From: Jie Zhan <zhanjie9@hisilicon.com> mainline inclusion from mainline-v6.13-rc1 commit c47195631960b626058c335aec31f186fa854f97 category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/9163 CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- The CPPC performance feedback counters could be 0 or unchanged when the target cpu is in a low-power idle state, e.g. power-gated or clock-gated. When the counters are 0, cppc_cpufreq_get_rate() returns 0 KHz, which makes cpufreq_online() get a false error and fail to generate a cpufreq policy. When the counters are unchanged, the existing cppc_perf_from_fbctrs() returns a cached desired perf, but some platforms may update the real frequency back to the desired perf reg. For the above cases in cppc_cpufreq_get_rate(), get the latest desired perf from the CPPC reg to reflect the frequency because some platforms may update the actual frequency back there; if failed, use the cached desired perf. Fixes: 6a4fec4f6d30 ("cpufreq: cppc: cppc_cpufreq_get_rate() returns zero in all error cases.") Signed-off-by: Jie Zhan <zhanjie9@hisilicon.com> Reviewed-by: Zeng Heng <zengheng4@huawei.com> Reviewed-by: Ionela Voinescu <ionela.voinescu@arm.com> Reviewed-by: Huisong Li <lihuisong@huawei.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Conflicts: drivers/cpufreq/cppc_cpufreq.c [drivers/cpufreq/cppc_cpufreq.c: The OLK-6.6 baseline already refactored the feedback-counter sampling into cppc_get_perf_ctrs_pair() (sampling on the target CPU with smp_call_on_cpu and a ktime based sampling interval, from an earlier backport series), so the patch's mechanical extraction into cppc_get_perf_ctrs_sample() was not introduced to avoid a redundant helper. The semantic changes were transplanted onto the baseline mechanism: cppc_perf_from_fbctrs() now returns 0 on zero or unchanged deltas (instead of the cached desired perf) and leaves it to callers, and cppc_cpufreq_get_rate() falls back to the latest desired perf register value (or the cached desired perf) via the out_invalid_counters path when the counters are invalid (-EFAULT) or the computed delivered perf is 0.] Signed-off-by: Pengjie Zhang <zhangpengjie2@huawei.com> Signed-off-by: Hongye Lin <linhongye@h-partners.com> --- drivers/cpufreq/cppc_cpufreq.c | 50 +++++++++++++++++++++++++++++++--- 1 file changed, 46 insertions(+), 4 deletions(-) diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c index bfe1f56e855b..9efaea2dbe83 100644 --- a/drivers/cpufreq/cppc_cpufreq.c +++ b/drivers/cpufreq/cppc_cpufreq.c @@ -113,6 +113,9 @@ static void __cppc_scale_freq_tick(struct cppc_freq_invariance *cppc_fi) perf = cppc_perf_from_fbctrs(cpu_data, &cppc_fi->prev_perf_fb_ctrs, &fb_ctrs); + if (!perf) + return; + cppc_fi->prev_perf_fb_ctrs = fb_ctrs; perf <<= SCHED_CAPACITY_SHIFT; @@ -773,13 +776,31 @@ static int cppc_perf_from_fbctrs(struct cppc_cpudata *cpu_data, delta_delivered = get_delta(fb_ctrs_t1->delivered, fb_ctrs_t0->delivered); - /* Check to avoid divide-by zero and invalid delivered_perf */ + /* + * Avoid divide-by zero and unchanged feedback counters. + * Leave it for callers to handle. + */ if (!delta_reference || !delta_delivered) - return cpu_data->perf_ctrls.desired_perf; + return 0; return (reference_perf * delta_delivered) / delta_reference; } +static int cppc_get_perf_ctrs_sample(int cpu, + struct cppc_perf_fb_ctrs *fb_ctrs_t0, + struct cppc_perf_fb_ctrs *fb_ctrs_t1) +{ + int ret; + + ret = cppc_get_perf_ctrs(cpu, fb_ctrs_t0); + if (ret) + return ret; + + udelay(2); /* 2usec delay between sampling */ + + return cppc_get_perf_ctrs(cpu, fb_ctrs_t1); +} + static unsigned int cppc_cpufreq_get_rate(unsigned int cpu) { struct cppc_perf_fb_ctrs fb_ctrs_t0 = {0}, fb_ctrs_t1 = {0}; @@ -801,12 +822,33 @@ static unsigned int cppc_cpufreq_get_rate(unsigned int cpu) udelay(2); /* 2usec delay between sampling */ ret = cppc_get_perf_ctrs(cpu, &fb_ctrs_t1); - if (ret) - return 0; + if (ret) { + if (ret == -EFAULT) + /* Any of the associated CPPC regs is 0. */ + goto out_invalid_counters; + else + return 0; + } delivered_perf = cppc_perf_from_fbctrs(cpu_data, &fb_ctrs_t0, &fb_ctrs_t1); + if (!delivered_perf) + goto out_invalid_counters; + + return cppc_perf_to_khz(&cpu_data->perf_caps, delivered_perf); + +out_invalid_counters: + /* + * Feedback counters could be unchanged or 0 when a cpu enters a + * low-power idle state, e.g. clock-gated or power-gated. + * Use desired perf for reflecting frequency. Get the latest register + * value first as some platforms may update the actual delivered perf + * there; if failed, resort to the cached desired perf. + */ + if (cppc_get_desired_perf(cpu, &delivered_perf)) + delivered_perf = cpu_data->perf_ctrls.desired_perf; + return cppc_perf_to_khz(&cpu_data->perf_caps, delivered_perf); } -- 2.33.0