up-to-date, regardless, for consistency.

Make it so.

Fixes: fa94d0c6e0f3 ("x86/MCE: Save microcode revision in machine check records")
Signed-off-by: Prarit Bhargava <prarit@...hat.com>
Cc: Tony Luck <tony.luck@...el.com>
Cc: sironi@...zon.de
Cc: stable@...r.kernel.org
Cc: x86-ml <x86@...nel.org>
Link: http://lkml.kernel.org/r/20180731112739.32338-1-prarit@redhat.com
[ Make commit message more precise. ]
Signed-off-by: Borislav Petkov <bp@...e.de>
---
 arch/x86/kernel/cpu/microcode/amd.c   | 4 ++++
 arch/x86/kernel/cpu/microcode/intel.c | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c
index 0624957aa068..63b072377ba4 100644
--- a/arch/x86/kernel/cpu/microcode/amd.c
+++ b/arch/x86/kernel/cpu/microcode/amd.c
@@ -537,6 +537,10 @@ static enum ucode_state apply_microcode_amd(int cpu)
 	uci->cpu_sig.rev = mc_amd->hdr.patch_id;
 	c->microcode = mc_amd->hdr.patch_id;
 
+	/* Update boot_cpu_data's revision too, if we're on the BSP: */
+	if (c->cpu_index == boot_cpu_data.cpu_index)
+		boot_cpu_data.microcode =  mc_amd->hdr.patch_id;
+
 	return UCODE_UPDATED;
 }
 
diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index 97ccf4c3b45b..256d336cbc04 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -851,6 +851,10 @@ static enum ucode_state apply_microcode_intel(int cpu)
 	uci->cpu_sig.rev = rev;
 	c->microcode = rev;
 
+	/* Update boot_cpu_data's revision too, if we're on the BSP: */
+	if (c->cpu_index == boot_cpu_data.cpu_index)
+		boot_cpu_data.microcode = rev;
+
 	return UCODE_UPDATED;
 }
 
-- 
2.18.0.321.gffc6fa0e3962


-- 
Regards/Gruss,
    Boris.

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