Re: [RESEND] x86/bus_lock: Don't assume the init value of DEBUGCTLMSR.BUS_LOCK_DETECT to be zero

[Chenyi Qiang]

On 8/2/2022 6:51 PM, Ingo Molnar wrote:
> * Chenyi Qiang <chenyi.qiang@xxxxxxxxx> wrote:
>
> > It's possible that BIOS/firmware has set DEBUGCTLMSR_BUS_LOCK_DETECT, or
> > this kernel has been kexec'd from a kernel that enabled bus lock
> > detection.
> >
> > Disable bus lock detection explicitly if not wanted.
>
> Makes sense.
>
> Just curious: in what circumstances does the BIOS/firmware set
> DEBUGCTLMSR_BUS_LOCK_DETECT? Does it use it, or does it enable it for some
> spurious reason, without really using the feature? (Assuming you are aware
> of instances where this happened - or was this simply a hypothetical?)

Yes, It's just a hypothetical for BIOS/firmware. Kexec is the real case 
I met with this problem.

> Thanks,
>
> 	Ingo