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 lists1p.gnu.org (lists1p.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 F29EDF94CA9 for ; Tue, 21 Apr 2026 19:58:27 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wFHDz-0003IK-1J; Tue, 21 Apr 2026 15:57:35 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wFHDx-0003Hn-7E for qemu-devel@nongnu.org; Tue, 21 Apr 2026 15:57:33 -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 1wFHDu-0006mx-SY for qemu-devel@nongnu.org; Tue, 21 Apr 2026 15:57:32 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1776801448; 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=pHYz/4QsY/KGeyY5wljzZ7re6nmspMhzUIggKdlvWSE=; b=B1k6qVRn6QfFwO3IsWUrhZJxWAyS2zLQ5MpLZZiikng6yM/kgsCGYSbqID8wpM7iL0NEuD hSzMM8ABzWf+D+S+KcarGdDkLQIRHZEhqY5HgKn50K0W4CuWAqeca+pNEm0pPkKtzwGFgO acRyjio5IwKvKsHADHWV5YiFdVbnYdM= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-18-Dtvjyj0LM7qO15oI8f4Fow-1; Tue, 21 Apr 2026 15:57:26 -0400 X-MC-Unique: Dtvjyj0LM7qO15oI8f4Fow-1 X-Mimecast-MFC-AGG-ID: Dtvjyj0LM7qO15oI8f4Fow_1776801445 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (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 mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 98A931956089; Tue, 21 Apr 2026 19:57:25 +0000 (UTC) Received: from localhost (unknown [10.44.32.90]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 656FC180045E; Tue, 21 Apr 2026 19:57:24 +0000 (UTC) Date: Tue, 21 Apr 2026 15:57:22 -0400 From: Stefan Hajnoczi To: Stefano Garzarella Cc: Jorge Moreira , hreitz@redhat.com, gmaglione@redhat.com, "Michael S . Tsirkin" , Hanna Czenczek , Pierrick Bouvier , qemu-devel@nongnu.org Subject: Re: [PATCH] vhost-user.rst: Explicitly allow front-end to write to kick FDs Message-ID: <20260421195722.GA466778@fedora> References: <20260411021205.3592118-1-jemoreira@google.com> <20260420181818.GC405461@fedora> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="4zTUmT6UpuYLZBuD" Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass client-ip=170.10.133.124; envelope-from=stefanha@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, SPF_HELO_PASS=-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: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org --4zTUmT6UpuYLZBuD Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Apr 21, 2026 at 06:49:32PM +0200, Stefano Garzarella wrote: > On Tue, 21 Apr 2026 at 18:06, Jorge Moreira wrote: > > > > > Do you know other backends we should check? > > > > CrosVm's: https://github.com/google/crosvm/tree/main/devices/src/virtio= /vhost_user_backend >=20 > Which do exactly the same > https://github.com/google/crosvm/blob/b49e336de56d6353ae06245de0c7fabec3d= b2d5e/devices/src/virtio/vhost_user_backend/handler.rs#L596 >=20 > No? To round this out, I looked at DPDK, one of the most popular vhost-user back-end implementations. The DPDK back-end starts/stops the rings in the vhost-user message handler rather than upon reading the kick fd: https://github.com/DPDK/dpdk/blob/main/lib/vhost/vhost_user.c#L3274 I think it would be nice to update the spec since it seems implementations aren't actually waiting for the kick fd. However, it is not central to the original discussion, so feel free to skip it if you want. Stefan --4zTUmT6UpuYLZBuD Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQEzBAEBCgAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmnn1qEACgkQnKSrs4Gr c8hWNAf/abatDMDU8EqyiSojC//fSxC4xPiejn6aCDITvFVtL4dp1eoW4+hW4rxm 5y/NCph2jgNW0bI+O0B/Chjibm9uaWRUmtDUeLAnyNN8/tYJLT9Kv+io8VHD46fw y7mGm08yq+/0/jFHwU+NG+jUT/cFjGn5UCHOfMOFzBA69XgQMCcJqcA1l0pMYun0 vlmKLZD0Di7V/vBg2v5uZQOSKF2kAkKWUcu6Y+ta/ldgi9fmYky1mC0/mtp9gTIB oL1NmkKlRRuW/b2SeVASyis734bLBwxtL20qCnVCkTAE7wr06NRMRvUKkgaRnKfB a1bWWILMgCAgUc3ZaOVhcQafJmT67Q== =PJPM -----END PGP SIGNATURE----- --4zTUmT6UpuYLZBuD--