From: Michael Ellerman <mpe@kernel.org>
To: Anup Patel <anup@brainfault.org>
Cc: opensbi@lists.infradead.org
Subject: Re: [PATCH] lib/sbi_pmu: Don't fallback to fixed counters when sscofpmf && !smcntrpmf
Date: Mon, 18 May 2026 11:13:44 +1000 [thread overview]
Message-ID: <bc946e89-a33f-4f29-8d4d-119f1a76d26e@kernel.org> (raw)
In-Reply-To: <CAAhSdy1FUMVpOAmTgdgyPwKRQ0Vepjoqh4NOq32kVUsYyT1jvw@mail.gmail.com>
On 11/5/2026 17:52, Anup Patel wrote:
> On Tue, Mar 24, 2026 at 5:59 PM Michael Ellerman <mpe@kernel.org> wrote:
>>
>> Currently when searching for a hardware counter for an event, if no
>> programmable counter is available, the code falls back to using a fixed
>> counter (mcycle/minstret) if one matches the event.
>>
>> However the fallback is incorrect when sscofpmf is present but
>> smcntrpmf is not. That's because with sscofpmf, programmable counters
>> support mode filtering, but the fixed counters do not (without
>> smcntrpmf). Even if the caller didn't configure mode filtering, by
>> default programmable counters don't count M mode when sscofpmf is
>> present, whereas mcycle/minstret do.
>>
>> Fix the logic to not fallback to a fixed counter if sscofpmf is present
>> but smcntrpmf is not.
>>
>> Signed-off-by: Michael Ellerman <mpe@kernel.org>
>
> Fixes tag is missing but I will add this at the time of merging.
Thanks.
cheers
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prev parent reply other threads:[~2026-05-18 1:13 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-24 12:29 [PATCH] lib/sbi_pmu: Don't fallback to fixed counters when sscofpmf && !smcntrpmf Michael Ellerman
2026-05-11 7:52 ` Anup Patel
2026-05-18 1:13 ` Michael Ellerman [this message]
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