[PATCH v2 1/2] cpufreq/amd-pstate: Push adjust_perf vfunc init into cpu_init

[PATCH v2 1/2] cpufreq/amd-pstate: Push adjust_perf vfunc init into cpu_init

[Mario Limonciello]

From: Mario Limonciello <mario.limonciello@amd.com>

As the driver can be changed in and out of different modes it's possible
that adjust_perf is assigned when it shouldn't be.

This could happen if an MSR design is started up in passive mode and then
switches to active mode.

To solve this explicitly clear `adjust_perf` in amd_pstate_epp_cpu_init().

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
Cc: Klara Modin <klarasmodin@gmail.com>
 drivers/cpufreq/amd-pstate.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 206725219d8c9..e480da818d6f5 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -1504,6 +1504,8 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
 		WRITE_ONCE(cpudata->cppc_cap1_cached, value);
 	}
 
+	current_pstate_driver->adjust_perf = NULL;
+
 	return 0;
 
 free_cpudata1:
@@ -1866,8 +1868,6 @@ static int __init amd_pstate_init(void)
 	/* capability check */
 	if (cpu_feature_enabled(X86_FEATURE_CPPC)) {
 		pr_debug("AMD CPPC MSR based functionality is supported\n");
-		if (cppc_state != AMD_PSTATE_ACTIVE)
-			current_pstate_driver->adjust_perf = amd_pstate_adjust_perf;
 	} else {
 		pr_debug("AMD CPPC shared memory based functionality is supported\n");
 		static_call_update(amd_pstate_cppc_enable, shmem_cppc_enable);
-- 
2.43.0

[PATCH v2 2/2] cpufreq/amd-pstate: Move registration after static function call update

[Mario Limonciello]

From: Mario Limonciello <mario.limonciello@amd.com>

On shared memory designs the static functions need to work before
registration is done or the system can hang at bootup.

Move the registration later in amd_pstate_init() to solve this.

Fixes: e238968a2087 ("cpufreq/amd-pstate: Remove the redundant amd_pstate_set_driver() call")
Reported-by: Klara Modin <klarasmodin@gmail.com>
Closes: https://lore.kernel.org/linux-pm/cf9c146d-bacf-444e-92e2-15ebf513af96@gmail.com/#t
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 drivers/cpufreq/amd-pstate.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index e480da818d6f5..f834cc8205e2a 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -1859,12 +1859,6 @@ static int __init amd_pstate_init(void)
 		return -ENODEV;
 	}
 
-	ret = amd_pstate_register_driver(cppc_state);
-	if (ret) {
-		pr_err("failed to register with return %d\n", ret);
-		return ret;
-	}
-
 	/* capability check */
 	if (cpu_feature_enabled(X86_FEATURE_CPPC)) {
 		pr_debug("AMD CPPC MSR based functionality is supported\n");
@@ -1875,6 +1869,12 @@ static int __init amd_pstate_init(void)
 		static_call_update(amd_pstate_update_perf, shmem_update_perf);
 	}
 
+	ret = amd_pstate_register_driver(cppc_state);
+	if (ret) {
+		pr_err("failed to register with return %d\n", ret);
+		return ret;
+	}
+
 	if (amd_pstate_prefcore) {
 		ret = amd_detect_prefcore(&amd_pstate_prefcore);
 		if (ret)
-- 
2.43.0

Re: [PATCH v2 1/2] cpufreq/amd-pstate: Push adjust_perf vfunc init into cpu_init

[Klara Modin]

On 2024-10-28 15:55, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello@amd.com>
> 
> As the driver can be changed in and out of different modes it's possible
> that adjust_perf is assigned when it shouldn't be.
> 
> This could happen if an MSR design is started up in passive mode and then
> switches to active mode.
> 
> To solve this explicitly clear `adjust_perf` in amd_pstate_epp_cpu_init().
> 
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
> Cc: Klara Modin <klarasmodin@gmail.com>
>   drivers/cpufreq/amd-pstate.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 206725219d8c9..e480da818d6f5 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -1504,6 +1504,8 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
>   		WRITE_ONCE(cpudata->cppc_cap1_cached, value);
>   	}
>   
> +	current_pstate_driver->adjust_perf = NULL;
> +
>   	return 0;
>   
>   free_cpudata1:
> @@ -1866,8 +1868,6 @@ static int __init amd_pstate_init(void)
>   	/* capability check */
>   	if (cpu_feature_enabled(X86_FEATURE_CPPC)) {
>   		pr_debug("AMD CPPC MSR based functionality is supported\n");
> -		if (cppc_state != AMD_PSTATE_ACTIVE)
> -			current_pstate_driver->adjust_perf = amd_pstate_adjust_perf;
>   	} else {
>   		pr_debug("AMD CPPC shared memory based functionality is supported\n");
>   		static_call_update(amd_pstate_cppc_enable, shmem_cppc_enable);

Both of these patches together also fix the problem I had.

Thanks,
Tested-by: Klara Modin <klarasmodin@gmail.com>

Re: [PATCH v2 1/2] cpufreq/amd-pstate: Push adjust_perf vfunc init into cpu_init

[Dhananjay Ugwekar]

On 10/28/2024 8:25 PM, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello@amd.com>
> 
> As the driver can be changed in and out of different modes it's possible
> that adjust_perf is assigned when it shouldn't be.
> 
> This could happen if an MSR design is started up in passive mode and then
> switches to active mode.
> 
> To solve this explicitly clear `adjust_perf` in amd_pstate_epp_cpu_init().
>

Great, this solves the overlooked issue as well, looks good to me.

You may also add,
Tested-by: Dhananjay Ugwekar <dhananjay.ugwekar@amd.com>

Thanks,
Dhananjay
 
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
> Cc: Klara Modin <klarasmodin@gmail.com>
>  drivers/cpufreq/amd-pstate.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 206725219d8c9..e480da818d6f5 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -1504,6 +1504,8 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
>  		WRITE_ONCE(cpudata->cppc_cap1_cached, value);
>  	}
>  
> +	current_pstate_driver->adjust_perf = NULL;
> +
>  	return 0;
>  
>  free_cpudata1:
> @@ -1866,8 +1868,6 @@ static int __init amd_pstate_init(void)
>  	/* capability check */
>  	if (cpu_feature_enabled(X86_FEATURE_CPPC)) {
>  		pr_debug("AMD CPPC MSR based functionality is supported\n");
> -		if (cppc_state != AMD_PSTATE_ACTIVE)
> -			current_pstate_driver->adjust_perf = amd_pstate_adjust_perf;
>  	} else {
>  		pr_debug("AMD CPPC shared memory based functionality is supported\n");
>  		static_call_update(amd_pstate_cppc_enable, shmem_cppc_enable);

Re: [PATCH v2 2/2] cpufreq/amd-pstate: Move registration after static function call update

[Dhananjay Ugwekar]

On 10/28/2024 8:25 PM, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello@amd.com>
> 
> On shared memory designs the static functions need to work before
> registration is done or the system can hang at bootup.
> 
> Move the registration later in amd_pstate_init() to solve this.

Looks good to me.
Also, 
Tested-by: Dhananjay Ugwekar <dhananjay.ugwekar@amd.com>

Thanks,
Dhananjay

> 
> Fixes: e238968a2087 ("cpufreq/amd-pstate: Remove the redundant amd_pstate_set_driver() call")
> Reported-by: Klara Modin <klarasmodin@gmail.com>
> Closes: https://lore.kernel.org/linux-pm/cf9c146d-bacf-444e-92e2-15ebf513af96@gmail.com/#t
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
>  drivers/cpufreq/amd-pstate.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index e480da818d6f5..f834cc8205e2a 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -1859,12 +1859,6 @@ static int __init amd_pstate_init(void)
>  		return -ENODEV;
>  	}
>  
> -	ret = amd_pstate_register_driver(cppc_state);
> -	if (ret) {
> -		pr_err("failed to register with return %d\n", ret);
> -		return ret;
> -	}
> -
>  	/* capability check */
>  	if (cpu_feature_enabled(X86_FEATURE_CPPC)) {
>  		pr_debug("AMD CPPC MSR based functionality is supported\n");
> @@ -1875,6 +1869,12 @@ static int __init amd_pstate_init(void)
>  		static_call_update(amd_pstate_update_perf, shmem_update_perf);
>  	}
>  
> +	ret = amd_pstate_register_driver(cppc_state);
> +	if (ret) {
> +		pr_err("failed to register with return %d\n", ret);
> +		return ret;
> +	}
> +
>  	if (amd_pstate_prefcore) {
>  		ret = amd_detect_prefcore(&amd_pstate_prefcore);
>  		if (ret)