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Penny Zheng
cf55bb7872
Users need to set "cpufreq=amd-cppc" in xen cmdline to enable amd-cppc driver, which selects ACPI Collaborative Performance and Power Control (CPPC) on supported AMD hardware to provide a finer grained frequency control mechanism. `verbose` option can also be included to support verbose print. When users setting "cpufreq=amd-cppc", a new amd-cppc driver shall be registered and used. All hooks for amd-cppc driver are transiently missing, and we temporarily make registration fail with -EOPNOTSUPP here. It will be fixed along with the implementation. New xen-pm internal flag XEN_PROCESSOR_PM_CPPC is introduced, to stand for cpufreq driver in CPPC mode. We define XEN_PROCESSOR_PM_CPPC 0x100, as it is the next value to use after 8-bits wide public xen-pm options. We also add sanity check on compile time. All XEN_PROCESSOR_PM_xxx checking shall be updated to consider "XEN_PROCESSOR_PM_CPPC" too. XEN_PROCESSOR_PM_CPPC and XEN_PROCESSOR_PM_PX are firstly set when Xen parsed relative driver signature from xen cmdline, and will become exclusive after cpufreq driver registration. It is because that platform could not support both or mixed mode (CPPC & legacy Px) operations, and only one cpufreq driver could be registerd in Xen at one time, such as on AMD, it is either amd-cppc or legacy P-states driver. Xen rely on XEN_PROCESSOR_PM_CPPC flag to tell current cpufreq driver is in CPPC mode, and accepts relative hypercall. It will neglect Px request and yields success. Signed-off-by: Penny Zheng <Penny.Zheng@amd.com> Acked-by: Jan Beulich <jbeulich@suse.com>
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