From: Lu Baolu Subject: Re: [RFCv2 PATCH 0/7] A General Accelerator Framework, WarpDrive Date: Mon, 3 Sep 2018 10:32:16 +0800 Message-ID: <81edb8ff-d046-34e5-aee7-d8564e2517c2@linux.intel.com> References: <20180903005204.26041-1-nek.in.cn@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: baolu.lu@linux.intel.com, linuxarm@huawei.com To: Kenneth Lee , Jonathan Corbet , Herbert Xu , "David S . Miller" , Joerg Roedel , Alex Williamson , Kenneth Lee , Hao Fang , Zhou Wang , Zaibo Xu , Philippe Ombredanne , Greg Kroah-Hartman , Thomas Gleixner , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, iommu@lists.linux-foundation.org, kvm@vger.kernel.org, linux-accelerators@lists.ozlabs.org, Sanjay Kumar Return-path: In-Reply-To: <20180903005204.26041-1-nek.in.cn@gmail.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org Hi, On 09/03/2018 08:51 AM, Kenneth Lee wrote: > From: Kenneth Lee > > WarpDrive is an accelerator framework to expose the hardware capabilities > directly to the user space. It makes use of the exist vfio and vfio-mdev > facilities. So the user application can send request and DMA to the > hardware without interaction with the kernel. This removes the latency > of syscall. > > WarpDrive is the name for the whole framework. The component in kernel > is called SDMDEV, Share Domain Mediated Device. Driver driver exposes its > hardware resource by registering to SDMDEV as a VFIO-Mdev. So the user > library of WarpDrive can access it via VFIO interface. > > The patchset contains document for the detail. Please refer to it for more > information. > > This patchset is intended to be used with Jean Philippe Brucker's SVA > patch [1], which enables not only IO side page fault, but also PASID > support to IOMMU and VFIO. > > With these features, WarpDrive can support non-pinned memory and > multi-process in the same accelerator device. We tested it in our SoC > integrated Accelerator (board ID: D06, Chip ID: HIP08). A reference work > tree can be found here: [2]. > > But it is not mandatory. This patchset is tested in the latest mainline > kernel without the SVA patches. So it supports only one process for each > accelerator. > > We have noticed the IOMMU aware mdev RFC announced recently [3]. > > The IOMMU aware mdev has similar idea but different intention comparing to > WarpDrive. It intends to dedicate part of the hardware resource to a VM. > And the design is supposed to be used with Scalable I/O Virtualization. > While sdmdev is intended to share the hardware resource with a big amount > of processes. It just requires the hardware supporting address > translation per process (PCIE's PASID or ARM SMMU's substream ID). > > But we don't see serious confliction on both design. We believe they can be > normalized as one. > > The patch 1 is document of the framework. The patch 2 and 3 add sdmdev > support. The patch 4, 5 and 6 is drivers for Hislicon's ZIP Accelerator > which is registered to both crypto and warpdrive(sdmdev) and can be > used from kernel or user space at the same time. The patch 7 is a user > space sample demonstrating how WarpDrive works. > > > Change History: > V2 changed from V1: > 1. Change kernel framework name from SPIMDEV (Share Parent IOMMU > Mdev) to SDMDEV (Share Domain Mdev). > 2. Allocate Hardware Resource when a new mdev is created (While > it is allocated when the mdev is openned) > 3. Unmap pages from the shared domain when the sdmdev iommu group is > detached. (This procedure is necessary, but missed in V1) > 4. Update document accordingly. > 5. Rebase to the latest kernel (4.19.0-rc1) > > According the review comment on RFCv1, We did try to use dma-buf > as back end of WarpDrive. It can work properly with the current > solution [4], but it cannot make use of process's > own memory address space directly. This is important to many > acceleration scenario. So dma-buf will be taken as a backup > alternative for noiommu scenario, it will be added in the future > version. > > > Refernces: > [1] https://www.spinics.net/lists/kernel/msg2651481.html > [2] https://github.com/Kenneth-Lee/linux-kernel-warpdrive/tree/warpdrive-sva-v0.5 > [3] https://lkml.org/lkml/2018/7/22/34 Please refer to the latest version posted here for discussion. https://lkml.org/lkml/2018/8/30/107 Best regards, Lu Baolu