Re: [PATCH v5 1/3] x86/cpufeatures: Enumerate #DB for bus lock detection

[Thomas Gleixner]

On Sat, Mar 13 2021 at 05:49, Fenghua Yu wrote:
> A bus lock is acquired though either split locked access to

s/though/through/
either a 

> writeback (WB) memory or any locked access to non-WB memory. This is
> typically >1000 cycles slower than an atomic operation within a cache
> line. It also disrupts performance on other cores.
>
> Some CPUs have ability to notify the kernel by an #DB trap after a user

the ability

> instruction acquires a bus lock and is executed. This allows the kernel
> to enforce user application throttling or mitigations. Both breakpoint
> and bus lock can trigger the #DB trap in the same instruction and the
> ordering of handling them is the kernel #DB handler's choice.

Thanks,

        tglx