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Wysocki" , Viresh Kumar , , CC: , Li RongQing Subject: [PATCH v4 1/2] cpufreq: acpi-cpufreq: fix P-state index mismatch in extract_io() Date: Thu, 10 Sep 2026 19:13:28 +0800 Message-ID: <20260910111329.2220-2-lirongqing@baidu.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20260910111329.2220-1-lirongqing@baidu.com> References: <20260910111329.2220-1-lirongqing@baidu.com> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-ClientProxiedBy: bjkjy-exc8.internal.baidu.com (172.31.50.52) To bjkjy-exc3.internal.baidu.com (172.31.50.47) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=baidu.com; s=selector1; t=1789038822; bh=RpVinj4s0Rh3TFJZafzq4jkBDp+N9yNwbfL62hb/wKU=; h=From:To:CC:Subject:Date:Message-ID:Content-Type; b=Z/Ji7Ktxd+cz4db5O+zKJhPYN5AYBi/uj+wpamNPoGALZD8GYYhd5fnus5jV5eoK+ ndEvWBcOhw39TA6w0AOAAO9cBqf8F8NDxvH6IXm1npq2tMOb/+uz1IbL9pJ0i8/xrA HoTJ0w+kH/ibGtqRIDyrjLCxtYt73yNWhdqIpKxlWCwWR2Ldr7Ei/ODBBxWRv6+geR iu1HqoCLq906vkvOJ62eSZTQjmUDIZ/4mBNPCKn3EKS1UWJpJ+xwnmoq9DlNJQNUfK VIu7GAtPY3LaxUJFUlNhzEl+J0OJRqYQQEw3VJBHlEwl3hg//82rEM87ssTrp/x8bO hul7BtDvVQZeg== From: Li RongQing When policy->freq_table is built in acpi_cpufreq_cpu_init(), entries that are not lower in frequency than the previous one are skipped. For each remaining entry, freq_table[].driver_data stores the original ACPI P-state index, so the index space of freq_table no longer matches perf->states[]. extract_io() currently walks perf->states[] with index i and uses the same i to index policy->freq_table[i]. When duplicate frequencies exist, this can associate a P-state status with the frequency of a different P-state. It can also access an invalid or sentinel entry in freq_table when the number of entries in perf->states[] is greater than the number of entries remaining in the frequency table. extract_io() is used on ACPI_ADR_SPACE_SYSTEM_IO platforms by the frequency verification path, which is enabled by the acpi_pstate_strict module parameter. With the mismatched lookup, check_freqs() can fail to match the frequency of the P-state that drv_write() has already programmed. It then sleeps through all 100 iterations - at least ~1 ms of usleep_range() plus 100 cross-CPU calls and I/O port reads, all with policy->rwsem held, and .target_index() returns -EAGAIN, leaving perf->state at its previous value while the hardware is running at the newly requested P-state. The cpufreq core consequently keeps policy->cur at the old frequency. Since __cpufreq_driver_target() returns early when the requested frequency equals policy->cur, the driver is not called again for that frequency and the control register is not rewritten. The hardware can therefore remain at a frequency that differs from the frequency known to the cpufreq core. Fix this by iterating over policy->freq_table and using pos->driver_data as the original ACPI P-state index when accessing perf->states[], as extract_msr() already does. Fixes: fe27cb358835 ("[CPUFREQ][2/8] acpi: reorganize code to make MSR support addition easier") Signed-off-by: Li RongQing Reviewed-by: Zhongqiu Han --- drivers/cpufreq/acpi-cpufreq.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c index 10ea603..a797bb2 100644 --- a/drivers/cpufreq/acpi-cpufreq.c +++ b/drivers/cpufreq/acpi-cpufreq.c @@ -197,14 +197,13 @@ static unsigned extract_io(struct cpufreq_policy *policy, u32 value) { struct acpi_cpufreq_data *data = policy->driver_data; struct acpi_processor_performance *perf; - int i; + struct cpufreq_frequency_table *pos; perf = to_perf_data(data); - for (i = 0; i < perf->state_count; i++) { - if (value == perf->states[i].status) - return policy->freq_table[i].frequency; - } + cpufreq_for_each_entry(pos, policy->freq_table) + if (value == perf->states[pos->driver_data].status) + return pos->frequency; return 0; } -- 2.9.4