From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758616AbbAGDBb (ORCPT ); Tue, 6 Jan 2015 22:01:31 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:46236 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756909AbbAGBwA (ORCPT ); Tue, 6 Jan 2015 20:52:00 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Boris Ostrovsky , Borislav Petkov Subject: [PATCH 3.18 44/84] x86, microcode: Dont initialize microcode code on paravirt Date: Tue, 6 Jan 2015 17:49:47 -0800 Message-Id: <20150107014030.448847660@linuxfoundation.org> X-Mailer: git-send-email 2.2.1 In-Reply-To: <20150107014029.012974975@linuxfoundation.org> References: <20150107014029.012974975@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Boris Ostrovsky commit a18a0f6850d4b286a5ebf02cd5b22fe496b86349 upstream. 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 Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/microcode/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -559,7 +559,7 @@ 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)