Re: [PATCH V2] ARM: mach-shmobile: Don't init CNTVOFF if PSCI is available

[Julien Grall]

On 10/05/2019 13:27, Oleksandr wrote:
> On 06.05.19 18:37, Julien Grall wrote:
> > Hi Oleksandr,
>
> Hi Julien
>
>
> > > ---
> > > Â arch/arm/mach-shmobile/setup-rcar-gen2.c | 13 ++++++++++++-
> > > Â 1 file changed, 12 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/arch/arm/mach-shmobile/setup-rcar-gen2.c 
> > > b/arch/arm/mach-shmobile/setup-rcar-gen2.c
> > > index eea60b2..bc8537b 100644
> > > --- a/arch/arm/mach-shmobile/setup-rcar-gen2.c
> > > +++ b/arch/arm/mach-shmobile/setup-rcar-gen2.c
> > > @@ -17,7 +17,9 @@
> > > Â #include <linux/of.h>
> > > Â #include <linux/of_fdt.h>
> > > Â #include <linux/of_platform.h>
> > > +#include <xen/xen.h>
> > > Â #include <asm/mach/arch.h>
> > > +#include <asm/psci.h>
> > > Â #include <asm/secure_cntvoff.h>
> > > Â #include "common.h"
> > > Â #include "rcar-gen2.h"
> > > @@ -63,7 +65,16 @@ void __init rcar_gen2_timer_init(void)
> > > ÂÂÂÂÂ void __iomem *base;
> > > ÂÂÂÂÂ u32 freq;
> > > Â -ÂÂÂ secure_cntvoff_init();
> > > +ÂÂÂ /*
> > > +ÂÂÂÂ * If PSCI is available then most likely we are running on PSCI-enabled
> > > +ÂÂÂÂ * U-Boot which, we assume, has already taken care of resetting CNTVOFF
> > > +ÂÂÂÂ * before switching to non-secure mode and we don't need to.
> > > +ÂÂÂÂ * Another check is to be sure that we are not running on top of Xen
> > > +ÂÂÂÂ * hypervisor, as CNTVOFF is controlled by hypervisor itself and
> > > +ÂÂÂÂ * shouldn't be touched by Dom0 in such case.
> >
> > If you are running on top of Xen, then PSCI will be available. So is there any 
> > real value to check the presence of Xen as well?
>
> I think, no. If the PSCI is a must to run Xen, then it is certainly an excessive 
> check. I will drop it in V3.

Xen does not offer another interface for SMP bring-up.

Cheers,

--
Julien Grall