Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760749AbcLPLE3 (ORCPT ); Fri, 16 Dec 2016 06:04:29 -0500 Received: from mx2.suse.de ([195.135.220.15]:51409 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757468AbcLPLEC (ORCPT ); Fri, 16 Dec 2016 06:04:02 -0500 Date: Fri, 16 Dec 2016 11:45:05 +0100 From: Borislav Petkov To: Juergen Gross Cc: Boris Ostrovsky , Linux Kernel Mailing List , xen-devel Subject: Re: Can't boot as Xen dom0 due to commit fe055896 Message-ID: <20161216104505.lk3s7fc7brrnmbq3@pd.tnic> References: <20161215164635.thm7ruio2ddnxszw@pd.tnic> <20161215171755.xpfuax7a6q3jofet@pd.tnic> <20161215173609.ornfok6lk5oro2pj@pd.tnic> <20161216090228.ri4alokiaagqtibt@pd.tnic> <29d252b8-67ff-bd61-f274-0ed75708cd55@suse.com> <20161216094326.bnkr5a2k3njmdeyi@pd.tnic> <7ca8a9b9-e374-8052-6be3-d3eda78c891a@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <7ca8a9b9-e374-8052-6be3-d3eda78c891a@suse.com> User-Agent: NeoMutt/20161014 (1.7.1) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1997 Lines: 84 On Fri, Dec 16, 2016 at 11:00:29AM +0100, Juergen Gross wrote: > Should work. I'm happy to test any patch. :-) I'm happy that you're happy to! :-) Let's try this below. Thanks! --- diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c index 6996413c78c3..c4bb2f7169f6 100644 --- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -44,7 +44,7 @@ #define DRIVER_VERSION "2.2" static struct microcode_ops *microcode_ops; -static bool dis_ucode_ldr; +static bool dis_ucode_ldr = true; LIST_HEAD(microcode_cache); @@ -76,6 +76,7 @@ struct cpu_info_ctx { static bool __init check_loader_disabled_bsp(void) { static const char *__dis_opt_str = "dis_ucode_ldr"; + u32 a, b, c, d; #ifdef CONFIG_X86_32 const char *cmdline = (const char *)__pa_nodebug(boot_command_line); @@ -88,8 +89,23 @@ static bool __init check_loader_disabled_bsp(void) bool *res = &dis_ucode_ldr; #endif - if (cmdline_find_option_bool(cmdline, option)) - *res = true; + if (!have_cpuid_p()) + return *res; + + a = 1; + c = 0; + native_cpuid(&a, &b, &c, &d); + + /* + * CPUID(1).ECX[31]: reserved for hypervisor use. This is still not + * completely accurate as xen pv guests don't see that CPUID bit set but + * that's good enough as they don't land on the BSP path anyway. + */ + if (c & BIT(31)) + return *res; + + if (cmdline_find_option_bool(cmdline, option) <= 0) + *res = false; return *res; } @@ -121,9 +137,6 @@ void __init load_ucode_bsp(void) if (check_loader_disabled_bsp()) return; - if (!have_cpuid_p()) - return; - vendor = x86_cpuid_vendor(); family = x86_cpuid_family(); @@ -157,9 +170,6 @@ void load_ucode_ap(void) if (check_loader_disabled_ap()) return; - if (!have_cpuid_p()) - return; - vendor = x86_cpuid_vendor(); family = x86_cpuid_family(); -- Regards/Gruss, Boris. SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --