From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932297AbeBTAA1 (ORCPT ); Mon, 19 Feb 2018 19:00:27 -0500 Received: from mga04.intel.com ([192.55.52.120]:19448 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932248AbeBTAAZ (ORCPT ); Mon, 19 Feb 2018 19:00:25 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,537,1511856000"; d="scan'208";a="202296316" From: "Van De Ven, Arjan" To: "valdis.kletnieks@vt.edu" CC: Jon Masters , David Woodhouse , Paolo Bonzini , "tglx@linutronix.de" , "x86@kernel.org" , "kvm@vger.kernel.org" , "torvalds@linux-foundation.org" , "linux-kernel@vger.kernel.org" , "Hansen, Dave" , "Ingo Molnar" Subject: RE: [PATCH 2/2] x86/speculation: Support "Enhanced IBRS" on future CPUs Thread-Topic: [PATCH 2/2] x86/speculation: Support "Enhanced IBRS" on future CPUs Thread-Index: AQHTpBYQl8Dyc4mRm0iZ20KRHB9/vaOif+eAgAADjgCAABy9AIAABnAAgAAEXACAAAFigIAEqxQAgAACw4CAAAOrgIAAC+oAgAASX4CABXcSgP//eu2wgACJV4D//3ujYA== Date: Tue, 20 Feb 2018 00:00:23 +0000 Message-ID: <0575AF4FD06DD142AD198903C74E1CC87A619255@ORSMSX103.amr.corp.intel.com> References: <1518449255-2182-1-git-send-email-dwmw@amazon.co.uk> <1518449255-2182-2-git-send-email-dwmw@amazon.co.uk> <7e2e5ad1-49b6-1fdb-4a62-8ad6aefc30a0@redhat.com> <1518509708.12890.33.camel@infradead.org> <27c85759-e662-d281-f8a0-0a80ca8ee18f@redhat.com> <1518517262.12890.43.camel@infradead.org> <1518518198.12890.48.camel@infradead.org> <02bd3fdd-1b73-6cab-fb09-38ba933396bd@redhat.com> <1518775136.7876.13.camel@infradead.org> <75287047-77a0-e0ff-c2e8-61c81641251e@redhat.com> <1518776517.7876.21.camel@infradead.org> <1518783021.7876.34.camel@infradead.org> <4882860e-23c5-75b3-ac02-c700f615156e@jonmasters.org> <0575AF4FD06DD142AD198903C74E1CC87A61923C@ORSMSX103.amr.corp.intel.com> <10373.1519084385@turing-police.cc.vt.edu> In-Reply-To: <10373.1519084385@turing-police.cc.vt.edu> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: dlp-product: dlpe-windows dlp-version: 11.0.0.116 dlp-reaction: no-action x-originating-ip: [10.22.254.138] Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id w1K00XH7023549 > On Mon, 19 Feb 2018 23:42:24 +0000, "Van De Ven, Arjan" said: > > > the guest is not the problem; guests obviously will already honor if Enhanced > > IBRS is enumerated. The problem is mixed migration pools where the > hypervisor > > may need to decide to not pass this enumeration through to the guest. > > For bonus points: What should happen to a VM that is live migrated from one > hypervisor to another, and the hypervisors have different IBRS support? Doctor Doctor it hurts when I do this.... Migration tends to only work between HV's that are relatively homogeneous, that's nothing new... folks who run clouds or bigger pools know this obviously.