On 7/27/2022 12:30 PM, Jane Chu wrote:
> 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/7ed50fd8-521e-cade-77b1-738b8bfb8...@oracle.com
>>>>
>>>>
>>>> Reviewed-by: Dan Williams <dan.j.willi...@intel.com>
>>>> Signed-off-by: Jane Chu <jane....@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..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.
This will work,
grain = min_not_zero(PAGE_SHIFT - 1,
hweight64(~mem_err->physical_addr_mask));
grain++;
but too sophisticated? I guess I prefer the simple "if" expression.
thanks,
-jane
>
> -jane
>
>> so that in the pmem poison case, 'grain' would be 8, not 7.
>>
>> thanks,
>> -jane
>>
>>>
>>> ...?
>>
>
