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Date:   Tue, 14 Apr 2020 12:46:24 +0530
From:   Gautham R Shenoy <ego@linux.vnet.ibm.com>
To:     Pratik Rajesh Sampat <psampat@linux.ibm.com>
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org,
        mpe@ellerman.id.au, skiboot@lists.ozlabs.org, oohall@gmail.com,
        ego@linux.vnet.ibm.com, linuxram@us.ibm.com,
        pratik.r.sampat@gmail.com
Subject: Re: [PATCH v6 1/3] powerpc/powernv: Introduce interface for
 self-restore support
Message-ID: <20200414071623.GE24277@in.ibm.com>
Reply-To: ego@linux.vnet.ibm.com
References: <20200326071034.12838-1-psampat@linux.ibm.com>
 <20200326071034.12838-2-psampat@linux.ibm.com>
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On Thu, Mar 26, 2020 at 12:40:32PM +0530, Pratik Rajesh Sampat wrote:
> Introduces an interface that helps determine support for the
> self-restore API. The commit is isomorphic to the original interface of
> declaring SPRs to self-restore.
> 
> Signed-off-by: Pratik Rajesh Sampat <psampat@linux.ibm.com>

This patch looks good to me.

Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>

> ---
>  arch/powerpc/platforms/powernv/idle.c | 200 +++++++++++++++++++-------
>  1 file changed, 152 insertions(+), 48 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c
> index 78599bca66c2..858ceb86394d 100644
> --- a/arch/powerpc/platforms/powernv/idle.c
> +++ b/arch/powerpc/platforms/powernv/idle.c
> @@ -32,10 +32,67 @@
>  #define P9_STOP_SPR_MSR 2000
>  #define P9_STOP_SPR_PSSCR      855
> 
> +/*
> + * Type of support for each SPR
> + * FIRMWARE_RESTORE: firmware restoration supported: calls self-restore OPAL API
> + */
> +#define UNSUPPORTED           0x0
> +#define FIRMWARE_RESTORE      0x1
> +
>  static u32 supported_cpuidle_states;
>  struct pnv_idle_states_t *pnv_idle_states;
>  int nr_pnv_idle_states;
> 
> +struct preferred_sprs {
> +	u64 spr;
> +	u32 supported_mode;
> +};
> +
> +/*
> + * Supported mode: Default support. Can be overwritten during system
> + *		   initialization
> + */
> +struct preferred_sprs preferred_sprs[] = {
> +	{
> +		.spr = SPRN_HSPRG0,
> +		.supported_mode = FIRMWARE_RESTORE,
> +	},
> +	{
> +		.spr = SPRN_LPCR,
> +		.supported_mode = FIRMWARE_RESTORE,
> +	},
> +	{
> +		.spr = SPRN_HMEER,
> +		.supported_mode = FIRMWARE_RESTORE,
> +	},
> +	{
> +		.spr = SPRN_HID0,
> +		.supported_mode = FIRMWARE_RESTORE,
> +	},
> +	{
> +		.spr = P9_STOP_SPR_MSR,
> +		.supported_mode = FIRMWARE_RESTORE,
> +	},
> +	{
> +		.spr = P9_STOP_SPR_PSSCR,
> +		.supported_mode = FIRMWARE_RESTORE,
> +	},
> +	{
> +		.spr = SPRN_HID1,
> +		.supported_mode = FIRMWARE_RESTORE,
> +	},
> +	{
> +		.spr = SPRN_HID4,
> +		.supported_mode = FIRMWARE_RESTORE,
> +	},
> +	{
> +		.spr = SPRN_HID5,
> +		.supported_mode = FIRMWARE_RESTORE,
> +	}
> +};
> +
> +const int nr_preferred_sprs = ARRAY_SIZE(preferred_sprs);
> +
>  /*
>   * The default stop state that will be used by ppc_md.power_save
>   * function on platforms that support stop instruction.
> @@ -61,78 +118,125 @@ static bool deepest_stop_found;
> 
>  static unsigned long power7_offline_type;
> 
> -static int pnv_save_sprs_for_deep_states(void)
> +static int pnv_self_restore_sprs(u64 pir, int cpu, u64 spr)
>  {
> -	int cpu;
> +	u64 reg_val;
>  	int rc;
> 
> -	/*
> -	 * hid0, hid1, hid4, hid5, hmeer and lpcr values are symmetric across
> -	 * all cpus at boot. Get these reg values of current cpu and use the
> -	 * same across all cpus.
> -	 */
> -	uint64_t lpcr_val	= mfspr(SPRN_LPCR);
> -	uint64_t hid0_val	= mfspr(SPRN_HID0);
> -	uint64_t hid1_val	= mfspr(SPRN_HID1);
> -	uint64_t hid4_val	= mfspr(SPRN_HID4);
> -	uint64_t hid5_val	= mfspr(SPRN_HID5);
> -	uint64_t hmeer_val	= mfspr(SPRN_HMEER);
> -	uint64_t msr_val = MSR_IDLE;
> -	uint64_t psscr_val = pnv_deepest_stop_psscr_val;
> -
> -	for_each_present_cpu(cpu) {
> -		uint64_t pir = get_hard_smp_processor_id(cpu);
> -		uint64_t hsprg0_val = (uint64_t)paca_ptrs[cpu];
> -
> -		rc = opal_slw_set_reg(pir, SPRN_HSPRG0, hsprg0_val);
> +	switch (spr) {
> +	case SPRN_HSPRG0:
> +		reg_val = (uint64_t)paca_ptrs[cpu];
> +		rc = opal_slw_set_reg(pir, SPRN_HSPRG0, reg_val);
>  		if (rc != 0)
>  			return rc;
> -
> -		rc = opal_slw_set_reg(pir, SPRN_LPCR, lpcr_val);
> +		break;
> +	case SPRN_LPCR:
> +		reg_val = mfspr(SPRN_LPCR);
> +		rc = opal_slw_set_reg(pir, SPRN_LPCR, reg_val);
>  		if (rc != 0)
>  			return rc;
> -
> +		break;
> +	case P9_STOP_SPR_MSR:
> +		reg_val = MSR_IDLE;
>  		if (cpu_has_feature(CPU_FTR_ARCH_300)) {
> -			rc = opal_slw_set_reg(pir, P9_STOP_SPR_MSR, msr_val);
> +			rc = opal_slw_set_reg(pir, P9_STOP_SPR_MSR, reg_val);
>  			if (rc)
>  				return rc;
> -
> -			rc = opal_slw_set_reg(pir,
> -					      P9_STOP_SPR_PSSCR, psscr_val);
> -
> +		}
> +		break;
> +	case P9_STOP_SPR_PSSCR:
> +		reg_val = pnv_deepest_stop_psscr_val;
> +		if (cpu_has_feature(CPU_FTR_ARCH_300)) {
> +			rc = opal_slw_set_reg(pir, P9_STOP_SPR_PSSCR, reg_val);
>  			if (rc)
>  				return rc;
>  		}
> -
> -		/* HIDs are per core registers */
> +		break;
> +	case SPRN_HMEER:
> +		reg_val = mfspr(SPRN_HMEER);
>  		if (cpu_thread_in_core(cpu) == 0) {
> -
> -			rc = opal_slw_set_reg(pir, SPRN_HMEER, hmeer_val);
> -			if (rc != 0)
> +			rc = opal_slw_set_reg(pir, SPRN_HMEER, reg_val);
> +			if (rc)
>  				return rc;
> -
> -			rc = opal_slw_set_reg(pir, SPRN_HID0, hid0_val);
> -			if (rc != 0)
> +		}
> +		break;
> +	case SPRN_HID0:
> +		reg_val = mfspr(SPRN_HID0);
> +		if (cpu_thread_in_core(cpu) == 0) {
> +			rc = opal_slw_set_reg(pir, SPRN_HID0, reg_val);
> +			if (rc)
>  				return rc;
> +		}
> +		break;
> +	case SPRN_HID1:
> +		reg_val = mfspr(SPRN_HID1);
> +		if (!cpu_has_feature(CPU_FTR_ARCH_300) &&
> +		    cpu_thread_in_core(cpu) == 0) {
> +			rc = opal_slw_set_reg(pir, SPRN_HID1, reg_val);
> +			if (rc)
> +				return rc;
> +		}
> +		break;
> +	case SPRN_HID4:
> +		reg_val = mfspr(SPRN_HID4);
> +		if (!cpu_has_feature(CPU_FTR_ARCH_300) &&
> +		    cpu_thread_in_core(cpu) == 0) {
> +			rc = opal_slw_set_reg(pir, SPRN_HID4, reg_val);
> +			if (rc)
> +				return rc;
> +		}
> +		break;
> +	case SPRN_HID5:
> +		reg_val = mfspr(SPRN_HID5);
> +		if (!cpu_has_feature(CPU_FTR_ARCH_300) &&
> +		    cpu_thread_in_core(cpu) == 0) {
> +			rc = opal_slw_set_reg(pir, SPRN_HID5, reg_val);
> +			if (rc)
> +				return rc;
> +		}
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +	return 0;
> +}
> 
> -			/* Only p8 needs to set extra HID regiters */
> -			if (!cpu_has_feature(CPU_FTR_ARCH_300)) {
> -
> -				rc = opal_slw_set_reg(pir, SPRN_HID1, hid1_val);
> -				if (rc != 0)
> -					return rc;
> -
> -				rc = opal_slw_set_reg(pir, SPRN_HID4, hid4_val);
> -				if (rc != 0)
> -					return rc;
> +static int pnv_self_save_restore_sprs(void)
> +{
> +	int rc, index, cpu;
> +	u64 pir;
> +	struct preferred_sprs curr_spr;
> 
> -				rc = opal_slw_set_reg(pir, SPRN_HID5, hid5_val);
> +	for_each_present_cpu(cpu) {
> +		pir = get_hard_smp_processor_id(cpu);
> +		for (index = 0; index < nr_preferred_sprs; index++) {
> +			curr_spr = preferred_sprs[index];
> +			/* HIDs are per core register */
> +			if (cpu_thread_in_core(cpu) != 0 &&
> +			    (curr_spr.spr == SPRN_HMEER ||
> +			     curr_spr.spr == SPRN_HID0  ||
> +			     curr_spr.spr == SPRN_HID1  ||
> +			     curr_spr.spr == SPRN_HID4  ||
> +			     curr_spr.spr == SPRN_HID5))
> +				continue;
> +			if (curr_spr.supported_mode & FIRMWARE_RESTORE) {
> +				rc = pnv_self_restore_sprs(pir, cpu,
> +							   curr_spr.spr);
>  				if (rc != 0)
>  					return rc;
>  			}
>  		}
>  	}
> +	return 0;
> +}
> 
> +static int pnv_save_sprs_for_deep_states(void)
> +{
> +	int rc;
> +
> +	rc = pnv_self_save_restore_sprs();
> +	if (rc != 0)
> +		return rc;
>  	return 0;
>  }
> 
> -- 
> 2.17.1
>