From patchwork Sat Feb 29 11:18:41 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Haren Myneni X-Patchwork-Id: 198035 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=-13.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_SANE_2 autolearn=ham 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 74A91C3F2CE for ; Sat, 29 Feb 2020 11:19:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3BAF3246AF for ; Sat, 29 Feb 2020 11:19:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726857AbgB2LT5 (ORCPT ); Sat, 29 Feb 2020 06:19:57 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:30627 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725747AbgB2LT5 (ORCPT ); Sat, 29 Feb 2020 06:19:57 -0500 Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 01TBFpYj086900; Sat, 29 Feb 2020 06:19:40 -0500 Received: from pps.reinject (localhost [127.0.0.1]) by mx0b-001b2d01.pphosted.com with ESMTP id 2yfmynt8an-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sat, 29 Feb 2020 06:19:40 -0500 Received: from m0098414.ppops.net (m0098414.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 01TBIXUA090569; Sat, 29 Feb 2020 06:19:39 -0500 Received: from ppma04dal.us.ibm.com (7a.29.35a9.ip4.static.sl-reverse.com [169.53.41.122]) by mx0b-001b2d01.pphosted.com with ESMTP id 2yfmynt8ag-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sat, 29 Feb 2020 06:19:39 -0500 Received: from pps.filterd (ppma04dal.us.ibm.com [127.0.0.1]) by ppma04dal.us.ibm.com (8.16.0.27/8.16.0.27) with SMTP id 01TBEVvx023069; Sat, 29 Feb 2020 11:19:38 GMT Received: from b01cxnp22034.gho.pok.ibm.com (b01cxnp22034.gho.pok.ibm.com [9.57.198.24]) by ppma04dal.us.ibm.com with ESMTP id 2yffk5tx6x-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sat, 29 Feb 2020 11:19:38 +0000 Received: from b01ledav005.gho.pok.ibm.com (b01ledav005.gho.pok.ibm.com [9.57.199.110]) by b01cxnp22034.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 01TBJcqc50135450 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sat, 29 Feb 2020 11:19:38 GMT Received: from b01ledav005.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id EE1E7AE060; Sat, 29 Feb 2020 11:19:37 +0000 (GMT) Received: from b01ledav005.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 47209AE05C; Sat, 29 Feb 2020 11:19:37 +0000 (GMT) Received: from [9.70.82.143] (unknown [9.70.82.143]) by b01ledav005.gho.pok.ibm.com (Postfix) with ESMTP; Sat, 29 Feb 2020 11:19:37 +0000 (GMT) Subject: [PATCH V2 9/9] Documentation/powerpc: VAS API From: Haren Myneni To: herbert@gondor.apana.org.au Cc: mpe@ellerman.id.au, mikey@neuling.org, sukadev@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org, linux-crypto@vger.kernel.org, npiggin@gmail.com In-Reply-To: <1582974266.18705.28.camel@hbabu-laptop> References: <1582974266.18705.28.camel@hbabu-laptop> Date: Sat, 29 Feb 2020 03:18:41 -0800 Message-ID: <1582975121.18705.58.camel@hbabu-laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.572 definitions=2020-02-29_03:2020-02-28,2020-02-29 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 clxscore=1015 priorityscore=1501 mlxlogscore=999 malwarescore=0 impostorscore=0 suspectscore=0 lowpriorityscore=0 bulkscore=0 spamscore=0 adultscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002290088 Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org Power9 introduced Virtual Accelerator Switchboard (VAS) which allows userspace to communicate with Nest Accelerator (NX) directly. But kernel has to establish channel to NX for userspace. This document describes user space API that application can use to establish communication channel. Signed-off-by: Sukadev Bhattiprolu Signed-off-by: Haren Myneni --- Documentation/powerpc/index.rst | 1 + Documentation/powerpc/vas-api.rst | 246 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 247 insertions(+) create mode 100644 Documentation/powerpc/vas-api.rst diff --git a/Documentation/powerpc/index.rst b/Documentation/powerpc/index.rst index 0d45f0f..afe2d5e 100644 --- a/Documentation/powerpc/index.rst +++ b/Documentation/powerpc/index.rst @@ -30,6 +30,7 @@ powerpc syscall64-abi transactional_memory ultravisor + vas-api .. only:: subproject and html diff --git a/Documentation/powerpc/vas-api.rst b/Documentation/powerpc/vas-api.rst new file mode 100644 index 0000000..13ce4e7 --- /dev/null +++ b/Documentation/powerpc/vas-api.rst @@ -0,0 +1,246 @@ +.. SPDX-License-Identifier: GPL-2.0 +.. _VAS-API: + +=================================================== +Virtual Accelerator Switchboard (VAS) userspace API +=================================================== + +Introduction +============ + +Power9 processor introduced Virtual Accelerator Switchboard (VAS) which +allows both userspace and kernel communicate to co-processor +(hardware accelerator) referred to as the Nest Accelerator (NX). The NX +unit comprises of one or more hardware engines or co-processor types +such as 842 compression, GZIP compression and encryption. On power9, +userspace applications will have access to only GZIP Compression engine +which supports ZLIB and GZIP compression algorithms in the hardware. + +To communicate with NX, kernel has to establish a channel or window and +then requests can be submitted directly without kernel involvement. +Requests to the GZIP engine must be formatted as a co-processor Request +Block (CRB) and these CRBs must be submitted to the NX using COPY/PASTE +instructions to paste the CRB to hardware address that is associated with +the engine's request queue. + +The GZIP engine provides two priority levels of requests: Normal and +High. Only Normal requests are supported from userspace right now. + +This document explains userspace API that is used to interact with +kernel to setup channel / window which can be used to send compression +requests directly to NX accelerator. + + +Overview +======== + +Application access to the GZIP engine is provided through +/dev/crypto/nx-gzip device node implemented by the VAS/NX device driver. +An application must open the /dev/crypto/nx-gzip device to obtain a file +descriptor (fd). Then should issue VAS_TX_WIN_OPEN ioctl with this fd to +establish connection to the engine. It means send window is opened on GZIP +engine for this process. Once a connection is established, the application +should use the mmap() system call to map the hardware address of engine's +request queue into the application's virtual address space. + +The application can then submit one or more requests to the the engine by +using copy/paste instructions and pasting the CRBs to the virtual address +(aka paste_address) returned by mmap(). User space can close the +established connection or send window by closing the file descriptior +(close(fd)) or upon the process exit. + +Note that applications can send several requests with the same window or +can establish multiple windows, but one window for each file descriptor. + +Following sections provide additional details and references about the +individual steps. + +NX-GZIP Device Node +=================== + +There is one /dev/crypto/nx-gzip node in the system and it provides +access to all GZIP engines in the system. The only valid operations on +/dev/crypto/nx-gzip are: + + * open() the device for read and write. + * issue VAS_TX_WIN_OPEN ioctl + * mmap() the engine's request queue into application's virtual + address space (i.e. get a paste_address for the co-processor + engine). + * close the device node. + +Other file operations on this device node are undefined. + +Note that the copy and paste operations go directly to the hardware and +do not go through this device. Refer COPY/PASTE document for more +details. + +Although a system may have several instances of the NX co-processor +engines (typically, one per P9 chip) there is just one +/dev/crypto/nx-gzip device node in the system. When the nx-gzip device +node is opened, Kernel opens send window on a suitable instance of NX +accelerator. It finds CPU on which the user process is executing and +determine the NX instance for the corresponding chip on which this CPU +belongs. + +Applications may chose a specific instance of the NX co-processor using +the vas_id field in the VAS_TX_WIN_OPEN ioctl as detailed below. + +A userspace library libnxz is available here but still in development: + https://github.com/abalib/power-gzip + +Applications that use inflate / deflate calls can link with libnxz +instead of libz and use NX GZIP compression without any modification. + +Open /dev/crypto/nx-gzip +======================== + +The nx-gzip device should be opened for read and write. No special +privileges are needed to open the device. Each window coreesponds to one +file descriptor. So if the userspace process needs multiple windows, +several open calls have to be issued. + +See open(2) system call man pages for other details such as return values, +error codes and restrictions. +codes and restrictions. + +VAS_TX_WIN_OPEN ioctl +===================== + +Applications should use the VAS_TX_WIN_OPEN ioctl as follows to establish +a connection with NX co-processor engine: + + :: + struct vas_tx_win_open_attr { + __u32 version; + __s16 vas_id; /* specific instance of vas or -1 + for default */ + __u16 reserved1; + __u64 flags; /* For future use */ + __u64 reserved2[6]; + }; + + version: The version field must be currently set to 1. + vas_id: If '-1' is passed, kernel will make a best-effort attempt + to assign an optimal instance of NX for the process. To + select the specific VAS instance, refer + "Discovery of available VAS engines" section below. + + flags, reserved1 and reserved2[6] fields are for future extension + and must be set to 0. + + The attributes attr for the VAS_TX_WIN_OPEN ioctl are defined as + follows: + #define VAS_MAGIC 'v' + #define VAS_TX_WIN_OPEN _IOW(VAS_MAGIC, 1, + struct vas_tx_win_open_attr) + + struct vas_tx_win_open_attr attr; + rc = ioctl(fd, VAS_TX_WIN_OPEN, &attr); + + The VAS_TX_WIN_OPEN ioctl returns 0 on success. On errors, it + returns -1 and sets the errno variable to indicate the error. + + Error conditions: + EINVAL fd does not refer to a valid VAS device. + EINVAL Invalid vas ID + EINVAL version is not set with proper value + EEXIST Window is already opened for the given fd + ENOMEM Memory is not available to allocate window + ENOSPC System has too many active windows (connections) + opened + EINVAL reserved fields are not set to 0. + + See the ioctl(2) man page for more details, error codes and + restrictions. + +mmap() NX-GZIP device +===================== + +The mmap() system call for a NX-GZIP device fd returns a paste_address +that the application can use to copy/paste its CRB to the hardware engines. + :: + + paste_addr = mmap(addr, size, prot, flags, fd, offset); + + Only restrictions on mmap for a NX-GZIP device fd are: + * size should be 4K page size + * offset parameter should be 0ULL + + Refer to mmap(2) man page for additional details/restrictions. + In addition to the error conditions listed on the mmap(2) man + page, can also fail with one of the following error codes: + + EINVAL fd is not associated with an open window + (i.e mmap() does not follow a successful call + to the VAS_TX_WIN_OPEN ioctl). + EINVAL offset field is not 0ULL. + +Discovery of available VAS engines +================================== + +Each available VAS instance in the system will have a device tree node +like /proc/device-tree/vas@* or /proc/device-tree/xscom@*/vas@*. +Determine the chip or VAS instance and use the corresponding ibm,vas-id +property value in this node to select specific VAS instance. + +Copy/Paste operations +===================== + +Applications should use the copy and paste instructions defined in the RFC +to copy/paste the CRB. + +CRB Specification and use NX +============================ + +Applications should format requests to the co-processor using the +co-processor Request Block (CRBs). Refer NX workbook for the format of +CRB and use NX from userspace such as sending requests and checking +request status. + +Simple example +============== + + :: + int use_nx_gzip() + { + int rc, fd; + void *addr; + struct vas_setup_attr txattr; + + fd = open("/dev/crypto/nx-gzip", O_RDWR); + if (fd < 0) { + fprintf(stderr, "open nx-gzip failed\n"); + return -1; + } + memset(&txattr, 0, sizeof(txattr)); + txattr.version = 1; + txattr.vas_id = -1 + rc = ioctl(fd, VAS_TX_WIN_OPEN, + (unsigned long)&txattr); + if (rc < 0) { + fprintf(stderr, "ioctl() n %d, error %d\n", + rc, errno); + return rc; + } + addr = mmap(NULL, 4096, PROT_READ|PROT_WRITE, + MAP_SHARED, fd, 0ULL); + if (addr == MAP_FAILED) { + fprintf(stderr, "mmap() failed, errno %d\n", + errno); + return -errno; + } + do { + //Format CRB request with compression or + //uncompression + // Refer tests for vas_copy/vas_paste + vas_copy((&crb, 0, 1); + vas_paste(addr, 0, 1); + // Poll on csb.flags with timeout + // csb address is listed in CRB + } while (true) + close(fd) or window can be closed upon process exit + } + + Refer https://github.com/abalib/power-gzip for tests or more + use cases.