From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752832AbaLFPbz (ORCPT ); Sat, 6 Dec 2014 10:31:55 -0500 Received: from mail.skyhub.de ([78.46.96.112]:54221 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752218AbaLFPbv (ORCPT ); Sat, 6 Dec 2014 10:31:51 -0500 From: Borislav Petkov To: X86 ML Cc: LKML Subject: [PATCH 2/3] x86, microcode: Don't initialize microcode code on paravirt Date: Sat, 6 Dec 2014 16:31:47 +0100 Message-Id: <1417879908-4851-3-git-send-email-bp@alien8.de> X-Mailer: git-send-email 2.0.0 In-Reply-To: <1417879908-4851-1-git-send-email-bp@alien8.de> References: <1417879908-4851-1-git-send-email-bp@alien8.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Boris Ostrovsky Paravirtual guests are not expected to load microcode into processors and therefore it is not necessary to initialize microcode loading logic. In fact, under certain circumstances initializing this logic may cause the guest to crash. Specifically, 32-bit kernels use __pa_nodebug() macro which does not work in Xen (the code path that leads to this macro happens during resume when we call mc_bp_resume()->load_ucode_ap() ->check_loader_disabled_ap()) Signed-off-by: Boris Ostrovsky Link: http://lkml.kernel.org/r/1417469264-31470-1-git-send-email-boris.ostrovsky@oracle.com Signed-off-by: Borislav Petkov --- arch/x86/kernel/cpu/microcode/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c index 2ce9051174e6..ebd232d7de4d 100644 --- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -557,7 +557,7 @@ static int __init microcode_init(void) struct cpuinfo_x86 *c = &cpu_data(0); int error; - if (dis_ucode_ldr) + if (paravirt_enabled() || dis_ucode_ldr) return 0; if (c->x86_vendor == X86_VENDOR_INTEL) -- 2.0.0