From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752783AbeDUIUE (ORCPT ); Sat, 21 Apr 2018 04:20:04 -0400 Received: from mail.skyhub.de ([5.9.137.197]:57138 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752743AbeDUIUA (ORCPT ); Sat, 21 Apr 2018 04:20:00 -0400 From: Borislav Petkov To: X86 ML Cc: LKML Subject: [PATCH 2/2] x86/microcode: Do not exit early from __reload_late() Date: Sat, 21 Apr 2018 10:19:30 +0200 Message-Id: <20180421081930.15741-2-bp@alien8.de> X-Mailer: git-send-email 2.13.0 In-Reply-To: <20180421081930.15741-1-bp@alien8.de> References: <20180421081930.15741-1-bp@alien8.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Borislav Petkov 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 our 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, I should've made that function not return before the post-synchronization. Oh well, I know better now... Reported-by: Vitezslav Samel Tested-by: Vitezslav Samel Tested-by: Ashok Raj Signed-off-by: Borislav Petkov Cc: Fixes: bb8c13d61a62 ("x86/microcode: Fix CPU synchronization routine") Link: http://lkml.kernel.org/r/20180418081140.GA2439@pc11.op.pod.cz --- 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; } /* -- 2.13.0