On 28.08.2025 12:02, Penny Zheng wrote:
> In order to provide backward compatibility with existing governors
> that represent performance as frequency, like ondemand, the _CPC
> table can optionally provide processor frequency range values, Lowest
> frequency and Nominal frequency, to let OS use Lowest Frequency/
> Performance and Nominal Frequency/Performance as anchor points to
> create linear mapping of CPPC performance to CPU frequency.
>
> As Xen is uncapable of parsing the ACPI dynamic table, we'd like to
> introduce a new sub-hypercall "XEN_PM_CPPC" to propagate required CPPC
> data from dom0 kernel to Xen.
> In the according handler set_cppc_pminfo(), we do _CPC and _PSD
> sanitization check, as both _PSD and _CPC info are necessary for correctly
> initializing cpufreq cores in CPPC mode.
> Users shall be warned that if we failed at this point,
> no fallback scheme, like legacy P-state could be switched to.
>
> A new flag "XEN_CPPC_INIT" is also introduced for cpufreq core initialised in
> CPPC mode. Then all .init flag checking shall be updated to
> consider "XEN_CPPC_INIT" too.
>
> We want to bypass construction of px statistic info in
> cpufreq_statistic_init()
> for CPPC mode, while not bypassing cpufreq_statistic_lock initialization for a
> good reason. The same check is unnecessary for cpufreq_statistic_exit(),
> since it has already been covered by px statistic variable
> "cpufreq_statistic_data" check
>
> Signed-off-by: Penny Zheng <penny.zh...@amd.com>
Acked-by: Jan Beulich <jbeul...@suse.com>
with two cosmetic issues taken care of (which I'll do while committing):
> @@ -693,6 +699,120 @@ int acpi_set_pdc_bits(unsigned int acpi_id,
> XEN_GUEST_HANDLE(uint32) pdc)
> return ret;
> }
>
> +static void print_CPPC(const struct xen_processor_cppc *cppc_data)
> +{
> + printk("\t_CPC: highest_perf=%u, lowest_perf=%u, "
> + "nominal_perf=%u, lowest_nonlinear_perf=%u, "
> + "nominal_mhz=%uMHz, lowest_mhz=%uMHz\n",
> + cppc_data->cpc.highest_perf, cppc_data->cpc.lowest_perf,
> + cppc_data->cpc.nominal_perf, cppc_data->cpc.lowest_nonlinear_perf,
> + cppc_data->cpc.nominal_mhz, cppc_data->cpc.lowest_mhz);
> +}
> +
> +int set_cppc_pminfo(unsigned int acpi_id,
> + const struct xen_processor_cppc *cppc_data)
> +{
> + int ret = 0, cpuid;
> + struct processor_pminfo *pm_info;
> +
> + cpuid = get_cpu_id(acpi_id);
> + if ( cpuid < 0 )
> + {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + if ( cppc_data->pad[0] || cppc_data->pad[1] || cppc_data->pad[2] )
> + {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + if ( cpufreq_verbose )
> + printk("Set CPU%d (ACPI ID %u) CPPC state info:\n",
> + cpuid, acpi_id);
> +
> + pm_info = processor_pminfo[cpuid];
> + if ( !pm_info )
> + {
> + pm_info = xvzalloc(struct processor_pminfo);
> + if ( !pm_info )
> + {
> + ret = -ENOMEM;
> + goto out;
> + }
> + processor_pminfo[cpuid] = pm_info;
> + }
> + pm_info->acpi_id = acpi_id;
> + pm_info->id = cpuid;
> + pm_info->cppc_data = *cppc_data;
> +
> + if ( (cppc_data->flags & XEN_CPPC_PSD) &&
> + !check_psd_pminfo(cppc_data->shared_type) )
Nit: Indentation is off by 1.
> + {
> + ret = -EINVAL;
> + goto out;
Indentation is still wrong here.
Jan
