Message-ID: <DBBPR08MB4538F9C5F3EAC189722F8F61F7659@DBBPR08MB4538.eurprd08.prod.outlook.com>
Date:   Wed, 10 Aug 2022 06:00:49 +0000
From:   Justin He <Justin.He@....com>
To:     Borislav Petkov <bp@...en8.de>
CC:     "Kani, Toshi" <toshi.kani@....com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>, James Morse <James.Morse@....com>,
        Tony Luck <tony.luck@...el.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Robert Richter <rric@...nel.org>,
        Shuai Xue <xueshuai@...ux.alibaba.com>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:EDAC-CORE" <linux-edac@...r.kernel.org>
Subject: RE: 回复: [PATCH] ACPI: APEI: move edac_init ahead of ghes platform drv register

Hi Borislav

> -----Original Message-----
> From: Borislav Petkov <bp@...en8.de>
> Sent: Wednesday, August 10, 2022 2:46 AM
> To: Justin He <Justin.He@....com>
> Cc: Kani, Toshi <toshi.kani@....com>; Rafael J. Wysocki <rafael@...nel.org>;
> Len Brown <lenb@...nel.org>; James Morse <James.Morse@....com>;
> Tony Luck <tony.luck@...el.com>; Mauro Carvalho Chehab
> <mchehab@...nel.org>; Robert Richter <rric@...nel.org>; Shuai Xue
> <xueshuai@...ux.alibaba.com>; Jarkko Sakkinen <jarkko@...nel.org>; ACPI
> Devel Maling List <linux-acpi@...r.kernel.org>; Linux Kernel Mailing List
> <linux-kernel@...r.kernel.org>; open list:EDAC-CORE
> <linux-edac@...r.kernel.org>
> Subject: Re: 回复: [PATCH] ACPI: APEI: move edac_init ahead of ghes
> platform drv register
>
> On Tue, Aug 09, 2022 at 07:15:43PM +0200, Borislav Petkov wrote:
> > Yes, I think you do. Lemme write something and you can finish it/test
> > it.
>
> Here's something to only show what I'm thinking of. It doesn't build because
> of:
>
> drivers/acpi/apei/ghes.c: In function ‘ghes_do_proc’:
> drivers/acpi/apei/ghes.c:651:25: error: implicit declaration of function
> ‘ghes_edac_report_mem_error’; did you mean
> ‘arch_apei_report_mem_error’? [-Werror=implicit-function-declaration]
>   651 |                         ghes_edac_report_mem_error(sev,
> mem_err);
>
>
> and that needs more thinking what to do. My idea currently is to do a notifier
> like we do for MCA...

There is still a small gap even if we use notifier for ghes edac report mem error.

The notifier will be registered only when calling module_init() of ghes_edac module.
Then there will be different behavior for ghes_do_proc:
1. if ghes_do_proc is invoked in the acpi_init code path, the notifier has NOT been registered,
ghes_edac_report_mem_err() does nothing.
2.If ghes_do_proc is invoked after module_init(), the notifier is registered, everything is fine.

Is this strange or any other side effects?

--
Cheers,
Justin (Jia He)
>
> And I'm not really happy about returning a list of ghes devices just so
> ghes_edac instances can get their struct device * pointers. Maybe we'll think
> of something better.
>
> But this is the general goal: not call module code from builtin code - i.e., call
> ghes_edac.c code from ghes.c. It works now because ghes_edac is forced
> builtin which is ugly as hell.
>
> Anyway, enough for today...
>
> ---
> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c index
> d91ad378c00d..0919317b8313 100644
> --- a/drivers/acpi/apei/ghes.c
> +++ b/drivers/acpi/apei/ghes.c
> @@ -118,6 +118,9 @@ module_param_named(disable, ghes_disable, bool,
> 0);  static LIST_HEAD(ghes_hed);  static DEFINE_MUTEX(ghes_list_mutex);
>
> +static LIST_HEAD(ghes_devs);
> +static DEFINE_MUTEX(ghes_devs_mutex);
> +
>  /*
>   * Because the memory area used to transfer hardware error information
>   * from BIOS to Linux can be determined only in NMI, IRQ or timer @@
> -1376,7 +1379,11 @@ static int ghes_probe(struct platform_device
> *ghes_dev)
>
>       platform_set_drvdata(ghes_dev, ghes);
>
> -     ghes_edac_register(ghes, &ghes_dev->dev);
> +     ghes->dev = &ghes_dev->dev;
> +
> +     mutex_lock(&ghes_devs_mutex);
> +     list_add_tail(&ghes->elist, &ghes_devs);
> +     mutex_unlock(&ghes_devs_mutex);
>
>       /* Handle any pending errors right away */
>       spin_lock_irqsave(&ghes_notify_lock_irq, flags); @@ -1440,8 +1447,6
> @@ static int ghes_remove(struct platform_device *ghes_dev)
>
>       ghes_fini(ghes);
>
> -     ghes_edac_unregister(ghes);
> -
>       kfree(ghes);
>
>       platform_set_drvdata(ghes_dev, NULL);
> @@ -1497,3 +1502,25 @@ void __init acpi_ghes_init(void)
>       else
>               pr_info(GHES_PFX "Failed to enable APEI firmware first
> mode.\n");  }
> +
> +/*
> + * Known x86 systems that prefer GHES error reporting:
> + */
> +static struct acpi_platform_list plat_list[] = {
> +     {"HPE   ", "Server  ", 0, ACPI_SIG_FADT, all_versions},
> +     { } /* End */
> +};
> +
> +struct list_head *ghes_get_devices(bool force) {
> +     int idx = -1;
> +
> +     if (IS_ENABLED(CONFIG_X86)) {
> +             idx = acpi_match_platform_list(plat_list);
> +             if (idx < 0 && !force)
> +                     return NULL;
> +     }
> +
> +     return &ghes_devs;
> +}
> +EXPORT_SYMBOL_GPL(ghes_get_devices);
> diff --git a/drivers/edac/Kconfig b/drivers/edac/Kconfig index
> 17562cf1fe97..df45db81858b 100644
> --- a/drivers/edac/Kconfig
> +++ b/drivers/edac/Kconfig
> @@ -53,8 +53,8 @@ config EDAC_DECODE_MCE
>         has been initialized.
>
>  config EDAC_GHES
> -     bool "Output ACPI APEI/GHES BIOS detected errors via EDAC"
> -     depends on ACPI_APEI_GHES && (EDAC=y)
> +     tristate "Output ACPI APEI/GHES BIOS detected errors via EDAC"
> +     depends on ACPI_APEI_GHES
>       select UEFI_CPER
>       help
>         Not all machines support hardware-driven error report. Some of those
> diff --git a/drivers/edac/ghes_edac.c b/drivers/edac/ghes_edac.c index
> c8fa7dcfdbd0..da6d1a9e107d 100644
> --- a/drivers/edac/ghes_edac.c
> +++ b/drivers/edac/ghes_edac.c
> @@ -59,6 +59,8 @@ module_param(force_load, bool, 0);
>
>  static bool system_scanned;
>
> +static struct list_head *ghes_devs;
> +
>  /* Memory Device - Type 17 of SMBIOS spec */  struct memdev_dmi_entry
> {
>       u8 type;
> @@ -376,34 +378,15 @@ void ghes_edac_report_mem_error(int sev, struct
> cper_sec_mem_err *mem_err)
>       spin_unlock_irqrestore(&ghes_lock, flags);  }
>
> -/*
> - * Known systems that are safe to enable this module.
> - */
> -static struct acpi_platform_list plat_list[] = {
> -     {"HPE   ", "Server  ", 0, ACPI_SIG_FADT, all_versions},
> -     { } /* End */
> -};
> -
> -int ghes_edac_register(struct ghes *ghes, struct device *dev)
> +static int ghes_edac_register(struct device *dev)
>  {
>       bool fake = false;
>       struct mem_ctl_info *mci;
>       struct ghes_pvt *pvt;
>       struct edac_mc_layer layers[1];
>       unsigned long flags;
> -     int idx = -1;
>       int rc = 0;
>
> -     if (IS_ENABLED(CONFIG_X86)) {
> -             /* Check if safe to enable on this system */
> -             idx = acpi_match_platform_list(plat_list);
> -             if (!force_load && idx < 0)
> -                     return -ENODEV;
> -     } else {
> -             force_load = true;
> -             idx = 0;
> -     }
> -
>       /* finish another registration/unregistration instance first */
>       mutex_lock(&ghes_reg_mutex);
>
> @@ -447,7 +430,7 @@ int ghes_edac_register(struct ghes *ghes, struct
> device *dev)
>               pr_info("This system has a very crappy BIOS: It doesn't even list the
> DIMMS.\n");
>               pr_info("Its SMBIOS info is wrong. It is doubtful that the error report
> would\n");
>               pr_info("work on such system. Use this driver with caution\n");
> -     } else if (idx < 0) {
> +     } else if (force_load) {
>               pr_info("This EDAC driver relies on BIOS to enumerate memory and
> get error reports.\n");
>               pr_info("Unfortunately, not all BIOSes reflect the memory layout
> correctly.\n");
>               pr_info("So, the end result of using this driver varies from vendor to
> vendor.\n"); @@ -517,7 +500,7 @@ int ghes_edac_register(struct ghes *ghes,
> struct device *dev)
>       return rc;
>  }
>
> -void ghes_edac_unregister(struct ghes *ghes)
> +static void ghes_edac_unregister(struct ghes *ghes)
>  {
>       struct mem_ctl_info *mci;
>       unsigned long flags;
> @@ -551,3 +534,30 @@ void ghes_edac_unregister(struct ghes *ghes)
>  unlock:
>       mutex_unlock(&ghes_reg_mutex);
>  }
> +
> +static int __init ghes_edac_init(void)
> +{
> +     struct ghes *g, *g_tmp;
> +
> +     ghes_devs = ghes_get_devices(force_load);
> +     if (ghes_devs)
> +             return -ENODEV;
> +
> +     list_for_each_entry_safe(g, g_tmp, ghes_devs, elist) {
> +             ghes_edac_register(g->dev);
> +     }
> +
> +     return 0;
> +}
> +module_init(ghes_edac_init);
> +
> +static void __exit ghes_edac_exit(void) {
> +     struct ghes *g, *g_tmp;
> +
> +
> +     list_for_each_entry_safe(g, g_tmp, ghes_devs, elist) {
> +             ghes_edac_unregister(g);
> +     }
> +}
> +module_exit(ghes_edac_exit);
> diff --git a/include/acpi/ghes.h b/include/acpi/ghes.h index
> 34fb3431a8f3..f39b75c3f9c6 100644
> --- a/include/acpi/ghes.h
> +++ b/include/acpi/ghes.h
> @@ -27,6 +27,8 @@ struct ghes {
>               struct timer_list timer;
>               unsigned int irq;
>       };
> +     struct device *dev;
> +     struct list_head elist;
>  };
>
>  struct ghes_estatus_node {
> @@ -69,35 +71,13 @@ int ghes_register_vendor_record_notifier(struct
> notifier_block *nb);
>   * @nb: pointer to the notifier_block structure of the vendor record handler.
>   */
>  void ghes_unregister_vendor_record_notifier(struct notifier_block *nb);
> +struct list_head *ghes_get_devices(bool force); #else static inline
> +struct list_head *ghes_get_devices(bool force) { return NULL; }
>  #endif
>
>  int ghes_estatus_pool_init(int num_ghes);
>
> -/* From drivers/edac/ghes_edac.c */
> -
> -#ifdef CONFIG_EDAC_GHES
> -void ghes_edac_report_mem_error(int sev, struct cper_sec_mem_err
> *mem_err);
> -
> -int ghes_edac_register(struct ghes *ghes, struct device *dev);
> -
> -void ghes_edac_unregister(struct ghes *ghes);
> -
> -#else
> -static inline void ghes_edac_report_mem_error(int sev,
> -                                    struct cper_sec_mem_err *mem_err)
> -{
> -}
> -
> -static inline int ghes_edac_register(struct ghes *ghes, struct device *dev) -{
> -     return -ENODEV;
> -}
> -
> -static inline void ghes_edac_unregister(struct ghes *ghes) -{ -} -#endif
> -
>  static inline int acpi_hest_get_version(struct acpi_hest_generic_data *gdata)
> {
>       return gdata->revision >> 8;
>
> --
> Regards/Gruss,
>     Boris.
>
> https://people.kernel.org/tglx/notes-about-netiquette
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