On 7/27/2022 11:56 AM, Dan Williams wrote:
> Jane Chu 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/[email protected]
>>
>> Reviewed-by: Dan Williams <[email protected]>
>> Signed-off-by: Jane Chu <[email protected]>
>> ---
>> 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..26d63818b2de 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 grain = PAGE_SHIFT;
>>
>> 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.
>> + */
>> + if (mem_err->validation_bits & CPER_MEM_VALID_PA_MASK) {
>> + grain = ~mem_err->physical_addr_mask + 1;
>> + if (grain == 1)
>> + grain = PAGE_SHIFT;
>
> Wait, if @grain is the number of bits to mask off the address, shouldn't
> this be something like:
>
> grain = min_not_zero(PAGE_SHIFT, hweight64(~mem_err->physical_addr_mask));
I see. I guess what you meant is
grain = min(PAGE_SHIFT, (1 + hweight64(~mem_err->physical_addr_mask)));
so that in the pmem poison case, 'grain' would be 8, not 7.
thanks,
-jane
>
> ...?
On 7/27/2022 12:24 PM, Jane Chu wrote:
> On 7/27/2022 11:56 AM, Dan Williams wrote:
>> Jane Chu 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/[email protected]
>>>
>>>
>>> Reviewed-by: Dan Williams <[email protected]>
>>> Signed-off-by: Jane Chu <[email protected]>
>>> ---
>>> 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..26d63818b2de 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 grain = PAGE_SHIFT;
>>> 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.
>>> + */
>>> + if (mem_err->validation_bits & CPER_MEM_VALID_PA_MASK) {
>>> + grain = ~mem_err->physical_addr_mask + 1;
>>> + if (grain == 1)
>>> + grain = PAGE_SHIFT;
>>
>> Wait, if @grain is the number of bits to mask off the address, shouldn't
>> this be something like:
>>
>> grain = min_not_zero(PAGE_SHIFT,
>> hweight64(~mem_err->physical_addr_mask));
>
> I see. I guess what you meant is
> grain = min(PAGE_SHIFT, (1 + hweight64(~mem_err->physical_addr_mask)));
Sorry, take that back, it won't work either.
-jane
> so that in the pmem poison case, 'grain' would be 8, not 7.
>
> thanks,
> -jane
>
>>
>> ...?
>