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

[Oleksandr]

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.


> Cheers,
--
Regards,

Oleksandr Tyshchenko