linux-kernel - Re: [PATCH] powercap, intel

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Message-ID: <566771EC.2020201@jp.fujitsu.com>
Date:	Wed, 9 Dec 2015 09:12:28 +0900
From:	Seiichi Ikarashi <s.ikarashi@...fujitsu.com>
To:	Prarit Bhargava <prarit@...hat.com>, <linux-kernel@...r.kernel.org>
CC:	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Jacob Pan <jacob.jun.pan@...ux.intel.com>,
	Radivoje Jovanovic <radivoje.jovanovic@...el.com>,
	Mathias Krause <minipli@...glemail.com>,
	Ajay Thomas <ajay.thomas.david.rajamanickam@...el.com>
Subject: Re: [PATCH] powercap, intel_rapl.c, fix BIOS lock check

On 2015-12-09 03:33, Prarit Bhargava wrote:
> Intel RAPL initialized on several systems where the BIOS lock bit (msr
> 0x610, bit 63) was set.  This occured because the return value of
> rapl_read_data_raw() was being checked, rather than the value of the variable
> passed in, locked.
> 
> This patch properly implments the rapl_read_data_raw() call to check the
> variable locked, and now the Intel RAPL driver outputs the warning:
> 
> 	intel_rapl: RAPL package 0 domain package locked by BIOS
> 
> and does not initialize for the package.
> 
> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
> Cc: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> Cc: Radivoje Jovanovic <radivoje.jovanovic@...el.com>
> Cc: Seiichi Ikarashi <s.ikarashi@...fujitsu.com>
> Cc: Mathias Krause <minipli@...glemail.com>
> Cc: Ajay Thomas <ajay.thomas.david.rajamanickam@...el.com>
> Signed-off-by: Prarit Bhargava <prarit@...hat.com>
> ---
>  drivers/powercap/intel_rapl.c |    6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/powercap/intel_rapl.c b/drivers/powercap/intel_rapl.c
> index cc97f08..0b0d09d 100644
> --- a/drivers/powercap/intel_rapl.c
> +++ b/drivers/powercap/intel_rapl.c
> @@ -1341,11 +1341,13 @@ static int rapl_detect_domains(struct rapl_package *rp, int cpu)
>  
>  	for (rd = rp->domains; rd < rp->domains + rp->nr_domains; rd++) {
>  		/* check if the domain is locked by BIOS */
> -		if (rapl_read_data_raw(rd, FW_LOCK, false, &locked)) {
> +		ret = rapl_read_data_raw(rd, FW_LOCK, false, &locked);
> +		if (ret)
> +			return ret;
> +		if (locked)
>  			pr_info("RAPL package %d domain %s locked by BIOS\n",
>  				rp->id, rd->name);
>  				rd->state |= DOMAIN_STATE_BIOS_LOCKED;
> -		}
>  	}

A good spot!
But this patch looks setting DOMAIN_STATE_BIOS_LOCKED bit to all package domains.
I suppose what you are going to do is like below.

--- a/drivers/powercap/intel_rapl.c	2015-11-02 09:05:25.000000000 +0900
+++ b/drivers/powercap/intel_rapl.c	2015-12-09 09:05:33.386142840 +0900
@@ -1340,10 +1340,13 @@ static int rapl_detect_domains(struct ra
 
 	for (rd = rp->domains; rd < rp->domains + rp->nr_domains; rd++) {
 		/* check if the domain is locked by BIOS */
-		if (rapl_read_data_raw(rd, FW_LOCK, false, &locked)) {
+		ret = rapl_read_data_raw(rd, FW_LOCK, false, &locked);
+		if (ret)
+			return ret;
+		if (locked) {
 			pr_info("RAPL package %d domain %s locked by BIOS\n",
 				rp->id, rd->name);
-				rd->state |= DOMAIN_STATE_BIOS_LOCKED;
+			rd->state |= DOMAIN_STATE_BIOS_LOCKED;
 		}
 	}
 

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