[PATCH 2/2] EDAC/ghes: Modularize ghes_edac driver to remove the dependency on ghes

From: Jia He
Date: Thu Aug 11 2022 - 05:17:49 EST

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Commit dc4e8c07e9e2 ("ACPI: APEI: explicit init of HEST and GHES in
apci_init()") introduced a bug that ghes_edac_register() would be invoked
before edac_init(). Because at that time, the bus "edac" hasn't been even
registered, this created sysfs /devices/mc0 instead of
/sys/devices/system/edac/mc/mc0 on an Ampere eMag server.

The solution is modularizing the ghes_edac driver.
Use a list to save the probing devices in ghes_probe(), and defer the
ghes_edac_register() to the new ghes_edac module_init() by iterating over
the devices list.

To resolve the build dependency of ghes_edac_report_mem_error() for ghes,
introduce a notifier which is registered by ghes_edac module. atomic
notifier is used because ghes_proc_in_irq() is in the irq context.

Co-developed-by: Borislav Petkov <bp@xxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxxxx>
Signed-off-by: Jia He <justin.he@xxxxxxx>
Fixes: dc4e8c07e9e2 ("ACPI: APEI: explicit init of HEST and GHES in apci_init()")
Cc: stable@xxxxxxxxxx
Cc: Shuai Xue <xueshuai@xxxxxxxxxxxxxxxxx>
---
drivers/acpi/apei/ghes.c | 49 +++++++++++++++++++++++---
drivers/edac/Kconfig | 4 +--
drivers/edac/ghes_edac.c | 74 ++++++++++++++++++++++++++++------------
include/acpi/ghes.h | 33 +++++-------------
4 files changed, 107 insertions(+), 53 deletions(-)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index d91ad378c00d..ed6519f3d45b 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -94,6 +94,8 @@
#define FIX_APEI_GHES_SDEI_CRITICAL __end_of_fixed_addresses
#endif

+ATOMIC_NOTIFIER_HEAD(ghes_report_chain);
+
static inline bool is_hest_type_generic_v2(struct ghes *ghes)
{
return ghes->generic->header.type == ACPI_HEST_TYPE_GENERIC_ERROR_V2;
@@ -118,6 +120,9 @@ 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
@@ -645,7 +650,7 @@ static bool 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(sev, mem_err);
+ atomic_notifier_call_chain(&ghes_report_chain, sev, mem_err);

arch_apei_report_mem_error(sev, mem_err);
queued = ghes_handle_memory_failure(gdata, sev);
@@ -1376,7 +1381,11 @@ 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 +1449,6 @@ 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 +1504,37 @@ 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);
+
+void ghes_register_report_chain(struct notifier_block *nb)
+{
+ atomic_notifier_chain_register(&ghes_report_chain, nb);
+}
+EXPORT_SYMBOL_GPL(ghes_register_report_chain);
+
+void ghes_unregister_report_chain(struct notifier_block *nb)
+{
+ atomic_notifier_chain_unregister(&ghes_report_chain, nb);
+}
+EXPORT_SYMBOL_GPL(ghes_unregister_report_chain);
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..3bdf8469882d 100644
--- a/drivers/edac/ghes_edac.c
+++ b/drivers/edac/ghes_edac.c
@@ -14,6 +14,7 @@
#include <linux/dmi.h>
#include "edac_module.h"
#include <ras/ras_event.h>
+#include <linux/notifier.h>

#define OTHER_DETAIL_LEN 400

@@ -59,6 +60,8 @@ 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;
@@ -267,11 +270,14 @@ static int print_mem_error_other_detail(const struct cper_sec_mem_err *mem, char
return n;
}

-void ghes_edac_report_mem_error(int sev, struct cper_sec_mem_err *mem_err)
+static int ghes_edac_report_mem_error(struct notifier_block *nb,
+ unsigned long val, void *data)
{
+ struct cper_sec_mem_err *mem_err = (struct cper_sec_mem_err *)data;
struct cper_mem_err_compact cmem;
struct edac_raw_error_desc *e;
struct mem_ctl_info *mci;
+ unsigned long sev = val;
struct ghes_pvt *pvt;
unsigned long flags;
char *p;
@@ -282,7 +288,7 @@ void ghes_edac_report_mem_error(int sev, struct cper_sec_mem_err *mem_err)
* know.
*/
if (WARN_ON_ONCE(in_nmi()))
- return;
+ return NOTIFY_OK;

spin_lock_irqsave(&ghes_lock, flags);

@@ -374,36 +380,24 @@ void ghes_edac_report_mem_error(int sev, struct cper_sec_mem_err *mem_err)

unlock:
spin_unlock_irqrestore(&ghes_lock, flags);
+
+ return NOTIFY_OK;
}

-/*
- * 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 */
+static struct notifier_block ghes_edac_mem_err_nb = {
+ .notifier_call = ghes_edac_report_mem_error,
+ .priority = 0,
};

-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 +441,7 @@ 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");
@@ -503,6 +497,8 @@ int ghes_edac_register(struct ghes *ghes, struct device *dev)
ghes_pvt = pvt;
spin_unlock_irqrestore(&ghes_lock, flags);

+ ghes_register_report_chain(&ghes_edac_mem_err_nb);
+
/* only set on success */
refcount_set(&ghes_refcount, 1);

@@ -517,7 +513,7 @@ 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;
@@ -548,6 +544,40 @@ void ghes_edac_unregister(struct ghes *ghes)
if (mci)
edac_mc_free(mci);

+ ghes_unregister_report_chain(&ghes_edac_mem_err_nb);
+
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;
+
+ if (!IS_ENABLED(CONFIG_X86))
+ force_load = true;
+
+ 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);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Output ACPI APEI/GHES BIOS detected errors module via EDAC");
diff --git a/include/acpi/ghes.h b/include/acpi/ghes.h
index 34fb3431a8f3..150c0b9500d6 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;
@@ -145,4 +125,7 @@ int ghes_notify_sea(void);
static inline int ghes_notify_sea(void) { return -ENOENT; }
#endif

+struct notifier_block;
+extern void ghes_register_report_chain(struct notifier_block *nb);
+extern void ghes_unregister_report_chain(struct notifier_block *nb);
#endif /* GHES_H */
--
2.25.1

Next message: Christoph Hellwig: "Re: [PATCH v1 1/2] PCI: dwc: drop dependency on ZONE_DMA32"
Previous message: Jia He: "[PATCH 1/2] efi/cper: export several helpers for ghes edac to use"
In reply to: Justin He: "RE: [PATCH 1/2] efi/cper: export several helpers for ghes edac to use"
Next in thread: Kani, Toshi: "RE: [PATCH 2/2] EDAC/ghes: Modularize ghes_edac driver to remove the dependency on ghes"
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