Re: [PATCH] socfpga_a10: reset CPU1 in socfpga_cpu_kill()

[yjin]

On 2017å05æ12æ 22:36, Mark Rutland wrote:
> On Wed, May 10, 2017 at 01:13:04AM -0400, yanjiang.jin@xxxxxxxxxxxxx wrote:
> > From: Yanjiang Jin <yanjiang.jin@xxxxxxxxxxxxx>
> >
> > Kexec's second kernel would hang if CPU1 isn't reset.
> >
> > Signed-off-by: Yanjiang Jin <yanjiang.jin@xxxxxxxxxxxxx>
> > ---
> >   arch/arm/mach-socfpga/platsmp.c | 12 +++++++++++-
> >   1 file changed, 11 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm/mach-socfpga/platsmp.c b/arch/arm/mach-socfpga/platsmp.c
> > index 0ee7677..db3940e 100644
> > --- a/arch/arm/mach-socfpga/platsmp.c
> > +++ b/arch/arm/mach-socfpga/platsmp.c
> > @@ -117,6 +117,16 @@ static int socfpga_cpu_kill(unsigned int cpu)
> >   {
> >   	return 1;
> >   }
> > +
> > +static int socfpga_a10_cpu_kill(unsigned int cpu)
> > +{
> > +	/* This will put CPU #1 into reset. */
> > +	if (socfpga_cpu1start_addr)
> > +		writel(RSTMGR_MPUMODRST_CPU1, rst_manager_base_addr +
> > +			SOCFPGA_A10_RSTMGR_MODMPURST);
> > +
> > +	return 1;
> > +}
> >   #endif
> I agree that currently, socfpga_cpu_die is completely bogus, as the CPU is just
> sat in WFI with the MMU, caches, etc enabled, and not actually off:
>
> static void socfpga_cpu_die(unsigned int cpu)
> {
>          /* Do WFI. If we wake up early, go back into WFI */
>          while (1)
>                  cpu_do_idle();
> }
>
> ... so that goes wrong as soon as the kerenl text gets ovewritten.
>
> However, AFAICT, this patch forcibly resets is without any teardown
> having happened. That will surely result in data being lost from the
> caches, for example.
>
> So I think this is incomplete.
Hi Mark,

I think I got what you mean. So far, flush_cache is the only thing that 
I can think of.
Can we just add flush_cache_all in cpu_die() now, and add other missing 
parts(if have) in the future.

Thanks!
Yanjiang

> Thanks,
> Mark.
>
> >   
> >   static const struct smp_operations socfpga_smp_ops __initconst = {
> > @@ -133,7 +143,7 @@ static int socfpga_cpu_kill(unsigned int cpu)
> >   	.smp_boot_secondary	= socfpga_a10_boot_secondary,
> >   #ifdef CONFIG_HOTPLUG_CPU
> >   	.cpu_die		= socfpga_cpu_die,
> > -	.cpu_kill		= socfpga_cpu_kill,
> > +	.cpu_kill		= socfpga_a10_cpu_kill,
> >   #endif
> >   };
> >   
> > --
> > 1.9.1
> >
> >
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