Re: [PATCH] irqchip/gic-v3: Fix GICD_CTLR_ARE_NS bit field

[Alim Akhtar]

Hi Marc,

On 03/07/2017 01:11 PM, Marc Zyngier wrote:
> On Tue, Mar 07 2017 at  4:07:05 am GMT, Alim Akhtar <alim.akhtar@xxxxxxxxxxx> wrote:
> > From: Alim Akhtar <alim.akhtar@xxxxxxxxx>
> >
> > As per GICv3 Architecture specification 8.9.4 field descriptions,
> > GICD_CTLR_ARE_NS is bit[5]. This patch correct the same.
> >
> > Fixes: 021f6537 ("irqchip: gic-v3: Initial support for GICv3")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Alim Akhtar <alim.akhtar@xxxxxxxxxxx>
> > ---
> >  include/linux/irqchip/arm-gic-v3.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
> > index e808f8a..4aaf639 100644
> > --- a/include/linux/irqchip/arm-gic-v3.h
> > +++ b/include/linux/irqchip/arm-gic-v3.h
> > @@ -57,7 +57,7 @@
> >
> >  #define GICD_CTLR_RWP			(1U << 31)
> >  #define GICD_CTLR_DS			(1U << 6)
> > -#define GICD_CTLR_ARE_NS		(1U << 4)
> > +#define GICD_CTLR_ARE_NS		(1U << 5)
> >  #define GICD_CTLR_ENABLE_G1A		(1U << 1)
> >  #define GICD_CTLR_ENABLE_G1		(1U << 0)
>
> No, the issue is much more subtle.
>
> - When the access is secure in a system that supports two security
>   states, this is bit[5] indeed.
>
> - When the access is non-secure in a system that supports two security
>   states, this is bit[4] (so that software written for a single security
>   mode can run on both side of the security fence).
>
> - In a system that only supports a single security state, this is bit[4]
>   too.
>
> Given that Linux is only designed to run on the non-secure side (at
> least when paired with GICv3), I stand by my original bit layout.
Ok, got it, thanks for clarification.

> Thanks,
>
>         M.