diff mbox series

[V12,4/7] cpufreq: Add a notification message that the highest perf has changed

Message ID 20231205063537.872834-5-li.meng@amd.com
State New
Headers show
Series amd-pstate preferred core | expand

Commit Message

Meng, Li (Jassmine) Dec. 5, 2023, 6:35 a.m. UTC
ACPI 6.5 section 8.4.6.1.1.1 specifies that Notify event 0x85 can be
emmitted to cause the the OSPM to re-evaluate the highest performance
register. Add support for this event.

Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Perry Yuan <perry.yuan@amd.com>
Signed-off-by: Meng Li <li.meng@amd.com>
Link: https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model.html#processor-device-notification-values
---
 drivers/acpi/processor_driver.c |  6 ++++++
 drivers/cpufreq/cpufreq.c       | 13 +++++++++++++
 include/linux/cpufreq.h         |  5 +++++
 3 files changed, 24 insertions(+)

Comments

Rafael J. Wysocki Dec. 6, 2023, 9:13 p.m. UTC | #1
On Wed, Dec 6, 2023 at 9:58 PM Rafael J. Wysocki <rafael@kernel.org> wrote:
>
> On Tue, Dec 5, 2023 at 7:38 AM Meng Li <li.meng@amd.com> wrote:
> >
> > ACPI 6.5 section 8.4.6.1.1.1 specifies that Notify event 0x85 can be
> > emmitted to cause the the OSPM to re-evaluate the highest performance
>
> Typos above.  Given the number of iterations of this patch, this is
> kind of disappointing.
>
> > register. Add support for this event.
>
> Also it would be nice to describe how this is supposed to work at
> least roughly, so it is not necessary to reverse-engineer the patch to
> find out that.
>
> > Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> > Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
> > Reviewed-by: Huang Rui <ray.huang@amd.com>
> > Reviewed-by: Perry Yuan <perry.yuan@amd.com>
> > Signed-off-by: Meng Li <li.meng@amd.com>
> > Link: https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model.html#processor-device-notification-values
> > ---
> >  drivers/acpi/processor_driver.c |  6 ++++++
> >  drivers/cpufreq/cpufreq.c       | 13 +++++++++++++
> >  include/linux/cpufreq.h         |  5 +++++
> >  3 files changed, 24 insertions(+)
> >
> > diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
> > index 4bd16b3f0781..29b2fb68a35d 100644
> > --- a/drivers/acpi/processor_driver.c
> > +++ b/drivers/acpi/processor_driver.c
> > @@ -27,6 +27,7 @@
> >  #define ACPI_PROCESSOR_NOTIFY_PERFORMANCE 0x80
> >  #define ACPI_PROCESSOR_NOTIFY_POWER    0x81
> >  #define ACPI_PROCESSOR_NOTIFY_THROTTLING       0x82
> > +#define ACPI_PROCESSOR_NOTIFY_HIGEST_PERF_CHANGED      0x85
> >
> >  MODULE_AUTHOR("Paul Diefenbaugh");
> >  MODULE_DESCRIPTION("ACPI Processor Driver");
> > @@ -83,6 +84,11 @@ static void acpi_processor_notify(acpi_handle handle, u32 event, void *data)
> >                 acpi_bus_generate_netlink_event(device->pnp.device_class,
> >                                                   dev_name(&device->dev), event, 0);
> >                 break;
> > +       case ACPI_PROCESSOR_NOTIFY_HIGEST_PERF_CHANGED:
> > +               cpufreq_update_highest_perf(pr->id);
>
> And the design appears to be a bit ad-hoc here.
>
> Because why does it have anything to do with cpufreq?

Well, clearly, cpufreq can be affected by this, but why would it be
not affected the same way as in the ACPI_PROCESSOR_NOTIFY_PERFORMANCE
case?

That is, why isn't cpufreq_update_limits() the right thing to do?
Rafael J. Wysocki Dec. 12, 2023, 1:43 p.m. UTC | #2
On Wed, Dec 6, 2023 at 10:13 PM Rafael J. Wysocki <rafael@kernel.org> wrote:
>
> On Wed, Dec 6, 2023 at 9:58 PM Rafael J. Wysocki <rafael@kernel.org> wrote:
> >
> > On Tue, Dec 5, 2023 at 7:38 AM Meng Li <li.meng@amd.com> wrote:
> > >
> > > ACPI 6.5 section 8.4.6.1.1.1 specifies that Notify event 0x85 can be
> > > emmitted to cause the the OSPM to re-evaluate the highest performance
> >
> > Typos above.  Given the number of iterations of this patch, this is
> > kind of disappointing.
> >
> > > register. Add support for this event.
> >
> > Also it would be nice to describe how this is supposed to work at
> > least roughly, so it is not necessary to reverse-engineer the patch to
> > find out that.
> >
> > > Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> > > Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
> > > Reviewed-by: Huang Rui <ray.huang@amd.com>
> > > Reviewed-by: Perry Yuan <perry.yuan@amd.com>
> > > Signed-off-by: Meng Li <li.meng@amd.com>
> > > Link: https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model.html#processor-device-notification-values
> > > ---
> > >  drivers/acpi/processor_driver.c |  6 ++++++
> > >  drivers/cpufreq/cpufreq.c       | 13 +++++++++++++
> > >  include/linux/cpufreq.h         |  5 +++++
> > >  3 files changed, 24 insertions(+)
> > >
> > > diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
> > > index 4bd16b3f0781..29b2fb68a35d 100644
> > > --- a/drivers/acpi/processor_driver.c
> > > +++ b/drivers/acpi/processor_driver.c
> > > @@ -27,6 +27,7 @@
> > >  #define ACPI_PROCESSOR_NOTIFY_PERFORMANCE 0x80
> > >  #define ACPI_PROCESSOR_NOTIFY_POWER    0x81
> > >  #define ACPI_PROCESSOR_NOTIFY_THROTTLING       0x82
> > > +#define ACPI_PROCESSOR_NOTIFY_HIGEST_PERF_CHANGED      0x85
> > >
> > >  MODULE_AUTHOR("Paul Diefenbaugh");
> > >  MODULE_DESCRIPTION("ACPI Processor Driver");
> > > @@ -83,6 +84,11 @@ static void acpi_processor_notify(acpi_handle handle, u32 event, void *data)
> > >                 acpi_bus_generate_netlink_event(device->pnp.device_class,
> > >                                                   dev_name(&device->dev), event, 0);
> > >                 break;
> > > +       case ACPI_PROCESSOR_NOTIFY_HIGEST_PERF_CHANGED:
> > > +               cpufreq_update_highest_perf(pr->id);
> >
> > And the design appears to be a bit ad-hoc here.
> >
> > Because why does it have anything to do with cpufreq?
>
> Well, clearly, cpufreq can be affected by this, but why would it be
> not affected the same way as in the ACPI_PROCESSOR_NOTIFY_PERFORMANCE
> case?
>
> That is, why isn't cpufreq_update_limits() the right thing to do?

Seriously, I'm not going to apply this patch so long as my comments
above are not addressed.
Meng, Li (Jassmine) Dec. 26, 2023, 8:26 a.m. UTC | #3
[AMD Official Use Only - General]

Hi Rafael:

> -----Original Message-----
> From: Rafael J. Wysocki <rafael@kernel.org>
> Sent: Tuesday, December 12, 2023 9:44 PM
> To: Meng, Li (Jassmine) <Li.Meng@amd.com>
> Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>; Huang, Ray
> <Ray.Huang@amd.com>; linux-pm@vger.kernel.org; linux-
> kernel@vger.kernel.org; x86@kernel.org; linux-acpi@vger.kernel.org; Shuah
> Khan <skhan@linuxfoundation.org>; linux-kselftest@vger.kernel.org;
> Fontenot, Nathan <Nathan.Fontenot@amd.com>; Sharma, Deepak
> <Deepak.Sharma@amd.com>; Deucher, Alexander
> <Alexander.Deucher@amd.com>; Limonciello, Mario
> <Mario.Limonciello@amd.com>; Huang, Shimmer
> <Shimmer.Huang@amd.com>; Yuan, Perry <Perry.Yuan@amd.com>; Du,
> Xiaojian <Xiaojian.Du@amd.com>; Viresh Kumar <viresh.kumar@linaro.org>;
> Borislav Petkov <bp@alien8.de>; Oleksandr Natalenko
> <oleksandr@natalenko.name>
> Subject: Re: [PATCH V12 4/7] cpufreq: Add a notification message that the
> highest perf has changed
>
> Caution: This message originated from an External Source. Use proper
> caution when opening attachments, clicking links, or responding.
>
>
> On Wed, Dec 6, 2023 at 10:13 PM Rafael J. Wysocki <rafael@kernel.org>
> wrote:
> >
> > On Wed, Dec 6, 2023 at 9:58 PM Rafael J. Wysocki <rafael@kernel.org>
> wrote:
> > >
> > > On Tue, Dec 5, 2023 at 7:38 AM Meng Li <li.meng@amd.com> wrote:
> > > >
> > > > ACPI 6.5 section 8.4.6.1.1.1 specifies that Notify event 0x85 can
> > > > be emmitted to cause the the OSPM to re-evaluate the highest
> > > > performance
> > >
> > > Typos above.  Given the number of iterations of this patch, this is
> > > kind of disappointing.
> > >
> > > > register. Add support for this event.
> > >
> > > Also it would be nice to describe how this is supposed to work at
> > > least roughly, so it is not necessary to reverse-engineer the patch
> > > to find out that.
> > >
> > > > Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> > > > Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
> > > > Reviewed-by: Huang Rui <ray.huang@amd.com>
> > > > Reviewed-by: Perry Yuan <perry.yuan@amd.com>
> > > > Signed-off-by: Meng Li <li.meng@amd.com>
> > > > Link:
> > > >
> https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model
> > > > .html#processor-device-notification-values
> > > > ---
> > > >  drivers/acpi/processor_driver.c |  6 ++++++
> > > >  drivers/cpufreq/cpufreq.c       | 13 +++++++++++++
> > > >  include/linux/cpufreq.h         |  5 +++++
> > > >  3 files changed, 24 insertions(+)
> > > >
> > > > diff --git a/drivers/acpi/processor_driver.c
> > > > b/drivers/acpi/processor_driver.c index 4bd16b3f0781..29b2fb68a35d
> > > > 100644
> > > > --- a/drivers/acpi/processor_driver.c
> > > > +++ b/drivers/acpi/processor_driver.c
> > > > @@ -27,6 +27,7 @@
> > > >  #define ACPI_PROCESSOR_NOTIFY_PERFORMANCE 0x80
> > > >  #define ACPI_PROCESSOR_NOTIFY_POWER    0x81
> > > >  #define ACPI_PROCESSOR_NOTIFY_THROTTLING       0x82
> > > > +#define ACPI_PROCESSOR_NOTIFY_HIGEST_PERF_CHANGED      0x85
> > > >
> > > >  MODULE_AUTHOR("Paul Diefenbaugh");
> MODULE_DESCRIPTION("ACPI
> > > > Processor Driver"); @@ -83,6 +84,11 @@ static void
> > > > acpi_processor_notify(acpi_handle handle, u32 event, void *data)
> > > >                 acpi_bus_generate_netlink_event(device->pnp.device_class,
> > > >                                                   dev_name(&device->dev), event, 0);
> > > >                 break;
> > > > +       case ACPI_PROCESSOR_NOTIFY_HIGEST_PERF_CHANGED:
> > > > +               cpufreq_update_highest_perf(pr->id);
> > >
> > > And the design appears to be a bit ad-hoc here.
> > >
> > > Because why does it have anything to do with cpufreq?
> >
> > Well, clearly, cpufreq can be affected by this, but why would it be
> > not affected the same way as in the
> ACPI_PROCESSOR_NOTIFY_PERFORMANCE
> > case?
> >
> > That is, why isn't cpufreq_update_limits() the right thing to do?
>
> Seriously, I'm not going to apply this patch so long as my comments above
> are not addressed.
[Meng, Li (Jassmine)]
Sorry for the delayed reply to the email.
BIOS/AGESA is responsible to issue the Notify 0x85 to OS that the preferred core has changed.
It will only affect the ranking of the preferred core, not the impact policy limits.
AMD P-state driver will set the priority of the cores based on the preferred core ranking, and prioritize selecting higher priority core to run the task.
Meng, Li (Jassmine) Dec. 27, 2023, 1:40 a.m. UTC | #4
[AMD Official Use Only - General]

Hi Rafael:

> -----Original Message-----
> From: Meng, Li (Jassmine)
> Sent: Tuesday, December 26, 2023 4:27 PM
> To: Rafael J. Wysocki <rafael@kernel.org>
> Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>; Huang, Ray
> <Ray.Huang@amd.com>; linux-pm@vger.kernel.org; linux-
> kernel@vger.kernel.org; x86@kernel.org; linux-acpi@vger.kernel.org; Shuah
> Khan <skhan@linuxfoundation.org>; linux-kselftest@vger.kernel.org;
> Fontenot, Nathan <Nathan.Fontenot@amd.com>; Sharma, Deepak
> <Deepak.Sharma@amd.com>; Deucher, Alexander
> <Alexander.Deucher@amd.com>; Limonciello, Mario
> <Mario.Limonciello@amd.com>; Huang, Shimmer
> <Shimmer.Huang@amd.com>; Yuan, Perry <Perry.Yuan@amd.com>; Du,
> Xiaojian <Xiaojian.Du@amd.com>; Viresh Kumar <viresh.kumar@linaro.org>;
> Borislav Petkov <bp@alien8.de>; Oleksandr Natalenko
> <oleksandr@natalenko.name>
> Subject: RE: [PATCH V12 4/7] cpufreq: Add a notification message that the
> highest perf has changed
>
> Hi Rafael:
>
> > -----Original Message-----
> > From: Rafael J. Wysocki <rafael@kernel.org>
> > Sent: Tuesday, December 12, 2023 9:44 PM
> > To: Meng, Li (Jassmine) <Li.Meng@amd.com>
> > Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>; Huang, Ray
> > <Ray.Huang@amd.com>; linux-pm@vger.kernel.org; linux-
> > kernel@vger.kernel.org; x86@kernel.org; linux-acpi@vger.kernel.org;
> > Shuah Khan <skhan@linuxfoundation.org>;
> > linux-kselftest@vger.kernel.org; Fontenot, Nathan
> > <Nathan.Fontenot@amd.com>; Sharma, Deepak
> <Deepak.Sharma@amd.com>;
> > Deucher, Alexander <Alexander.Deucher@amd.com>; Limonciello, Mario
> > <Mario.Limonciello@amd.com>; Huang, Shimmer
> <Shimmer.Huang@amd.com>;
> > Yuan, Perry <Perry.Yuan@amd.com>; Du, Xiaojian
> <Xiaojian.Du@amd.com>;
> > Viresh Kumar <viresh.kumar@linaro.org>; Borislav Petkov
> > <bp@alien8.de>; Oleksandr Natalenko <oleksandr@natalenko.name>
> > Subject: Re: [PATCH V12 4/7] cpufreq: Add a notification message that
> > the highest perf has changed
> >
> > Caution: This message originated from an External Source. Use proper
> > caution when opening attachments, clicking links, or responding.
> >
> >
> > On Wed, Dec 6, 2023 at 10:13 PM Rafael J. Wysocki <rafael@kernel.org>
> > wrote:
> > >
> > > On Wed, Dec 6, 2023 at 9:58 PM Rafael J. Wysocki <rafael@kernel.org>
> > wrote:
> > > >
> > > > On Tue, Dec 5, 2023 at 7:38 AM Meng Li <li.meng@amd.com> wrote:
> > > > >
> > > > > ACPI 6.5 section 8.4.6.1.1.1 specifies that Notify event 0x85
> > > > > can be emmitted to cause the the OSPM to re-evaluate the highest
> > > > > performance
> > > >
> > > > Typos above.  Given the number of iterations of this patch, this
> > > > is kind of disappointing.
> > > >
> > > > > register. Add support for this event.
> > > >
> > > > Also it would be nice to describe how this is supposed to work at
> > > > least roughly, so it is not necessary to reverse-engineer the
> > > > patch to find out that.
> > > >
> > > > > Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> > > > > Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
> > > > > Reviewed-by: Huang Rui <ray.huang@amd.com>
> > > > > Reviewed-by: Perry Yuan <perry.yuan@amd.com>
> > > > > Signed-off-by: Meng Li <li.meng@amd.com>
> > > > > Link:
> > > > >
> > https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model
> > > > > .html#processor-device-notification-values
> > > > > ---
> > > > >  drivers/acpi/processor_driver.c |  6 ++++++
> > > > >  drivers/cpufreq/cpufreq.c       | 13 +++++++++++++
> > > > >  include/linux/cpufreq.h         |  5 +++++
> > > > >  3 files changed, 24 insertions(+)
> > > > >
> > > > > diff --git a/drivers/acpi/processor_driver.c
> > > > > b/drivers/acpi/processor_driver.c index
> > > > > 4bd16b3f0781..29b2fb68a35d
> > > > > 100644
> > > > > --- a/drivers/acpi/processor_driver.c
> > > > > +++ b/drivers/acpi/processor_driver.c
> > > > > @@ -27,6 +27,7 @@
> > > > >  #define ACPI_PROCESSOR_NOTIFY_PERFORMANCE 0x80
> > > > >  #define ACPI_PROCESSOR_NOTIFY_POWER    0x81
> > > > >  #define ACPI_PROCESSOR_NOTIFY_THROTTLING       0x82
> > > > > +#define ACPI_PROCESSOR_NOTIFY_HIGEST_PERF_CHANGED
> 0x85
> > > > >
> > > > >  MODULE_AUTHOR("Paul Diefenbaugh");
> > MODULE_DESCRIPTION("ACPI
> > > > > Processor Driver"); @@ -83,6 +84,11 @@ static void
> > > > > acpi_processor_notify(acpi_handle handle, u32 event, void *data)
> > > > >                 acpi_bus_generate_netlink_event(device->pnp.device_class,
> > > > >                                                   dev_name(&device->dev), event, 0);
> > > > >                 break;
> > > > > +       case ACPI_PROCESSOR_NOTIFY_HIGEST_PERF_CHANGED:
> > > > > +               cpufreq_update_highest_perf(pr->id);
> > > >
> > > > And the design appears to be a bit ad-hoc here.
> > > >
> > > > Because why does it have anything to do with cpufreq?
> > >
> > > Well, clearly, cpufreq can be affected by this, but why would it be
> > > not affected the same way as in the
> > ACPI_PROCESSOR_NOTIFY_PERFORMANCE
> > > case?
> > >
> > > That is, why isn't cpufreq_update_limits() the right thing to do?
> >
> > Seriously, I'm not going to apply this patch so long as my comments
> > above are not addressed.
> [Meng, Li (Jassmine)]
> Sorry for the delayed reply to the email.
> BIOS/AGESA is responsible to issue the Notify 0x85 to OS that the preferred
> core has changed.
> It will only affect the ranking of the preferred core, not the impact policy
> limits.
> AMD P-state driver will set the priority of the cores based on the preferred
> core ranking, and prioritize selecting higher priority core to run the task.
[Meng, Li (Jassmine)]
From ACPI v6.5, Table 5.197 Processor Device Notification Values:
Hex value               Description
0x80                    Performance Present Capabilities Changed. Used to notify OSPM that the number of supported processor performance states has changed. This notification causes OSPM to re-evaluate the _PPC object. See Section 8.4.5.3 for more information.

0x85                    Highest Performance Changed. Used to notify OSPM that the value of the CPPC Highest Performance Register has changed.

I think they are different notify events, so they need different functions to handle these events.

Also see: https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model.html#processor-device-notification-values
diff mbox series

Patch

diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
index 4bd16b3f0781..29b2fb68a35d 100644
--- a/drivers/acpi/processor_driver.c
+++ b/drivers/acpi/processor_driver.c
@@ -27,6 +27,7 @@ 
 #define ACPI_PROCESSOR_NOTIFY_PERFORMANCE 0x80
 #define ACPI_PROCESSOR_NOTIFY_POWER	0x81
 #define ACPI_PROCESSOR_NOTIFY_THROTTLING	0x82
+#define ACPI_PROCESSOR_NOTIFY_HIGEST_PERF_CHANGED	0x85
 
 MODULE_AUTHOR("Paul Diefenbaugh");
 MODULE_DESCRIPTION("ACPI Processor Driver");
@@ -83,6 +84,11 @@  static void acpi_processor_notify(acpi_handle handle, u32 event, void *data)
 		acpi_bus_generate_netlink_event(device->pnp.device_class,
 						  dev_name(&device->dev), event, 0);
 		break;
+	case ACPI_PROCESSOR_NOTIFY_HIGEST_PERF_CHANGED:
+		cpufreq_update_highest_perf(pr->id);
+		acpi_bus_generate_netlink_event(device->pnp.device_class,
+						  dev_name(&device->dev), event, 0);
+		break;
 	default:
 		acpi_handle_debug(handle, "Unsupported event [0x%x]\n", event);
 		break;
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 934d35f570b7..14a4cbc6dd05 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -2717,6 +2717,19 @@  void cpufreq_update_limits(unsigned int cpu)
 }
 EXPORT_SYMBOL_GPL(cpufreq_update_limits);
 
+/**
+ * cpufreq_update_highest_perf - Update highest performance for a given CPU.
+ * @cpu: CPU to update the highest performance for.
+ *
+ * Invoke the driver's ->update_highest_perf callback if present
+ */
+void cpufreq_update_highest_perf(unsigned int cpu)
+{
+	if (cpufreq_driver->update_highest_perf)
+		cpufreq_driver->update_highest_perf(cpu);
+}
+EXPORT_SYMBOL_GPL(cpufreq_update_highest_perf);
+
 /*********************************************************************
  *               BOOST						     *
  *********************************************************************/
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 1c5ca92a0555..f62257b2a42f 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -235,6 +235,7 @@  int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu);
 void refresh_frequency_limits(struct cpufreq_policy *policy);
 void cpufreq_update_policy(unsigned int cpu);
 void cpufreq_update_limits(unsigned int cpu);
+void cpufreq_update_highest_perf(unsigned int cpu);
 bool have_governor_per_policy(void);
 bool cpufreq_supports_freq_invariance(void);
 struct kobject *get_governor_parent_kobj(struct cpufreq_policy *policy);
@@ -263,6 +264,7 @@  static inline bool cpufreq_supports_freq_invariance(void)
 	return false;
 }
 static inline void disable_cpufreq(void) { }
+static inline void cpufreq_update_highest_perf(unsigned int cpu) { }
 #endif
 
 #ifdef CONFIG_CPU_FREQ_STAT
@@ -380,6 +382,9 @@  struct cpufreq_driver {
 	/* Called to update policy limits on firmware notifications. */
 	void		(*update_limits)(unsigned int cpu);
 
+	/* Called to update highest performance on firmware notifications. */
+	void		(*update_highest_perf)(unsigned int cpu);
+
 	/* optional */
 	int		(*bios_limit)(int cpu, unsigned int *limit);