From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B8E69C43334 for ; Tue, 12 Jul 2022 19:15:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233244AbiGLTPo (ORCPT ); Tue, 12 Jul 2022 15:15:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41936 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235620AbiGLTNX (ORCPT ); Tue, 12 Jul 2022 15:13:23 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E446A6325; Tue, 12 Jul 2022 11:53:36 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id B380A6157B; Tue, 12 Jul 2022 18:53:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B82DBC3411C; Tue, 12 Jul 2022 18:53:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1657652015; bh=kC8Yo+zlmSXkHVKbkmutWgRB5JaAAmyWQj1eufr2znI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ba5cASgEz/I0y1xKYRStRFbBZljzcYWQd9pQeXwLTeSwIjcLuEjjL0fZADl884LLK GeRKESAOgQYh7Vj77Y60VlSiv0cvsQKfI5/aqFcHrB5m+vizfPnXKrP4Nalu9OhlAr EWjy+iDuHkG4Rv9hrPPrNjTKH5aV96J6NZkvK+PI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andrew Cooper , Borislav Petkov , Thadeu Lima de Souza Cascardo Subject: [PATCH 5.18 54/61] x86/cpu/amd: Enumerate BTC_NO Date: Tue, 12 Jul 2022 20:39:51 +0200 Message-Id: <20220712183239.052853854@linuxfoundation.org> X-Mailer: git-send-email 2.37.0 In-Reply-To: <20220712183236.931648980@linuxfoundation.org> References: <20220712183236.931648980@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andrew Cooper commit 26aae8ccbc1972233afd08fb3f368947c0314265 upstream. BTC_NO indicates that hardware is not susceptible to Branch Type Confusion. Zen3 CPUs don't suffer BTC. Hypervisors are expected to synthesise BTC_NO when it is appropriate given the migration pool, to prevent kernels using heuristics. [ bp: Massage. ] Signed-off-by: Andrew Cooper Signed-off-by: Borislav Petkov [cascardo: no X86_FEATURE_BRS] Signed-off-by: Thadeu Lima de Souza Cascardo Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/kernel/cpu/amd.c | 21 +++++++++++++++------ arch/x86/kernel/cpu/common.c | 6 ++++-- 3 files changed, 20 insertions(+), 8 deletions(-) --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -321,6 +321,7 @@ #define X86_FEATURE_VIRT_SSBD (13*32+25) /* Virtualized Speculative Store Bypass Disable */ #define X86_FEATURE_AMD_SSB_NO (13*32+26) /* "" Speculative Store Bypass is fixed in hardware. */ #define X86_FEATURE_CPPC (13*32+27) /* Collaborative Processor Performance Control */ +#define X86_FEATURE_BTC_NO (13*32+29) /* "" Not vulnerable to Branch Type Confusion */ /* Thermal and Power Management Leaf, CPUID level 0x00000006 (EAX), word 14 */ #define X86_FEATURE_DTHERM (14*32+ 0) /* Digital Thermal Sensor */ --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -890,12 +890,21 @@ static void init_amd_zn(struct cpuinfo_x node_reclaim_distance = 32; #endif - /* - * Fix erratum 1076: CPB feature bit not being set in CPUID. - * Always set it, except when running under a hypervisor. - */ - if (!cpu_has(c, X86_FEATURE_HYPERVISOR) && !cpu_has(c, X86_FEATURE_CPB)) - set_cpu_cap(c, X86_FEATURE_CPB); + /* Fix up CPUID bits, but only if not virtualised. */ + if (!cpu_has(c, X86_FEATURE_HYPERVISOR)) { + + /* Erratum 1076: CPB feature bit not being set in CPUID. */ + if (!cpu_has(c, X86_FEATURE_CPB)) + set_cpu_cap(c, X86_FEATURE_CPB); + + /* + * Zen3 (Fam19 model < 0x10) parts are not susceptible to + * Branch Type Confusion, but predate the allocation of the + * BTC_NO bit. + */ + if (c->x86 == 0x19 && !cpu_has(c, X86_FEATURE_BTC_NO)) + set_cpu_cap(c, X86_FEATURE_BTC_NO); + } } static void init_amd(struct cpuinfo_x86 *c) --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1385,8 +1385,10 @@ static void __init cpu_set_bug_bits(stru !arch_cap_mmio_immune(ia32_cap)) setup_force_cpu_bug(X86_BUG_MMIO_STALE_DATA); - if ((cpu_matches(cpu_vuln_blacklist, RETBLEED) || (ia32_cap & ARCH_CAP_RSBA))) - setup_force_cpu_bug(X86_BUG_RETBLEED); + if (!cpu_has(c, X86_FEATURE_BTC_NO)) { + if (cpu_matches(cpu_vuln_blacklist, RETBLEED) || (ia32_cap & ARCH_CAP_RSBA)) + setup_force_cpu_bug(X86_BUG_RETBLEED); + } if (cpu_matches(cpu_vuln_whitelist, NO_MELTDOWN)) return;