Re: [PATCH v3 08/16] perf: Force architectures to opt-in to guest callbacks

[Sean Christopherson <seanjc@xxxxxxxxxx>]

On Wed, Sep 22, 2021, Sean Christopherson wrote:
> On Wed, Sep 22, 2021, Paolo Bonzini wrote:
> > On 22/09/21 02:05, Sean Christopherson wrote:
> > > @@ -1273,6 +1274,11 @@ static inline unsigned int 
> > > perf_guest_handle_intel_pt_intr(void)
> > >   }
> > >   extern void perf_register_guest_info_callbacks(struct 
> > > perf_guest_info_callbacks *cbs);
> > >   extern void perf_unregister_guest_info_callbacks(struct 
> > > perf_guest_info_callbacks *cbs);
> > > +#else
> > > +static inline unsigned int perf_guest_state(void)                 { 
> > > return 0; }
> > > +static inline unsigned long perf_guest_get_ip(void)               { 
> > > return 0; }
> > > +static inline unsigned int perf_guest_handle_intel_pt_intr(void) { 
> > > return 0; }
> > > +#endif /* CONFIG_GUEST_PERF_EVENTS */
> > 
> > Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> > 
> > Having perf_guest_handle_intel_pt_intr in generic code is a bit off.  Of
> > course it has to be in the struct, but the wrapper might be placed in
> > arch/x86/include/asm/perf_event.h as well (applies to patch 7 as well).
> 
> Yeah, I went with this option purely to keep everything bundled together.  I 
> have
> no strong opinion.

Scratch, that, I do have an opinion.  perf_guest_handle_intel_pt_intr() is in
common code because the callbacks themselves and perf_get_guest_cbs() are 
defined
in linux/perf_event.h, _after_ asm/perf_event.h is included.

arch/x86/include/asm/perf_event.h is quite bereft of includes, so there's no
obvious landing spot for those two things, and adding a new header seems like
overkill.