Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1757056AbeAHPIO (ORCPT <rfc822;ralf@linux-mips.org> + 1 other);
        Mon, 8 Jan 2018 10:08:14 -0500
Received: from merlin.infradead.org ([205.233.59.134]:51864 "EHLO
        merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1757400AbeAHPIN (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Mon, 8 Jan 2018 10:08:13 -0500
Date: Mon, 8 Jan 2018 16:08:00 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
        Andy Lutomirski <luto@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Greg KH <gregkh@linuxfoundation.org>,
        Dave Hansen <dave.hansen@intel.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Andi Kleen <ak@linux.intel.com>,
        Arjan Van De Ven <arjan.van.de.ven@intel.com>,
        David Woodhouse <dwmw@amazon.co.uk>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 4/8] x86/spec_ctrl: Add sysctl knobs to enable/disable
 SPEC_CTRL feature
Message-ID: <20180108150800.GI32035@hirez.programming.kicks-ass.net>
References: <cover.1515204614.git.tim.c.chen@linux.intel.com>
 <b77c0cfc2d50ebdaa721f95012fd735cc374f04c.1515204614.git.tim.c.chen@linux.intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <b77c0cfc2d50ebdaa721f95012fd735cc374f04c.1515204614.git.tim.c.chen@linux.intel.com>
User-Agent: Mutt/1.9.2 (2017-12-15)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Return-Path: <linux-kernel-owner@vger.kernel.org>

On Fri, Jan 05, 2018 at 06:12:19PM -0800, Tim Chen wrote:
> +void scan_spec_ctrl_feature(struct cpuinfo_x86 *c)
> +{
> +	if ((!c->cpu_index) && (boot_cpu_has(X86_FEATURE_SPEC_CTRL))) {

We should test X86_BUG_SPECTRE_V1 here too before default enabling this,
no?

> +		if (!ibrs_admin_disabled) {
> +			dynamic_ibrs = 1;
> +			ibrs_enabled = IBRS_ENABLED;
> +		}
> +	}
> +}