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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 48A7AC43387 for ; Mon, 14 Jan 2019 10:02:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 206FC2086D for ; Mon, 14 Jan 2019 10:02:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726665AbfANKC1 (ORCPT ); Mon, 14 Jan 2019 05:02:27 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:57740 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726649AbfANKC1 (ORCPT ); Mon, 14 Jan 2019 05:02:27 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 64C6CA78; Mon, 14 Jan 2019 02:02:26 -0800 (PST) Received: from [10.1.196.93] (en101.cambridge.arm.com [10.1.196.93]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id EACA23F5AF; Mon, 14 Jan 2019 02:02:22 -0800 (PST) Subject: Re: [PATCH v3 1/7] sysfs/cpu: Allow individual architectures to select vulnerabilities To: jeremy.linton@arm.com, linux-arm-kernel@lists.infradead.org Cc: catalin.marinas@arm.com, will.deacon@arm.com, marc.zyngier@arm.com, dave.martin@arm.com, shankerd@codeaurora.org, linux-kernel@vger.kernel.org, ykaukab@suse.de, julien.thierry@arm.com, mlangsdo@redhat.com, Steven.Price@arm.com, stefan.wahren@i2se.com, gregkh@linuxfoundation.org, rafael@kernel.org, tglx@linutronix.de, jpoimboe@redhat.com, konrad.wilk@oracle.com, mingo@kernel.org, longman@redhat.com, ak@linux.intel.com, jkosina@suse.cz References: <20190109235544.2992426-1-jeremy.linton@arm.com> <20190109235544.2992426-2-jeremy.linton@arm.com> From: Suzuki K Poulose Message-ID: <901f2f29-aa06-13ad-1995-f9f22184e39d@arm.com> Date: Mon, 14 Jan 2019 10:02:21 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20190109235544.2992426-2-jeremy.linton@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/01/2019 23:55, Jeremy Linton wrote: > As suggested on the list, https://lkml.org/lkml/2019/1/4/282, there are > a number of cases where its useful for a system to avoid exporting a > sysfs entry for a given vulnerability. This set adds an architecture > specific callback which returns the bitmap of vulnerabilities the > architecture would like to advertise. > > Signed-off-by: Jeremy Linton > Cc: Greg Kroah-Hartman > Cc: Rafael J. Wysocki > Cc: Thomas Gleixner > Cc: Josh Poimboeuf > Cc: Konrad Rzeszutek Wilk > Cc: Ingo Molnar > Cc: Waiman Long > Cc: Andi Kleen > Cc: Jiri Kosina > --- > drivers/base/cpu.c | 19 +++++++++++++++++++ > include/linux/cpu.h | 7 +++++++ > 2 files changed, 26 insertions(+) > > diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c > index eb9443d5bae1..35f6dfb24cd6 100644 > --- a/drivers/base/cpu.c > +++ b/drivers/base/cpu.c > @@ -561,6 +561,11 @@ static struct attribute *cpu_root_vulnerabilities_attrs[] = { > NULL > }; > > +uint __weak arch_supported_vuln_attr_fields(void) > +{ > + return VULN_MELTDOWN|VULN_SPECTREV1|VULN_SPECTREV2|VULN_SSB|VULN_L1TF; > +} > + > static const struct attribute_group cpu_root_vulnerabilities_group = { > .name = "vulnerabilities", > .attrs = cpu_root_vulnerabilities_attrs, > @@ -568,6 +573,20 @@ static const struct attribute_group cpu_root_vulnerabilities_group = { > > static void __init cpu_register_vulnerabilities(void) > { > + int fld; > + int max_fields = ARRAY_SIZE(cpu_root_vulnerabilities_attrs) - 1; > + struct attribute **hd = cpu_root_vulnerabilities_attrs; > + uint enabled_fields = arch_supported_vuln_attr_fields(); > + > + /* only enable entries requested by the arch code */ > + for (fld = 0; fld < max_fields; fld++) { > + if (enabled_fields & 1 << fld) { > + *hd = cpu_root_vulnerabilities_attrs[fld]; > + hd++; > + } > + } > + *hd = NULL; > + nit: Could we use "is_visible" callback in the attribute group to check this dynamically ? > if (sysfs_create_group(&cpu_subsys.dev_root->kobj, > &cpu_root_vulnerabilities_group)) > pr_err("Unable to register CPU vulnerabilities\n"); > diff --git a/include/linux/cpu.h b/include/linux/cpu.h > index 218df7f4d3e1..5e45814bcc24 100644 > --- a/include/linux/cpu.h > +++ b/include/linux/cpu.h > @@ -189,4 +189,11 @@ static inline void cpu_smt_check_topology_early(void) { } > static inline void cpu_smt_check_topology(void) { } > #endif > > +/* generic cpu vulnerability attributes */ > +#define VULN_MELTDOWN 0x01 > +#define VULN_SPECTREV1 0x02 > +#define VULN_SPECTREV2 0x04 > +#define VULN_SSB 0x08 > +#define VULN_L1TF 0x10 nit: May use BIT() ? Cheers Suzuki