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 X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4462AC433ED for ; Thu, 13 May 2021 20:20:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0A3DC6143D for ; Thu, 13 May 2021 20:20:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232784AbhEMUVk (ORCPT ); Thu, 13 May 2021 16:21:40 -0400 Received: from mga05.intel.com ([192.55.52.43]:57877 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232818AbhEMUVf (ORCPT ); Thu, 13 May 2021 16:21:35 -0400 IronPort-SDR: /3X1vYOgWxQTYuMwt7qmNCM5nhTmi4UAuS/4F7wpIoIZqvRS0tYhaEk1g8CdxH5OpPJCe0l4FS MjLH4zjMrEcg== X-IronPort-AV: E=McAfee;i="6200,9189,9983"; a="285555805" X-IronPort-AV: E=Sophos;i="5.82,296,1613462400"; d="scan'208";a="285555805" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 May 2021 13:20:25 -0700 IronPort-SDR: fu89eSgt8ytKtTWsJolPOEYiSCFNxJtIam2iDf5Tgl+MzDM5PSCYYcoxWd45jHs2fcU1fzUMtM vxT3BGdZuWXw== X-IronPort-AV: E=Sophos;i="5.82,296,1613462400"; d="scan'208";a="542614246" Received: from jacob-builder.jf.intel.com (HELO jacob-builder) ([10.7.199.155]) by orsmga004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 May 2021 13:20:24 -0700 Date: Thu, 13 May 2021 13:22:51 -0700 From: Jacob Pan To: "Luck, Tony" Cc: Jason Gunthorpe , Christoph Hellwig , LKML , "iommu@lists.linux-foundation.org" , Joerg Roedel , Lu Baolu , Jean-Philippe Brucker , "Liu, Yi L" , "Raj, Ashok" , "Tian, Kevin" , "Jiang, Dave" , "wangzhou1@hisilicon.com" , "zhangfei.gao@linaro.org" , "vkoul@kernel.org" , David Woodhouse , jacob.jun.pan@linux.intel.com Subject: Re: [PATCH v4 1/2] iommu/sva: Tighten SVA bind API with explicit flags Message-ID: <20210513132251.0ff89b90@jacob-builder> In-Reply-To: <20210513195749.GA801830@agluck-desk2.amr.corp.intel.com> References: <20210513060012.0fcc7653@jacob-builder> <20210513133834.GC1002214@nvidia.com> <20210513081050.5cf6a6ed@jacob-builder> <20210513173303.GL1002214@nvidia.com> <20210513185349.GA801495@agluck-desk2.amr.corp.intel.com> <20210513190040.GR1002214@nvidia.com> <20210513192014.GU1002214@nvidia.com> <20210513124621.01421173@jacob-builder> <20210513195749.GA801830@agluck-desk2.amr.corp.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 Tony, On Thu, 13 May 2021 12:57:49 -0700, "Luck, Tony" wrote: > On Thu, May 13, 2021 at 12:46:21PM -0700, Jacob Pan wrote: > > It seems there are two options: > > 1. Add a new IOMMU API to set up a system PASID with a *separate* IOMMU > > page table/domain, mark the device is PASID only with a flag. Use DMA > > APIs to explicit map/unmap. Based on this PASID-only flag, Vendor IOMMU > > driver will decide whether to use system PASID domain during map/unmap. > > Not clear if we also need to make IOVA==kernel VA. > > > > 2. Add a new IOMMU API to setup a system PASID which points to > > init_mm.pgd. This API only allows trusted device to bind with the > > system PASID at its own risk. There is no need for DMA API. This is the > > same as the current code except with an explicit API. > > > > Which option? > > Option #1 looks cleaner to me. Option #2 gives access to bits > of memory that the users of system PASID shouldn't ever need > to touch ... just map regions of memory that the kernel has > a "struct page" for. > > What does "use DMA APIs to explicitly map/unmap" mean? Is that > for the whole region? > If we map the entire kernel direct map during system PASID setup, then we don't need to use DMA API to map/unmap certain range. I was thinking this system PASID page table could be on-demand. The mapping is built by explicit use of DMA map/unmap APIs. > I'm expecting that once this system PASID has been initialized, > then any accelerator device with a kernel use case would use the > same PASID. I.e. DSA for page clearing, IAX for ZSwap compression > & decompression, etc. > OK, sounds like we have to map the entire kernel VA with struct page as you said. So we still by-pass DMA APIs, can we all agree on that? > -Tony Thanks, Jacob 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 X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 602F4C433B4 for ; Thu, 13 May 2021 20:20:32 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C6F3361421 for ; Thu, 13 May 2021 20:20:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C6F3361421 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 6E1F4402D7; Thu, 13 May 2021 20:20:31 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id lqO5l7TNKYG0; Thu, 13 May 2021 20:20:30 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp2.osuosl.org (Postfix) with ESMTP id 65620400B8; Thu, 13 May 2021 20:20:30 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 2A67EC000D; Thu, 13 May 2021 20:20:30 +0000 (UTC) Received: from smtp3.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id A77CFC0001 for ; Thu, 13 May 2021 20:20:28 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id 7F59F608EC for ; Thu, 13 May 2021 20:20:28 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 45-QbzvCPGbo for ; Thu, 13 May 2021 20:20:27 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by smtp3.osuosl.org (Postfix) with ESMTPS id 0E88260637 for ; Thu, 13 May 2021 20:20:26 +0000 (UTC) IronPort-SDR: U7EVcKMaWmDNip81DY+1C/4P6F3xhwgeVO5TNmbIk5KiHxJuYvH+CJFeL6Ta35SIrKHsDEIyx7 tLU5oOF8MlyA== X-IronPort-AV: E=McAfee;i="6200,9189,9983"; a="200096654" X-IronPort-AV: E=Sophos;i="5.82,296,1613462400"; d="scan'208";a="200096654" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 May 2021 13:20:24 -0700 IronPort-SDR: fu89eSgt8ytKtTWsJolPOEYiSCFNxJtIam2iDf5Tgl+MzDM5PSCYYcoxWd45jHs2fcU1fzUMtM vxT3BGdZuWXw== X-IronPort-AV: E=Sophos;i="5.82,296,1613462400"; d="scan'208";a="542614246" Received: from jacob-builder.jf.intel.com (HELO jacob-builder) ([10.7.199.155]) by orsmga004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 May 2021 13:20:24 -0700 Date: Thu, 13 May 2021 13:22:51 -0700 From: Jacob Pan To: "Luck, Tony" Subject: Re: [PATCH v4 1/2] iommu/sva: Tighten SVA bind API with explicit flags Message-ID: <20210513132251.0ff89b90@jacob-builder> In-Reply-To: <20210513195749.GA801830@agluck-desk2.amr.corp.intel.com> References: <20210513060012.0fcc7653@jacob-builder> <20210513133834.GC1002214@nvidia.com> <20210513081050.5cf6a6ed@jacob-builder> <20210513173303.GL1002214@nvidia.com> <20210513185349.GA801495@agluck-desk2.amr.corp.intel.com> <20210513190040.GR1002214@nvidia.com> <20210513192014.GU1002214@nvidia.com> <20210513124621.01421173@jacob-builder> <20210513195749.GA801830@agluck-desk2.amr.corp.intel.com> Organization: OTC X-Mailer: Claws Mail 3.17.5 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Cc: "vkoul@kernel.org" , "Tian, Kevin" , "Jiang, Dave" , "Raj, Ashok" , David Woodhouse , LKML , Christoph Hellwig , "iommu@lists.linux-foundation.org" , Jason Gunthorpe , "zhangfei.gao@linaro.org" , Jean-Philippe Brucker X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" Hi Tony, On Thu, 13 May 2021 12:57:49 -0700, "Luck, Tony" wrote: > On Thu, May 13, 2021 at 12:46:21PM -0700, Jacob Pan wrote: > > It seems there are two options: > > 1. Add a new IOMMU API to set up a system PASID with a *separate* IOMMU > > page table/domain, mark the device is PASID only with a flag. Use DMA > > APIs to explicit map/unmap. Based on this PASID-only flag, Vendor IOMMU > > driver will decide whether to use system PASID domain during map/unmap. > > Not clear if we also need to make IOVA==kernel VA. > > > > 2. Add a new IOMMU API to setup a system PASID which points to > > init_mm.pgd. This API only allows trusted device to bind with the > > system PASID at its own risk. There is no need for DMA API. This is the > > same as the current code except with an explicit API. > > > > Which option? > > Option #1 looks cleaner to me. Option #2 gives access to bits > of memory that the users of system PASID shouldn't ever need > to touch ... just map regions of memory that the kernel has > a "struct page" for. > > What does "use DMA APIs to explicitly map/unmap" mean? Is that > for the whole region? > If we map the entire kernel direct map during system PASID setup, then we don't need to use DMA API to map/unmap certain range. I was thinking this system PASID page table could be on-demand. The mapping is built by explicit use of DMA map/unmap APIs. > I'm expecting that once this system PASID has been initialized, > then any accelerator device with a kernel use case would use the > same PASID. I.e. DSA for page clearing, IAX for ZSwap compression > & decompression, etc. > OK, sounds like we have to map the entire kernel VA with struct page as you said. So we still by-pass DMA APIs, can we all agree on that? > -Tony Thanks, Jacob _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu