Re: [patch V4 part 4 11/24] x86/mce: Use untraced rd/wrmsr in the MCE offline/crash check

[Andy Lutomirski]

On Tue, May 5, 2020 at 7:16 AM Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
>
> mce_check_crashing_cpu() is called right at the entry of the MCE
> handler. It uses mce_rdmsr() and mce_wrmsr() which are wrappers around
> rdmsr() and wrmsr() to handle the MCE error injection mechanism, which is
> pointless in this context, i.e. when the MCE hits an offline CPU or the
> system is already marked crashing.
>
> The MSR access can also be traced, so use the untraceable variants. This
> is also safe vs. XEN paravirt as these MSRs are not affected by XEN PV
> modifications.


Acked-by: Andy Lutomirski <luto@xxxxxxxxxx>