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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C2341C433FE for ; Fri, 24 Dec 2021 08:55:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352129AbhLXIzw (ORCPT ); Fri, 24 Dec 2021 03:55:52 -0500 Received: from out30-132.freemail.mail.aliyun.com ([115.124.30.132]:59862 "EHLO out30-132.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352117AbhLXIzv (ORCPT ); Fri, 24 Dec 2021 03:55:51 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R181e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04407;MF=xueshuai@linux.alibaba.com;NM=1;PH=DS;RN=13;SR=0;TI=SMTPD_---0V.c4Jon_1640336146; Received: from 30.240.114.155(mailfrom:xueshuai@linux.alibaba.com fp:SMTPD_---0V.c4Jon_1640336146) by smtp.aliyun-inc.com(127.0.0.1); Fri, 24 Dec 2021 16:55:48 +0800 Message-ID: <75dedf3a-41c7-980e-a8a8-74d116ae6663@linux.alibaba.com> Date: Fri, 24 Dec 2021 16:55:46 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Subject: Re: [RESEND PATCH v4] ACPI: Move sdei_init and ghes_init ahead to handle platform errors earlier Content-Language: en-US To: Bjorn Helgaas , "Rafael J. Wysocki" Cc: bp@alien8.de, tony.luck@intel.com, james.morse@arm.com, lenb@kernel.org, bhelgaas@google.com, zhangliguang@linux.alibaba.com, zhuo.song@linux.alibaba.com, linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org References: <20211224001716.GA1324143@bhelgaas> From: Shuai Xue In-Reply-To: <20211224001716.GA1324143@bhelgaas> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Bjorn, Thank you for your comments. 在 2021/12/24 AM8:17, Bjorn Helgaas 写道: > [+to Rafael, question about HEST/GHES/SDEI init] > > On Thu, Dec 23, 2021 at 04:11:11PM +0800, Shuai Xue wrote: >> 在 2021/12/22 AM7:17, Bjorn Helgaas 写道: >>> On Thu, Dec 16, 2021 at 09:34:56PM +0800, Shuai Xue wrote: >>>> On an ACPI system, ACPI is initialised very early from a subsys_initcall(), >>>> while SDEI is not ready until a subsys_initcall_sync(). >>>> >>>> The SDEI driver provides functions (e.g. apei_sdei_register_ghes, >>>> apei_sdei_unregister_ghes) to register or unregister event callback for >>>> dispatcher in firmware. When the GHES driver probing, it registers the >>>> corresponding callback according to the notification type specified by >>>> GHES. If the GHES notification type is SDEI, the GHES driver will call >>>> apei_sdei_register_ghes to register event call. >>>> >>>> When the firmware emits an event, it migrates the handling of the event >>>> into the kernel at the registered entry-point __sdei_asm_handler. And >>>> finally, the kernel will call the registered event callback and return >>>> status_code to indicate the status of event handling. SDEI_EV_FAILED >>>> indicates that the kernel failed to handle the event. >>>> >>>> Consequently, when an error occurs during kernel booting, the kernel is >>>> unable to handle and report errors until the GHES driver is initialized by >>>> device_initcall(), in which the event callback is registered. All errors >>>> that occurred before GHES initialization are missed and there is no chance >>>> to report and find them again. >>>> >>>> From commit e147133a42cb ("ACPI / APEI: Make hest.c manage the estatus >>>> memory pool") was merged, ghes_init() relies on acpi_hest_init() to manage >>>> the estatus memory pool. On the other hand, ghes_init() relies on >>>> sdei_init() to detect the SDEI version and the framework for registering >>>> and unregistering events. >>> >>>> By the way, I don't figure out why acpi_hest_init is called in >>>> acpi_pci_root_init, it don't rely on any other thing. May it could >>>> be moved further, following acpi_iort_init in acpi_init. > >>>> sdei_init() relies on ACPI table which is initialized >>>> subsys_initcall(): acpi_init(), acpi_bus_init(), acpi_load_tables(), >>>> acpi_tb_laod_namespace(). May it should be also moved further, >>>> after acpi_load_tables. > >>>> In this patch, move sdei_init and ghes_init as far ahead as >>>> possible, right after acpi_hest_init(). >>> >>> I'm having a hard time figuring out the reason for this patch. >>> >>> Apparently the relevant parts are sdei_init() and ghes_init(). >>> Today they are executed in that order: >>> >>> subsys_initcall_sync(sdei_init); >>> device_initcall(ghes_init); >>> >>> After this patch, they would be executed in the same order, but called >>> explicitly instead of as initcalls: >>> >>> acpi_pci_root_init() >>> { >>> acpi_hest_init(); >>> sdei_init(); >>> ghes_init(); >>> ... >>> >>> Explicit calls are certainly better than initcalls, but that doesn't >>> seem to be the reason for this patch. >>> >>> Does this patch fix a bug? If so, what is the bug? >> >> Yes. When the kernel booting, the console logs many times from firmware >> before GHES drivers init: >> >> Trip in MM PCIe RAS handle(Intr:910) >> Clean PE[1.1.1] ERR_STS:0x4000100 -> 0 INT_STS:F0000000 >> Find RP(98:1.0) >> --Walk dev(98:1.0) CE:0 UCE:4000 >> ... >> ERROR: sdei_dispatch_event(32a) ret:-1 >> --handler(910) end >> >> This is because the callback function has not been registered yet. >> Previously reported errors will be overwritten by new ones. Therefore, >> all errors that occurred before GHES initialization are missed >> and there is no chance to report and find them again. >> >>> You say that currently "errors that occur before GHES initialization >>> are missed". Isn't that still true after this patch? Does this patch >>> merely reduce the time before GHES initialization? If so, I'm >>> dubious, because we have to tolerate an arbitrary amount of time >>> there. >> >> After this patch, there are still errors missing. As you mentioned, >> we have to tolerate it until the software reporting capability is built. >> >> Yes, this patch merely reduce the time before GHES initialization. > > It's not a bug that errors that happen before the callback are lost. > At least, it's not a *Linux* bug. It might be a poor design of the > firmware error reporting interface. > > If the only point of this patch is to reduce the time before GHES > initialization, the commit log should clearly say that. Yep, it is a design defect of firmware. I will explicitly document the purpose of this patch in next version. >> The boot dmesg before this patch: >> >> [ 3.688586] HEST: Table parsing has been initialized. >> ... >> [ 33.204340] calling sdei_init+0x0/0x120 @ 1 >> [ 33.208645] sdei: SDEIv1.0 (0x0) detected in firmware. >> ... >> [ 36.005390] calling ghes_init+0x0/0x11c @ 1 >> [ 36.190021] GHES: APEI firmware first mode is enabled by APEI bit and WHEA _OSC. >> >> >> After this patch, the boot dmesg like bellow: >> >> [ 3.688664] HEST: Table parsing has been initialized. >> [ 3.688691] sdei: SDEIv1.0 (0x0) detected in firmware. >> [ 3.694557] GHES: APEI firmware first mode is enabled by APEI bit and WHEA _OSC. After this patch, we use explicit call to init GHES rather than initcall. The GHES message here is just to prove that GHES initialization is advanced to 3.694557 seconds. > [Tangent: I think this GHES message is confusing. What "APEI bit" > does this refer to? The only bits I remember are the Flags bits in > HEST Error Source Descriptor Entries, e.g., ACPI v6.3, sec 18.3.2. >From the log code behavior, the APEI bit refers to OSC_SB_APEI_SUPPORT. (BIT 4, ACPI v6.4, sec 6.2.11.2, table Table 6.13 Platform-Wide _OSC Capabilities DWORD 2. [1]) /* code in drivers/acpi/apei/ghes.c */ if (rc == 0 && osc_sb_apei_support_acked) pr_info(GHES_PFX "APEI firmware first mode is enabled by APEI bit and WHEA _OSC.\n"); /* code in drivers/acpi/bus.c */ osc_sb_apei_support_acked = capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_APEI_SUPPORT; > "WHEA _OSC" means nothing to me, and I didn't find anything useful > with grep, other than that "WHEA" might be an obsolete name for what > we now call "APEI". Yep, WHEA is an obsolete name. I think apei_osc_setup() is added for compatibility in commit eccddd32ced0 ("ACPI, APEI, Add APEI bit support in generic _OSC call")' The ACPI spec Platform-Wide OSPM Capabilities defines UUID "0811B06E-4A27-44F9-8D60-3CBBC22E7B48" is used in acpi_bus_osc_support(). The Microsoft WHEA defines UUID "ed855e0c-6c90-47bf-a62a-26de0fc5ad5c" that is used in apei_osc_setup(). [2][3] >From the discussion[4], the GHES message is to distinguish between the two specs. To avoid confusion, can we change the message as follow. - generic _OSC succeeded, APEI _OSC failed: APEI firmware first mode is enabled by APEI bit. - generic _OSC failed, APEI _OSC succeeded: APEI firmware first mode is enabled by WHEA _OSC. - both succeeded: APEI firmware first mode is enabled by APEI bit and WHEA _OSC. - both failed: Failed to enable APEI firmware first mode! > I don't think there's anything in _OSC that mentions "firmware first." > > I don't remember anything in the spec about a way to *enable* Firmware > First Error Handling needing (I'm looking at ACPI v6.3, sec 18.4). > > I think the "firmware first" information is useless to the OS -- as > far as I can tell, the spec says nothing about anything the OS should > do based on the FIRMWARE_FIRST bits.] GHES works in "Firmware First" mode to report platform hardware error and it depends on APEI interface. (drivers/acpi/apei/ghes.c) * Generic Hardware Error Source provides a way to report platform * hardware errors (such as that from chipset). It works in so called * "Firmware First" mode, that is, hardware errors are reported to * firmware firstly, then reported to Linux by firmware. Based on above, I think the GHES message just means that this booting kernel supports APEI or WHEA, and GHES report Firmware first errors on this machine. Is it fine to keep the message? >> As we can see, the initialization of GHES is advanced by 33 seconds. >> So, in my opinion, this patch is necessary, right? >> (It should be noted that the effect of optimization varies with the platform.) > >>>> -device_initcall(ghes_init); >>> >>>> void __init acpi_pci_root_init(void) >>>> { >>>> acpi_hest_init(); >>>> + sdei_init(); >>>> + ghes_init(); >>> >>> What's the connection between PCI, SDEI, and GHES? As far as I can >>> tell, SDEI and GHES are not PCI-specific, so it doesn't seem like they >>> should be initialized here in acpi_pci_root_init(). >> >> The only reason is that acpi_hest_init() is initialized here. >> >> From commit e147133a42cb ("ACPI / APEI: Make hest.c manage the estatus >> memory pool") was merged, ghes_init() relies on acpi_hest_init() to manage >> the estatus memory pool. On the other hand, ghes_init() relies on >> sdei_init() to detect the SDEI version and the framework for registering >> and unregistering events. The dependencies are as follows >> >> ghes_init() => acpi_hest_init() >> ghes_init() => sdei_init() >> >> I don't figure out why acpi_hest_init() is called in >> acpi_pci_root_init(), it don't rely on any other thing. >> I am wondering that should we moved all of them further? e.g. >> following acpi_iort_init() in acpi_init(). > > I don't know why acpi_hest_init() is called from acpi_pci_root_init(). > It looks like HEST can support error sources other than PCI (IA-32 > Machine Checks, NMIs, GHES, etc.) It was added by 415e12b23792 > ("PCI/ACPI: Request _OSC control once for each root bridge (v3)"); > maybe Rafael remembers why. > > Seem like acpi_hest_init(), sdei_init(), and ghes_init() should all go > somewhere else, but I don't know where. Maybe somewhere in > acpi_init()? I tried to move them into acpi_init(), and it works well. @@ -1251,6 +1251,9 @@ static int __init acpi_init(void) pci_mmcfg_late_init(); acpi_iort_init(); + acpi_hest_init(); + sdei_init(); + ghes_init(); acpi_scan_init(); acpi_ec_init(); What's your opinion? Best Regards, Shuai [1] https://uefi.org/specs/ACPI/6.4/06_Device_Configuration/Device_Configuration.html#platform-wide-osc-capabilities-dword-2 [2] https://www.mail-archive.com/ubuntu-bugs@lists.ubuntu.com/msg4718503.html [3] http://www.guyreams.com/PDF/whea.pdf [4] https://patchwork.kernel.org/project/linux-acpi/patch/1308640587-24502-5-git-send-email-ying.huang@intel.com/#1978922