Re: [PATCH v5 1/2] ACPI: APEI: set memory failure flags as MF_ACTION_REQUIRED on synchronous events

[Shuai Xue]

On 2023/4/12 AM11:55, Xiaofei Tan wrote:
> 
> Reviewed-by: Xiaofei Tan <tanxiaofei@xxxxxxxxxx>

Thank you :)

Cheers,
Shuai

> 
> 在 2023/4/11 18:48, Shuai Xue 写道:
>> There are two major types of uncorrected recoverable (UCR) errors :
>>
>> - Action Required (AR): The error is detected and the processor already
>>    consumes the memory. OS requires to take action (for example, offline
>>    failure page/kill failure thread) to recover this uncorrectable error.
>>
>> - Action Optional (AO): The error is detected out of processor execution
>>    context. Some data in the memory are corrupted. But the data have not
>>    been consumed. OS is optional to take action to recover this
>>    uncorrectable error.
>>
>> The essential difference between AR and AO errors is that AR is a
>> synchronous event, while AO is an asynchronous event. The hardware will
>> signal a synchronous exception (Machine Check Exception on X86 and
>> Synchronous External Abort on Arm64) when an error is detected and the
>> memory access has been architecturally executed.
>>
>> When APEI firmware first is enabled, a platform may describe one error
>> source for the handling of synchronous errors (e.g. MCE or SEA notification
>> ), or for handling asynchronous errors (e.g. SCI or External Interrupt
>> notification). In other words, we can distinguish synchronous errors by
>> APEI notification. For AR errors, kernel will kill current process
>> accessing the poisoned page by sending SIGBUS with BUS_MCEERR_AR. In
>> addition, for AO errors, kernel will notify the process who owns the
>> poisoned page by sending SIGBUS with BUS_MCEERR_AO in early kill mode.
>> However, the GHES driver always sets mf_flags to 0 so that all UCR errors
>> are handled as AO errors in memory failure.
>>
>> To this end, set memory failure flags as MF_ACTION_REQUIRED on synchronous
>> events.
>>
>> Fixes: ba61ca4aab47 ("ACPI, APEI, GHES: Add hardware memory error recovery support")'
>> Signed-off-by: Shuai Xue <xueshuai@xxxxxxxxxxxxxxxxx>
>> Tested-by: Ma Wupeng <mawupeng1@xxxxxxxxxx>
>> ---
>>   drivers/acpi/apei/ghes.c | 29 +++++++++++++++++++++++------
>>   1 file changed, 23 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
>> index 34ad071a64e9..c479b85899f5 100644
>> --- a/drivers/acpi/apei/ghes.c
>> +++ b/drivers/acpi/apei/ghes.c
>> @@ -101,6 +101,20 @@ static inline bool is_hest_type_generic_v2(struct ghes *ghes)
>>       return ghes->generic->header.type == ACPI_HEST_TYPE_GENERIC_ERROR_V2;
>>   }
>>   +/*
>> + * A platform may describe one error source for the handling of synchronous
>> + * errors (e.g. MCE or SEA), or for handling asynchronous errors (e.g. SCI
>> + * or External Interrupt). On x86, the HEST notifications are always
>> + * asynchronous, so only SEA on ARM is delivered as a synchronous
>> + * notification.
>> + */
>> +static inline bool is_hest_sync_notify(struct ghes *ghes)
>> +{
>> +    u8 notify_type = ghes->generic->notify.type;
>> +
>> +    return notify_type == ACPI_HEST_NOTIFY_SEA;
>> +}
>> +
>>   /*
>>    * This driver isn't really modular, however for the time being,
>>    * continuing to use module_param is the easiest way to remain
>> @@ -477,7 +491,7 @@ static bool ghes_do_memory_failure(u64 physical_addr, int flags)
>>   }
>>     static bool ghes_handle_memory_failure(struct acpi_hest_generic_data *gdata,
>> -                       int sev)
>> +                       int sev, bool sync)
>>   {
>>       int flags = -1;
>>       int sec_sev = ghes_severity(gdata->error_severity);
>> @@ -491,7 +505,7 @@ static bool ghes_handle_memory_failure(struct acpi_hest_generic_data *gdata,
>>           (gdata->flags & CPER_SEC_ERROR_THRESHOLD_EXCEEDED))
>>           flags = MF_SOFT_OFFLINE;
>>       if (sev == GHES_SEV_RECOVERABLE && sec_sev == GHES_SEV_RECOVERABLE)
>> -        flags = 0;
>> +        flags = sync ? MF_ACTION_REQUIRED : 0;
>>         if (flags != -1)
>>           return ghes_do_memory_failure(mem_err->physical_addr, flags);
>> @@ -499,9 +513,11 @@ static bool ghes_handle_memory_failure(struct acpi_hest_generic_data *gdata,
>>       return false;
>>   }
>>   -static bool ghes_handle_arm_hw_error(struct acpi_hest_generic_data *gdata, int sev)
>> +static bool ghes_handle_arm_hw_error(struct acpi_hest_generic_data *gdata,
>> +                       int sev, bool sync)
>>   {
>>       struct cper_sec_proc_arm *err = acpi_hest_get_payload(gdata);
>> +    int flags = sync ? MF_ACTION_REQUIRED : 0;
>>       bool queued = false;
>>       int sec_sev, i;
>>       char *p;
>> @@ -526,7 +542,7 @@ static bool ghes_handle_arm_hw_error(struct acpi_hest_generic_data *gdata, int s
>>            * and don't filter out 'corrected' error here.
>>            */
>>           if (is_cache && has_pa) {
>> -            queued = ghes_do_memory_failure(err_info->physical_fault_addr, 0);
>> +            queued = ghes_do_memory_failure(err_info->physical_fault_addr, flags);
>>               p += err_info->length;
>>               continue;
>>           }
>> @@ -647,6 +663,7 @@ static bool ghes_do_proc(struct ghes *ghes,
>>       const guid_t *fru_id = &guid_null;
>>       char *fru_text = "";
>>       bool queued = false;
>> +    bool sync = is_hest_sync_notify(ghes);
>>         sev = ghes_severity(estatus->error_severity);
>>       apei_estatus_for_each_section(estatus, gdata) {
>> @@ -664,13 +681,13 @@ static bool ghes_do_proc(struct ghes *ghes,
>>               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);
>> +            queued = ghes_handle_memory_failure(gdata, sev, sync);
>>           }
>>           else if (guid_equal(sec_type, &CPER_SEC_PCIE)) {
>>               ghes_handle_aer(gdata);
>>           }
>>           else if (guid_equal(sec_type, &CPER_SEC_PROC_ARM)) {
>> -            queued = ghes_handle_arm_hw_error(gdata, sev);
>> +            queued = ghes_handle_arm_hw_error(gdata, sev, sync);
>>           } else {
>>               void *err = acpi_hest_get_payload(gdata);
>>