Re: 4.15.17 regression: bisected: timeout during microcode update

From: Borislav Petkov
Date: Thu Apr 19 2018 - 06:48:41 EST


On Thu, Apr 19, 2018 at 07:35:31AM +0200, Vitezslav Samel wrote:
> > - Can you remove your builtin microcode,
> > - rename the /lib/firmware/intel-ucode so we don't find it during late loading.
> > - let the system boot completely
> > - then rename the intel-ucode back for this test.
> > - write 1 to reload and see if that update succeeds or fails?
>
> Just tested, it fails.

Can you apply the below patch, do the exact same exercise and catch the
output? Over serial console or netconsole or if nothing else, do a video
of the screen with a phone and upload it somewhere?

Thx.

---
diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index 10c4fc2c91f8..374ec1d75d89 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -553,6 +553,8 @@ static int __reload_late(void *info)
enum ucode_state err;
int ret = 0;

+ pr_info("%s: CPU%d\n", __func__, cpu);
+
/*
* Wait for all CPUs to arrive. A load will not be attempted unless all
* CPUs show up.
@@ -560,6 +562,8 @@ static int __reload_late(void *info)
if (__wait_for_cpus(&late_cpus_in, NSEC_PER_SEC))
return -1;

+ pr_info("%s: CPU%d reloading\n", __func__, cpu);
+
spin_lock(&update_lock);
apply_microcode_local(&err);
spin_unlock(&update_lock);
@@ -571,9 +575,12 @@ static int __reload_late(void *info)
} else if (err == UCODE_UPDATED || err == UCODE_OK) {
ret = 1;
} else {
+ pr_info("%s: CPU%d returning 0x%x\n", __func__, cpu, ret);
return ret;
}

+ pr_info("%s: CPU%d waiting to exit\n", __func__, cpu);
+
/*
* Increase the wait timeout to a safe value here since we're
* serializing the microcode update and that could take a while on a

--
Regards/Gruss,
Boris.

SUSE Linux GmbH, GF: Felix ImendÃrffer, Jane Smithard, Graham Norton, HRB 21284 (AG NÃrnberg)
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