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 X-Spam-Level: X-Spam-Status: No, score=-6.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4B283C4360F for ; Fri, 5 Apr 2019 14:31:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1C178206DD for ; Fri, 5 Apr 2019 14:31:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731140AbfDEObN (ORCPT ); Fri, 5 Apr 2019 10:31:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47592 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730587AbfDEObN (ORCPT ); Fri, 5 Apr 2019 10:31:13 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E645E308FF30; Fri, 5 Apr 2019 14:31:12 +0000 (UTC) Received: from treble (ovpn-123-87.rdu2.redhat.com [10.10.123.87]) by smtp.corp.redhat.com (Postfix) with ESMTPS id AFB2F60C7A; Fri, 5 Apr 2019 14:31:03 +0000 (UTC) Date: Fri, 5 Apr 2019 09:31:01 -0500 From: Josh Poimboeuf To: Borislav Petkov Cc: linux-kernel@vger.kernel.org, x86@kernel.org, Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Jiri Kosina , Waiman Long , Andrea Arcangeli , Jon Masters , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , linuxppc-dev@lists.ozlabs.org, Martin Schwidefsky , Heiko Carstens , linux-s390@vger.kernel.org, Catalin Marinas , Will Deacon , linux-arm-kernel@lists.infradead.org, linux-arch@vger.kernel.org, Greg Kroah-Hartman , Tyler Hicks , Linus Torvalds Subject: Re: [PATCH RFC 2/5] x86/speculation: Add support for 'cpu_spec_mitigations=' cmdline options Message-ID: <20190405143101.ksj7ayjis4p52dgt@treble> References: <78c63cb08f36f55407f534d49cc2543079e44dbb.1554396090.git.jpoimboe@redhat.com> <20190405135712.GF23348@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190405135712.GF23348@zn.tnic> User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.49]); Fri, 05 Apr 2019 14:31:13 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 05, 2019 at 03:57:12PM +0200, Borislav Petkov wrote: > > diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h > > index 2bb3a648fc12..7e95b310f869 100644 > > --- a/arch/x86/include/asm/processor.h > > +++ b/arch/x86/include/asm/processor.h > > @@ -982,6 +982,7 @@ void microcode_check(void); > > > > enum l1tf_mitigations { > > L1TF_MITIGATION_OFF, > > + L1TF_MITIGATION_DEFAULT, > > L1TF_MITIGATION_FLUSH_NOWARN, > > L1TF_MITIGATION_FLUSH, > > L1TF_MITIGATION_FLUSH_NOSMT, > > diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c > > index 2da82eff0eb4..65b95fb95ba5 100644 > > --- a/arch/x86/kernel/cpu/bugs.c > > +++ b/arch/x86/kernel/cpu/bugs.c > > @@ -308,8 +308,11 @@ spectre_v2_parse_user_cmdline(enum spectre_v2_mitigation_cmd v2_cmd) > > > > ret = cmdline_find_option(boot_command_line, "spectre_v2_user", > > arg, sizeof(arg)); > > - if (ret < 0) > > + if (ret < 0) { > > + if (cpu_spec_mitigations == CPU_SPEC_MITIGATIONS_OFF) > > + return SPECTRE_V2_USER_CMD_NONE; > > Instead of sprinkling that test in those three functions, just do it > once above in check_bugs(), before those *_select_mitigation() functions > get to run and depending on the value, you either run them or use the > default settings, for the OFF case, for example. My thinking was that the individual options could be used to override the global option. But maybe that's overkill? I dunno. > > return SPECTRE_V2_USER_CMD_AUTO; > > + } > > > > for (i = 0; i < ARRAY_SIZE(v2_user_options); i++) { > > if (match_option(arg, ret, v2_user_options[i].option)) { > > @@ -444,8 +447,11 @@ static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void) > > return SPECTRE_V2_CMD_NONE; > > > > ret = cmdline_find_option(boot_command_line, "spectre_v2", arg, sizeof(arg)); > > - if (ret < 0) > > + if (ret < 0) { > > + if (cpu_spec_mitigations == CPU_SPEC_MITIGATIONS_OFF) > > + return SPECTRE_V2_CMD_NONE; > > return SPECTRE_V2_CMD_AUTO; > > + } > > > > for (i = 0; i < ARRAY_SIZE(mitigation_options); i++) { > > if (!match_option(arg, ret, mitigation_options[i].option)) > > @@ -677,8 +683,11 @@ static enum ssb_mitigation_cmd __init ssb_parse_cmdline(void) > > } else { > > ret = cmdline_find_option(boot_command_line, "spec_store_bypass_disable", > > arg, sizeof(arg)); > > - if (ret < 0) > > + if (ret < 0) { > > + if (cpu_spec_mitigations == CPU_SPEC_MITIGATIONS_OFF) > > + return SPEC_STORE_BYPASS_CMD_NONE; > > return SPEC_STORE_BYPASS_CMD_AUTO; > > + } > > > > for (i = 0; i < ARRAY_SIZE(ssb_mitigation_options); i++) { > > if (!match_option(arg, ret, ssb_mitigation_options[i].option)) > > @@ -955,7 +964,7 @@ void x86_spec_ctrl_setup_ap(void) > > #define pr_fmt(fmt) "L1TF: " fmt > > > > /* Default mitigation for L1TF-affected CPUs */ > > -enum l1tf_mitigations l1tf_mitigation __ro_after_init = L1TF_MITIGATION_FLUSH; > > +enum l1tf_mitigations l1tf_mitigation __ro_after_init = L1TF_MITIGATION_DEFAULT; > > #if IS_ENABLED(CONFIG_KVM_INTEL) > > EXPORT_SYMBOL_GPL(l1tf_mitigation); > > #endif > > @@ -1010,8 +1019,23 @@ static void __init l1tf_select_mitigation(void) > > > > override_cache_bits(&boot_cpu_data); > > > > + if (l1tf_mitigation == L1TF_MITIGATION_DEFAULT) { > > + switch (cpu_spec_mitigations) { > > + case CPU_SPEC_MITIGATIONS_OFF: > > + l1tf_mitigation = L1TF_MITIGATION_OFF; > > + break; > > + case CPU_SPEC_MITIGATIONS_AUTO: > > + l1tf_mitigation = L1TF_MITIGATION_FLUSH; > > + break; > > + case CPU_SPEC_MITIGATIONS_AUTO_NOSMT: > > + l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOSMT; > > + break; > > + } > > + } > > + > > switch (l1tf_mitigation) { > > case L1TF_MITIGATION_OFF: > > + case L1TF_MITIGATION_DEFAULT: > > case L1TF_MITIGATION_FLUSH_NOWARN: > > case L1TF_MITIGATION_FLUSH: > > break; > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > > index ab432a930ae8..83b5bdc3c777 100644 > > --- a/arch/x86/kvm/vmx/vmx.c > > +++ b/arch/x86/kvm/vmx/vmx.c > > @@ -233,6 +233,7 @@ static int vmx_setup_l1d_flush(enum vmx_l1d_flush_state l1tf) > > case L1TF_MITIGATION_FLUSH_NOWARN: > > case L1TF_MITIGATION_FLUSH: > > case L1TF_MITIGATION_FLUSH_NOSMT: > > + case L1TF_MITIGATION_DEFAULT: > > l1tf = VMENTER_L1D_FLUSH_COND; > > break; > > case L1TF_MITIGATION_FULL: > > @@ -6686,6 +6687,7 @@ static int vmx_vm_init(struct kvm *kvm) > > case L1TF_MITIGATION_FLUSH: > > case L1TF_MITIGATION_FLUSH_NOSMT: > > case L1TF_MITIGATION_FULL: > > + case L1TF_MITIGATION_DEFAULT: > > /* > > * Warn upon starting the first VM in a potentially > > * insecure environment. > > The L1TF bits need to be a separate patch. I assume you mean just the part where L1TF_MITIGATION_DEFAULT is added? -- Josh