Re: [Xen-devel] [PATCH v5 RESEND 13/17] x86/VPMU: Add privileged PMU mode

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 04/26/2014 04:39 AM, Tian, Kevin wrote:
> > From: Boris Ostrovsky [mailto:boris.ostrovsky@xxxxxxxxxx]
> > Sent: Wednesday, April 23, 2014 8:51 PM
> >
> > Add support for privileged PMU mode which allows privileged domain (dom0)
> > profile both itself (and the hypervisor) and the guests. While this mode is on
> > profiling in guests is disabled.
> >
> > Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> > ---
> >   xen/arch/x86/hvm/vpmu.c  | 97
> > +++++++++++++++++++++++++++++++++---------------
> >   xen/arch/x86/traps.c     |  6 ++-
> >   xen/include/public/pmu.h |  3 ++
> >   3 files changed, 76 insertions(+), 30 deletions(-)
> >
> > diff --git a/xen/arch/x86/hvm/vpmu.c b/xen/arch/x86/hvm/vpmu.c
> > index abc4c1f..dc416f9 100644
> > --- a/xen/arch/x86/hvm/vpmu.c
> > +++ b/xen/arch/x86/hvm/vpmu.c
> > @@ -88,7 +88,8 @@ int vpmu_do_wrmsr(unsigned int msr, uint64_t
> > msr_content)
> >   {
> >       struct vpmu_struct *vpmu = vcpu_vpmu(current);
> >
> > -    if ( !(vpmu_mode & XENPMU_MODE_ON) )
> > +    if ( (vpmu_mode == XENPMU_MODE_OFF) ||
> > +         ((vpmu_mode & XENPMU_MODE_PRIV)
> > && !is_control_domain(current->domain)) )
> >           return 0;
> how about combining above checks into a macro, e.g.
>
> #define vpmu_is_on(mode, vcpu)                  \
>         ((mode == XENPMU_MODE_ON) ||    \
>         ((mode & XENPMU_MODE_PRIV) && is_control_domain(vcpu->domain)))
I am not sure it's worth it for just two appearances of this code 
fragment. I'll see if this is more common though.

-boris

> Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>

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