Hi.
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@xxxxxxxxxx>
Signed-off-by: Prarit Bhargava <prarit@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Cc: sironi@xxxxxxxxx
Cc: tony.luck@xxxxxxxxx
---
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
After this patch, do we preserve an original microcode version
somewhere? If no, why? Sometimes it is useful while debugging another
crash because of faulty microcode.
Thanks.
--
Oleksandr Natalenko (post-factum)
