Messages in this thread Patch in this message | | | Date | Tue, 24 Apr 2018 00:52:24 -0700 | From | tip-bot for Borislav Petkov <> | Subject | [tip:x86/urgent] x86/microcode: Do not exit early from __reload_late() |
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Commit-ID: 09e182d17e8891dd73baba961a0f5a82e9274c97 Gitweb: https://git.kernel.org/tip/09e182d17e8891dd73baba961a0f5a82e9274c97 Author: Borislav Petkov <bp@suse.de> AuthorDate: Sat, 21 Apr 2018 10:19:30 +0200 Committer: Thomas Gleixner <tglx@linutronix.de> CommitDate: Tue, 24 Apr 2018 09:48:22 +0200
x86/microcode: Do not exit early from __reload_late()
Vitezslav reported a case where the
"Timeout during microcode update!"
panic would hit. After a deeper look, it turned out that his .config had CONFIG_HOTPLUG_CPU disabled which practically made save_mc_for_early() a no-op.
When that happened, the discovered microcode patch wasn't saved into the cache and the late loading path wouldn't find any.
This, then, lead to early exit from __reload_late() and thus CPUs waiting until the timeout is reached, leading to the panic.
In hindsight, that function should have been written so it does not return before the post-synchronization. Oh well, I know better now...
Fixes: bb8c13d61a62 ("x86/microcode: Fix CPU synchronization routine") Reported-by: Vitezslav Samel <vitezslav@samel.cz> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Vitezslav Samel <vitezslav@samel.cz> Tested-by: Ashok Raj <ashok.raj@intel.com> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20180418081140.GA2439@pc11.op.pod.cz Link: https://lkml.kernel.org/r/20180421081930.15741-2-bp@alien8.de
--- arch/x86/kernel/cpu/microcode/core.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c index 10c4fc2c91f8..77e201301528 100644 --- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -564,14 +564,12 @@ static int __reload_late(void *info) apply_microcode_local(&err); spin_unlock(&update_lock); + /* siblings return UCODE_OK because their engine got updated already */ if (err > UCODE_NFOUND) { pr_warn("Error reloading microcode on CPU %d\n", cpu); - return -1; - /* siblings return UCODE_OK because their engine got updated already */ + ret = -1; } else if (err == UCODE_UPDATED || err == UCODE_OK) { ret = 1; - } else { - return ret; } /*
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