[Skiboot] [PATCH] System reset IPI facility and Mambo implementation

[Alistair Popple]

On Fri, 3 Feb 2017 12:24:47 AM Nicholas Piggin wrote:
> Add an opal call OPAL_SIGNAL_SYSTEM_RESET which allows system reset
> exceptions to be raised on other CPUs and act as an NMI IPI. There
> is an initial simple Mambo implementation, but allowances are made
> for a more complex hardware implementation.
>
> This is based on the hardware implementation patch by Alistair Popple.
>
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
> ---
> Hi,
>
> I'm not sure what the state of Alistair's patch is, but it may
> make testing easier to initially add this mambo implementation.

My implementation on or P8 hardware probably needs a bit more work and
testing which I haven't found the time to do yet. Having a solid way
for the kernel to call these functions would greatly assist testing
though and this looks like it matches the OPAL API needed for the HW.

Reviewed-by: Alistair Popple <alistair at popple.id.au>

Thanks!

>
> Thanks,
> Nick
>
>  doc/opal-api/opal-signal-system-reset-145.txt | 31 +++++++++++++++++
>  include/opal-api.h                            |  3 +-
>  platforms/mambo/mambo.c                       | 48 +++++++++++++++++++++++++++
>  3 files changed, 81 insertions(+), 1 deletion(-)
>  create mode 100644 doc/opal-api/opal-signal-system-reset-145.txt
>
> diff --git a/doc/opal-api/opal-signal-system-reset-145.txt b/doc/opal-api/opal-signal-system-reset-145.txt
> new file mode 100644
> index 00000000..25b96dbb
> --- /dev/null
> +++ b/doc/opal-api/opal-signal-system-reset-145.txt
> @@ -0,0 +1,31 @@
> +OPAL_SIGNAL_SYSTEM_RESET
> +-------------------
> +
> +#define OPAL_SIGNAL_SYSTEM_RESET			145
> +
> +int64_t signal_system_reset(int32_t cpu_nr)
> +
> +Arguments:
> +
> +  int32_t cpu_nr
> +    Either the cpu server number of the target cpu to reset, or
> +    SYS_RESET_ALL (-1) to indicate all cpus should be reset, or
> +    SYS_RESET_ALL_OTHERS (-2) to indicate all but the current cpu
> +    should be reset.
> +
> +This OPAL call causes the specified cpu(s) to be reset to the system
> +reset exception handler (0x100).
> +
> +The exact contents of system registers (e.g., SRR1 wakeup causes) may
> +vary depending on implementation and should not be relied upon.
> +
> +Resetting active threads on the same core as this call is run may
> +not be supported by some platforms. In that case, OPAL_PARTIAL will be
> +returned and NONE of the interrupts will be delivered.
> +
> +Return Values:
> +OPAL_SUCCESS: the power down was updated successful
> +OPAL_PARAMETER: a parameter was incorrect
> +OPAL_HARDWARE: hardware indicated failure during instruction ramming
> +OPAL_PARTIAL: not all requested cpus could be reset at this time
> +OPAL_UNSUPPORTED: this processor generation is not supported
> diff --git a/include/opal-api.h b/include/opal-api.h
> index c891db97..c32a2fde 100644
> --- a/include/opal-api.h
> +++ b/include/opal-api.h
> @@ -200,7 +200,8 @@
>  #define OPAL_XIVE_RESERVED2			142
>  #define OPAL_XIVE_RESERVED3			143
>  #define OPAL_XIVE_RESERVED4			144
> -#define OPAL_LAST				144
> +#define OPAL_SIGNAL_SYSTEM_RESET		145
> +#define OPAL_LAST				145
>
>  /* Device tree flags */
>
> diff --git a/platforms/mambo/mambo.c b/platforms/mambo/mambo.c
> index 976efeac..3131db9c 100644
> --- a/platforms/mambo/mambo.c
> +++ b/platforms/mambo/mambo.c
> @@ -19,6 +19,7 @@
>  #include <device.h>
>  #include <console.h>
>  #include <chip.h>
> +#include <cpu.h>
>  #include <opal-api.h>
>  #include <opal-internal.h>
>  #include <time-utils.h>
> @@ -211,8 +212,55 @@ static void mambo_rtc_init(void)
>  	opal_register(OPAL_RTC_READ, mambo_rtc_read, 2);
>  }
>
> +static void mambo_system_reset_cpu(struct cpu_thread *cpu)
> +{
> +	uint32_t core_id;
> +	uint32_t thread_id;
> +	char tcl_cmd[50];
> +
> +	core_id = pir_to_core_id(cpu->pir);
> +	thread_id = pir_to_thread_id(cpu->pir);
> +
> +	snprintf(tcl_cmd, sizeof(tcl_cmd), "mysim cpu %i:%i interrupt SystemReset", core_id, thread_id);
> +	callthru_tcl(tcl_cmd, strlen(tcl_cmd));
> +}
> +
> +#define SYS_RESET_ALL		-1
> +#define SYS_RESET_ALL_OTHERS	-2
> +
> +static int64_t mambo_signal_system_reset(int32_t cpu_nr)
> +{
> +	struct cpu_thread *cpu;
> +
> +	if (cpu_nr < 0) {
> +		if (cpu_nr < SYS_RESET_ALL_OTHERS)
> +			return OPAL_PARAMETER;
> +
> +		for_each_cpu(cpu) {
> +			if (cpu_nr == SYS_RESET_ALL_OTHERS && cpu == this_cpu())
> +				continue;
> +			mambo_system_reset_cpu(cpu);
> +		}
> +		return OPAL_SUCCESS;
> +
> +	} else {
> +		cpu = find_cpu_by_server(cpu_nr);
> +		if (!cpu)
> +			return OPAL_PARAMETER;
> +
> +		mambo_system_reset_cpu(cpu);
> +		return OPAL_SUCCESS;
> +	}
> +}
> +
> +static void mambo_sreset_init(void)
> +{
> +	opal_register(OPAL_SIGNAL_SYSTEM_RESET, mambo_signal_system_reset, 1);
> +}
> +
>  static void mambo_platform_init(void)
>  {
> +	mambo_sreset_init();
>  	mambo_rtc_init();
>  	bogus_disk_flash_init();
>  }
>