Re: [PATCH v5 1/3] xen/x86: add nmi continuation framework

[Jürgen Groß <jgross@xxxxxxxx>]

On 12.11.20 14:41, Jan Beulich wrote:
> On 12.11.2020 14:14, Juergen Gross wrote:
> > --- a/xen/arch/x86/genapic/x2apic.c
> > +++ b/xen/arch/x86/genapic/x2apic.c
> > @@ -89,6 +89,7 @@ static unsigned int cpu_mask_to_apicid_x2apic_cluster(const 
> > cpumask_t *cpumask)
> >   
> >   static void send_IPI_self_x2apic(uint8_t vector)
> >   {
> > +    /* NMI continuation handling relies on using a shorthand here. */
> >       apic_wrmsr(APIC_SELF_IPI, vector);
> >   }
> I'm inclined to drop this hunk again - I did ask for ...
>
> > --- a/xen/arch/x86/smp.c
> > +++ b/xen/arch/x86/smp.c
> > @@ -163,6 +163,7 @@ void send_IPI_self(int vector)
> >   
> >   void send_IPI_self_legacy(uint8_t vector)
> >   {
> > +    /* NMI continuation handling relies on using a shorthand here. */
> >       send_IPI_shortcut(APIC_DEST_SELF, vector, APIC_DEST_PHYSICAL);
> >   }
> ... this one only simply because x2APIC doesn't have the same restriction.
It would still be bad if the x2APIC variant would e.g. use
send_IPI_mask_x2apic_cluster() due to its usage of
per_cpu(scratch_mask).

Juergen

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