Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753624AbeADQEt (ORCPT + 1 other); Thu, 4 Jan 2018 11:04:49 -0500 Received: from smtp.ctxuk.citrix.com ([185.25.65.24]:60284 "EHLO SMTP.EU.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753604AbeADQEr (ORCPT ); Thu, 4 Jan 2018 11:04:47 -0500 X-IronPort-AV: E=Sophos;i="5.45,507,1508803200"; d="scan'208";a="65595547" Subject: Re: Avoid speculative indirect calls in kernel To: Paolo Bonzini , "Woodhouse, David" , "pavel@ucw.cz" CC: "linux-kernel@vger.kernel.org" , "tim.c.chen@linux.intel.com" , "torvalds@linux-foundation.org" , "tglx@linutronix.de" , "andi@firstfloor.org" , "aarcange@redhat.com" , "gnomes@lxorguk.ukuu.org.uk" , "dave.hansen@intel.com" , "gregkh@linux-foundation.org" References: <20180103230934.15788-1-andi@firstfloor.org> <20180104114231.GB1702@amd> <1515066469.12987.112.camel@amazon.co.uk> <94b12025-b27c-04d2-8726-c07a3af6b265@redhat.com> <7a3584c6-0c00-d807-5130-13d1f4b34102@citrix.com> <1515079777.12987.149.camel@amazon.co.uk> From: Andrew Cooper Message-ID: Date: Thu, 4 Jan 2018 15:37:40 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Content-Language: en-GB X-ClientProxiedBy: AMSPEX02CAS01.citrite.net (10.69.22.112) To AMSPEX02CL02.citrite.net (10.69.22.126) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On 04/01/18 15:32, Paolo Bonzini wrote: > On 04/01/2018 16:29, Woodhouse, David wrote: >> Adding that for KVM is in the Linux IBRS patch set that I've seen. >> Didn't we already have a conversation about how the Linux patch set >> does it as an atomically-switched MSR while you've done it manually in >> Xen because it's faster? > I'm also doing it manually in the RHEL versions of the KVM patches, for > what it's worth. Actually, I did it manually in Xen because I was expecting IBRS on AMD, and there are no MSR load/save lists for PV or SVM guests.  (Also yes, I've been reliably informed that manually is much faster than VT-x load/save lists.) ~Andrew