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

[Ricardo Neri]

On Tue, Mar 10, 2026 at 10:35:30AM +0100, Borislav Petkov wrote:
> 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 */

Thank you very much for your comments, Boris!

> >  #define X86_FEATURE_HFI			(14*32+19) /* "hfi" Hardware Feedback Interface */
> 
> Leave a space here to denote there's a hole

Sure.

> 
> > +#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." :)

Indeed, I had the feeling.

> 
> 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?

Sure, I will take your suggestion.

> 
> >  /* 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)

Would it be OK to name it THERM_DPTI_ENABLE? It would be more consistent
with the naming of the other bits.

> 
> >  
> >  #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

Same here, would it be OK to name it PACKAGE_THERM_DPTI_ACK for consistency
with other bits' names?

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

Sure.

Thanks and BR,
Ricardo