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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 788EEC47257 for ; Thu, 7 May 2020 16:20:13 +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 4307F208D6 for ; Thu, 7 May 2020 16:20:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="GndBY8N/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4307F208D6 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]:60024 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jWjFs-0004O7-EM for qemu-devel@archiver.kernel.org; Thu, 07 May 2020 12:20:12 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:40218) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jWjEx-0003wN-Bq for qemu-devel@nongnu.org; Thu, 07 May 2020 12:19:15 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:26841 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 1jWjEw-0002VU-2b for qemu-devel@nongnu.org; Thu, 07 May 2020 12:19:14 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588868352; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=UQXyZfXby0uC+Gd+Q/92Y8G7Z/N+m3sT33Qo0XzpTp8=; b=GndBY8N/Gq+UAvsJTg0Xj4DKS0XLfdced7Ncx9DF18B2uVqFFhyy0uI6f3AkHB10pq7o2H KsYTMb/2lcUrKyIcnSYgCHsyDxNOqqw0RDj3fAx+vq8s8DElVMcIfifMjacfat3+Kb5y5h m6dqRead3Wyj0Eff7mJFV7jlLio2moA= 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-461-p32K0elkOPi5SUuOxB8rcw-1; Thu, 07 May 2020 12:19:10 -0400 X-MC-Unique: p32K0elkOPi5SUuOxB8rcw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7017A461 for ; Thu, 7 May 2020 16:19:09 +0000 (UTC) Received: from angien.pipo.sk (unknown [10.40.208.39]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B44E52618B; Thu, 7 May 2020 16:19:00 +0000 (UTC) Date: Thu, 7 May 2020 18:18:57 +0200 From: Peter Krempa To: Gerd Hoffmann Subject: Re: device hotplug & file handles Message-ID: <20200507161857.GK2102825@angien.pipo.sk> References: <20200507144914.4zg3753uh3kytz6g@sirius.home.kraxel.org> MIME-Version: 1.0 In-Reply-To: <20200507144914.4zg3753uh3kytz6g@sirius.home.kraxel.org> X-PGP-Key-ID: 0xD018682B X-PGP-Key-Fingerprint: D294 FF38 A6A2 BF40 6C75 5DEF 36EC 16AC D018 682B User-Agent: Mutt/1.13.4 (2020-02-15) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Received-SPF: pass client-ip=207.211.31.120; envelope-from=pkrempa@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/07 03:56:18 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=0.001, 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_H2=-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: libvir-list@redhat.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, May 07, 2020 at 16:49:14 +0200, Gerd Hoffmann wrote: > Hi, >=20 > For usb device pass-through (aka -device usb-host) it would be very > useful to pass file handles from libvirt to qemu. The workflow would > change from ... >=20 > (1) libvirt enables access to /dev/usb/$bus/$dev > (2) libvirt passes $bus + $dev (using hostbus + hostaddr properties) > to qemu. > (3) qemu opens /dev/usb/$bus/$dev >=20 > ... to ... >=20 > (1) libvirt opens /dev/usb/$bus/$dev > (2) libvirt passes filehandle to qemu. >=20 > Question is how can we pass the file descriptor best? My idea would be > to simply add an fd property to usb-host: >=20 > * Coldplug would be "-device usb-host,fd=3D" (cmd line). > * Hotplug would be "device_add usb-host,fd=3D" (monitor). We have prior art for both approaches so it's fine. >=20 > Will that work from libvirt point of view? Sure! Just please make sure that the new approach is detectable somehow. Either via device-list-properties or query-qmp-schema. > Or does anyone have an better idea? >=20 > thanks, > Gerd >=20 > PS: background: https://bugzilla.redhat.com/show_bug.cgi?id=3D1595525 >=20