From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44780) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bDvgr-0004kT-Uy for qemu-devel@nongnu.org; Fri, 17 Jun 2016 11:28:14 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bDvgm-0001oH-TT for qemu-devel@nongnu.org; Fri, 17 Jun 2016 11:28:12 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45262) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bDvgm-0001oD-Ot for qemu-devel@nongnu.org; Fri, 17 Jun 2016 11:28:08 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 678805277E for ; Fri, 17 Jun 2016 15:28:08 +0000 (UTC) References: <1466097133-5489-1-git-send-email-dgilbert@redhat.com> <1466097133-5489-5-git-send-email-dgilbert@redhat.com> <20160616202449.GY18662@thinpad.lan.raisama.net> <20160617081505.GA2273@work-vm> <20160617131815.GA18662@thinpad.lan.raisama.net> <20160617151900.GE18662@thinpad.lan.raisama.net> From: Paolo Bonzini Message-ID: Date: Fri, 17 Jun 2016 17:28:03 +0200 MIME-Version: 1.0 In-Reply-To: <20160617151900.GE18662@thinpad.lan.raisama.net> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eduardo Habkost Cc: "Dr. David Alan Gilbert" , qemu-devel@nongnu.org, aarcange@redhat.com, Marcel Apfelbaum , "Michael S. Tsirkin" On 17/06/2016 17:19, Eduardo Habkost wrote: > > > So, what happens if the guest play tricks in bits 40-45 when QEMU > > > sets the limit to 40 but we are running in a 46-bit host? Is it > > > really a problem? I assumed it would be safe. > > > > The guest expects a "reserved bit set" page fault, but doesn't get one. > > Wait, are you talking about migration only, or are you really > talking about running current QEMU (hardcoded to 40) on a 46-bit > host? I'm not talking about migration, above. I'm talking about both. :( > We really can't emulate a 40-bit machine in a 46-bit host? I > didn't expect that. Unfortunately that's the case. :( Paolo