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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E51BBC433F5 for ; Tue, 15 Mar 2022 15:46:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344330AbiCOPrV (ORCPT ); Tue, 15 Mar 2022 11:47:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59196 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233153AbiCOPrT (ORCPT ); Tue, 15 Mar 2022 11:47:19 -0400 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8DF3A13CD6 for ; Tue, 15 Mar 2022 08:46:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1647359163; x=1678895163; h=date:from:to:cc:subject:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=9l3zMa1N2Xp5sxnI3YEfCtneKtd5sTYwcoovBFmuHj4=; b=G3MJkA+PAusSvx/IgXHx+fsINNxwIkW04249ernYmvtxXmLH0nHLJIjm w15AHQ4bKv5SKtxKtLWfaN+igqwTxKJk+Egt/SPBf+gIDmz5ph90bd5bn 8ReY2XiHZFivLWvQuhJlVaVOI7w5IJ+M4jPouyCjB/CE6I56gKyDlS48W o0e7zU6lwYUlMKPK7dRS3T9S+7st4dgVH0vAIMS0EzWpM4CBhVDLZXlY+ PP9Y60tHc3/C8XOYdIimhg7zhUpzQsVDdD4FMC1bogpcNMd8FOkZ8lO6x Lande3L5GtWx4u2nowcU6DQ0DndVKkgM/tnECqjcU0nm0yqBPWLBPBQ62 Q==; X-IronPort-AV: E=McAfee;i="6200,9189,10286"; a="256291448" X-IronPort-AV: E=Sophos;i="5.90,184,1643702400"; d="scan'208";a="256291448" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Mar 2022 08:45:57 -0700 X-IronPort-AV: E=Sophos;i="5.90,184,1643702400"; d="scan'208";a="515921223" Received: from jacob-builder.jf.intel.com (HELO jacob-builder) ([10.7.198.157]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Mar 2022 08:45:56 -0700 Date: Tue, 15 Mar 2022 08:49:12 -0700 From: Jacob Pan To: "Tian, Kevin" Cc: "iommu@lists.linux-foundation.org" , LKML , Joerg Roedel , "Jason Gunthorpe" , Christoph Hellwig , Lu Baolu , Jean-Philippe Brucker , "Pan, Jacob jun" , "Raj, Ashok" , "Kumar, Sanjay K" , "Jiang, Dave" , "Luck, Tony" , "Zanussi, Tom" , "Williams, Dan J" , "Liu, Yi L" , jacob.jun.pan@linux.intel.com Subject: Re: [PATCH v2 0/8] Enable PASID for DMA API users Message-ID: <20220315084912.52f98cf8@jacob-builder> In-Reply-To: References: <20220315050713.2000518-1-jacob.jun.pan@linux.intel.com> Organization: OTC X-Mailer: Claws Mail 3.17.5 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Kevin, On Tue, 15 Mar 2022 08:16:59 +0000, "Tian, Kevin" wrote: > > From: Jacob Pan > > Sent: Tuesday, March 15, 2022 1:07 PM > > > > Some modern accelerators such as Intel's Data Streaming Accelerator > > (DSA) require PASID in DMA requests to be operational. Specifically, > > the work submissions with ENQCMD on shared work queues require PASIDs. > > The use cases > > include both user DMA with shared virtual addressing (SVA) and in-kernel > > DMA similar to legacy DMA w/o PASID. Here we address the latter. > > > > DMA mapping API is the de facto standard for in-kernel DMA. However, it > > operates on a per device or Requester ID(RID) basis which is not > > PASID-aware. To leverage DMA API for devices relies on PASIDs, this > > patchset introduces the following APIs > > > > 1. A driver facing API that enables DMA API PASID usage: > > iommu_enable_pasid_dma(struct device *dev, ioasid_t &pasid); > > Should this be called dma_enable_pasid() since it's about DMA API? Doing > so also avoids the driver to include iommu.h. > PASID is still tied to IOMMU, drivers who wants to use this must explicitly put dependency on IOMMU. So I prefer not to give that illusion. > Thanks > Kevin Thanks, Jacob