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[SRU,H,I,1/1] cpufreq: intel_pstate: Clear HWP desired on suspend/shutdown and offline

Message ID 20211117194435.175399-2-philip.cox@canonical.com
State New
Headers show
Series cpufreq: intel_pstate: Clear HWP desired on suspend/shutdown and offline | expand

Commit Message

Philip Cox Nov. 17, 2021, 7:44 p.m. UTC 
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>

BugLink: https://bugs.launchpad.net/bugs/1950584

Commit a365ab6b9dfb ("cpufreq: intel_pstate: Implement the
->adjust_perf() callback") caused intel_pstate to use nonzero HWP
desired values in certain usage scenarios, but it did not prevent
them from being leaked into the confugirations in which HWP desired
is expected to be 0.

The failing scenarios are switching the driver from the passive
mode to the active mode and starting a new kernel via kexec() while
intel_pstate is running in the passive mode.

To address this issue, ensure that HWP desired will be cleared on
offline and suspend/shutdown.

Fixes: a365ab6b9dfb ("cpufreq: intel_pstate: Implement the ->adjust_perf() callback")
Reported-by: Julia Lawall <julia.lawall@inria.fr>
Tested-by: Julia Lawall <julia.lawall@inria.fr>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
(cherry picked from commit dbea75fe18f60e364de6d994fc938a24ba249d81)
Signed-off-by: Philip Cox <philip.cox@canonical.com>
---
 drivers/cpufreq/intel_pstate.c | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

Comments

Stefan Bader Nov. 19, 2021, 8:35 a.m. UTC | #1 
On 17.11.21 20:44, Philip Cox wrote:
> From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1950584
> 
> Commit a365ab6b9dfb ("cpufreq: intel_pstate: Implement the
> ->adjust_perf() callback") caused intel_pstate to use nonzero HWP
> desired values in certain usage scenarios, but it did not prevent
> them from being leaked into the confugirations in which HWP desired
> is expected to be 0.
> 
> The failing scenarios are switching the driver from the passive
> mode to the active mode and starting a new kernel via kexec() while
> intel_pstate is running in the passive mode.
> 
> To address this issue, ensure that HWP desired will be cleared on
> offline and suspend/shutdown.
> 
> Fixes: a365ab6b9dfb ("cpufreq: intel_pstate: Implement the ->adjust_perf() callback")
> Reported-by: Julia Lawall <julia.lawall@inria.fr>
> Tested-by: Julia Lawall <julia.lawall@inria.fr>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> (cherry picked from commit dbea75fe18f60e364de6d994fc938a24ba249d81)
> Signed-off-by: Philip Cox <philip.cox@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
> ---
>   drivers/cpufreq/intel_pstate.c | 32 ++++++++++++++++++++++++++++++--
>   1 file changed, 30 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> index d483383dcfb9..d2089adcebc3 100644
> --- a/drivers/cpufreq/intel_pstate.c
> +++ b/drivers/cpufreq/intel_pstate.c
> @@ -910,9 +910,16 @@ static void intel_pstate_hwp_offline(struct cpudata *cpu)
>   		 */
>   		value &= ~GENMASK_ULL(31, 24);
>   		value |= HWP_ENERGY_PERF_PREFERENCE(cpu->epp_cached);
> -		WRITE_ONCE(cpu->hwp_req_cached, value);
>   	}
>   
> +	/*
> +	 * Clear the desired perf field in the cached HWP request value to
> +	 * prevent nonzero desired values from being leaked into the active
> +	 * mode.
> +	 */
> +	value &= ~HWP_DESIRED_PERF(~0L);
> +	WRITE_ONCE(cpu->hwp_req_cached, value);
> +
>   	value &= ~GENMASK_ULL(31, 0);
>   	min_perf = HWP_LOWEST_PERF(cpu->hwp_cap_cached);
>   
> @@ -2766,6 +2773,27 @@ static int intel_cpufreq_cpu_exit(struct cpufreq_policy *policy)
>   	return intel_pstate_cpu_exit(policy);
>   }
>   
> +static int intel_cpufreq_suspend(struct cpufreq_policy *policy)
> +{
> +	intel_pstate_suspend(policy);
> +
> +	if (hwp_active) {
> +		struct cpudata *cpu = all_cpu_data[policy->cpu];
> +		u64 value = READ_ONCE(cpu->hwp_req_cached);
> +
> +		/*
> +		 * Clear the desired perf field in MSR_HWP_REQUEST in case
> +		 * intel_cpufreq_adjust_perf() is in use and the last value
> +		 * written by it may not be suitable.
> +		 */
> +		value &= ~HWP_DESIRED_PERF(~0L);
> +		wrmsrl_on_cpu(cpu->cpu, MSR_HWP_REQUEST, value);
> +		WRITE_ONCE(cpu->hwp_req_cached, value);
> +	}
> +
> +	return 0;
> +}
> +
>   static struct cpufreq_driver intel_cpufreq = {
>   	.flags		= CPUFREQ_CONST_LOOPS,
>   	.verify		= intel_cpufreq_verify_policy,
> @@ -2775,7 +2803,7 @@ static struct cpufreq_driver intel_cpufreq = {
>   	.exit		= intel_cpufreq_cpu_exit,
>   	.offline	= intel_pstate_cpu_offline,
>   	.online		= intel_pstate_cpu_online,
> -	.suspend	= intel_pstate_suspend,
> +	.suspend	= intel_cpufreq_suspend,
>   	.resume		= intel_pstate_resume,
>   	.update_limits	= intel_pstate_update_limits,
>   	.name		= "intel_cpufreq",
>
diff mbox series

Patch

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index d483383dcfb9..d2089adcebc3 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -910,9 +910,16 @@  static void intel_pstate_hwp_offline(struct cpudata *cpu)
 		 */
 		value &= ~GENMASK_ULL(31, 24);
 		value |= HWP_ENERGY_PERF_PREFERENCE(cpu->epp_cached);
-		WRITE_ONCE(cpu->hwp_req_cached, value);
 	}
 
+	/*
+	 * Clear the desired perf field in the cached HWP request value to
+	 * prevent nonzero desired values from being leaked into the active
+	 * mode.
+	 */
+	value &= ~HWP_DESIRED_PERF(~0L);
+	WRITE_ONCE(cpu->hwp_req_cached, value);
+
 	value &= ~GENMASK_ULL(31, 0);
 	min_perf = HWP_LOWEST_PERF(cpu->hwp_cap_cached);
 
@@ -2766,6 +2773,27 @@  static int intel_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 	return intel_pstate_cpu_exit(policy);
 }
 
+static int intel_cpufreq_suspend(struct cpufreq_policy *policy)
+{
+	intel_pstate_suspend(policy);
+
+	if (hwp_active) {
+		struct cpudata *cpu = all_cpu_data[policy->cpu];
+		u64 value = READ_ONCE(cpu->hwp_req_cached);
+
+		/*
+		 * Clear the desired perf field in MSR_HWP_REQUEST in case
+		 * intel_cpufreq_adjust_perf() is in use and the last value
+		 * written by it may not be suitable.
+		 */
+		value &= ~HWP_DESIRED_PERF(~0L);
+		wrmsrl_on_cpu(cpu->cpu, MSR_HWP_REQUEST, value);
+		WRITE_ONCE(cpu->hwp_req_cached, value);
+	}
+
+	return 0;
+}
+
 static struct cpufreq_driver intel_cpufreq = {
 	.flags		= CPUFREQ_CONST_LOOPS,
 	.verify		= intel_cpufreq_verify_policy,
@@ -2775,7 +2803,7 @@  static struct cpufreq_driver intel_cpufreq = {
 	.exit		= intel_cpufreq_cpu_exit,
 	.offline	= intel_pstate_cpu_offline,
 	.online		= intel_pstate_cpu_online,
-	.suspend	= intel_pstate_suspend,
+	.suspend	= intel_cpufreq_suspend,
 	.resume		= intel_pstate_resume,
 	.update_limits	= intel_pstate_update_limits,
 	.name		= "intel_cpufreq",