Re: [Xen-devel] [PATCH v2 08/13] x86/PMU: Interface for setting PMU mode and flags

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 09/25/2013 10:11 AM, Jan Beulich wrote:
> > > > On 20.09.13 at 11:42, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> wrote:
> > --- a/xen/include/public/xen.h
> > +++ b/xen/include/public/xen.h
> > @@ -101,6 +101,7 @@ DEFINE_XEN_GUEST_HANDLE(xen_ulong_t);
> >   #define __HYPERVISOR_kexec_op             37
> >   #define __HYPERVISOR_tmem_op              38
> >   #define __HYPERVISOR_xc_reserved_op       39 /* reserved for XenClient */
> > +#define __HYPERVISOR_xenpmu_op            40
> >   
> >   /* Architecture-specific hypercall definitions. */
> >   #define __HYPERVISOR_arch_0               48
> I wonder whether you wouldn't better use an arch-specific hypercall
> number here - there's really very little that's generic in what I have
> seen so far.
Some of xenpmu commands (querying PMU mode/flags, PMU 
initialization/de-initialization)
seem generic to me. They may call arch-specific routines.

> > +/* Parameters structure for HYPERVISOR_xenpmu_op call */
> > +struct xenpmu_params {
> > +    /* IN/OUT parameters */
> > +    union {
> > +        struct version {
> > +            uint8_t maj;
> > +            uint8_t min;
> > +        } version;
> > +        uint64_t pad;
> > +    };
> > +    union {
> > +        uint64_t val;
> > +        void *valp;
> Without there also being a handle here I can't see how you could
> make use of the pointer.
Tha't really a placeholder, valp is not used anywhere. I can replace it
with XEN_GUEST_HANDLE.

-boris




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