From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Oleksandr Tyshchenko <olekstysh@gmail.com>
Cc: Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Julien Grall <julien.grall@arm.com>,
Simon Horman <horms@verge.net.au>,
Magnus Damm <magnus.damm@gmail.com>,
Russell King <linux@armlinux.org.uk>,
Biju Das <biju.das@bp.renesas.com>,
Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Subject: Re: [PATCH V2] ARM: mach-shmobile: Don't init CNTVOFF if PSCI is available
Date: Fri, 3 May 2019 13:38:42 +0200 [thread overview]
Message-ID: <CAMuHMdVYff-YsGxJykT_p31iyw9f4yVY967_i166TSm__WRG9g@mail.gmail.com> (raw)
In-Reply-To: <1556882268-27451-1-git-send-email-olekstysh@gmail.com>
Hi Oleksandr,
On Fri, May 3, 2019 at 1:21 PM Oleksandr Tyshchenko <olekstysh@gmail.com> wrote:
> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
>
> If PSCI is available then most likely we are running on PSCI-enabled
> U-Boot which, we assume, has already taken care of resetting CNTVOFF
> before switching to non-secure mode and we don't need to.
>
> Also, don't init CNTVOFF if we are running on top of Xen hypervisor,
> as CNTVOFF is controlled by hypervisor itself and shouldn't be touched
> by Dom0 in such case.
>
> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
> CC: Julien Grall <julien.grall@arm.com>
Thanks for your patch!
> ---
> You can find previous discussion here:
> https://lkml.org/lkml/2019/4/17/810
>
> Changes in v2:
> - Clarify patch subject/description
> - Don't use CONFIG_ARM_PSCI option, check whether the PSCI is available,
> by using psci_smp_available()
> - Check whether we are running on top of Xen, by using xen_domain()
> ---
> arch/arm/mach-shmobile/setup-rcar-gen2.c | 13 ++++++++++++-
> 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 @@
> #include <linux/of.h>
> #include <linux/of_fdt.h>
> #include <linux/of_platform.h>
> +#include <xen/xen.h>
> #include <asm/mach/arch.h>
> +#include <asm/psci.h>
> #include <asm/secure_cntvoff.h>
> #include "common.h"
> #include "rcar-gen2.h"
> @@ -63,7 +65,16 @@ void __init rcar_gen2_timer_init(void)
> void __iomem *base;
> u32 freq;
>
> - secure_cntvoff_init();
> + /*
> + * If PSCI is available then most likely we are running on PSCI-enabled
> + * U-Boot which, we assume, has already taken care of resetting CNTVOFF
> + * before switching to non-secure mode and we don't need to.
> + * Another check is to be sure that we are not running on top of Xen
> + * hypervisor, as CNTVOFF is controlled by hypervisor itself and
> + * shouldn't be touched by Dom0 in such case.
> + */
> + if (!psci_smp_available() && !xen_domain())
> + secure_cntvoff_init();
>
> if (of_machine_is_compatible("renesas,r8a7745") ||
> of_machine_is_compatible("renesas,r8a77470") ||
How do you prevent secure_cntvoff_init() from being called for secondary
CPUs in arch/arm/mach-shmobile/headsmp-apmu.S?
With PSCI, it is not called if "enable-method" in DT is "psci"', so that case
is covered, I guess.
What about XEN? Do you override the "enable-method"?
If yes, perhaps a check for "renesas,apmu" is more appropriate?
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2019-05-03 11:38 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-03 11:17 [PATCH V2] ARM: mach-shmobile: Don't init CNTVOFF if PSCI is available Oleksandr Tyshchenko
2019-05-03 11:38 ` Geert Uytterhoeven [this message]
2019-05-03 12:28 ` Oleksandr
2019-05-06 15:37 ` Julien Grall
2019-05-10 12:27 ` Oleksandr
2019-05-10 12:53 ` Julien Grall
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