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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=unavailable 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 7D1B4C433DB for ; Tue, 16 Feb 2021 15:33:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4DE2764E10 for ; Tue, 16 Feb 2021 15:33:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229927AbhBPPda (ORCPT ); Tue, 16 Feb 2021 10:33:30 -0500 Received: from frasgout.his.huawei.com ([185.176.79.56]:2571 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230291AbhBPPcS (ORCPT ); Tue, 16 Feb 2021 10:32:18 -0500 Received: from fraeml738-chm.china.huawei.com (unknown [172.18.147.200]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4Dg4bg5FgHz67pv0; Tue, 16 Feb 2021 23:27:43 +0800 (CST) Received: from lhreml710-chm.china.huawei.com (10.201.108.61) by fraeml738-chm.china.huawei.com (10.206.15.219) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Tue, 16 Feb 2021 16:31:33 +0100 Received: from localhost (10.47.75.223) by lhreml710-chm.china.huawei.com (10.201.108.61) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Tue, 16 Feb 2021 15:31:32 +0000 Date: Tue, 16 Feb 2021 15:30:26 +0000 From: Jonathan Cameron To: Ben Widawsky CC: , , , , , Bjorn Helgaas , "Chris Browy" , Christoph Hellwig , "Dan Williams" , David Hildenbrand , David Rientjes , Ira Weiny , "Jon Masters" , Rafael Wysocki , Randy Dunlap , Vishal Verma , "John Groves (jgroves)" , "Kelley, Sean V" , Ariel Sibley Subject: Re: [PATCH v4 5/9] cxl/mem: Add a "RAW" send command Message-ID: <20210216153026.00005e33@Huawei.com> In-Reply-To: <20210216014538.268106-6-ben.widawsky@intel.com> References: <20210216014538.268106-1-ben.widawsky@intel.com> <20210216014538.268106-6-ben.widawsky@intel.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; i686-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.47.75.223] X-ClientProxiedBy: lhreml717-chm.china.huawei.com (10.201.108.68) To lhreml710-chm.china.huawei.com (10.201.108.61) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 15 Feb 2021 17:45:34 -0800 Ben Widawsky wrote: > The CXL memory device send interface will have a number of supported > commands. The raw command is not such a command. Raw commands allow > userspace to send a specified opcode to the underlying hardware and > bypass all driver checks on the command. The primary use for this > command is to [begrudgingly] allow undocumented vendor specific hardware > commands. > > While not the main motivation, it also allows prototyping new hardware > commands without a driver patch and rebuild. > > While this all sounds very powerful it comes with a couple of caveats: > 1. Bug reports using raw commands will not get the same level of > attention as bug reports using supported commands (via taint). > 2. Supported commands will be rejected by the RAW command. > > With this comes new debugfs knob to allow full access to your toes with > your weapon of choice. > > Cc: Ariel Sibley > Signed-off-by: Ben Widawsky > Reviewed-by: Dan Williams (v2) Whilst I'm definitely dubious about introducing this interface so early in development, I haven't found any problems with 'how' it has been done. I guess it's now just up to us to hassle our hardware colleagues into only using this facility when absolutely necessary... Reviewed-by: Jonathan Cameron > --- > drivers/cxl/Kconfig | 18 +++++ > drivers/cxl/mem.c | 132 +++++++++++++++++++++++++++++++++++ > include/uapi/linux/cxl_mem.h | 12 +++- > 3 files changed, 161 insertions(+), 1 deletion(-) > > diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig > index 9e80b311e928..97dc4d751651 100644 > --- a/drivers/cxl/Kconfig > +++ b/drivers/cxl/Kconfig > @@ -32,4 +32,22 @@ config CXL_MEM > Chapter 2.3 Type 3 CXL Device in the CXL 2.0 specification. > > If unsure say 'm'. > + > +config CXL_MEM_RAW_COMMANDS > + bool "RAW Command Interface for Memory Devices" > + depends on CXL_MEM > + help > + Enable CXL RAW command interface. > + > + The CXL driver ioctl interface may assign a kernel ioctl command > + number for each specification defined opcode. At any given point in > + time the number of opcodes that the specification defines and a device > + may implement may exceed the kernel's set of associated ioctl function > + numbers. The mismatch is either by omission, specification is too new, > + or by design. When prototyping new hardware, or developing / debugging > + the driver it is useful to be able to submit any possible command to > + the hardware, even commands that may crash the kernel due to their > + potential impact to memory currently in use by the kernel. > + > + If developing CXL hardware or the driver say Y, otherwise say N. > endif > diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c > index a4298cb1182d..6b4feb0ce47d 100644 > --- a/drivers/cxl/mem.c > +++ b/drivers/cxl/mem.c > @@ -1,6 +1,8 @@ > // SPDX-License-Identifier: GPL-2.0-only > /* Copyright(c) 2020 Intel Corporation. All rights reserved. */ > #include > +#include > +#include > #include > #include > #include > @@ -42,7 +44,14 @@ > > enum opcode { > CXL_MBOX_OP_INVALID = 0x0000, > + CXL_MBOX_OP_RAW = CXL_MBOX_OP_INVALID, > + CXL_MBOX_OP_ACTIVATE_FW = 0x0202, > CXL_MBOX_OP_IDENTIFY = 0x4000, > + CXL_MBOX_OP_SET_PARTITION_INFO = 0x4101, > + CXL_MBOX_OP_SET_LSA = 0x4103, > + CXL_MBOX_OP_SET_SHUTDOWN_STATE = 0x4204, > + CXL_MBOX_OP_SCAN_MEDIA = 0x4304, > + CXL_MBOX_OP_GET_SCAN_MEDIA = 0x4305, > CXL_MBOX_OP_MAX = 0x10000 > }; > > @@ -92,6 +101,8 @@ struct cxl_memdev { > > static int cxl_mem_major; > static DEFINE_IDA(cxl_memdev_ida); > +static struct dentry *cxl_debugfs; > +static bool cxl_raw_allow_all; > > /** > * struct cxl_mem_command - Driver representation of a memory device command > @@ -128,6 +139,49 @@ struct cxl_mem_command { > */ > static struct cxl_mem_command mem_commands[] = { > CXL_CMD(IDENTIFY, 0, 0x43), > +#ifdef CONFIG_CXL_MEM_RAW_COMMANDS > + CXL_CMD(RAW, ~0, ~0), > +#endif > +}; > + > +/* > + * Commands that RAW doesn't permit. The rationale for each: > + * > + * CXL_MBOX_OP_ACTIVATE_FW: Firmware activation requires adjustment / > + * coordination of transaction timeout values at the root bridge level. > + * > + * CXL_MBOX_OP_SET_PARTITION_INFO: The device memory map may change live > + * and needs to be coordinated with HDM updates. > + * > + * CXL_MBOX_OP_SET_LSA: The label storage area may be cached by the > + * driver and any writes from userspace invalidates those contents. > + * > + * CXL_MBOX_OP_SET_SHUTDOWN_STATE: Set shutdown state assumes no writes > + * to the device after it is marked clean, userspace can not make that > + * assertion. > + * > + * CXL_MBOX_OP_[GET_]SCAN_MEDIA: The kernel provides a native error list that > + * is kept up to date with patrol notifications and error management. > + */ > +static u16 cxl_disabled_raw_commands[] = { > + CXL_MBOX_OP_ACTIVATE_FW, > + CXL_MBOX_OP_SET_PARTITION_INFO, > + CXL_MBOX_OP_SET_LSA, > + CXL_MBOX_OP_SET_SHUTDOWN_STATE, > + CXL_MBOX_OP_SCAN_MEDIA, > + CXL_MBOX_OP_GET_SCAN_MEDIA, > +}; > + > +/* > + * Command sets that RAW doesn't permit. All opcodes in this set are > + * disabled because they pass plain text security payloads over the > + * user/kernel boundary. This functionality is intended to be wrapped > + * behind the keys ABI which allows for encrypted payloads in the UAPI > + */ > +static u8 security_command_sets[] = { > + 0x44, /* Sanitize */ > + 0x45, /* Persistent Memory Data-at-rest Security */ > + 0x46, /* Security Passthrough */ > }; > > #define cxl_for_each_cmd(cmd) \ > @@ -158,6 +212,16 @@ static int cxl_mem_wait_for_doorbell(struct cxl_mem *cxlm) > return 0; > } > > +static bool cxl_is_security_command(u16 opcode) > +{ > + int i; > + > + for (i = 0; i < ARRAY_SIZE(security_command_sets); i++) > + if (security_command_sets[i] == (opcode >> 8)) > + return true; > + return false; > +} > + > static void cxl_mem_mbox_timeout(struct cxl_mem *cxlm, > struct mbox_cmd *mbox_cmd) > { > @@ -426,6 +490,9 @@ static int handle_mailbox_cmd_from_user(struct cxl_mem *cxlm, > cxl_command_names[cmd->info.id].name, mbox_cmd.opcode, > cmd->info.size_in); > > + dev_WARN_ONCE(dev, cmd->info.id == CXL_MEM_COMMAND_ID_RAW, > + "raw command path used\n"); > + > rc = __cxl_mem_mbox_send_cmd(cxlm, &mbox_cmd); > cxl_mem_mbox_put(cxlm); > if (rc) > @@ -457,6 +524,29 @@ static int handle_mailbox_cmd_from_user(struct cxl_mem *cxlm, > return rc; > } > > +static bool cxl_mem_raw_command_allowed(u16 opcode) > +{ > + int i; > + > + if (!IS_ENABLED(CONFIG_CXL_MEM_RAW_COMMANDS)) > + return false; > + > + if (security_locked_down(LOCKDOWN_NONE)) > + return false; > + > + if (cxl_raw_allow_all) > + return true; > + > + if (cxl_is_security_command(opcode)) > + return false; > + > + for (i = 0; i < ARRAY_SIZE(cxl_disabled_raw_commands); i++) > + if (cxl_disabled_raw_commands[i] == opcode) > + return false; > + > + return true; > +} > + > /** > * cxl_validate_cmd_from_user() - Check fields for CXL_MEM_SEND_COMMAND. > * @cxlm: &struct cxl_mem device whose mailbox will be used. > @@ -468,6 +558,7 @@ static int handle_mailbox_cmd_from_user(struct cxl_mem *cxlm, > * * %-ENOTTY - Invalid command specified. > * * %-EINVAL - Reserved fields or invalid values were used. > * * %-ENOMEM - Input or output buffer wasn't sized properly. > + * * %-EPERM - Attempted to use a protected command. > * > * The result of this command is a fully validated command in @out_cmd that is > * safe to send to the hardware. > @@ -492,6 +583,40 @@ static int cxl_validate_cmd_from_user(struct cxl_mem *cxlm, > if (send_cmd->in.size > cxlm->payload_size) > return -EINVAL; > > + /* > + * Checks are bypassed for raw commands but a WARN/taint will occur > + * later in the callchain > + */ > + if (send_cmd->id == CXL_MEM_COMMAND_ID_RAW) { > + const struct cxl_mem_command temp = { > + .info = { > + .id = CXL_MEM_COMMAND_ID_RAW, > + .flags = 0, > + .size_in = send_cmd->in.size, > + .size_out = send_cmd->out.size, > + }, > + .opcode = send_cmd->raw.opcode > + }; > + > + if (send_cmd->raw.rsvd) > + return -EINVAL; > + > + /* > + * Unlike supported commands, the output size of RAW commands > + * gets passed along without further checking, so it must be > + * validated here. > + */ > + if (send_cmd->out.size > cxlm->payload_size) > + return -EINVAL; > + > + if (!cxl_mem_raw_command_allowed(send_cmd->raw.opcode)) > + return -EPERM; > + > + memcpy(out_cmd, &temp, sizeof(temp)); > + > + return 0; > + } > + > if (send_cmd->flags & ~CXL_MEM_COMMAND_FLAG_MASK) > return -EINVAL; > > @@ -1153,6 +1278,7 @@ static struct pci_driver cxl_mem_driver = { > > static __init int cxl_mem_init(void) > { > + struct dentry *mbox_debugfs; > dev_t devt; > int rc; > > @@ -1169,11 +1295,17 @@ static __init int cxl_mem_init(void) > return rc; > } > > + cxl_debugfs = debugfs_create_dir("cxl", NULL); > + mbox_debugfs = debugfs_create_dir("mbox", cxl_debugfs); > + debugfs_create_bool("raw_allow_all", 0600, mbox_debugfs, > + &cxl_raw_allow_all); > + > return 0; > } > > static __exit void cxl_mem_exit(void) > { > + debugfs_remove_recursive(cxl_debugfs); > pci_unregister_driver(&cxl_mem_driver); > unregister_chrdev_region(MKDEV(cxl_mem_major, 0), CXL_MEM_MAX_DEVS); > } > diff --git a/include/uapi/linux/cxl_mem.h b/include/uapi/linux/cxl_mem.h > index 18cea908ad0b..8eb669150ecb 100644 > --- a/include/uapi/linux/cxl_mem.h > +++ b/include/uapi/linux/cxl_mem.h > @@ -22,6 +22,7 @@ > #define CXL_CMDS \ > ___C(INVALID, "Invalid Command"), \ > ___C(IDENTIFY, "Identify Command"), \ > + ___C(RAW, "Raw device command"), \ > ___C(MAX, "invalid / last command") > > #define ___C(a, b) CXL_MEM_COMMAND_ID_##a > @@ -115,6 +116,9 @@ struct cxl_mem_query_commands { > * @id: The command to send to the memory device. This must be one of the > * commands returned by the query command. > * @flags: Flags for the command (input). > + * @raw: Special fields for raw commands > + * @raw.opcode: Opcode passed to hardware when using the RAW command. > + * @raw.rsvd: Must be zero. > * @rsvd: Must be zero. > * @retval: Return value from the memory device (output). > * @in.size: Size of the payload to provide to the device (input). > @@ -135,7 +139,13 @@ struct cxl_mem_query_commands { > struct cxl_send_command { > __u32 id; > __u32 flags; > - __u32 rsvd; > + union { > + struct { > + __u16 opcode; > + __u16 rsvd; > + } raw; > + __u32 rsvd; > + }; > __u32 retval; > > struct {