Hi, Resending since I messed up the To: line. Sorry about that.
This patch series adds Hardware-Controlled Performance States (HWP) for Intel processors to Xen. v2 was only partially reviewed, so v3 is mostly a reposting of v2. In v2 & v3, I think I addressed all comments for v1. I kept patch 11 "xenpm: Factor out a non-fatal cpuid_parse variant", with a v2 comment explaining why I keep it. v3 adds "xen/x86: Tweak PDC bits when using HWP". Qubes testing revealed an issue where enabling HWP can crash firwmare code (maybe SMM). This requires a Linux change to get the PDC bits from Xen and pass them to ACPI. Roger has a patch [0] to set the PDC bits. Roger's 3 patch series was tested with "xen/x86: Tweak PDC bits when using HWP" on affected hardware and allowed proper operation. Previous cover letter: With HWP, the processor makes its own determinations for frequency selection, though users can set some parameters and preferences. There is also Turbo Boost which dynamically pushes the max frequency if possible. The existing governors don't work with HWP since they select frequencies and HWP doesn't expose those. Therefore a dummy hwp-interal governor is used that doesn't do anything. xenpm get-cpufreq-para is extended to show HWP parameters, and set-cpufreq-hwp is added to set them. A lightly loaded OpenXT laptop showed ~1W power savings according to powertop. A mostly idle Fedora system (dom0 only) showed a more modest power savings. This for for a 10th gen 6-core 1600 MHz base 4900 MHZ max cpu. In the default balance mode, Turbo Boost doesn't exceed 4GHz. Tweaking the energy_perf preference with `xenpm set-cpufreq-hwp balance ene:64`, I've seen the CPU hit 4.7GHz before throttling down and bouncing around between 4.3 and 4.5 GHz. Curiously the other cores read ~4GHz when turbo boost takes affect. This was done after pinning all dom0 cores, and using taskset to pin to vCPU/pCPU 11 and running a bash tightloop. HWP defaults to disabled and running with the existing HWP configuration - it doesn't reconfigure by default. It can be enabled with cpufreq=xen:hwp. Hardware Duty Cycling (HDC) is another feature to autonomously powerdown things. It defaults to enabled when HWP is enabled, but HDC can be disabled on the command line. cpufreq=xen:hwp,no-hdc I've only tested on 8th gen and 10th gen systems with activity window and energy_perf support. So the pathes for CPUs lacking those features are untested. Fast MSR support was removed in v2. The model specific checking was not done properly, and I don't have hardware to test with. Since writes are expected to be infrequent, I just removed the code. This changes the systcl_pm_op hypercall, so that wants review. Regards, Jason [0] https://lore.kernel.org/xen-devel/20221121102113.41893-3-roger....@citrix.com/ Jason Andryuk (14): cpufreq: Allow restricting to internal governors only cpufreq: Add perf_freq to cpuinfo cpufreq: Export intel_feature_detect cpufreq: Add Hardware P-State (HWP) driver xenpm: Change get-cpufreq-para output for internal xen/x86: Tweak PDC bits when using HWP cpufreq: Export HWP parameters to userspace libxc: Include hwp_para in definitions xenpm: Print HWP parameters xen: Add SET_CPUFREQ_HWP xen_sysctl_pm_op libxc: Add xc_set_cpufreq_hwp xenpm: Factor out a non-fatal cpuid_parse variant xenpm: Add set-cpufreq-hwp subcommand CHANGELOG: Add Intel HWP entry CHANGELOG.md | 1 + docs/misc/xen-command-line.pandoc | 8 +- tools/include/xenctrl.h | 6 + tools/libs/ctrl/xc_pm.c | 18 + tools/misc/xenpm.c | 355 +++++++++++- xen/arch/x86/acpi/cpufreq/Makefile | 1 + xen/arch/x86/acpi/cpufreq/cpufreq.c | 15 +- xen/arch/x86/acpi/cpufreq/hwp.c | 633 ++++++++++++++++++++++ xen/arch/x86/acpi/lib.c | 5 + xen/arch/x86/cpu/mcheck/mce_intel.c | 6 + xen/arch/x86/include/asm/cpufeature.h | 13 +- xen/arch/x86/include/asm/msr-index.h | 14 + xen/drivers/acpi/pmstat.c | 23 + xen/drivers/cpufreq/cpufreq.c | 40 ++ xen/drivers/cpufreq/utility.c | 1 + xen/include/acpi/cpufreq/cpufreq.h | 14 + xen/include/acpi/cpufreq/processor_perf.h | 4 + xen/include/acpi/pdc_intel.h | 1 + xen/include/public/sysctl.h | 57 ++ 19 files changed, 1187 insertions(+), 28 deletions(-) create mode 100644 xen/arch/x86/acpi/cpufreq/hwp.c -- 2.40.0
