From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:56754) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gkZrB-00045g-68 for qemu-devel@nongnu.org; Fri, 18 Jan 2019 14:31:09 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gkZrA-00080N-0l for qemu-devel@nongnu.org; Fri, 18 Jan 2019 14:31:08 -0500 Received: from mx1.redhat.com ([209.132.183.28]:52318) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gkZr9-0007wz-Ka for qemu-devel@nongnu.org; Fri, 18 Jan 2019 14:31:07 -0500 Date: Fri, 18 Jan 2019 19:31:02 +0000 From: "Dr. David Alan Gilbert" Message-ID: <20190118193102.GJ2146@work-vm> References: <20190118100159.GA2483@work-vm> <8f0f7339-5f47-46d0-20a9-343badad4d0f@redhat.com> <20190118101633.GC2146@work-vm> <20190118102102.GH20660@redhat.com> <328f912c-e332-3bdc-d333-55c4af1a1fa1@redhat.com> <19ec0017-bd05-a847-b211-ebbdb141ebf6@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <19ec0017-bd05-a847-b211-ebbdb141ebf6@redhat.com> Subject: Re: [Qemu-devel] Live migration from Qemu 2.12 hosts to Qemu 3.2 hosts, with VMX flag enabled in the guest? List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: Mark Mielke , Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , qemu-devel@nongnu.org, christian.ehrhardt@canonical.com * Paolo Bonzini (pbonzini@redhat.com) wrote: > On 18/01/19 14:41, Mark Mielke wrote: > > It is useful to understand the risk. However, this is the same risk we > > have been successfully living with for several years now, and it seems > > abrupt to declare 3.1 and 3.2 as the Qemu version beyond which migration > > requires a whole cluster restart whether or not a L2 guest had been, or > > will ever be started on any of the guests. > > Only if nested was enabled for the kvm_intel module. If you didn't > enable it, you didn't see any change with 3.1. > > Nested was enabled for kvm_amd years ago. It was a mistake, but that's > why we didn't add such a blocker for AMD. Still, it should have probably been machine-type tied; there's lots and lots of broken things we've done in the past which we've kept compatibility with on old machine types. Dave > Paolo -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK