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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 2798AC04FFE for ; Wed, 8 May 2024 12:51:58 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1s4glw-0005PO-Io; Wed, 08 May 2024 08:51:48 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1s4glt-0005Oj-M5 for qemu-devel@nongnu.org; Wed, 08 May 2024 08:51:45 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1s4glq-00021T-TH for qemu-devel@nongnu.org; Wed, 08 May 2024 08:51:44 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1715172701; h=from:from:reply-to: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=3W/ScREmjvqUXIhjdT57Hp+BVufKIZBlTgrfJcfKQhM=; b=FKwsdUFoATQhTC9knudbf8x5MVAQQ20UN9IB3lq2Dlue9LidMfxyDxrTGHN7Qg1hAt1Zfb j0lYE0reZ2PFda63Legu5CmDNUnGVNQm4x/kPStSeXsQKhPJBYsVOom0rAzvR4Xab4w3cC KzPjj9oe8kgixBXoFD+Z3Jb0sEmGFIA= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-528-Wjl6glZ-NdS_KtiO_r3oMQ-1; Wed, 08 May 2024 08:51:38 -0400 X-MC-Unique: Wjl6glZ-NdS_KtiO_r3oMQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id F2B3F1C4C39B; Wed, 8 May 2024 12:51:36 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.29]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B5B18C0157C; Wed, 8 May 2024 12:51:35 +0000 (UTC) Date: Wed, 8 May 2024 13:51:33 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Paolo Bonzini Cc: Stefano Garzarella , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Roman Kiryanov , Peter Maydell , alex.bennee@linaro.org, QEMU Developers , JP Cottin , Erwin Jansen , Mehdi Alizadeh Subject: Re: Hermetic virtio-vsock in QEMU Message-ID: References: <5o3xyylget6hqhdaya5cj5tnbmmpzxk6u53cp6jhpviev6ez4m@ri6ady5zc6n3> <30baeb56-64d2-4ea3-8e53-6a5c50999979@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <30baeb56-64d2-4ea3-8e53-6a5c50999979@redhat.com> User-Agent: Mutt/2.2.12 (2023-09-09) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.8 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -26 X-Spam_score: -2.7 X-Spam_bar: -- X-Spam_report: (-2.7 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.582, 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=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Wed, May 08, 2024 at 02:37:52PM +0200, Paolo Bonzini wrote: > On 5/8/24 11:38, Stefano Garzarella wrote: > > On Wed, May 08, 2024 at 01:13:09PM GMT, Marc-André Lureau wrote: > > > Hi > > > > > > On Wed, May 8, 2024 at 11:50 AM Stefano Garzarella > > > wrote: > > > > > > > > Hi Roman, > > > > > > > > On Tue, May 07, 2024 at 11:20:50PM GMT, Roman Kiryanov wrote: > > > > >Hi Stefano, > > > > > > > > > >On Tue, May 7, 2024 at 1:10 AM Stefano Garzarella > > > > wrote: > > > > >> I have no experience with Windows, but what we need for > > > > vhost-user is: > > > > >> > > > > >> - AF_UNIX and be able to send file descriptors using ancillary data > > > > >>    (i.e. SCM_RIGHTS) > > > > > > > > > >As far as I understand, Windows does NOT support SCM_RIGHTS > > > > over AF_UNIX. > > > > > > > > Thank you for the information. This is unfortunate and does not allow > > > > us to use vhost-user as it is on Windows. > > > > > > > > > > fwiw, Windows has other mechanisms to share resources between processes. > > > > > > To share/pass sockets, you can use WSADuplicateSocket. For shared > > > memory and other resources, DuplicateHandle API. > > > > Cool, thanks for sharing that. So it could be done, but I think we need > > to extend the vhost-user protocol to work with Windows. > > It would be possible to implement the memfd backend for Windows, using the > CreateFileMapping() API. > > However, the vhost-user protocol's VHOST_USER_SET_MEM_TABLE requests do not > have any padding that can be used to pass the handle to the target. An > extended version would be necessary. > > One difference between Unix and Windows is that, if the vhost-server messes > up the handling of messages from the socket, and therefore it does not close > the handle, it is leaked forever. This is not a huge deal per se, but I > think it means that QEMU is not allowed to "open" a privileged vhost-user > server process with PROCESS_DUP_HANDLE rights (translation: QEMU cannot > provide duplicate handles to a privileged vhost-user server process). > > Also I'm not sure what the cost of DuplicateHandle() is, and whether it's a > good idea to do it for every region on every VHOST_USER_SET_MEM_TABLE > request. But VHOST_USER_SET_MEM_TABLE is not a fast path, so perhaps it's > okay. > > I think a virtio-vsock implementation in QEMU would be easier, lacking > another usecase for vhost-user on Windows. > > The main design question is whether multiple virtio-vsock devices for the > same guest should share the CID space or not (I think it should, but I'm not > 100% sure). To connect host<->guest you could have a QOM object, here I am > naming it vsock-forward as an example: Designwise, a native VSOCK backend in QEMU really should implement the same approach defined by firecracker, so that we have interoperability with systemd, firecracker and cloud-hypervisor. See https://gitlab.com/qemu-project/qemu/-/issues/2095 https://github.com/firecracker-microvm/firecracker/blob/main/docs/vsock.md#firecracker-virtio-vsock-design This involves multiple UNIX sockets on the host 1 * /some/path - QEMU listens on this, and accepts connections from other host processes. The client sends "PORT " to indicate that guest port it is connecting to n * /some/path_$PORT - QEMU connect to this for outgoing connections from the guest. Other host processes need to listen on whatever path_$PORT need to be serviced IOW, from a CLI pov, QEMU should need nothing more than -object vsock-forward,prefix=/some/path With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|