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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 205E8C001DC for ; Mon, 17 Jul 2023 22:52:17 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 0A24510E2BD; Mon, 17 Jul 2023 22:52:14 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by gabe.freedesktop.org (Postfix) with ESMTPS id 2CF2B10E2BD for ; Mon, 17 Jul 2023 22:52:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1689634329; 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=8wy84DSSq8n2YYiK0mWellsvoswCFp/2kMAmdZ+UHHc=; b=WSU35uqKWX5qXsL9Eqi4qqS9SCAvtRdUoP1pqlX2O/1cZK2gLwhVZqB5eExNH9bGJCaIvz BDObKB9Pjgy9nnNWI0Mg64rgQFu1m48ni/wL21sFRtdMbxZw6ZsGTbH7RccOeY6fV1KDLB hn5FNoggx6POG5Pi2hj0zNHisqxMXTQ= Received: from mail-io1-f69.google.com (mail-io1-f69.google.com [209.85.166.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-272-dKD08AOdOreDe1fJPM2AKg-1; Mon, 17 Jul 2023 18:52:07 -0400 X-MC-Unique: dKD08AOdOreDe1fJPM2AKg-1 Received: by mail-io1-f69.google.com with SMTP id ca18e2360f4ac-786fa88a6f0so317984239f.1 for ; Mon, 17 Jul 2023 15:52:07 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1689634327; x=1692226327; h=content-transfer-encoding:mime-version:organization:references :in-reply-to:message-id:subject:cc:to:from:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=8wy84DSSq8n2YYiK0mWellsvoswCFp/2kMAmdZ+UHHc=; b=EbURV3/Kt1pjrAf7vNIauMvEMtukWa7mwKPR8uO31IwKecUH1a1zs43AW3o40/tyfN 0yleFK+WUmMDD4TjtamYbUEwavrwMGg9hZ5wazyPnEdeIlmjZlWL9mZrnddOC+KeY3es E6s37D5PoMNZN8IWCwymaFgrxNsDDjTOrYgq4rI7Gsc6M8Ax/RN3qmep2K+3D99wet0+ tuhW1JKhJEt65B94GevPH5MnfPU1uu3pyZFQyouI7J2jOVBFJRJWY6mu4Xqs+eo2atEG V+dO0tbOJLM9iBHgfJlXxbMMndszx/UUgkMbSFUkfHOY7thuiR/OlDJuinYyBL3RD8sr 7KrA== X-Gm-Message-State: ABy/qLaNf1jcuQwFzDJiGk1b9qF/KgczlXSOcboMhwTGEqK8YhZ8tcPT 2U4YOnqOLalGgoM//SunoEoyxGKM51umWx4miU0ltZ47M10ms8jWm5c6YI+gu2epiXtlHMv7Vh5 yMSws5fdm3CBiwxk/BSrT8c5CNfNE X-Received: by 2002:a92:c651:0:b0:347:693a:7300 with SMTP id 17-20020a92c651000000b00347693a7300mr1012087ill.26.1689634327107; Mon, 17 Jul 2023 15:52:07 -0700 (PDT) X-Google-Smtp-Source: APBJJlGlBYmCdY1EaUds5QDcX7E6PqePOm9wJTOwk2wgOBkeJp+9wxIVvWJlHjSTuTXhWw/m+atXtQ== X-Received: by 2002:a92:c651:0:b0:347:693a:7300 with SMTP id 17-20020a92c651000000b00347693a7300mr1012015ill.26.1689634326829; Mon, 17 Jul 2023 15:52:06 -0700 (PDT) Received: from redhat.com ([38.15.36.239]) by smtp.gmail.com with ESMTPSA id d10-20020a92ddca000000b00341c0710169sm242627ilr.46.2023.07.17.15.52.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Jul 2023 15:52:06 -0700 (PDT) Date: Mon, 17 Jul 2023 16:52:03 -0600 From: Alex Williamson To: Jason Gunthorpe Message-ID: <20230717165203.4ee6b1e6.alex.williamson@redhat.com> In-Reply-To: References: <20230630155936.3015595-1-jaz@semihalf.com> <20230714-gauner-unsolidarisch-fc51f96c61e8@brauner> <20230717130831.0f18381a.alex.williamson@redhat.com> Organization: Red Hat MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Intel-gfx] [PATCH 0/2] eventfd: simplify signal helpers X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-aio@kvack.org, Muchun Song , Tony Krowiak , Matthew Rosato , Paul Durrant , Tom Rix , Jason Wang , Roman Gushchin , dri-devel@lists.freedesktop.org, Michal Hocko , Heiko Carstens , linux-mm@kvack.org, Kirti Wankhede , netdev@vger.kernel.org, Vineeth Vijayan , Diana Craciun , Borislav Petkov , Alexander Gordeev , Fei Li , Xuan Zhuo , Marcin Wojtas , Arnd Bergmann , Leon Romanovsky , Harald Freudenberger , x86@kernel.org, Halil Pasic , Ingo Molnar , Moritz Fischer , Frederic Barrat , Xu Yilun , Christian Borntraeger , linux-fpga@vger.kernel.org, Wu Hao , Jason Herne , Eric Farman , Dave Hansen , Andrew Donnellan , Vasily Gorbik , linux-s390@vger.kernel.org, Dominik Behr , intel-gfx@lists.freedesktop.org, Sean Christopherson , Eric Auger , Greg Kroah-Hartman , Shakeel Butt , kvm@vger.kernel.org, Rodrigo Vivi , cgroups@vger.kernel.org, Thomas Gleixner , virtualization@lists.linux-foundation.org, intel-gvt-dev@lists.freedesktop.org, io-uring@vger.kernel.org, Jens Axboe , Christian Brauner , Grzegorz Jaszczyk , Oded Gabbay , linux-usb@vger.kernel.org, Peter Oberparleiter , linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org, Benjamin LaHaise , "Michael S. Tsirkin" , Sven Schnelle , Johannes Weiner , linux-fsdevel@vger.kernel.org, Paolo Bonzini , Vitaly Kuznetsov , David Woodhouse , linuxppc-dev@lists.ozlabs.org, Pavel Begunkov Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Mon, 17 Jul 2023 19:12:16 -0300 Jason Gunthorpe wrote: > On Mon, Jul 17, 2023 at 01:08:31PM -0600, Alex Williamson wrote: > > > What would that mechanism be? We've been iterating on getting the > > serialization and buffering correct, but I don't know of another means > > that combines the notification with a value, so we'd likely end up with > > an eventfd only for notification and a separate ring buffer for > > notification values. > > All FDs do this. You just have to make a FD with custom > file_operations that does what this wants. The uAPI shouldn't be able > to tell if the FD is backing it with an eventfd or otherwise. Have the > kernel return the FD instead of accepting it. Follow the basic design > of eg mlx5vf_save_fops Sure, userspace could poll on any fd and read a value from it, but at that point we're essentially duplicating a lot of what eventfd provides for a minor(?) semantic difference over how the counter value is interpreted. Using an actual eventfd allows the ACPI notification to work as just another interrupt index within the existing vfio IRQ uAPI. Thanks, Alex