[PATCH v2 04/12] powerpc/pseries/ras: avoid calling rtas_token in NMI paths

[Mahesh J Salgaonkar]

On 2020-03-25 20:34:02 Wed, Nicholas Piggin wrote:
> In the interest of reducing code and possible failures in the
> machine check and system reset paths, grab the "ibm,nmi-interlock"
> token at init time.
> 
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>

Reviewed-by: Mahesh Salgaonkar <mahesh at linux.ibm.com>

Thanks,
-Mahesh.
> ---
>  arch/powerpc/include/asm/firmware.h    |  1 +
>  arch/powerpc/platforms/pseries/ras.c   |  2 +-
>  arch/powerpc/platforms/pseries/setup.c | 13 ++++++++++---
>  3 files changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/firmware.h b/arch/powerpc/include/asm/firmware.h
> index ca33f4ef6cb4..6003c2e533a0 100644
> --- a/arch/powerpc/include/asm/firmware.h
> +++ b/arch/powerpc/include/asm/firmware.h
> @@ -128,6 +128,7 @@ extern void machine_check_fwnmi(void);
> 
>  /* This is true if we are using the firmware NMI handler (typically LPAR) */
>  extern int fwnmi_active;
> +extern int ibm_nmi_interlock_token;
> 
>  extern unsigned int __start___fw_ftr_fixup, __stop___fw_ftr_fixup;
> 
> diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c
> index 1d7f973c647b..c74d5e740922 100644
> --- a/arch/powerpc/platforms/pseries/ras.c
> +++ b/arch/powerpc/platforms/pseries/ras.c
> @@ -458,7 +458,7 @@ static struct rtas_error_log *fwnmi_get_errinfo(struct pt_regs *regs)
>   */
>  static void fwnmi_release_errinfo(void)
>  {
> -	int ret = rtas_call(rtas_token("ibm,nmi-interlock"), 0, 1, NULL);
> +	int ret = rtas_call(ibm_nmi_interlock_token, 0, 1, NULL);
>  	if (ret != 0)
>  		printk(KERN_ERR "FWNMI: nmi-interlock failed: %d\n", ret);
>  }
> diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
> index 17d17f064a2d..c31acd7ce0c0 100644
> --- a/arch/powerpc/platforms/pseries/setup.c
> +++ b/arch/powerpc/platforms/pseries/setup.c
> @@ -83,6 +83,7 @@ unsigned long CMO_PageSize = (ASM_CONST(1) << IOMMU_PAGE_SHIFT_4K);
>  EXPORT_SYMBOL(CMO_PageSize);
> 
>  int fwnmi_active;  /* TRUE if an FWNMI handler is present */
> +int ibm_nmi_interlock_token;
> 
>  static void pSeries_show_cpuinfo(struct seq_file *m)
>  {
> @@ -113,9 +114,14 @@ static void __init fwnmi_init(void)
>  	struct slb_entry *slb_ptr;
>  	size_t size;
>  #endif
> +	int ibm_nmi_register_token;
> 
> -	int ibm_nmi_register = rtas_token("ibm,nmi-register");
> -	if (ibm_nmi_register == RTAS_UNKNOWN_SERVICE)
> +	ibm_nmi_register_token = rtas_token("ibm,nmi-register");
> +	if (ibm_nmi_register_token == RTAS_UNKNOWN_SERVICE)
> +		return;
> +
> +	ibm_nmi_interlock_token = rtas_token("ibm,nmi-interlock");
> +	if (WARN_ON(ibm_nmi_interlock_token == RTAS_UNKNOWN_SERVICE))
>  		return;
> 
>  	/* If the kernel's not linked at zero we point the firmware at low
> @@ -123,7 +129,8 @@ static void __init fwnmi_init(void)
>  	system_reset_addr  = __pa(system_reset_fwnmi) - PHYSICAL_START;
>  	machine_check_addr = __pa(machine_check_fwnmi) - PHYSICAL_START;
> 
> -	if (0 == rtas_call(ibm_nmi_register, 2, 1, NULL, system_reset_addr,
> +	if (0 == rtas_call(ibm_nmi_register_token, 2, 1, NULL,
> +				system_reset_addr,
>  				machine_check_addr))
>  		fwnmi_active = 1;
> 
> -- 
> 2.23.0
> 

-- 
Mahesh J Salgaonkar