| Message ID | 20230517162817.8538-2-wyes.karny@amd.com |
|---|---|
| State | New |
| Headers | show |
| Series | cpufreq/amd-pstate: Fix null pointer dereference when frequency invariance is disabled | expand |
Hi Rafael, On 24 May 19:47, Rafael J. Wysocki wrote: > On Wed, May 17, 2023 at 6:29 PM Wyes Karny <wyes.karny@amd.com> wrote: > > > > From: "Gautham R. Shenoy" <gautham.shenoy@amd.com> > > > > 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: Wyes Karny <wyes.karny@amd.com> > > Signed-off-by: Gautham R. Shenoy <gautham.shenoy@amd.com> > > --- > > 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, > > -- > > Applied along with the [2/3], thanks! > > Do you need them in 6.4 or would 6.5 be sufficient? Also do you need > them to go into "stable"? Sorry for late reply. Thanks for picking this for 6.4 and stable. I see the patch is not applying to the 6.3-stable tree. I'll check that. Thanks & Regards, Wyes
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,