From: Avadhut Naik avadhut.naik@amd.com

mainline inclusion from mainline-v6.8-rc6 commit 8ec7071385508822892cabc2c0cb74333859407a category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I9JNPZ

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id...

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To support GHES_ASSIST on Machine Check Architecture (MCA) error sources, a set of GHES structures is provided by the system firmware for each MCA error source. Each of these sets consists of a GHES structure for each MCA bank on each logical CPU, with all structures of a set sharing a common Related Source ID, equal to the Source ID of one of the MCA error source structures.[1] On SOCs with large core counts, this typically equates to tens of thousands of GHES_ASSIST structures for MCA under "/sys/bus/platform/drivers/GHES".

Support for GHES_ASSIST however, hasn't been implemented in the kernel. As such, the information provided through these structures is not consumed by Linux. Moreover, these GHES_ASSIST structures for MCA, which are supposed to provide supplemental information in context of an error reported by hardware, are setup as independent error sources by the kernel during HEST initialization.

Additionally, if the Type field of the Notification structure, associated with these GHES_ASSIST structures for MCA, is set to Polled, the kernel sets up a timer for each individual structure. The duration of the timer is derived from the Poll Interval field of the Notification structure. On SOCs with high core counts, this will result in tens of thousands of timers expiring periodically causing unnecessary preemptions and wastage of CPU cycles. The problem will particularly intensify if Poll Interval duration is not sufficiently high.

Since GHES_ASSIST support is not present in kernel, skip initialization of GHES_ASSIST structures for MCA to eliminate their performance impact.

[1] ACPI specification 6.5, section 18.7

Signed-off-by: Avadhut Naik avadhut.naik@amd.com Reviewed-by: Yazen Ghannam yazen.ghannam@amd.com Reviewed-by: Tony Luck tony.luck@intel.com Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Xiongfeng Wang wangxiongfeng2@huawei.com --- drivers/acpi/apei/hest.c | 51 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+)

diff --git a/drivers/acpi/apei/hest.c b/drivers/acpi/apei/hest.c index 6aef1ee5e1bd..20d757687e3d 100644 --- a/drivers/acpi/apei/hest.c +++ b/drivers/acpi/apei/hest.c @@ -37,6 +37,20 @@ EXPORT_SYMBOL_GPL(hest_disable);

static struct acpi_table_hest *__read_mostly hest_tab;

+/* + * Since GHES_ASSIST is not supported, skip initialization of GHES_ASSIST + * structures for MCA. + * During HEST parsing, detected MCA error sources are cached from early + * table entries so that the Flags and Source Id fields from these cached + * values are then referred to in later table entries to determine if the + * encountered GHES_ASSIST structure should be initialized. + */ +static struct { + struct acpi_hest_ia_corrected *cmc; + struct acpi_hest_ia_machine_check *mc; + struct acpi_hest_ia_deferred_check *dmc; +} mces; + static const int hest_esrc_len_tab[ACPI_HEST_TYPE_RESERVED] = { [ACPI_HEST_TYPE_IA32_CHECK] = -1, /* need further calculation */ [ACPI_HEST_TYPE_IA32_CORRECTED_CHECK] = -1, @@ -70,22 +84,54 @@ static int hest_esrc_len(struct acpi_hest_header *hest_hdr) cmc = (struct acpi_hest_ia_corrected *)hest_hdr; len = sizeof(*cmc) + cmc->num_hardware_banks * sizeof(struct acpi_hest_ia_error_bank); + mces.cmc = cmc; } else if (hest_type == ACPI_HEST_TYPE_IA32_CHECK) { struct acpi_hest_ia_machine_check *mc; mc = (struct acpi_hest_ia_machine_check *)hest_hdr; len = sizeof(*mc) + mc->num_hardware_banks * sizeof(struct acpi_hest_ia_error_bank); + mces.mc = mc; } else if (hest_type == ACPI_HEST_TYPE_IA32_DEFERRED_CHECK) { struct acpi_hest_ia_deferred_check *mc; mc = (struct acpi_hest_ia_deferred_check *)hest_hdr; len = sizeof(*mc) + mc->num_hardware_banks * sizeof(struct acpi_hest_ia_error_bank); + mces.dmc = mc; } BUG_ON(len == -1);

return len; };

+/* + * GHES and GHESv2 structures share the same format, starting from + * Source Id and ending in Error Status Block Length (inclusive). + */ +static bool is_ghes_assist_struct(struct acpi_hest_header *hest_hdr) +{ + struct acpi_hest_generic *ghes; + u16 related_source_id; + + if (hest_hdr->type != ACPI_HEST_TYPE_GENERIC_ERROR && + hest_hdr->type != ACPI_HEST_TYPE_GENERIC_ERROR_V2) + return false; + + ghes = (struct acpi_hest_generic *)hest_hdr; + related_source_id = ghes->related_source_id; + + if (mces.cmc && mces.cmc->flags & ACPI_HEST_GHES_ASSIST && + related_source_id == mces.cmc->header.source_id) + return true; + if (mces.mc && mces.mc->flags & ACPI_HEST_GHES_ASSIST && + related_source_id == mces.mc->header.source_id) + return true; + if (mces.dmc && mces.dmc->flags & ACPI_HEST_GHES_ASSIST && + related_source_id == mces.dmc->header.source_id) + return true; + + return false; +} + typedef int (*apei_hest_func_t)(struct acpi_hest_header *hest_hdr, void *data);

static int apei_hest_parse(apei_hest_func_t func, void *data) @@ -114,6 +160,11 @@ static int apei_hest_parse(apei_hest_func_t func, void *data) return -EINVAL; }

+ if (is_ghes_assist_struct(hest_hdr)) { + hest_hdr = (void *)hest_hdr + len; + continue; + } + rc = func(hest_hdr, data); if (rc) return rc;