hulk inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I99VPY CVE: NA -------------------------------- When the nominal_freq recorded by the kernel is equal to the lowest_freq, and the frequency adjustment operation is triggered externally, there is a logic error in cppc_perf_to_khz()/cppc_khz_to_perf(), resulting in perf and khz conversion errors. Fix this by adding the branch processing logic when nominal_freq is equal to lowest_freq. Fixes: ec1c7ad47664 ("cpufreq: CPPC: Fix performance/frequency conversion") Signed-off-by: liwei <liwei728@huawei.com> --- drivers/cpufreq/cppc_cpufreq.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c index 156ef2c40464..5ceededf514c 100644 --- a/drivers/cpufreq/cppc_cpufreq.c +++ b/drivers/cpufreq/cppc_cpufreq.c @@ -98,7 +98,7 @@ static u64 cppc_get_dmi_max_khz(void) * use them to convert perf to freq and vice versa. The conversion is * extrapolated as an affine function passing by the 2 points: * - (Low perf, Low freq) - * - (Nominal perf, Nominal perf) + * - (Nominal perf, Nominal freq) */ static unsigned int cppc_cpufreq_perf_to_khz(struct cppc_cpudata *cpu_data, unsigned int perf) @@ -109,8 +109,14 @@ static unsigned int cppc_cpufreq_perf_to_khz(struct cppc_cpudata *cpu_data, u64 mul, div; if (caps->lowest_freq && caps->nominal_freq) { - mul = caps->nominal_freq - caps->lowest_freq; - div = caps->nominal_perf - caps->lowest_perf; + /* Avoid the special case when nominal_freq is equal to lowest_freq */ + if (caps->nominal_freq == caps->lowest_freq) { + mul = caps->nominal_freq; + div = caps->nominal_perf; + } else { + mul = caps->nominal_freq - caps->lowest_freq; + div = caps->nominal_perf - caps->lowest_perf; + } offset = caps->nominal_freq - div64_u64(caps->nominal_perf * mul, div); } else { if (!max_khz) @@ -134,8 +140,14 @@ static unsigned int cppc_cpufreq_khz_to_perf(struct cppc_cpudata *cpu_data, u64 mul, div; if (caps->lowest_freq && caps->nominal_freq) { - mul = caps->nominal_perf - caps->lowest_perf; - div = caps->nominal_freq - caps->lowest_freq; + /* Avoid special case when nominal_freq is equal to lowest_freq */ + if (caps->nominal_freq == caps->lowest_freq) { + mul = caps->nominal_perf; + div = caps->nominal_freq; + } else { + mul = caps->nominal_perf - caps->lowest_perf; + div = caps->nominal_freq - caps->lowest_freq; + } offset = caps->nominal_perf - div64_u64(caps->nominal_freq * mul, div); } else { if (!max_khz) -- 2.25.1