Hi James, Thanks for reviewing the patch.
On 2020/10/1 21:44, James Morse wrote:
> Hi Tanxiaofei,
>
> (sorry for the late reply)
>
> On 28/09/2020 03:02, Xiaofei Tan wrote:
>> After the commit 8fcc4ae6faf8 ("arm64: acpi: Make apei_claim_sea()
>> synchronise with APEI's irq work") applied, do_sea() return directly
>> for user-mode if apei_claim_sea() handled any error record. Therefore,
>> each error record reported by the user-mode SEA must be effectively
>> processed in APEI GHES driver.
>>
>> Currently, GHES driver only processes Memory Error Section.(Ignore PCIe
>> Error Section, as it has nothing to do with SEA). It is not enough.
>> Because ARM Processor Error could also be used for SEA in some hardware
>> platforms, such as Kunpeng9xx series. We can't ask them to switch to
>> use Memory Error Section for two reasons:
>> 1)The server was delivered to customers, and it will introduce
>> compatibility issue.
>
>> 2)It make sense to use ARM Processor Error Section. Because either
>> cache or memory errors could generate SEA when consumed by a processor.
>>
>> Do memory failure handling for ARM Processor Error Section just like
>> for Memory Error Section.
>
>
>> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
>> index 99df00f..ca0aa97 100644
>> --- a/drivers/acpi/apei/ghes.
>> +++ b/drivers/acpi/apei/ghes.c
>> @@ -441,28 +441,35 @@ static void ghes_kick_task_work(struct callback_head *head)
>
>> +static bool ghes_handle_arm_hw_error(struct acpi_hest_generic_data *gdata, int sev)
>> +{
>> + struct cper_sec_proc_arm *err = acpi_hest_get_payload(gdata);
>> + struct cper_arm_err_info *err_info;
>> + bool queued = false;
>> + int sec_sev, i;
>> +
>> + log_arm_hw_error(err);
>> +
>> + sec_sev = ghes_severity(gdata->error_severity);
>> + if (sev != GHES_SEV_RECOVERABLE || sec_sev != GHES_SEV_RECOVERABLE)
>> + return false;
>> +
>> + err_info = (struct cper_arm_err_info *) (err + 1);
>> + for (i = 0; i < err->err_info_num; i++, err_info++) {
>
> err_info has its own length, could we use that in case someone comes up with a new table
> version? (like this, old versions of the kernel will read mis-aligned structures)
>
The length of err_info is hard written in "ARM Processor Error Section", always 32 bytes.
If someone comes up with a new table version, must also be this length. It seems no much
differences to change to use the fixed 32 bytes here.
>
>> + if (!(err_info->validation_bits & CPER_ARM_INFO_VALID_PHYSICAL_ADDR))
>> + continue;
>> +
>> + if (err_info->type != CPER_ARM_CACHE_ERROR) {
>> + pr_warn_ratelimited(FW_WARN GHES_PFX
>> + "Physical address should be invalid for %s\n",
>
> Should? A bus-error could have a valid physical address. I can't see anything in the spec
> that forbids this.
Really? Our platform can't physical address for bus-error.
I remember you asked this in earlier version patch, which is why i skipped non-cache error.
In general we shouldn't try to validate what firmware is doing.
>
>
>> + err_info->type < ARRAY_SIZE(cper_proc_error_type_strs) ?
>> + cper_proc_error_type_strs[err_info->type] : "unknown error type");
>> + continue;
>> + }
>
> I think we should warn for the cases this handler doesn't cover, but we should try to
> catch all of them. e.g:
>
> | bool is_cache = (err_info->type == CPER_ARM_CACHE_ERROR);
> | bool has_pa = (err_info->validation_bits & CPER_ARM_INFO_VALID_PHYSICAL_ADDR)
> |
> | if (!is_cache || !has_pa) {
> | pr_warn_ratelimited(..."Unhandled processor error type %s\n", ...);
> | continue;
> | }
>
OK
>
> For cache errors, (err_info->error_info & BIT(26)) has its own corrected/uncorrected flag.
> You filter out 'overall corrected' section types earlier, could you check this error
> record before invoking memory_failure()?
>
Do you mean skip corrected error in a recoverable or fatal error section ?
We only use the severity type of section header, and this corrected/uncorrected flag
may not be filled correctly in firmware.
> (sections may contain a set of errors. I'm not convinced a 'corrected section' can't
> contain latent uncorrected errors, it just means the machine didn't need that data yet)
>
If contain uncorrected errors, then the error section should be defined as recoverable.
>
>
>> + if (ghes_do_memory_failure(err_info->physical_fault_addr, 0))
>> + queued = true;
>
> May as well:
> | return ghes_do_memory_failure(...);
>
We can't return directly from here, as other error info may not have been handled.
>
>> + }
>> +
>> + return queued;
>
> (and make this:
> | return false
> )
>
>> +}
>
>
>
> Thanks,
>
> James
>
> .
>
--
thanks
tanxiaofei
