Message-ID: <20170726072404.3cb283c5@vento.lan>
Date:   Wed, 26 Jul 2017 07:24:04 -0300
From:   Mauro Carvalho Chehab <mchehab@...radead.org>
To:     Borislav Petkov <bp@...en8.de>
Cc:     linux-edac <linux-edac@...r.kernel.org>,
        Tony Luck <tony.luck@...el.com>,
        Toshimitsu Kani <toshi.kani@....com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] EDAC, ghes: Make it a proper module

Em Wed, 26 Jul 2017 10:48:27 +0200
Borislav Petkov <bp@...en8.de> escreveu:

> From: Borislav Petkov <bp@...e.de>
> 
> Register with the GHES notifier chain so that there's no need to call
> into the module with ghes_edac_report_mem_error().

Hmm... I'm not seeing any implementation that would allow setting
between firmware first, hardware first or "auto", as we've discussed.

> 
> Signed-off-by: Borislav Petkov <bp@...e.de>
> ---
>  drivers/acpi/apei/ghes.c |  18 +++----
>  drivers/edac/Kconfig     |   4 +-
>  drivers/edac/ghes_edac.c | 129 ++++++++++++++++++++++++-----------------------
>  include/acpi/ghes.h      |  25 ---------
>  4 files changed, 74 insertions(+), 102 deletions(-)
> 
> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
> index 3f05f5ff3461..37cd698cacd2 100644
> --- a/drivers/acpi/apei/ghes.c
> +++ b/drivers/acpi/apei/ghes.c
> @@ -475,11 +475,11 @@ static void ghes_handle_memory_failure(struct acpi_hest_generic_data *gdata, int
>  static void ghes_do_proc(struct ghes *ghes,
>  			 const struct acpi_hest_generic_status *estatus)
>  {
> -	int sev, sec_sev;
>  	struct acpi_hest_generic_data *gdata;
>  	guid_t *sec_type;
>  	guid_t *fru_id = &NULL_UUID_LE;
>  	char *fru_text = "";
> +	int sev, sec_sev;
>  
>  	sev = ghes_severity(estatus->error_severity);
>  	apei_estatus_for_each_section(estatus, gdata) {
> @@ -494,7 +494,8 @@ static void ghes_do_proc(struct ghes *ghes,
>  		if (guid_equal(sec_type, &CPER_SEC_PLATFORM_MEM)) {
>  			struct cper_sec_mem_err *mem_err = acpi_hest_get_payload(gdata);
>  
> -			ghes_edac_report_mem_error(ghes, sev, mem_err);
> +
> +			atomic_notifier_call_chain(&ghes_edac_chain, sev, &mem_err);
>  
>  			arch_apei_report_mem_error(sev, mem_err);
>  			ghes_handle_memory_failure(gdata, sev);
> @@ -1153,10 +1154,6 @@ static int ghes_probe(struct platform_device *ghes_dev)
>  		goto err;
>  	}
>  
> -	rc = ghes_edac_register(ghes, &ghes_dev->dev);
> -	if (rc < 0)
> -		goto err;
> -
>  	switch (generic->notify.type) {
>  	case ACPI_HEST_NOTIFY_POLLED:
>  		setup_deferrable_timer(&ghes->timer, ghes_poll_func,
> @@ -1169,13 +1166,13 @@ static int ghes_probe(struct platform_device *ghes_dev)
>  		if (rc) {
>  			pr_err(GHES_PFX "Failed to map GSI to IRQ for generic hardware error source: %d\n",
>  			       generic->header.source_id);
> -			goto err_edac_unreg;
> +			goto err;
>  		}
>  		rc = request_irq(ghes->irq, ghes_irq_func, 0, "GHES IRQ", ghes);
>  		if (rc) {
>  			pr_err(GHES_PFX "Failed to register IRQ for generic hardware error source: %d\n",
>  			       generic->header.source_id);
> -			goto err_edac_unreg;
> +			goto err;
>  		}
>  		break;
>  
> @@ -1204,8 +1201,7 @@ static int ghes_probe(struct platform_device *ghes_dev)
>  	ghes_proc(ghes);
>  
>  	return 0;
> -err_edac_unreg:
> -	ghes_edac_unregister(ghes);
> +
>  err:
>  	if (ghes) {
>  		ghes_fini(ghes);
> @@ -1255,8 +1251,6 @@ static int ghes_remove(struct platform_device *ghes_dev)
>  
>  	ghes_fini(ghes);
>  
> -	ghes_edac_unregister(ghes);
> -
>  	kfree(ghes);
>  
>  	platform_set_drvdata(ghes_dev, NULL);
> diff --git a/drivers/edac/Kconfig b/drivers/edac/Kconfig
> index 96afb2aeed18..fdd8278ca89a 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
>  	help
>  	  Not all machines support hardware-driven error report. Some of those
>  	  provide a BIOS-driven error report mechanism via ACPI, using the
> diff --git a/drivers/edac/ghes_edac.c b/drivers/edac/ghes_edac.c
> index 6f80eb65c26c..ecd34b8bd27e 100644
> --- a/drivers/edac/ghes_edac.c
> +++ b/drivers/edac/ghes_edac.c
> @@ -5,6 +5,9 @@
>   * License version 2.
>   *
>   * Copyright (c) 2013 by Mauro Carvalho Chehab
> + *	     (c) 2017 Borislav Petkov
> + *
> + * Borislav Petkov: turn it into a proper module.
>   *
>   * Red Hat Inc. http://www.redhat.com
>   */
> @@ -28,10 +31,10 @@ struct ghes_edac_pvt {
>  	char msg[80];
>  };
>  
> -static LIST_HEAD(ghes_reglist);
> -static DEFINE_MUTEX(ghes_edac_lock);
> -static int ghes_edac_mc_num;
> +static struct ghes_edac_pvt *ghes_pvt;
>  
> +/* Hand it into EDAC's core so that we have a device to operate on. */
> +static struct device dummy_dev;
>  
>  /* Memory Device - Type 17 of SMBIOS spec */
>  struct memdev_dmi_entry {
> @@ -163,24 +166,21 @@ static void ghes_edac_dmidecode(const struct dmi_header *dh, void *arg)
>  	}
>  }
>  
> -void ghes_edac_report_mem_error(struct ghes *ghes, int sev,
> -				struct cper_sec_mem_err *mem_err)
> +static int report_mem_error(struct notifier_block *nb, unsigned long sev, void *data)
>  {
> +	struct cper_sec_mem_err *mem_err = data;
>  	enum hw_event_mc_err_type type;
>  	struct edac_raw_error_desc *e;
>  	struct mem_ctl_info *mci;
> -	struct ghes_edac_pvt *pvt = NULL;
> -	char *p;
> +	struct ghes_edac_pvt *pvt = ghes_pvt;
>  	u8 grain_bits;
> +	char *p;
>  
> -	list_for_each_entry(pvt, &ghes_reglist, list) {
> -		if (ghes == pvt->ghes)
> -			break;
> -	}
>  	if (!pvt) {
> -		pr_err("Internal error: Can't find EDAC structure\n");
> -		return;
> +		edac_pr_err("Internal error: Can't find EDAC structure\n");
> +		return NOTIFY_DONE;
>  	}
> +
>  	mci = pvt->mci;
>  	e = &mci->error_desc;
>  
> @@ -400,23 +400,40 @@ void ghes_edac_report_mem_error(struct ghes *ghes, int sev,
>  
>  	/* Report the error via EDAC API */
>  	edac_raw_mc_handle_error(type, mci, e);
> +
> +	return NOTIFY_DONE;
>  }
> -EXPORT_SYMBOL_GPL(ghes_edac_report_mem_error);
>  
> -int ghes_edac_register(struct ghes *ghes, struct device *dev)
> +static struct notifier_block ghes_nb = {
> +	.notifier_call  = report_mem_error,
> +};
> +
> +static const char * const fake_msg =
> +"This EDAC driver relies on BIOS to enumerate memory and get error reports.\n"
> +"Unfortunately, not all BIOSes reflect the memory layout correctly.\n"
> +"So, the end result of using this driver varies from vendor to vendor.\n"
> +"If you find incorrect reports, please contact your hardware vendor\n"
> +"to correct its BIOS.";
> +
> +static const char * const super_crap_msg =
> +"This system has a very crappy BIOS: It doesn't even list the DIMMS.\n"
> +"Its SMBIOS info is wrong. It is doubtful that the error report would\n"
> +"work on such system. Use this driver with caution.";

I would also add a note saying that the BIOS may be masking errors.

> +
> +static int __init ghes_edac_register(void)
>  {
> +	struct ghes_edac_pvt *pvt = ghes_pvt;
>  	bool fake = false;
>  	int rc, num_dimm = 0;
>  	struct mem_ctl_info *mci;
>  	struct edac_mc_layer layers[1];
> -	struct ghes_edac_pvt *pvt;
>  	struct ghes_edac_dimm_fill dimm_fill;
>  
>  	/* Get the number of DIMMs */
>  	dmi_walk(ghes_edac_count_dimms, &num_dimm);
>  
>  	/* Check if we've got a bogus BIOS */
> -	if (num_dimm == 0) {
> +	if (!num_dimm) {
>  		fake = true;
>  		num_dimm = 1;
>  	}
> @@ -429,21 +446,17 @@ int ghes_edac_register(struct ghes *ghes, struct device *dev)
>  	 * We need to serialize edac_mc_alloc() and edac_mc_add_mc(),
>  	 * to avoid duplicated memory controller numbers
>  	 */
> -	mutex_lock(&ghes_edac_lock);
> -	mci = edac_mc_alloc(ghes_edac_mc_num, ARRAY_SIZE(layers), layers,
> -			    sizeof(*pvt));
> +	mci = edac_mc_alloc(1, ARRAY_SIZE(layers), layers, sizeof(*pvt));
>  	if (!mci) {
> -		pr_info("Can't allocate memory for EDAC data\n");
> -		mutex_unlock(&ghes_edac_lock);
> +		edac_pr_err("Can't allocate memory for EDAC data\n");
>  		return -ENOMEM;
>  	}
>  
>  	pvt = mci->pvt_info;
>  	memset(pvt, 0, sizeof(*pvt));
> -	list_add_tail(&pvt->list, &ghes_reglist);
> -	pvt->ghes = ghes;
>  	pvt->mci  = mci;
> -	mci->pdev = dev;
> +
> +	mci->pdev = &dummy_dev;
>  
>  	mci->mtype_cap = MEM_FLAG_EMPTY;
>  	mci->edac_ctl_cap = EDAC_FLAG_NONE;
> @@ -452,21 +465,12 @@ int ghes_edac_register(struct ghes *ghes, struct device *dev)
>  	mci->ctl_name = "ghes_edac";
>  	mci->dev_name = "ghes";
>  
> -	if (!ghes_edac_mc_num) {
> -		if (!fake) {
> -			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");
> -			pr_info("If you find incorrect reports, please contact your hardware vendor\n");
> -			pr_info("to correct its BIOS.\n");
> -			pr_info("This system has %d DIMM sockets.\n",
> -				num_dimm);
> -		} else {
> -			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");
> -		}
> -	}
> +	if (!fake)
> +		edac_pr_info("%s\n", fake_msg);
> +	else
> +		edac_pr_info("%s\n", super_crap_msg);
> +
> +	edac_pr_info("This system has %d DIMM sockets.\n", num_dimm);
>  
>  	if (!fake) {
>  		/*
> @@ -475,13 +479,11 @@ int ghes_edac_register(struct ghes *ghes, struct device *dev)
>  		 * Keep it in blank for the other memory controllers, as
>  		 * there's no reliable way to properly credit each DIMM to
>  		 * the memory controller, as different BIOSes fill the
> -		 * DMI bank location fields on different ways
> +		 * DMI bank location fields in different ways.
>  		 */
> -		if (!ghes_edac_mc_num) {
> -			dimm_fill.count = 0;
> -			dimm_fill.mci = mci;
> -			dmi_walk(ghes_edac_dmidecode, &dimm_fill);
> -		}
> +		dimm_fill.count = 0;
> +		dimm_fill.mci = mci;
> +		dmi_walk(ghes_edac_dmidecode, &dimm_fill);
>  	} else {
>  		struct dimm_info *dimm = EDAC_DIMM_PTR(mci->layers, mci->dimms,
>  						       mci->n_layers, 0, 0, 0);
> @@ -495,30 +497,31 @@ int ghes_edac_register(struct ghes *ghes, struct device *dev)
>  
>  	rc = edac_mc_add_mc(mci);
>  	if (rc < 0) {
> -		pr_info("Can't register at EDAC core\n");
> +		edac_pr_err("Can't register with EDAC core\n");
>  		edac_mc_free(mci);
> -		mutex_unlock(&ghes_edac_lock);
>  		return -ENODEV;
>  	}
>  
> -	ghes_edac_mc_num++;
> -	mutex_unlock(&ghes_edac_lock);
> +	ghes_register_edac_chain(&ghes_nb);
> +
>  	return 0;
>  }
> -EXPORT_SYMBOL_GPL(ghes_edac_register);
> +module_init(ghes_edac_register);
>  
> -void ghes_edac_unregister(struct ghes *ghes)
> +static void __exit ghes_edac_unregister(void)
>  {
>  	struct mem_ctl_info *mci;
> -	struct ghes_edac_pvt *pvt, *tmp;
> -
> -	list_for_each_entry_safe(pvt, tmp, &ghes_reglist, list) {
> -		if (ghes == pvt->ghes) {
> -			mci = pvt->mci;
> -			edac_mc_del_mc(mci->pdev);
> -			edac_mc_free(mci);
> -			list_del(&pvt->list);
> -		}
> -	}
> +
> +	ghes_unregister_edac_chain(&ghes_nb);
> +
> +	mci = find_mci_by_dev(&dummy_dev);
> +	WARN_ON(!mci);
> +
> +	edac_mc_del_mc(mci->pdev);
> +	edac_mc_free(mci);
> +
>  }
> -EXPORT_SYMBOL_GPL(ghes_edac_unregister);
> +module_exit(ghes_edac_unregister);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("GHES error decoding module");
> diff --git a/include/acpi/ghes.h b/include/acpi/ghes.h
> index 506b6a197738..c02b8eb91bd6 100644
> --- a/include/acpi/ghes.h
> +++ b/include/acpi/ghes.h
> @@ -51,31 +51,6 @@ enum {
>  	GHES_SEV_PANIC = 0x3,
>  };
>  
> -/* From drivers/edac/ghes_edac.c */
> -
> -#ifdef CONFIG_EDAC_GHES
> -void ghes_edac_report_mem_error(struct ghes *ghes, 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(struct ghes *ghes, int sev,
> -				       struct cper_sec_mem_err *mem_err)
> -{
> -}
> -
> -static inline int ghes_edac_register(struct ghes *ghes, struct device *dev)
> -{
> -	return 0;
> -}
> -
> -static inline void ghes_edac_unregister(struct ghes *ghes)
> -{
> -}
> -#endif
>  void ghes_register_edac_chain(struct notifier_block *nb);
>  void ghes_unregister_edac_chain(struct notifier_block *nb);
>  



Thanks,
Mauro

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