ZhaoLiu 0c2ce08ca1 x86_64: Preparation for ITMT scheduling in Guest ... With Intel Turbo Boost Max Technology 3.0, (ITMT), the maximum turbo frequencies of some cores in a CPU package may be higher than for the other cores in the same package. In that case, make the scheduler prefer to run tasks on the CPUs with higher max turbo frequencies, to achieve better performance. When vCPUs 1:1 map to pCPUs, ITMT scheduling feature can benefit performance of Guest. So when user sets `--itmt`, crosvm will check if `--host-cpu-topology` is set or if `--cpu-affinity` is set for 1:1 mapping. In kernel, ITMT scheduling feature depends on intel_pstate driver and ACPI CPPC support. To setup intel_pstate driver and pass CPPC capability check, we need emulate related MSRs in userspace: - MSR_HWP_CAPABILITIES and MSR_TURBO_RATIO_LIMIT: intel_pstate driver only needs to read. So we passthrough them to Guest. But please note, to be compatible with the configuration in initramfs, use `FromCPU0` Temporarily. - MSR_PM_ENABLE and MSR_HWP_REQUEST: they are MSRs to control HWP. When intel_pstate driver is initializing, the driver will close/open HWP by writing into MSR_PM_ENABLE, and the driver also needs to set performance policy by writing some hints into MSR_HWP_REQUEST. Note that we don't want Guest's behavior to affect the performance control of the host, so use 'emulate' handler for them. - MSR_PLATFORM_INFO: this MSR is emulated in kernel with a fault value by default. intel_pstate doesn't want this fault value, so we ask this MSR to exit to userspace and give it a real value. - MSR_IA32_PERF_CTL: intel_pstate driver use this MSR to set the min pstate in the initialization. So use 'emulate' handler for this MSR. Since of `FromCPU0` setting of MSR_HWP_CAPABILITIES, ITMT scheduling will set the same priority for each core so optimization will not work. BUG=b:225375705 TEST=Set `--itmt` and check /proc/sys/kernel/sched_itmt_enabled Change-Id: Icfa85ffa15c3b977c3b62a1f8a379c4c2f5fc49d Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3575511 Commit-Queue: Zhao Liu <zhao1.liu@intel.corp-partner.google.com> Tested-by: kokoro <noreply+kokoro@google.com> Reviewed-by: Junichi Uekawa <uekawa@chromium.org> Commit-Queue: Junichi Uekawa <uekawa@chromium.org>		2022-04-25 08:21:16 +00:00
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src	x86_64: Preparation for ITMT scheduling in Guest	2022-04-25 08:21:16 +00:00
Cargo.toml	crosvm: Support MSR emulation	2022-04-25 07:50:55 +00:00