From 4badf2eb1e986bdbf34dd2f5d4c979553a86fe54 Mon Sep 17 00:00:00 2001 From: "Gautham R. Shenoy" Date: Wed, 17 May 2023 16:28:15 +0000 Subject: [PATCH 1/3] cpufreq: amd-pstate: Add ->fast_switch() callback Schedutil normally calls the adjust_perf callback for drivers with adjust_perf callback available and fast_switch_possible flag set. However, when frequency invariance is disabled and schedutil tries to invoke fast_switch. So, there is a chance of kernel crash if this function pointer is not set. To protect against this scenario add fast_switch callback to amd_pstate driver. Fixes: 1d215f0319c2 ("cpufreq: amd-pstate: Add fast switch function for AMD P-State") Signed-off-by: Gautham R. Shenoy Signed-off-by: Wyes Karny Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/amd-pstate.c | 36 ++++++++++++++++++++++++++++++------ 1 file changed, 30 insertions(+), 6 deletions(-) diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c index 5a3d4aa0f45a..45711fc0a856 100644 --- a/drivers/cpufreq/amd-pstate.c +++ b/drivers/cpufreq/amd-pstate.c @@ -444,9 +444,8 @@ static int amd_pstate_verify(struct cpufreq_policy_data *policy) return 0; } -static int amd_pstate_target(struct cpufreq_policy *policy, - unsigned int target_freq, - unsigned int relation) +static int amd_pstate_update_freq(struct cpufreq_policy *policy, + unsigned int target_freq, bool fast_switch) { struct cpufreq_freqs freqs; struct amd_cpudata *cpudata = policy->driver_data; @@ -465,14 +464,37 @@ static int amd_pstate_target(struct cpufreq_policy *policy, des_perf = DIV_ROUND_CLOSEST(target_freq * cap_perf, cpudata->max_freq); - cpufreq_freq_transition_begin(policy, &freqs); + WARN_ON(fast_switch && !policy->fast_switch_enabled); + /* + * If fast_switch is desired, then there aren't any registered + * transition notifiers. See comment for + * cpufreq_enable_fast_switch(). + */ + if (!fast_switch) + cpufreq_freq_transition_begin(policy, &freqs); + amd_pstate_update(cpudata, min_perf, des_perf, - max_perf, false, policy->governor->flags); - cpufreq_freq_transition_end(policy, &freqs, false); + max_perf, fast_switch, policy->governor->flags); + + if (!fast_switch) + cpufreq_freq_transition_end(policy, &freqs, false); return 0; } +static int amd_pstate_target(struct cpufreq_policy *policy, + unsigned int target_freq, + unsigned int relation) +{ + return amd_pstate_update_freq(policy, target_freq, false); +} + +static unsigned int amd_pstate_fast_switch(struct cpufreq_policy *policy, + unsigned int target_freq) +{ + return amd_pstate_update_freq(policy, target_freq, true); +} + static void amd_pstate_adjust_perf(unsigned int cpu, unsigned long _min_perf, unsigned long target_perf, @@ -715,6 +737,7 @@ static int amd_pstate_cpu_exit(struct cpufreq_policy *policy) freq_qos_remove_request(&cpudata->req[1]); freq_qos_remove_request(&cpudata->req[0]); + policy->fast_switch_possible = false; kfree(cpudata); return 0; @@ -1309,6 +1332,7 @@ static struct cpufreq_driver amd_pstate_driver = { .flags = CPUFREQ_CONST_LOOPS | CPUFREQ_NEED_UPDATE_LIMITS, .verify = amd_pstate_verify, .target = amd_pstate_target, + .fast_switch = amd_pstate_fast_switch, .init = amd_pstate_cpu_init, .exit = amd_pstate_cpu_exit, .suspend = amd_pstate_cpu_suspend, From 249b62c448de7117c18531d626aed6e153cdfd75 Mon Sep 17 00:00:00 2001 From: Wyes Karny Date: Wed, 17 May 2023 16:28:16 +0000 Subject: [PATCH 2/3] cpufreq: amd-pstate: Remove fast_switch_possible flag from active driver amd_pstate active mode driver is only compatible with static governors. Therefore it doesn't need fast_switch functionality. Remove fast_switch_possible flag from amd_pstate active mode driver. Fixes: ffa5096a7c33 ("cpufreq: amd-pstate: implement Pstate EPP support for the AMD processors") Signed-off-by: Wyes Karny Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/amd-pstate.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c index 45711fc0a856..ac54779f5a49 100644 --- a/drivers/cpufreq/amd-pstate.c +++ b/drivers/cpufreq/amd-pstate.c @@ -1102,7 +1102,6 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy) policy->policy = CPUFREQ_POLICY_POWERSAVE; if (boot_cpu_has(X86_FEATURE_CPPC)) { - policy->fast_switch_possible = true; ret = rdmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_REQ, &value); if (ret) return ret; @@ -1125,7 +1124,6 @@ free_cpudata1: static int amd_pstate_epp_cpu_exit(struct cpufreq_policy *policy) { pr_debug("CPU %d exiting\n", policy->cpu); - policy->fast_switch_possible = false; return 0; } From 3bf8c6307bad5c0cc09cde982e146d847859b651 Mon Sep 17 00:00:00 2001 From: Wyes Karny Date: Thu, 18 May 2023 05:58:19 +0000 Subject: [PATCH 3/3] cpufreq: amd-pstate: Update policy->cur in amd_pstate_adjust_perf() Driver should update policy->cur after updating the frequency. Currently amd_pstate doesn't update policy->cur when `adjust_perf` is used. Which causes /proc/cpuinfo to show wrong cpu frequency. Fix this by updating policy->cur with correct frequency value in adjust_perf function callback. - Before the fix: (setting min freq to 1.5 MHz) [root@amd]# cat /proc/cpuinfo | grep "cpu MHz" | sort | uniq --count 1 cpu MHz : 1777.016 1 cpu MHz : 1797.160 1 cpu MHz : 1797.270 189 cpu MHz : 400.000 - After the fix: (setting min freq to 1.5 MHz) [root@amd]# cat /proc/cpuinfo | grep "cpu MHz" | sort | uniq --count 1 cpu MHz : 1753.353 1 cpu MHz : 1756.838 1 cpu MHz : 1776.466 1 cpu MHz : 1776.873 1 cpu MHz : 1777.308 1 cpu MHz : 1779.900 183 cpu MHz : 1805.231 1 cpu MHz : 1956.815 1 cpu MHz : 2246.203 1 cpu MHz : 2259.984 Fixes: 1d215f0319c2 ("cpufreq: amd-pstate: Add fast switch function for AMD P-State") Signed-off-by: Wyes Karny [ rjw: Subject edits ] Cc: 5.17+ # 5.17+ Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/amd-pstate.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c index ac54779f5a49..ddd346a239e0 100644 --- a/drivers/cpufreq/amd-pstate.c +++ b/drivers/cpufreq/amd-pstate.c @@ -501,12 +501,14 @@ static void amd_pstate_adjust_perf(unsigned int cpu, unsigned long capacity) { unsigned long max_perf, min_perf, des_perf, - cap_perf, lowest_nonlinear_perf; + cap_perf, lowest_nonlinear_perf, max_freq; struct cpufreq_policy *policy = cpufreq_cpu_get(cpu); struct amd_cpudata *cpudata = policy->driver_data; + unsigned int target_freq; cap_perf = READ_ONCE(cpudata->highest_perf); lowest_nonlinear_perf = READ_ONCE(cpudata->lowest_nonlinear_perf); + max_freq = READ_ONCE(cpudata->max_freq); des_perf = cap_perf; if (target_perf < capacity) @@ -523,6 +525,10 @@ static void amd_pstate_adjust_perf(unsigned int cpu, if (max_perf < min_perf) max_perf = min_perf; + des_perf = clamp_t(unsigned long, des_perf, min_perf, max_perf); + target_freq = div_u64(des_perf * max_freq, max_perf); + policy->cur = target_freq; + amd_pstate_update(cpudata, min_perf, des_perf, max_perf, true, policy->governor->flags); cpufreq_cpu_put(policy);