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 09095C44512 for ; Thu, 16 Jul 2026 14:47:12 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 114BA10E32C; Thu, 16 Jul 2026 14:47:12 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; secure) header.d=ziepe.ca header.i=@ziepe.ca header.b="ZuALOWyR"; dkim-atps=neutral Received: from mail-qk1-f171.google.com (mail-qk1-f171.google.com [209.85.222.171]) by gabe.freedesktop.org (Postfix) with ESMTPS id E5FE210E32C for ; Thu, 16 Jul 2026 14:47:10 +0000 (UTC) Received: by mail-qk1-f171.google.com with SMTP id af79cd13be357-92e50979c71so655412085a.3 for ; Thu, 16 Jul 2026 07:47:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; t=1784213230; x=1784818030; darn=lists.freedesktop.org; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=qeHYNuBQJ85xO4pHC/1GrXrbttQdCZhEoDnW/IVqBNU=; b=ZuALOWyR7pB593A3v0TpJeokpHEXTslYM13XNVJLJGxPULttujvO66r7IpjVBEXk2w BMqLxkUB5zS1DoxcPlQlb9YfFtwdTyA+oBvaQ90k/7trHKl7RegxJtrp7dIJnlbyeCH1 PfNPuepic+xeGvF7OHN01RmynIkXeAlfVgHIit5im/o6uJiStuIMP84hSGjPcyNEFbak ek2Se/lr9P9k3gq/3/wwjLAf0k7wG+2j8d0tFBdr2Ms0c8H6GFjYFqQAcMHliCzAEGJC tkQU/wL/WOTkB6P5UlOP+oYHeIX2MLMg+Etyc6CLMmpvogmeaCtA1Lk7KUjRshd6HGj4 YnOQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1784213230; x=1784818030; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=qeHYNuBQJ85xO4pHC/1GrXrbttQdCZhEoDnW/IVqBNU=; b=Sx8r43TSapCmFWtO6Bla4/G0XyJLAEgA3elQAELvCmrNJV/+4hi86CCZeUU0q86Svk x/3M0QT45XaGBsk/FMaNkHqpQWkmB9eDviVAZ3VsP4InTPWHlNJhfG4doXcQIAJo6neN y7jvH8+igH8Q67lW2JcuGg3yYycLkgE3uzey0rOQHT+jY0NYTvdTB75E0OaCKzkvztQr VayWdHmMPhRfMyC0mnuZ7LSFyxGMQvOh3XAmvmJctH0KHohtDfhtYpScUFU3f/RBWpj5 sHaqmITpqzDZG6kAj64EOyu4Emf5ZLkZqVtq2MwJSnOedxaxmQyyypNcv+3qtFEmF22L nd0g== X-Forwarded-Encrypted: i=1; AHgh+Rq6+MjKnjQ8PhONdNoByH50QIL3FFMhKZ7hX68OQWgr5EMM7+5clEj5+bQb4epguFIWLCtbFzZG4U8=@lists.freedesktop.org X-Gm-Message-State: AOJu0YwcVtiWjtRKAMamD4bB7CCSFqCtvAUEW3KdL7cPfiXnDMSkwHAg Ba4FHOBeMFsXmyOBIq9W3QlDm5LYeWgngBU/e64gzk0EL6ekraRYlikdTbdC1cPMqEI= X-Gm-Gg: AfdE7cmoPGvzTxb7X53B4QLyyJSSxXZItNpggNjSitx42X7LhfutbnxozPDCHmAChhU 0pNPtiykzzmEo9bKOxEzuI0arLKhqwB8d8MOgMZHWPADHkF8tMK2TsI3YEa1TQ5DQdKIMZa9iAT CBfFPzvqyqJlgaVS2HU7BSyPzECwAayDep1QUbRV6SSHHEkQUg2P4D6tKvbaUngBAhLGJIFy+Nj 7HMwU3JPcbhVkau1SYxUgUSvKMlqIVKqQX/Hafvw8nN6qznsj+xeWv7viayCUoKLaxgrhwbvwxr bh0yejkdSKItmkQTlERxYqGG6IZa4zHvYcswAdhSLQ6Vx++bLjCTfIDWLo6AyIOp9GoFyEJiPlc +i7dA2ty03w4bQgzZaiz6mCkxjJWf8FoJIL0ndDuIPQT5ftn9BMsgdO4fW94n/nzC5d2pF4M= X-Received: by 2002:a05:620a:3952:b0:92e:ee51:e9d5 with SMTP id af79cd13be357-9309627ac1bmr854483285a.43.1784213229539; Thu, 16 Jul 2026 07:47:09 -0700 (PDT) Received: from ziepe.ca ([159.2.72.92]) by smtp.gmail.com with ESMTPSA id af79cd13be357-930ada3a1c3sm36671085a.20.2026.07.16.07.47.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Jul 2026 07:47:08 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wkNMi-00000002Yhx-0bks; Thu, 16 Jul 2026 11:47:08 -0300 Date: Thu, 16 Jul 2026 11:47:08 -0300 From: Jason Gunthorpe To: fengchengwen Cc: Zhiping Zhang , Leon Romanovsky , Michael Guralnik , Sumit Semwal , Christian Konig , Alex Williamson , Bjorn Helgaas , kvm@vger.kernel.org, linux-rdma@vger.kernel.org, linux-pci@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: Re: [PATCH v12 0/4] vfio/dma-buf: add TPH support for peer-to-peer access Message-ID: <20260716144708.GD210048@ziepe.ca> References: <20260715204008.3911275-1-zhipingz@meta.com> <7dd5c995-a23c-4d3a-9ba0-7fc77972339f@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7dd5c995-a23c-4d3a-9ba0-7fc77972339f@huawei.com> X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Thu, Jul 16, 2026 at 09:07:35AM +0800, fengchengwen wrote: > Because cross-Root-Port P2P traffic with ST does not affect the host, but > merely the completer may experience some performance degradation because > it lacks the TPH hint. In this case, I suggest adding restrictions in the > uAPI. I don't think this is complexity is worth doing for something that has no functional impact. There is no difference between supplying the TPH and not supplying it, so may as well supply it. Jason