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Huang Shijie reports that, when profiling a guest from the host with a number of events that exceeds the number of available counters, the reported counts are wildly inaccurate. Without the counter oversubscription, the reported counts are correct. Their investigation indicates that upon counter rotation (which takes place on the back of a timer interrupt), we fail to re-apply the guest EL0 enabling, leading to the counting of host events instead of guest events. In order to solve this, add yet another hook between the host PMU driver and KVM, re-applying the guest EL0 configuration if the right conditions apply (the host is VHE, we are in interrupt context, and we interrupted a running vcpu). This triggers a new vcpu request which will apply the correct configuration on guest reentry. With this, we have the correct counts, even when the counters are oversubscribed. Reported-by: Huang Shijie <shijie@os.amperecomputing.com> Suggested-by: Oliver Upton <oliver.upton@linux.dev> Tested_by: Huang Shijie <shijie@os.amperecomputing.com> Signed-off-by: Marc Zyngier <maz@kernel.org> Cc: Leo Yan <leo.yan@linaro.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20230809013953.7692-1-shijie@os.amperecomputing.com Acked-by: Mark Rutland <mark.rutland@arm.com> Link: https://lore.kernel.org/r/20230820090108.177817-1-maz@kernel.org |
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| .. | ||
| amlogic | ||
| arm_cspmu | ||
| hisilicon | ||
| alibaba_uncore_drw_pmu.c | ||
| apple_m1_cpu_pmu.c | ||
| arm-cci.c | ||
| arm-ccn.c | ||
| arm-cmn.c | ||
| arm_dmc620_pmu.c | ||
| arm_dsu_pmu.c | ||
| arm_pmu.c | ||
| arm_pmu_acpi.c | ||
| arm_pmu_platform.c | ||
| arm_pmuv3.c | ||
| arm_smmuv3_pmu.c | ||
| arm_spe_pmu.c | ||
| cxl_pmu.c | ||
| fsl_imx8_ddr_perf.c | ||
| fsl_imx9_ddr_perf.c | ||
| Kconfig | ||
| Makefile | ||
| marvell_cn10k_ddr_pmu.c | ||
| marvell_cn10k_tad_pmu.c | ||
| qcom_l2_pmu.c | ||
| qcom_l3_pmu.c | ||
| riscv_pmu.c | ||
| riscv_pmu_legacy.c | ||
| riscv_pmu_sbi.c | ||
| thunderx2_pmu.c | ||
| xgene_pmu.c | ||