Re: [PATCH 2/2] xen/arm: gic-v3: Allow Xen to run on hardware reporting GICv4

[Ian Campbell <ian.campbell@citrix.com>]

On Mon, 2015-09-14 at 16:32 +0100, Julien Grall wrote:
> It seems that there is some hardware which report start to report GICv4

s/report start to reports/reports/ ?

Also, this is an odd way to express it, what you mean is that some hardware
is now shipping with GICv4. Unless you are trying to imply that they are
claiming to be GICv4 without actually being so?

(If we agree on some wording I can modify this text on commit, subject to
the discussion below).

> in the GIC*_PIDR2 register.
> 
> As GICv4 is a superset of GICv3, it should just work on Xen.
> 
> Reported-by: Andre Przywara <andre.przywara@arm.com>
> Signed-off-by: Julien Grall <julien.grall@citrix.com>
> ---
>  xen/arch/arm/gic-v3.c             | 4 ++--
>  xen/include/asm-arm/gic_v3_defs.h | 1 +
>  2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
> index 4d623bf..1e3c19b 100644
> --- a/xen/arch/arm/gic-v3.c
> +++ b/xen/arch/arm/gic-v3.c
> @@ -640,7 +640,7 @@ static int __init gicv3_populate_rdist(void)
>          void __iomem *ptr = gicv3.rdist_regions[i].map_base;
>  
>          reg = readl_relaxed(ptr + GICR_PIDR2) & GIC_PIDR2_ARCH_MASK;
> -        if ( reg != GIC_PIDR2_ARCH_GICv3 )
> +        if ( reg != GIC_PIDR2_ARCH_GICv3 && reg != GIC_PIDR2_ARCH_GICv4 )

Once we have GICv5, 6, etc this is going to get unwieldy, shall we switch
to a switch now?

>          {
>              dprintk(XENLOG_ERR,
>                      "GICv3: No redistributor present @%"PRIpaddr"\n",

I wonder if GICv3 ought to become GICv%d, on the other hand this is really
the GICv3 driver driving a v4 in v3 "mode", so maybe v3 is the best
logging.