Re: [PATCH 1/4] x86/thermal: Add bit definitions for Intel Directed Package Thermal Interrupt

[Borislav Petkov]

On Mon, Mar 09, 2026 at 03:19:24PM -0700, Ricardo Neri wrote:
> Add CPUID and MSR bit definitions required to support Intel Directed
> Package Thermal Interrupts.
> 
> A CPU requests directed package-level thermal interrupts by setting bit 25
> in IA32_THERM_INTERRUPT. Hardware acknowledges by setting bit 25 in
> IA32_PACKAGE_THERM_STATUS, indicating that only CPUs that opted in will
> receive the interrupt. If no CPU in the package requests it, delivery
> falls back to broadcast.
> 
> Signed-off-by: Ricardo Neri <ricardo.neri-calderon@xxxxxxxxxxxxxxx>
> ---
>  arch/x86/include/asm/cpufeatures.h | 1 +
>  arch/x86/include/asm/msr-index.h   | 2 ++
>  2 files changed, 3 insertions(+)
> 
> diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
> index dbe104df339b..487bf9da0cef 100644
> --- a/arch/x86/include/asm/cpufeatures.h
> +++ b/arch/x86/include/asm/cpufeatures.h
> @@ -364,6 +364,7 @@
>  #define X86_FEATURE_HWP_PKG_REQ		(14*32+11) /* "hwp_pkg_req" HWP Package Level Request */
>  #define X86_FEATURE_HWP_HIGHEST_PERF_CHANGE (14*32+15) /* HWP Highest perf change */
>  #define X86_FEATURE_HFI			(14*32+19) /* "hfi" Hardware Feedback Interface */

Leave a space here to denote there's a hole

> +#define X86_FEATURE_DIRECTED_PKG_THRM_INTR (14*32+24) /* Intel Directed Package Thermal Interrupt */

Also, can we agree on one naming and stick to it?

What you have there basically screams "OMG, I am trying to say *everything*
in that single define name but there's no room." :)

Also, the defines you have here are all a little bit different and good luck
matching what is what in a couple of months.

So, how about

#define X86_FEATURE_DPTI	 (14*32+24) /* Intel Directed Package Thermal Interrupt */

and the comment explains what the acronym is?

>  /* AMD SVM Feature Identification, CPUID level 0x8000000a (EDX), word 15 */
>  #define X86_FEATURE_NPT			(15*32+ 0) /* "npt" Nested Page Table support */
> diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
> index 6673601246b3..aa1c652a9581 100644
> --- a/arch/x86/include/asm/msr-index.h
> +++ b/arch/x86/include/asm/msr-index.h
> @@ -995,6 +995,7 @@
>  #define THERM_INT_HIGH_ENABLE		(1 << 0)
>  #define THERM_INT_LOW_ENABLE		(1 << 1)
>  #define THERM_INT_PLN_ENABLE		(1 << 24)
> +#define THERM_DIRECTED_INTR_ENABLE	(1 << 25)

And then you can do:

#define DPTI_ENABLE	(1 << 25)

>  
>  #define MSR_IA32_THERM_STATUS		0x0000019c
>  
> @@ -1024,6 +1025,7 @@
>  
>  #define PACKAGE_THERM_STATUS_PROCHOT		(1 << 0)
>  #define PACKAGE_THERM_STATUS_POWER_LIMIT	(1 << 10)
> +#define PACKAGE_THERM_STATUS_DIRECTED_INTR_ACK	(1 << 25)

Ditto here:

	DPTI_ACK

And you can always add comments explaining the acronym...

-- 
Regards/Gruss,
    Boris.

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