Alexander Chuprunov 1db95da299 lib: sbi: sbi_pmu: fixed hw counters start for hart ...

Generally, hardware performance counters can only be started, stopped,
or configured from machine-mode using mcountinhibit and mhpmeventX CSRs.
Also, in opensbi only sbi_pmu_ctr_cfg_match() managed mhpmeventX. But
in generic Linux driver, when perf starts, Linux calls both
sbi_pmu_ctr_cfg_match() and sbi_pmu_ctr_start(), while after hart suspend
only sbi_pmu_ctr_start() command called through SBI interface. This doesn't
work properly in case when suspend state resets HPM registers. In order
to keep counter integrity, sbi_pmu_ctr_start() modified. First, we're saving
hw_counters_data, and after hart suspend this value is restored if
event is currently active.

Signed-off-by: Alexander Chuprunov <alexander.chuprunov@syntacore.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20250918090706.2217603-2-alexander.chuprunov@syntacore.com
Signed-off-by: Anup Patel <anup@brainfault.org>

2025-10-27 16:56:16 +05:30

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