From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:34648 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755327AbeD3T1o (ORCPT ); Mon, 30 Apr 2018 15:27:44 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vitezslav Samel , Borislav Petkov , Thomas Gleixner , Ashok Raj Subject: [PATCH 4.14 87/91] x86/microcode: Do not exit early from __reload_late() Date: Mon, 30 Apr 2018 12:25:09 -0700 Message-Id: <20180430184008.830295165@linuxfoundation.org> In-Reply-To: <20180430184004.216234025@linuxfoundation.org> References: <20180430184004.216234025@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Borislav Petkov commit 09e182d17e8891dd73baba961a0f5a82e9274c97 upstream. 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 Signed-off-by: Borislav Petkov Signed-off-by: Thomas Gleixner Tested-by: Vitezslav Samel Tested-by: Ashok Raj 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 Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/microcode/core.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) --- 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; } /*