Currently, when we attempt to read the upper 32 bits of a firmware
counter on RV64 or higher, we just set `sbiret.value` to 0 without
validating the counter index. The SBI specification requires us to set
`sbiret.error` to `SBI_ERR_INVALID_PARAM` if the counter index points to
a hardware counter or an invalid counter. Add a validation check to
ensure compliance with the specification on RV64 or higher.
Fixes: 51951d9e9a ("lib: sbi_pmu: Implement sbi_pmu_counter_fw_read_hi")
Signed-off-by: James Raphael Tiovalen <jamestiotio@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20260125090643.190748-1-jamestiotio@gmail.com
Signed-off-by: Anup Patel <anup@brainfault.org>
Currently, we immediately return the result of `fw_counter_start` if the
event code is 0xFFFF. However, this skips setting the bit in the
`fw_counters_started` bitmap even if the platform-specific call
succeeds. Restore the original behavior of returning early only on an
error so that we still set the bit in the bitmap. This prevents multiple
starts of the same FW counter. This also aligns the expectations of
`pmu_ctr_start_fw` with `pmu_ctr_stop_fw` since we cannot assume that
the platform-specific functions to start and stop FW counters will
modify the bitmap state.
Fixes: 57d3aa3b0d ("lib: sbi_pmu: Introduce fw_counter_write_value API")
Signed-off-by: James Raphael Tiovalen <jamestiotio@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20260116165304.180441-1-jamestiotio@gmail.com
Signed-off-by: Anup Patel <anup@brainfault.org>
Currently, OpenSBI returns SBI_ERR_ALREADY_STARTED when attempting to
start a HW counter that is already started and SBI_ERR_ALREADY_STOPPED
when attempting to stop a HW counter that is already stopped. However,
this is not yet implemented for FW counters.
Add the necessary checks to return the same error codes when attempting
the same actions on FW counters.
Signed-off-by: James Raphael Tiovalen <jamestiotio@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20251213104146.422972-1-jamestiotio@gmail.com
Signed-off-by: Anup Patel <anup@brainfault.org>
Currently, when configuring a matching programmable HPM counter with
Sscofpmf being present, cidx_base > 2, and cidx_mask == 0 to monitor
either the CPU_CYCLES or INSTRUCTIONS hardware event,
sbi_pmu_ctr_cfg_match will succeed but it will configure the
corresponding fixed counter instead of the counter specified by the
cidx_base parameter.
During counter configuration, the following issues may arise:
- If the SKIP_MATCH flag is set, an out-of-bounds memory read of the
phs->active_events array would occur, which could lead to undefined
behavior.
- If the CLEAR_VALUE flag is set, the corresponding fixed counter will
be reset, which could be considered unexpected behavior.
- If the AUTO_START flag is set, pmu_ctr_start_hw will silently start
the fixed counter, even though it has already started. From the
supervisor's perspective, nothing has changed, which could be confusing.
The supervisor will not see the SBI_ERR_ALREADY_STARTED error code since
sbi_pmu_ctr_cfg_match does not return the error code of
pmu_ctr_start_hw.
The only way to detect these issues is to check the ctr_idx return value
of sbi_pmu_ctr_cfg_match and compare it with cidx_base.
Fix these issues by returning the SBI_ERR_INVALID_PARAM error code if
the cidx_mask parameter value being passed in is 0 since an invalid
parameter should not lead to a successful sbi_pmu_ctr_cfg_match but with
unexpected side effects.
Following a similar rationale, add the validation check to
sbi_pmu_ctr_start and sbi_pmu_ctr_stop as well since sbi_fls is
undefined when the mask is 0.
This also aligns OpenSBI's behavior with KVM's.
Signed-off-by: James Raphael Tiovalen <jamestiotio@gmail.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20250520132533.30974-1-jamestiotio@gmail.com
Signed-off-by: Anup Patel <anup@brainfault.org>
