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 99BAAC76196 for ; Fri, 31 Mar 2023 08:14:59 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pi9tS-0000C4-Aa; Fri, 31 Mar 2023 04:13:54 -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 1pi9tK-0000BM-IO for qemu-devel@nongnu.org; Fri, 31 Mar 2023 04:13:47 -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 1pi9tH-0006ES-4g for qemu-devel@nongnu.org; Fri, 31 Mar 2023 04:13:45 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1680250422; 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=llU5Q4RVR6+mBDZt1ZybpdUqjw47E78xceF3oxXZTFk=; b=PTBQmx7IUN1n5z1RXs89G3cL3H3NDzf2jNPc7cprs6bbA0ineDNSbIj+dNqVv8j5iWqsVR bcAQLUSoCSNsbDuVA3iVd+Q8PNdeS3N+odUIddlJb3yqwByHPpKNpZynlVwgdplLu747h3 ytgZQ2FyyTOAQoU3EYPpy1cFihwq210= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-352-D4tW6CxPNs6EjkuPEaTykg-1; Fri, 31 Mar 2023 04:13:38 -0400 X-MC-Unique: D4tW6CxPNs6EjkuPEaTykg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 7D54B884341; Fri, 31 Mar 2023 08:13:38 +0000 (UTC) Received: from redhat.com (unknown [10.33.36.67]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 32C704020C82; Fri, 31 Mar 2023 08:13:36 +0000 (UTC) Date: Fri, 31 Mar 2023 09:13:33 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Jason Wang Cc: Andrew Melnychenko , mst@redhat.com, pbonzini@redhat.com, marcandre.lureau@redhat.com, thuth@redhat.com, philmd@linaro.org, armbru@redhat.com, eblake@redhat.com, qemu-devel@nongnu.org, toke@redhat.com, mprivozn@redhat.com, yuri.benditovich@daynix.com, yan@daynix.com Subject: Re: [RFC PATCH 3/5] ebpf: Added declaration/initialization routines. Message-ID: References: <20230330001522.120774-1-andrew@daynix.com> <20230330001522.120774-4-andrew@daynix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/2.2.9 (2022-11-12) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 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: -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_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 Fri, Mar 31, 2023 at 04:03:39PM +0800, Jason Wang wrote: > On Fri, Mar 31, 2023 at 3:59 PM Daniel P. Berrangé wrote: > > > > On Fri, Mar 31, 2023 at 03:48:18PM +0800, Jason Wang wrote: > > > On Thu, Mar 30, 2023 at 4:34 PM Daniel P. Berrangé wrote: > > > > > > > > On Thu, Mar 30, 2023 at 02:54:32PM +0800, Jason Wang wrote: > > > > > On Thu, Mar 30, 2023 at 8:33 AM Andrew Melnychenko wrote: > > > > > > > > > > Who or how the ABI compatibility is preserved between libvirt and Qemu? > > > > > > > > There's no real problem with binary compatibility to solve any more. > > > > > > > > When libvirt first launches a QEMU VM, it will fetch the eBPF programs > > > > it needs from that running QEMU using QMP. WHen it later needs to > > > > enable features that use eBPF, it already has the program data that > > > > matches the running QEMU > > > > > > Ok, then who will validate the eBPF program? I don't think libvirt can > > > trust what is received from Qemu otherwise arbitrary eBPF programs > > > could be executed by Qemu in this way. One example is that when guests > > > escape to Qemu it can modify the rss_bpf__elf_bytes. Though > > > BPF_PROG_TYPE_SOCKET_FILTER gives some of the restrictions, we still > > > need to evaluate side effects of this. Or we need to find other ways > > > like using the binary in libvirt or use rx filter events. > > > > As I mentioned, when libvirt first launches QEMU it will fetch the > > eBPF programs and keep them for later use. At that point the guest > > CPUs haven't started running, and so QEMU it still sufficiently > > trustworthy. > > Well, this means the QMP command is safe only before Qemu starts to > run VCPU. I'm not sure this is a good design. Or at least we need to > fail the QMP command if VCPU starts to run. Currently QEMU has the ability to just create the eBPF programs itself at will, when it is launched in a privileged scenario regardless of guest CPU state. In terms of QMP, the reporting of QEMU PIDs for its various vCPU, I/O threads is also not to be trusted after vCPU starts if the guest workload is not trustworthy. I feel this is more of docs problem to explain the caveats that apps should be aware of. 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 :|