Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932508AbaLAVTl (ORCPT ); Mon, 1 Dec 2014 16:19:41 -0500 Received: from aserp1040.oracle.com ([141.146.126.69]:34654 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932379AbaLAVTk (ORCPT ); Mon, 1 Dec 2014 16:19:40 -0500 From: Boris Ostrovsky To: bp@suse.de Cc: x86@kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, david.vrabel@citrix.com, konrad.wilk@oracle.com, boris.ostrovsky@oracle.com Subject: [PATCH] x86, microcode: Don't initialize microcode code on paravirt Date: Mon, 1 Dec 2014 16:27:44 -0500 Message-Id: <1417469264-31470-1-git-send-email-boris.ostrovsky@oracle.com> X-Mailer: git-send-email 1.7.1 X-Source-IP: ucsinet21.oracle.com [156.151.31.93] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- arch/x86/kernel/cpu/microcode/core.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c index 2ce9051..ebd232d 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) -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/