| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <7f0b280d-9c22-46dc-a924-a85591e1034d@huawei.com>
Date: Thu, 22 Jan 2026 16:56:03 +0800
From: "zhenglifeng (A)" <zhenglifeng1@...wei.com>
To: Sumit Gupta <sumitg@...dia.com>
CC: <rafael@...nel.org>, <viresh.kumar@...aro.org>, <pierre.gondois@....com>,
<ionela.voinescu@....com>, <lenb@...nel.org>, <robert.moore@...el.com>,
<corbet@....net>, <rdunlap@...radead.org>, <ray.huang@....com>,
<gautham.shenoy@....com>, <mario.limonciello@....com>, <perry.yuan@....com>,
<zhanjie9@...ilicon.com>, <linux-pm@...r.kernel.org>,
<linux-acpi@...r.kernel.org>, <linux-doc@...r.kernel.org>,
<acpica-devel@...ts.linux.dev>, <linux-kernel@...r.kernel.org>,
<linux-tegra@...r.kernel.org>, <treding@...dia.com>, <jonathanh@...dia.com>,
<vsethi@...dia.com>, <ksitaraman@...dia.com>, <sanjayc@...dia.com>,
<nhartman@...dia.com>, <bbasu@...dia.com>
Subject: Re: [PATCH v6 4/9] ACPI: CPPC: Add cppc_get_perf() API to read
performance controls
On 2026/1/20 22:56, Sumit Gupta wrote:
> Add cppc_get_perf() function to read values of performance control
> registers including desired_perf, min_perf, max_perf, energy_perf,
> and auto_sel.
>
> This provides a read interface to complement the existing
> cppc_set_perf() write interface for performance control registers.
>
> Note that auto_sel is read by cppc_get_perf() but not written by
> cppc_set_perf() to avoid unintended mode changes during performance
> updates. It can be updated with existing dedicated cppc_set_auto_sel()
> API.
>
> Use cppc_get_perf() in cppc_cpufreq_get_cpu_data() to initialize
> perf_ctrls with current hardware register values during cpufreq
> policy initialization.
>
> Signed-off-by: Sumit Gupta <sumitg@...dia.com>
> ---
> drivers/acpi/cppc_acpi.c | 80 ++++++++++++++++++++++++++++++++++
> drivers/cpufreq/cppc_cpufreq.c | 6 +++
> include/acpi/cppc_acpi.h | 5 +++
> 3 files changed, 91 insertions(+)
>
> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> index a09bdabaa804..de35aeb07833 100644
> --- a/drivers/acpi/cppc_acpi.c
> +++ b/drivers/acpi/cppc_acpi.c
> @@ -1739,6 +1739,86 @@ int cppc_set_enable(int cpu, bool enable)
> }
> EXPORT_SYMBOL_GPL(cppc_set_enable);
>
> +/**
> + * cppc_get_perf - Get a CPU's performance controls.
> + * @cpu: CPU for which to get performance controls.
> + * @perf_ctrls: ptr to cppc_perf_ctrls. See cppc_acpi.h
> + *
> + * Return: 0 for success with perf_ctrls, -ERRNO otherwise.
> + */
> +int cppc_get_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
> +{
> + struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
> + struct cpc_register_resource *desired_perf_reg,
> + *min_perf_reg, *max_perf_reg,
> + *energy_perf_reg, *auto_sel_reg;
> + u64 desired_perf = 0, min = 0, max = 0, energy_perf = 0, auto_sel = 0;
> + int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
> + struct cppc_pcc_data *pcc_ss_data = NULL;
> + int ret = 0, regs_in_pcc = 0;
> +
> + if (!cpc_desc) {
> + pr_debug("No CPC descriptor for CPU:%d\n", cpu);
> + return -ENODEV;
> + }
> +
> + if (!perf_ctrls) {
> + pr_debug("Invalid perf_ctrls pointer\n");
> + return -EINVAL;
> + }
> +
> + desired_perf_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
> + min_perf_reg = &cpc_desc->cpc_regs[MIN_PERF];
> + max_perf_reg = &cpc_desc->cpc_regs[MAX_PERF];
> + energy_perf_reg = &cpc_desc->cpc_regs[ENERGY_PERF];
> + auto_sel_reg = &cpc_desc->cpc_regs[AUTO_SEL_ENABLE];
> +
> + /* Are any of the regs PCC ?*/
> + if (CPC_IN_PCC(desired_perf_reg) || CPC_IN_PCC(min_perf_reg) ||
> + CPC_IN_PCC(max_perf_reg) || CPC_IN_PCC(energy_perf_reg) ||
> + CPC_IN_PCC(auto_sel_reg)) {
> + if (pcc_ss_id < 0) {
> + pr_debug("Invalid pcc_ss_id for CPU:%d\n", cpu);
> + return -ENODEV;
> + }
> + pcc_ss_data = pcc_data[pcc_ss_id];
> + regs_in_pcc = 1;
> + down_write(&pcc_ss_data->pcc_lock);
> + /* Ring doorbell once to update PCC subspace */
> + if (send_pcc_cmd(pcc_ss_id, CMD_READ) < 0) {
> + ret = -EIO;
> + goto out_err;
> + }
> + }
> +
> + /* Read optional elements if present */
> + if (CPC_SUPPORTED(max_perf_reg))
> + cpc_read(cpu, max_perf_reg, &max);
> + perf_ctrls->max_perf = max;
> +
> + if (CPC_SUPPORTED(min_perf_reg))
> + cpc_read(cpu, min_perf_reg, &min);
> + perf_ctrls->min_perf = min;
> +
> + if (CPC_SUPPORTED(desired_perf_reg))
> + cpc_read(cpu, desired_perf_reg, &desired_perf);
> + perf_ctrls->desired_perf = desired_perf;
desired_perf_reg is not an optional one, so it has to be supported.
> +
> + if (CPC_SUPPORTED(energy_perf_reg))
> + cpc_read(cpu, energy_perf_reg, &energy_perf);
> + perf_ctrls->energy_perf = energy_perf;
> +
> + if (CPC_SUPPORTED(auto_sel_reg))
> + cpc_read(cpu, auto_sel_reg, &auto_sel);
> + perf_ctrls->auto_sel = (bool)auto_sel;
> +
> +out_err:
> + if (regs_in_pcc)
> + up_write(&pcc_ss_data->pcc_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(cppc_get_perf);
> +
> /**
> * cppc_set_perf - Set a CPU's performance controls.
> * @cpu: CPU for which to set performance controls.
> diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
> index c95dcd7719c3..229880c4eedb 100644
> --- a/drivers/cpufreq/cppc_cpufreq.c
> +++ b/drivers/cpufreq/cppc_cpufreq.c
> @@ -594,6 +594,12 @@ static struct cppc_cpudata *cppc_cpufreq_get_cpu_data(unsigned int cpu)
> goto free_mask;
> }
>
> + ret = cppc_get_perf(cpu, &cpu_data->perf_ctrls);
> + if (ret) {
> + pr_debug("Err reading CPU%d perf ctrls: ret:%d\n", cpu, ret);
> + goto free_mask;
> + }
> +
> return cpu_data;
>
> free_mask:
> diff --git a/include/acpi/cppc_acpi.h b/include/acpi/cppc_acpi.h
> index 4d644f03098e..3fc796c0d902 100644
> --- a/include/acpi/cppc_acpi.h
> +++ b/include/acpi/cppc_acpi.h
> @@ -151,6 +151,7 @@ extern int cppc_get_desired_perf(int cpunum, u64 *desired_perf);
> extern int cppc_get_nominal_perf(int cpunum, u64 *nominal_perf);
> extern int cppc_get_highest_perf(int cpunum, u64 *highest_perf);
> extern int cppc_get_perf_ctrs(int cpu, struct cppc_perf_fb_ctrs *perf_fb_ctrs);
> +extern int cppc_get_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls);
> extern int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls);
> extern int cppc_set_enable(int cpu, bool enable);
> extern int cppc_get_perf_caps(int cpu, struct cppc_perf_caps *caps);
> @@ -193,6 +194,10 @@ static inline int cppc_get_perf_ctrs(int cpu, struct cppc_perf_fb_ctrs *perf_fb_
> {
> return -EOPNOTSUPP;
> }
> +static inline int cppc_get_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
> +{
> + return -EOPNOTSUPP;
> +}
> static inline int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
> {
> return -EOPNOTSUPP;
Powered by blists - more mailing lists