[PATCH v2] arch/x86: Fix boot_cpu_data.microcode version output

[Prarit Bhargava]

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 <b...@alien8.com>
Signed-off-by: Prarit Bhargava <pra...@redhat.com>
Cc: sta...@vger.kernel.org
Cc: sir...@amazon.de
Cc: tony.l...@intel.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