Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752715AbcLFBB1 (ORCPT ); Mon, 5 Dec 2016 20:01:27 -0500 Received: from mail.kernel.org ([198.145.29.136]:51434 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752560AbcLFBBW (ORCPT ); Mon, 5 Dec 2016 20:01:22 -0500 From: Andy Lutomirski To: x86@kernel.org Cc: One Thousand Gnomes , Borislav Petkov , "linux-kernel@vger.kernel.org" , Brian Gerst , Matthew Whitehead , Andy Lutomirski Subject: [RFC PATCH 3/6] x86/cpu: Re-apply forced caps every time cpu caps are re-read Date: Mon, 5 Dec 2016 17:01:12 -0800 Message-Id: X-Mailer: git-send-email 2.9.3 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1186 Lines: 34 Calling get_cpu_cap() will reset a bunch of CPU features. This will cause the system to lose track of force-set and force-cleared featueres in the words that are reset until the end of CPU initialization. This can cause X86_FEATURE_FPU, for example, to change back and forth during boot and potentially confuse CPU setup. To minimize the chance of confusion, re-apply forced caps every time get_cpu_cap() is called. Signed-off-by: Andy Lutomirski --- arch/x86/kernel/cpu/common.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 347ae0a19380..24e1e4004d42 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -758,6 +758,13 @@ void get_cpu_cap(struct cpuinfo_x86 *c) c->x86_capability[CPUID_8000_000A_EDX] = cpuid_edx(0x8000000a); init_scattered_cpuid_features(c); + + /* + * Clear/Set all flags overridden by options, after probe. + * This needs to happen each time we re-probe, which may happen + * several times during CPU initialization. + */ + apply_forced_caps(c); } static void identify_cpu_without_cpuid(struct cpuinfo_x86 *c) -- 2.9.3