linux-kernel - [PATCH v2] arch/x86: Fix boot_cpu

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Date:   Tue, 31 Jul 2018 07:27:39 -0400
From:   Prarit Bhargava <prarit@...hat.com>
To:     bp@...en8.de
Cc:     linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org,
        sironi@...zon.de, tony.luck@...el.com,
        Prarit Bhargava <prarit@...hat.com>, stable@...r.kernel.org
Subject: [PATCH v2] arch/x86: Fix boot_cpu_data.microcode version output

I tested this on AMD Ryzen & Intel Broadwell system and dumped the
boot_cpu_data before and after a microcode update.  On the Intel
system I also did a fatal MCE using mce-inject to confirm the output
from the mce handling code.

P.

---8<---

On systems where a runtime microcode update has occurred the microcode
version output in a MCE log record is wrong because
boot_cpu_data.microcode is not updated during runtime.

Update boot_cpu_data.microcode when the BSP's microcode is updated.

Fixes: fa94d0c6e0f3 ("x86/MCE: Save microcode revision in machine check records")
Suggested-by: Borislav Petkov <bp@...en8.com>
Signed-off-by: Prarit Bhargava <prarit@...hat.com>
Cc: stable@...r.kernel.org
Cc: sironi@...zon.de
Cc: tony.luck@...el.com
---
Changes in v2: Use mc_amd->hdr.patch_id on AMD

 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;
 }
 
-- 
2.17.0