[v8,3/4] intel_idle: Provide the default enter_dead() handler

Recent Intel platforms require idle driver to provide information about
the MWAIT hint used to enter the deepest idle state in the play_dead
code.

Provide the default enter_dead() handler for all of the platforms and
allow overwriting with a custom handler for each platform if needed.

Signed-off-by: Patryk Wlazlyn <patryk.wlazlyn@linux.intel.com>
---
 drivers/idle/intel_idle.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

On Wed, Dec 4, 2024 at 3:08 PM Patryk Wlazlyn
<patryk.wlazlyn@linux.intel.com> wrote:
>
> Recent Intel platforms require idle driver to provide information about
> the MWAIT hint used to enter the deepest idle state in the play_dead
> code.
>
> Provide the default enter_dead() handler for all of the platforms and
> allow overwriting with a custom handler for each platform if needed.

My changelog for this patch:

"A subsequent change is going to make native_play_dead() rely on the
idle driver to put CPUs going offline into appropriate idle states.

For this reason, provide the default :enter_dead() handler for all of
the idle states on all platforms supported by intel_idle with an
option to override it with a custom handler if needed."

> Signed-off-by: Patryk Wlazlyn <patryk.wlazlyn@linux.intel.com>
> ---
>  drivers/idle/intel_idle.c | 18 ++++++++++++++++--
>  1 file changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
> index ac4d8faa3886..c6874a6dbe95 100644
> --- a/drivers/idle/intel_idle.c
> +++ b/drivers/idle/intel_idle.c
> @@ -56,6 +56,7 @@
>  #include <asm/mwait.h>
>  #include <asm/spec-ctrl.h>
>  #include <asm/fpu/api.h>
> +#include <asm/smp.h>
>
>  #define INTEL_IDLE_VERSION "0.5.1"
>
> @@ -227,6 +228,16 @@ static __cpuidle int intel_idle_s2idle(struct cpuidle_device *dev,
>         return 0;
>  }
>
> +static __cpuidle void intel_idle_enter_dead(struct cpuidle_device *dev,
> +                                           int index)
> +{
> +       struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
> +       struct cpuidle_state *state = &drv->states[index];
> +       unsigned long eax = flg2MWAIT(state->flags);
> +
> +       mwait_play_dead(eax);
> +}
> +
>  /*
>   * States are indexed by the cstate number,
>   * which is also the index into the MWAIT hint array.
> @@ -1798,6 +1809,7 @@ static void __init intel_idle_init_cstates_acpi(struct cpuidle_driver *drv)
>                         state->flags |= CPUIDLE_FLAG_TIMER_STOP;
>
>                 state->enter = intel_idle;
> +               state->enter_dead = intel_idle_enter_dead;
>                 state->enter_s2idle = intel_idle_s2idle;
>         }
>  }
> @@ -2143,10 +2155,12 @@ static void __init intel_idle_init_cstates_icpu(struct cpuidle_driver *drv)
>                 if (intel_idle_max_cstate_reached(cstate))
>                         break;
>
> -               if (!cpuidle_state_table[cstate].enter &&
> -                   !cpuidle_state_table[cstate].enter_s2idle)
> +               if (!cpuidle_state_table[cstate].enter)

I don't think that the above change belongs to this patch.  If I'm
mistaken, it should be mentioned in the changelog and the reason for
making it should be explained.

>                         break;
>
> +               if (!cpuidle_state_table[cstate].enter_dead)
> +                       cpuidle_state_table[cstate].enter_dead = intel_idle_enter_dead;
> +
>                 /* If marked as unusable, skip this state. */
>                 if (cpuidle_state_table[cstate].flags & CPUIDLE_FLAG_UNUSABLE) {
>                         pr_debug("state %s is disabled\n",
> --

Hi Patryk,

kernel test robot noticed the following build warnings:

[auto build test WARNING on rafael-pm/linux-next]
[also build test WARNING on rafael-pm/bleeding-edge linus/master v6.13-rc2 next-20241213]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Patryk-Wlazlyn/x86-smp-Allow-calling-mwait_play_dead-with-an-arbitrary-hint/20241204-221157
base:   https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next
patch link:    https://lore.kernel.org/r/20241204140828.11699-4-patryk.wlazlyn%40linux.intel.com
patch subject: [PATCH v8 3/4] intel_idle: Provide the default enter_dead() handler
config: x86_64-randconfig-071-20241216 (https://download.01.org/0day-ci/archive/20241216/202412160941.mXBc9usk-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241216/202412160941.mXBc9usk-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202412160941.mXBc9usk-lkp@intel.com/

All warnings (new ones prefixed by >>):

   vmlinux.o: warning: objtool: acpi_processor_ffh_play_dead+0xbe: mwait_play_dead() is missing a __noreturn annotation
>> vmlinux.o: warning: objtool: intel_idle_enter_dead+0x29: mwait_play_dead() is missing a __noreturn annotation