From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 0BEFF265CB5; Wed, 9 Apr 2025 15:27:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744212445; cv=none; b=NvDyPNo/8fnmvT3zfYye2iarSV530za+YXyHBe1gcjH3GU+33jw7DfIvfpr3A6kHaUeXlxx7vmXL2f171wJLHZJEMaugKcvEyfmCpGDAhz4/tC7+//GfYDGsfpse1y2EWRZRnWuESSLJfPK7jnVBYyCx82MhpBSE8oPF9BGG/b0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744212445; c=relaxed/simple; bh=X3NxPrh/Dg6zmeDRgnBwY1KySOioOX8BKWZl/rmzgB4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=CFMLnP+b4A9yvlRv5bbePu/bYATYdOjM5l5ano+QTK8W36yNAg19LQg2VUyCJ5FdV6L9A9H2SHbd+GtAKObF0+VyRhDVp/7aaQvejHQqtlIi+NKTn8dumGeSGncc5aWCflMT8nk2NfsvGnxTHnLOPNpTy9jv463lSdUfpkGmI/M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=HiVZXeJW; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="HiVZXeJW" 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 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 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