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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 36C4CC36002 for ; Wed, 9 Apr 2025 15:33:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=UjQX7nAQGu8VWkUrRyRpYAcZbBxisvkDjd3TARXNRv0=; b=JMdm8kwhUGQQMdYmVjQUW0qH2T N5939OkSjKUrUIoMSfjDjkUR5N39oIHtuw6nuPCH5SoVOjFtM3tuhCIhm/hL92PH2q8uoGocCRAwB F6TZi2RrV+WjjRuEuwcC+TXB8iGmogv9RM6o0LxZTfiTnJ+cvyTzGer8H2KRoaovzsc7LDSuG2UF2 xAf9zjfktxBxFZHW74u+MV6eJLStBFGyYRBcsfrf4/pMiiHRrRRP3e2bxZPnnyu4iZ/inHmJhkno0 RLH2cIAHb4QcDwYVKU/HO/ma9DF85zdi6Ihsbi6ifA9Icd5mek76jp7bk5VM/hyqZamxRv1pir8f3 KYxHuZgw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1u2XQ6-00000007hIL-1Hf7; Wed, 09 Apr 2025 15:32:54 +0000 Received: from linux.microsoft.com ([13.77.154.182]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1u2XKm-00000007gI4-3SbZ for linux-arm-kernel@lists.infradead.org; Wed, 09 Apr 2025 15:27:26 +0000 Received: from [10.137.184.60] (unknown [131.107.160.188]) by linux.microsoft.com (Postfix) with ESMTPSA id 0A0262114D8A; Wed, 9 Apr 2025 08:27:23 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 0A0262114D8A DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1744212443; bh=UjQX7nAQGu8VWkUrRyRpYAcZbBxisvkDjd3TARXNRv0=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=HiVZXeJWF7w0t2l/4IF8J5ryv6/ZPUKUQ5aYykBziIutp4bcub2znNWPE/Y1Dh/Ge wPcrUU54yJBi/OX2udWa8QfGVA5UwpUJ3rEDsQtkbu2LYD/m1xFmP6y1gt8crnOdXG kECFhb2Vi1RaczcV6Pkxw/I1DktSimbBtg4Gwcdg= Message-ID: Date: Wed, 9 Apr 2025 08:27:22 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH hyperv-next 5/6] arch, drivers: Add device struct bitfield to not bounce-buffer To: Christoph Hellwig Cc: aleksander.lobakin@intel.com, andriy.shevchenko@linux.intel.com, arnd@arndb.de, bp@alien8.de, catalin.marinas@arm.com, corbet@lwn.net, dakr@kernel.org, dan.j.williams@intel.com, dave.hansen@linux.intel.com, decui@microsoft.com, gregkh@linuxfoundation.org, haiyangz@microsoft.com, hpa@zytor.com, James.Bottomley@HansenPartnership.com, Jonathan.Cameron@huawei.com, kys@microsoft.com, leon@kernel.org, lukas@wunner.de, luto@kernel.org, m.szyprowski@samsung.com, martin.petersen@oracle.com, mingo@redhat.com, peterz@infradead.org, quic_zijuhu@quicinc.com, robin.murphy@arm.com, tglx@linutronix.de, wei.liu@kernel.org, will@kernel.org, iommu@lists.linux.dev, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, x86@kernel.org, apais@microsoft.com, benhill@microsoft.com, bperkins@microsoft.com, sunilmut@microsoft.com References: <20250409000835.285105-1-romank@linux.microsoft.com> <20250409000835.285105-6-romank@linux.microsoft.com> <20250409105229.GA5721@lst.de> Content-Language: en-US From: Roman Kisel In-Reply-To: <20250409105229.GA5721@lst.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250409_082724_899115_53480E5C X-CRM114-Status: GOOD ( 11.49 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 4/9/2025 3:52 AM, Christoph Hellwig wrote: > On Tue, Apr 08, 2025 at 05:08:34PM -0700, Roman Kisel wrote: >> Bounce-buffering makes the system spend more time copying >> I/O data. When the I/O transaction take place between >> a confidential and a non-confidential endpoints, there is >> no other way around. >> >> Introduce a device bitfield to indicate that the device >> doesn't need to perform bounce buffering. The capable >> device may employ it to save on copying data around. > > I have no idea what this is supposed to mean, you need to explain it > much better. Thanks for reviewing! I'll fix the description. > -- Thank you, Roman