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SubjectRe: [PATCH v6] x86/mce: retrieve poison range from hardware
Date
On 8/2/2022 3:59 AM, Ingo Molnar wrote:
>
> * Jane Chu <jane.chu@oracle.com> wrote:
>
>> With Commit 7917f9cdb503 ("acpi/nfit: rely on mce->misc to determine
>> poison granularity") that changed nfit_handle_mce() callback to report
>> badrange according to 1ULL << MCI_MISC_ADDR_LSB(mce->misc), it's been
>> discovered that the mce->misc LSB field is 0x1000 bytes, hence injecting
>> 2 back-to-back poisons and the driver ends up logging 8 badblocks,
>> because 0x1000 bytes is 8 512-byte.
>>
>> Dan Williams noticed that apei_mce_report_mem_error() hardcode
>> the LSB field to PAGE_SHIFT instead of consulting the input
>> struct cper_sec_mem_err record. So change to rely on hardware whenever
>> support is available.
>>
>> Link: https://lore.kernel.org/r/7ed50fd8-521e-cade-77b1-738b8bfb8502@oracle.com
>>
>> Reviewed-by: Dan Williams <dan.j.williams@intel.com>
>> Signed-off-by: Jane Chu <jane.chu@oracle.com>
>> ---
>> arch/x86/kernel/cpu/mce/apei.c | 14 +++++++++++++-
>> 1 file changed, 13 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/kernel/cpu/mce/apei.c b/arch/x86/kernel/cpu/mce/apei.c
>> index 717192915f28..e2439c7872ba 100644
>> --- a/arch/x86/kernel/cpu/mce/apei.c
>> +++ b/arch/x86/kernel/cpu/mce/apei.c
>> @@ -29,15 +29,27 @@
>> void apei_mce_report_mem_error(int severity, struct cper_sec_mem_err *mem_err)
>> {
>> struct mce m;
>> + int lsb;
>>
>> if (!(mem_err->validation_bits & CPER_MEM_VALID_PA))
>> return;
>>
>> + /*
>> + * Even if the ->validation_bits are set for address mask,
>> + * to be extra safe, check and reject an error radius '0',
>> + * and fallback to the default page size.
>> + */
>
> speling nit:
>
> s/fallback/fall back
>
>> + if (mem_err->validation_bits & CPER_MEM_VALID_PA_MASK)
>> + lsb = find_first_bit((const unsigned long *)
>> + &mem_err->physical_addr_mask, PAGE_SHIFT);
>
> I think we can write this in a shorter form and in a single line:
>
> lsb = find_first_bit((void *)&mem_err->physical_addr_mask, PAGE_SHIFT);
>
> (Ignore checkpatch if it wants to break the line.)
>
> Untested.
>
> Assuming my suggestion is correct and with those addressed:
>
> Reviewed-by: Ingo Molnar <mingo@kernel.org>

Thanks! Just tested the change, v7 coming next.

-jane

>
> Thanks,
>
> Ingo

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