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Date: Fri, 5 Feb 2021 13:54:04 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Shiju Jose <shiju.jose@...wei.com>, Borislav Petkov <bp@...en8.de>,
James Morse <james.morse@....com>
Cc: "open list:EDAC-CORE" <linux-edac@...r.kernel.org>,
ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Tony Luck <tony.luck@...el.com>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Len Brown <lenb@...nel.org>,
Robert Richter <rrichter@...vell.com>,
Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
linuxarm@...neuler.org, xuwei5@...wei.com,
Jonathan Cameron <jonathan.cameron@...wei.com>,
John Garry <john.garry@...wei.com>,
tanxiaofei <tanxiaofei@...wei.com>,
shameerali.kolothum.thodi@...wei.com, salil.mehta@...wei.com
Subject: Re: [PATCH v2 1/2] EDAC/ghes: Add EDAC device for reporting the CPU
cache errors
On Fri, Jan 29, 2021 at 1:03 PM Shiju Jose <shiju.jose@...wei.com> wrote:
>
> CPU L2 cache corrected errors are detected occasionally on
> few of our ARM64 hardware boards. Though it is rare, the
> probability of the CPU cache errors frequently occurring
> can't be avoided. The earlier failure detection by monitoring
> the cache corrected errors for the frequent occurrences and
> taking preventive action could prevent more serious hardware
> faults.
>
> On Intel architectures, cache corrected errors are reported and
> the affected cores are offlined in the architecture specific method.
> http://www.mcelog.org/cache.html
>
> However for the firmware-first error reporting, specifically on
> ARM64 architectures, there is no provision present for reporting
> the cache corrected error count to the user-space and taking
> preventive action such as offline the affected cores.
>
> For this purpose, it was suggested to create the CPU EDAC
> device for the CPU caches for reporting the cache error count
> for the firmware-first error reporting.
> The EDAC device blocks for the CPU caches would be created
> based on the cache information obtained from the cpu_cacheinfo.
>
> User-space application could monitor the recorded corrected error
> count for the earlier hardware failure detection and could take
> preventive action, such as offline the corresponding CPU core/s.
>
> Add an EDAC device and device blocks for the CPU caches
> based on the cache information from the cpu_cacheinfo.
> The cache's corrected error count would be stored in the
> /sys/devices/system/edac/cpu/cpu*/cache*/ce_count.
>
> Issues and possible solutions,
> 1.Cache info is not available for the CPUs offline.
> EDAC device interface requires creating EDAC device
> and device blocks together. It requires the number
> of caches per CPU as device blocks for the creation.
> However, this info is not available for the
> offlined CPUs.
> Tested Solution: Find the max number of caches among
> online CPUs, create the EDAC device for CPUs caches
> and get and populate the cache info for an offline
> CPU later, when the error is reported on that CPU for
> the first time.
>
> 2. Reporting error count for the Shared caches.
> There are few possible solutions,
> Tested Solution:
> Kernel would report a new error count for a shared cache
> through the EDAC device block for that CPU on which the error
> is reported. Then user-space application would sum the total
> error count from EDAC device block of all the CPUs in the
> shared CPU list of that shared cache.
>
> For the firmware-first error reporting, add an interface in the
> ghes_edac allow to report a CPU corrected error count.
>
> Suggested-by: James Morse <james.morse@....com>
> Signed-off-by: Shiju Jose <shiju.jose@...wei.com>
Boris, James, I need your input here.
> ---
> Documentation/ABI/testing/sysfs-devices-edac | 15 ++
> drivers/acpi/apei/ghes.c | 8 +-
> drivers/edac/Kconfig | 12 ++
> drivers/edac/ghes_edac.c | 186 +++++++++++++++++++
> include/acpi/ghes.h | 27 +++
> 5 files changed, 247 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-devices-edac b/Documentation/ABI/testing/sysfs-devices-edac
> index 256a9e990c0b..56a18b0af419 100644
> --- a/Documentation/ABI/testing/sysfs-devices-edac
> +++ b/Documentation/ABI/testing/sysfs-devices-edac
> @@ -155,3 +155,18 @@ Description: This attribute file displays the total count of uncorrectable
> errors that have occurred on this DIMM. If panic_on_ue is set, this
> counter will not have a chance to increment, since EDAC will panic the
> system
> +
> +What: /sys/devices/system/edac/cpu/cpu*/cache*/ce_count
> +Date: December 2020
> +Contact: linux-edac@...r.kernel.org
> +Description: This attribute file displays the total count of correctable
> + errors that have occurred on this CPU cache. This count is very important
> + to examine. CEs provide early indications that a cache is beginning
> + to fail. This count field should be monitored for non-zero values
> + and report such information to the system administrator.
> +
> +What: /sys/devices/system/edac/cpu/cpu*/cache*/ue_count
> +Date: December 2020
> +Contact: linux-edac@...r.kernel.org
> +Description: This attribute file displays the total count of uncorrectable
> + errors that have occurred on this CPU cache.
> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
> index fce7ade2aba9..139540f2c8f4 100644
> --- a/drivers/acpi/apei/ghes.c
> +++ b/drivers/acpi/apei/ghes.c
> @@ -1452,4 +1452,10 @@ static int __init ghes_init(void)
> err:
> return rc;
> }
> -device_initcall(ghes_init);
> +
> +/*
> + * device_initcall_sync() is added instead of the device_initcall()
> + * because the CPU cacheinfo should be populated and is required for
> + * adding the CPU cache edac device in the ghes_edac_register().
> + */
> +device_initcall_sync(ghes_init);
> diff --git a/drivers/edac/Kconfig b/drivers/edac/Kconfig
> index 81c42664f21b..39fb53aa9cd9 100644
> --- a/drivers/edac/Kconfig
> +++ b/drivers/edac/Kconfig
> @@ -74,6 +74,18 @@ config EDAC_GHES
>
> In doubt, say 'Y'.
>
> +config EDAC_GHES_CPU_CACHE_ERROR
> + bool "EDAC device for reporting firmware-first BIOS detected CPU cache error count"
> + depends on EDAC_GHES
> + depends on (ARM64 || COMPILE_TEST)
> + help
> + EDAC device for the firmware-first BIOS detected CPU cache error count,
> + reported via ACPI APEI/GHES. By enabling this option, EDAC device for
> + the CPU hierarchy and edac device blocks for the caches would be created.
> + The cache error count is shared with the userspace via the CPU EDAC
> + device's sysfs interface. This option is architecure independent though
> + currently it is tested and enabled for ARM64 only.
> +
> config EDAC_AMD64
> tristate "AMD64 (Opteron, Athlon64)"
> depends on AMD_NB && EDAC_DECODE_MCE
> diff --git a/drivers/edac/ghes_edac.c b/drivers/edac/ghes_edac.c
> index 6d1ddecbf0da..400b50be0c33 100644
> --- a/drivers/edac/ghes_edac.c
> +++ b/drivers/edac/ghes_edac.c
> @@ -12,6 +12,9 @@
> #include <acpi/ghes.h>
> #include <linux/edac.h>
> #include <linux/dmi.h>
> +#if defined(CONFIG_EDAC_GHES_CPU_CACHE_ERROR)
> +#include <linux/cacheinfo.h>
> +#endif
> #include "edac_module.h"
> #include <ras/ras_event.h>
>
> @@ -57,6 +60,21 @@ module_param(force_load, bool, 0);
>
> static bool system_scanned;
>
> +#if defined(CONFIG_EDAC_GHES_CPU_CACHE_ERROR)
> +struct ghes_edac_cpu_block {
> + int cpu;
> + u8 level;
> + u8 type;
> + int block_nr;
> + bool info_populated;
> +};
> +
> +static struct ghes_edac_cpu_block __percpu *edac_cpu_block_list;
> +
> +static struct edac_device_ctl_info *cpu_edac_dev;
> +static unsigned int num_caches_per_cpu;
> +#endif
> +
> /* Memory Device - Type 17 of SMBIOS spec */
> struct memdev_dmi_entry {
> u8 type;
> @@ -225,6 +243,164 @@ static void enumerate_dimms(const struct dmi_header *dh, void *arg)
> hw->num_dimms++;
> }
>
> +#if defined(CONFIG_EDAC_GHES_CPU_CACHE_ERROR)
> +static void ghes_edac_get_cpu_cacheinfo(void)
> +{
> + int cpu;
> + struct cpu_cacheinfo *this_cpu_ci;
> +
> + /*
> + * Find the maximum number of caches present in the CPU heirarchy
> + * among the online CPUs.
> + */
> + for_each_online_cpu(cpu) {
> + this_cpu_ci = get_cpu_cacheinfo(cpu);
> + if (!this_cpu_ci)
> + continue;
> + if (num_caches_per_cpu < this_cpu_ci->num_leaves)
> + num_caches_per_cpu = this_cpu_ci->num_leaves;
> + }
> +}
> +
> +static int ghes_edac_add_cpu_device(struct device *dev)
> +{
> + int rc;
> +
> + cpu_edac_dev = edac_device_alloc_ctl_info(0, "cpu", num_possible_cpus(),
> + "cache", num_caches_per_cpu, 0, NULL,
> + 0, edac_device_alloc_index());
> + if (!cpu_edac_dev) {
> + pr_warn("ghes-edac cpu edac device registration failed\n");
> + return -ENOMEM;
> + }
> +
> + cpu_edac_dev->dev = dev;
> + cpu_edac_dev->ctl_name = "cpu_edac_dev";
> + cpu_edac_dev->dev_name = "ghes";
> + cpu_edac_dev->mod_name = "ghes_edac.c";
> + rc = edac_device_add_device(cpu_edac_dev);
> + if (rc > 0) {
> + pr_warn("edac_device_add_device failed\n");
> + edac_device_free_ctl_info(cpu_edac_dev);
> + return -ENOMEM;
> + }
> +
> + return 0;
> +}
> +
> +static void ghes_edac_delete_cpu_device(void)
> +{
> + num_caches_per_cpu = 0;
> + if (cpu_edac_dev) {
> + edac_device_del_device(cpu_edac_dev->dev);
> + edac_device_free_ctl_info(cpu_edac_dev);
> + }
> + free_percpu(edac_cpu_block_list);
> +}
> +
> +static int ghes_edac_populate_cache_info(int cpu)
> +{
> + struct ghes_edac_cpu_block *block;
> + struct cpu_cacheinfo *this_cpu_ci;
> + struct cacheinfo *this_leaf;
> + int i, num_caches;
> +
> + this_cpu_ci = get_cpu_cacheinfo(cpu);
> + if (!this_cpu_ci || !this_cpu_ci->info_list || !this_cpu_ci->num_leaves)
> + return -EINVAL;
> +
> + this_leaf = this_cpu_ci->info_list;
> + /*
> + * Cache info would not be available for a CPU which is offline. However EDAC device
> + * creation requires the number of device blocks (for example max number of caches
> + * among CPUs). The cache info in the edac_cpu_block_list would be populated when
> + * the first error is reported on that cpu. Thus we need to restrict the number
> + * of caches if the CPU's num_leaves exceed the max number of caches per cpu
> + * calculated in the init time.
> + */
> + num_caches = min(num_caches_per_cpu, this_cpu_ci->num_leaves);
> +
> + /*
> + * The edac CPU cache device blocks entries in the sysfs should match with the
> + * CPU cache structure in the sysfs so that the affected cpus for a shared cache
> + * can be easily extracted in the userspace.
> + */
> + block = per_cpu_ptr(edac_cpu_block_list, cpu);
> + for (i = 0; i < num_caches; i++) {
> + block->cpu = cpu;
> + block->level = this_leaf->level;
> + block->type = this_leaf->type;
> + block->block_nr = i;
> + block->info_populated = true;
> + this_leaf++;
> + block++;
> + }
> +
> + return 0;
> +}
> +
> +static void ghes_edac_create_cpu_device(struct device *dev)
> +{
> + int cpu;
> +
> + if (!num_caches_per_cpu)
> + return;
> +
> + /*
> + * Allocate EDAC CPU cache list.
> + * EDAC device interface require creating the CPU cache hierarchy for all
> + * the CPUs together. Thus need to allocate edac_cpu_block_list for the
> + * maximum number of caches per cpu among all the CPUs irrespective of
> + * the number of caches per CPU might vary.
> + */
> + edac_cpu_block_list = __alloc_percpu(sizeof(struct ghes_edac_cpu_block) * num_caches_per_cpu,
> + __alignof__(u64));
> + if (!edac_cpu_block_list)
> + return;
> +
> + if (ghes_edac_add_cpu_device(dev)) {
> + ghes_edac_delete_cpu_device();
> + return;
> + }
> +
> + /*
> + * Populate EDAC CPU cache list with cache's information.
> + */
> + for_each_online_cpu(cpu)
> + ghes_edac_populate_cache_info(cpu);
> +}
> +
> +void ghes_edac_report_cpu_error(struct ghes_einfo_cpu *einfo)
> +{
> + struct ghes_edac_cpu_block *block;
> + int i;
> +
> + if (!einfo || !(einfo->ce_count) || !num_caches_per_cpu)
> + return;
> +
> + /*
> + * EDAC device require the number of device blocks (for example max number of caches
> + * among CPUs) during the creation. For the CPUs that were offline in the cpu edac
> + * init and become online later, the cache info would be populated when the first
> + * error is reported on that cpu.
> + */
> + block = per_cpu_ptr(edac_cpu_block_list, einfo->cpu);
> + if (!block->info_populated) {
> + if (ghes_edac_populate_cache_info(einfo->cpu))
> + return;
> + }
> +
> + for (i = 0; i < num_caches_per_cpu; i++) {
> + if ((block->level == einfo->cache_level) && (block->type == einfo->cache_type)) {
> + edac_device_handle_ce_count(cpu_edac_dev, einfo->ce_count,
> + einfo->cpu, block->block_nr, "");
> + break;
> + }
> + block++;
> + }
> +}
> +#endif
> +
> static void ghes_scan_system(void)
> {
> if (system_scanned)
> @@ -232,6 +408,8 @@ static void ghes_scan_system(void)
>
> dmi_walk(enumerate_dimms, &ghes_hw);
>
> + ghes_edac_get_cpu_cacheinfo();
> +
> system_scanned = true;
> }
>
> @@ -620,6 +798,10 @@ int ghes_edac_register(struct ghes *ghes, struct device *dev)
> goto unlock;
> }
>
> +#if defined(CONFIG_EDAC_GHES_CPU_CACHE_ERROR)
> + ghes_edac_create_cpu_device(dev);
> +#endif
> +
> spin_lock_irqsave(&ghes_lock, flags);
> ghes_pvt = pvt;
> spin_unlock_irqrestore(&ghes_lock, flags);
> @@ -669,6 +851,10 @@ void ghes_edac_unregister(struct ghes *ghes)
> if (mci)
> edac_mc_free(mci);
>
> +#if defined(CONFIG_EDAC_GHES_CPU_CACHE_ERROR)
> + ghes_edac_delete_cpu_device();
> +#endif
> +
> unlock:
> mutex_unlock(&ghes_reg_mutex);
> }
> diff --git a/include/acpi/ghes.h b/include/acpi/ghes.h
> index 34fb3431a8f3..e019ad88fdc3 100644
> --- a/include/acpi/ghes.h
> +++ b/include/acpi/ghes.h
> @@ -73,6 +73,24 @@ void ghes_unregister_vendor_record_notifier(struct notifier_block *nb);
>
> int ghes_estatus_pool_init(int num_ghes);
>
> +/**
> + * struct ghes_einfo_cpu - structure to pass the CPU error info to the edac
> + * @cpu: CPU index.
> + * @error_type: error type, cache/TLB/bus/ etc.
> + * @cache_level: cache level.
> + * @cache_type: ACPI cache type.
> + * @ue_count: CPU uncorrectable error count.
> + * @ce_count: CPU correctable error count.
> + */
> +struct ghes_einfo_cpu {
> + int cpu;
> + u8 error_type;
> + u8 cache_level;
> + u8 cache_type;
> + u16 ue_count;
> + u16 ce_count;
> +};
> +
> /* From drivers/edac/ghes_edac.c */
>
> #ifdef CONFIG_EDAC_GHES
> @@ -98,6 +116,15 @@ static inline void ghes_edac_unregister(struct ghes *ghes)
> }
> #endif
>
> +#ifdef CONFIG_EDAC_GHES_CPU_CACHE_ERROR
> +void ghes_edac_report_cpu_error(struct ghes_einfo_cpu *einfo_cpu);
> +
> +#else
> +static inline void ghes_edac_report_cpu_error(struct ghes_einfo_cpu *einfo_cpu)
> +{
> +}
> +#endif
> +
> static inline int acpi_hest_get_version(struct acpi_hest_generic_data *gdata)
> {
> return gdata->revision >> 8;
> --
> 2.17.1
>
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