* [PATCH V2] ARM: mach-shmobile: Don't init CNTVOFF if PSCI is available
@ 2019-05-03 11:17 Oleksandr Tyshchenko
2019-05-03 11:38 ` Geert Uytterhoeven
2019-05-06 15:37 ` Julien Grall
0 siblings, 2 replies; 6+ messages in thread
From: Oleksandr Tyshchenko @ 2019-05-03 11:17 UTC (permalink / raw)
To: linux-renesas-soc, linux-kernel
Cc: julien.grall, horms, magnus.damm, linux, biju.das, Oleksandr Tyshchenko
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>
---
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") ||
--
2.7.4
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH V2] ARM: mach-shmobile: Don't init CNTVOFF if PSCI is available 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 2019-05-03 12:28 ` Oleksandr 2019-05-06 15:37 ` Julien Grall 1 sibling, 1 reply; 6+ messages in thread From: Geert Uytterhoeven @ 2019-05-03 11:38 UTC (permalink / raw) To: Oleksandr Tyshchenko Cc: Linux-Renesas, Linux Kernel Mailing List, Julien Grall, Simon Horman, Magnus Damm, Russell King, Biju Das, Oleksandr Tyshchenko 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 ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH V2] ARM: mach-shmobile: Don't init CNTVOFF if PSCI is available 2019-05-03 11:38 ` Geert Uytterhoeven @ 2019-05-03 12:28 ` Oleksandr 0 siblings, 0 replies; 6+ messages in thread From: Oleksandr @ 2019-05-03 12:28 UTC (permalink / raw) To: Geert Uytterhoeven Cc: Linux-Renesas, Linux Kernel Mailing List, Julien Grall, Simon Horman, Magnus Damm, Russell King, Biju Das, Oleksandr Tyshchenko On 03.05.19 14:38, Geert Uytterhoeven wrote: > Hi Oleksandr, Hi Geert > > 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! Thank you for review! > >> --- >> 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? Good question. > > With PSCI, it is not called if "enable-method" in DT is "psci"', so that case > is covered, I guess. Yes. > > What about XEN? Do you override the "enable-method"? > If yes, perhaps a check for "renesas,apmu" is more appropriate? No, I don't override. The correct way to run Xen would be to use PSCI, so Linux shouldn't do any platform low level operation with secondary CPU cores (on/off, reset, etc) by itself when running on top of Xen hypervisor. As Xen brings available secondary cores up before starting first domain (Dom0) using PSCI CPU_ON call to FW, and these cores are entered Xen in Hyp mode, so any attempts from Dom0 to perform CPU power management directly (using APMU, RST, etc) may result in something not good. I think that in case when someone wants to run Xen on R-Car Gen2 system (which is SMP) without PSCI enabled, we need to forbid even trying to start secondary cores using APMU. What do you think? > > Gr{oetje,eeting}s, > > Geert > -- Regards, Oleksandr Tyshchenko ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH V2] ARM: mach-shmobile: Don't init CNTVOFF if PSCI is available 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 @ 2019-05-06 15:37 ` Julien Grall 2019-05-10 12:27 ` Oleksandr 1 sibling, 1 reply; 6+ messages in thread From: Julien Grall @ 2019-05-06 15:37 UTC (permalink / raw) To: Oleksandr Tyshchenko, linux-renesas-soc, linux-kernel Cc: horms, magnus.damm, linux, biju.das, Oleksandr Tyshchenko Hi Oleksandr, On 5/3/19 12:17 PM, Oleksandr Tyshchenko 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> > > --- > 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 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? Cheers, -- Julien Grall ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH V2] ARM: mach-shmobile: Don't init CNTVOFF if PSCI is available 2019-05-06 15:37 ` Julien Grall @ 2019-05-10 12:27 ` Oleksandr 2019-05-10 12:53 ` Julien Grall 0 siblings, 1 reply; 6+ messages in thread From: Oleksandr @ 2019-05-10 12:27 UTC (permalink / raw) To: Julien Grall, linux-renesas-soc, linux-kernel Cc: horms, magnus.damm, linux, biju.das, Oleksandr Tyshchenko On 06.05.19 18:37, Julien Grall wrote: > Hi Oleksandr, Hi Julien >> --- >> 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 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 ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH V2] ARM: mach-shmobile: Don't init CNTVOFF if PSCI is available 2019-05-10 12:27 ` Oleksandr @ 2019-05-10 12:53 ` Julien Grall 0 siblings, 0 replies; 6+ messages in thread From: Julien Grall @ 2019-05-10 12:53 UTC (permalink / raw) To: Oleksandr, linux-renesas-soc, linux-kernel Cc: horms, magnus.damm, linux, biju.das, Oleksandr Tyshchenko On 10/05/2019 13:27, Oleksandr wrote: > > On 06.05.19 18:37, Julien Grall wrote: >> Hi Oleksandr, > > Hi Julien > > >>> --- >>> 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 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 ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2019-05-10 12:53 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 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 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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