Re: [Xen-devel] [RFC PATCH v2 07/22] ARM: vGIC: introduce priority setter/getter

[Julien Grall <julien.grall@xxxxxxx>]

On 16/08/17 17:48, Andre Przywara wrote:
> Hi,
>
> On 11/08/17 15:10, Julien Grall wrote:
> > Hi Andre,
> >
> > On 21/07/17 20:59, Andre Przywara wrote:
> > > Since the GICs MMIO access always covers a number of IRQs at once,
> > > introduce wrapper functions which loop over those IRQs, take their
> > > locks and read or update the priority values.
> > > This will be used in a later patch.
> > >
> > > Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
> > > ---
> > >  xen/arch/arm/vgic.c        | 37 +++++++++++++++++++++++++++++++++++++
> > >  xen/include/asm-arm/vgic.h |  5 +++++
> > >  2 files changed, 42 insertions(+)
> > >
> > > diff --git a/xen/arch/arm/vgic.c b/xen/arch/arm/vgic.c
> > > index 434b7e2..b2c9632 100644
> > > --- a/xen/arch/arm/vgic.c
> > > +++ b/xen/arch/arm/vgic.c
> > > @@ -243,6 +243,43 @@ static int vgic_get_virq_priority(struct vcpu *v,
> > > unsigned int virq)
> > >      return ACCESS_ONCE(rank->priority[virq & INTERRUPT_RANK_MASK]);
> > >  }
> > >
> > > +#define MAX_IRQS_PER_IPRIORITYR 4
> > The name gives the impression that you may have IPRIORITYR with only 1
> > IRQ. But this is not true. The registers is always 4. However, you are
> > able to access using byte or word.
> >
> > > +uint32_t vgic_fetch_irq_priority(struct vcpu *v, unsigned int nrirqs,
> > I am well aware that the vgic code is mixing between virq and irq.
> > Moving forward, we should use virq to avoid confusion.
> >
> > > +                                 unsigned int first_irq)
> > Please stay consistent, with the naming. Either nr_irqs/first_irq or
> > nrirqs/firstirq. But not a mix.
> I totally agree, but check this out:
> xen/include/asm-arm/irq.h:#define nr_irqs NR_IRQS
>
> So wherever you write nr_irqs in *any* part of ARM IRQ code you end up
> with a compile error ...
> Not easy to fix, though, hence I moved to the name without the
> underscore, even though I don't really like it.
Oh. On a side note, nr_irqs does not cover all the IRQs. It only covers 
up to SPIs. Which is a little bit odd.
Anyway, maybe you would rename it to nr. I think it is fairly straight 
forward that you deal with IRQ.
Cheers,

--
Julien Grall

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