RISC-V: KVM: Fix perf-backed counter accounting across stop and read

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pmu_ctr_read() adds the event count returned by perf_event_read_value()
to counter_val, which can accumulate the same count repeatedly across
reads. kvm_riscv_vcpu_pmu_ctr_stop() also leaves counter_val stale by
not folding the current event count into it.

Make reads of perf-backed counters side-effect free, and use
perf_event_pause() when stopping a counter to fold the current event
count into counter_val while resetting it. This preserves the counter
value across stop/start and lets the snapshot path use counter_val
directly.

Fixes: 0cb74b65d2 ("RISC-V: KVM: Implement perf support without sampling")
Signed-off-by: SeungJu Cheon <suunj1331@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20260825083719.643970-4-suunj1331@gmail.com
Signed-off-by: Anup Patel <anup@brainfault.org>

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SeungJu Cheon 2026-08-25 17:37:19 +09:00 • committed by Anup Patel

parent 057dd2639c

commit c7e2cc38c5

1 changed files with 8 additions and 8 deletions

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arch/riscv/kvm/vcpu_pmu.c

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