Hi, On 09/03/2018 08:51 AM, Kenneth Lee wrote:
From: Kenneth Lee <liguozhu@xxxxxxxxxxxxx> 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
