Re: [lm-sensors] [PATCH] coretemp: fix reading of microcode

[Guenter Roeck <guenter.roeck@ericsson.com>]

On Fri, Oct 08, 2010 at 04:59:38AM -0400, Jan Beulich wrote:
> According to the documentation, simply reading the respective MSR
> isn't sufficient: It should be written with zeros, cpuid(1) be
> executed, and then read (see arch/x86/kernel/cpu/intel.c for an
> example).
> 
> v2: Fail probe when microcode revision cannot be determined, but is
> needed to check for proper operation.
> 
> Signed-off-by: Jan Beulich <jbeulich@novell.com>
> Cc: Fenghua Yu <fenghua.yu@intel.com>
> Cc: Chen Gong <gong.chen@linux.intel.com>
> Cc: Jean Delvare <khali@linux-fr.org>
> 
> ---
>  drivers/hwmon/coretemp.c |   20 ++++++++++++++++++--
>  1 file changed, 18 insertions(+), 2 deletions(-)
> 
> --- linux-2.6.36-rc7/drivers/hwmon/coretemp.c
> +++ 2.6.36-rc7-coretemp-ucode/drivers/hwmon/coretemp.c
> @@ -292,6 +292,15 @@ static int __devinit get_tjmax(struct cp
>  	}
>  }
>  
> +static void __devinit get_ucode_rev_on_cpu(void *edx)
> +{
> +	u32 eax;
> +
> +	wrmsr(MSR_IA32_UCODE_REV, 0, 0);
> +	sync_core();
> +	rdmsr(MSR_IA32_UCODE_REV, eax, *(u32 *)edx);
> +}
> +
>  static int __devinit coretemp_probe(struct platform_device *pdev)
>  {
>  	struct coretemp_data *data;
> @@ -327,8 +336,15 @@ static int __devinit coretemp_probe(stru
>  
>  	if ((c->x86_model = 0xe) && (c->x86_mask < 0xc)) {
>  		/* check for microcode update */
> -		rdmsr_on_cpu(data->id, MSR_IA32_UCODE_REV, &eax, &edx);
> -		if (edx < 0x39) {
> +		err = smp_call_function_single(data->id, get_ucode_rev_on_cpu,
> +					       &edx, 1);
> +		if (err) {
> +			dev_err(&pdev->dev,
> +				"Cannot determine microcode revision of "
> +				"CPU#%u (%d)!\n", data->id, err);
> +			err = -ENODEV;
> +			goto exit_free;
> +		} else if (edx < 0x39) {
>  			err = -ENODEV;
>  			dev_err(&pdev->dev,
>  				"Errata AE18 not fixed, update BIOS or "
> 
Do we have a conclusion on this ? Looks like no one Acked it, and there was
a suggestion to provice a generic piece of code to retrieve the ucode version.
Turns out the ucode revision is already available via ucode_cpu_info[cpu].cpu_sig.rev
unless I am missing something.

Guenter

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