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SubjectRe: [PATCH v2 2/5] x86/mce/inject: Warn the user on a not set valid bit in MCA_STATUS
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Hi Boris,

On 10/26/21 5:02 AM, Borislav Petkov wrote:

> On Tue, Oct 19, 2021 at 06:36:38PM -0500, Smita Koralahalli wrote:
>> MCA handlers check the valid bit in each status register (MCA_STATUS[Val])
>> and will likely ignore signatures if the valid bit is not set.
>>
>> Warn the user if the valid bit is not set before doing error injection.
>>
>> Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>
>> ---
>> v2:
>> Added a warning statement instead of setting the valid bit.
>> ---
>> arch/x86/kernel/cpu/mce/inject.c | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/arch/x86/kernel/cpu/mce/inject.c b/arch/x86/kernel/cpu/mce/inject.c
>> index 601efd104bb4..a993dc3d0333 100644
>> --- a/arch/x86/kernel/cpu/mce/inject.c
>> +++ b/arch/x86/kernel/cpu/mce/inject.c
>> @@ -487,6 +487,9 @@ static void do_inject(void)
>>
>> i_mce.tsc = rdtsc_ordered();
>>
>> + if (!(i_mce.status & MCI_STATUS_VAL))
>> + pr_warn("Handlers might ignore signatures with Val=0 in MCA_STATUS\n");
>> +
>> if (i_mce.misc)
>> i_mce.status |= MCI_STATUS_MISCV;
>>
>> --
> So what's the real reason for this?
>
> You've injected and you didn't get any feedback and were wondering why?
>
> If handlers ignore !VAL MCEs, why don't you simply set it
> unconditionally on entry to do_inject()?

Like how it was done here?
https://lkml.kernel.org/r/20210915232739.6367-3-Smita.KoralahalliChannabasappa@amd.com

Thanks,


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