Jane Chu wrote:
> 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.
An "if" is fine, I was more pointing out that:
hweight64(~mem_err->physical_addr_mask) + 1
...and:
~mem_err->physical_addr_mask + 1;
...give different results.
