From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 49783C433DF for ; Tue, 16 Jun 2020 17:20:58 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0BD6B20707 for ; Tue, 16 Jun 2020 17:20:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="atEtkg36" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0BD6B20707 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:54296 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jlFGb-0001Mt-8C for qemu-devel@archiver.kernel.org; Tue, 16 Jun 2020 13:20:57 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:49078) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jlFC9-0002n9-Oo for qemu-devel@nongnu.org; Tue, 16 Jun 2020 13:16:21 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:31215 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jlFC8-0000X4-2e for qemu-devel@nongnu.org; Tue, 16 Jun 2020 13:16:21 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1592327779; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=wqp9+vP9WDPWv11Aw91e2+Rmy9fgS5L478vkJsRDV0E=; b=atEtkg364c66/A6gpK0WJ6D6GqUNIbkPw8Z6bsphi0S4ZGuJjj45a/dxwiFhSwEkv6qTqe ovemJKDOIr1KHYxvObbc8JUw+i3gjnsbVUQ7F0d0+cr0mqMl2nv+SMkyfHgG2GXww6kRHB PXoBwryO235fM2L+RkxiruFtPZWcrfQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-214-FeuRWj2fMt2zbt3bKdMYqg-1; Tue, 16 Jun 2020 13:16:14 -0400 X-MC-Unique: FeuRWj2fMt2zbt3bKdMYqg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A09F1EC1A2; Tue, 16 Jun 2020 17:16:13 +0000 (UTC) Received: from work-vm (ovpn-112-42.ams2.redhat.com [10.36.112.42]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CBA7B79303; Tue, 16 Jun 2020 17:16:08 +0000 (UTC) Date: Tue, 16 Jun 2020 18:16:06 +0100 From: "Dr. David Alan Gilbert" To: Gerd Hoffmann Subject: Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture Message-ID: <20200616171606.GI2788@work-vm> References: <99779e9c-f05f-501b-b4be-ff719f140a88@canonical.com> <20200616165043.24y2cp53axk7uggy@sirius.home.kraxel.org> <20200616165746.GH2788@work-vm> <20200616171026.jhlhtewp6j6vj44m@sirius.home.kraxel.org> MIME-Version: 1.0 In-Reply-To: <20200616171026.jhlhtewp6j6vj44m@sirius.home.kraxel.org> User-Agent: Mutt/1.14.0 (2020-05-02) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.120; envelope-from=dgilbert@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/16 02:45:54 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: pedro.principeza@canonical.com, ehabkost@redhat.com, dann.frazier@canonical.com, "Guilherme G. Piccoli" , qemu-devel@nongnu.org, christian.ehrhardt@canonical.com, lersek@redhat.com, fw@gpiccoli.net Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Gerd Hoffmann (kraxel@redhat.com) wrote: > Hi, > > > > If we can somehow make a *trustable* physbits value available to the > > > guest, then yes, we can go that route. But the guest physbits we have > > > today unfortunately don't cut it. > > > > In downstream RH qemu, we run with host-physbits as default; so it's reasonably > > trustworthy; > > Can the guest figure somehow whenever it is trustworthy or not? At any one point in time there may be things that it can try and see how the CPU responds but I'm not 100% sure. I know there are some bodges in to make some MSR values 1 padded by the right amount when crossing sizes that generally work. (were those PAM registers or something - vague memories of an old bug) > > of course that doesn't help you across a migration between > > hosts with different sizes (e.g. an E5 Xeon to an E3). > > Making physbits configurable for migration compatibility is fine if qemu > outlaws the problematic guest physbits > host physbits case and throws > an error in that case. I'm not sure that guest < host is entirely safe either though; although it seems to work. Dave > take care, > Gerd > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK