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KVM: arm64: PMU: Fix period computation for 64bit counters with 32bit overflow

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Fix the bogus masking when computing the period of a 64bit counter
with 32bit overflow. It really should be treated like a 32bit counter
for the purpose of the period.

Reported-by: Ricardo Koller <ricarkol@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/Y4jbosgHbUDI0WF4@google.com
This commit is contained in:
Marc Zyngier 2022-12-05 12:05:51 +00:00
parent 64d6820d64
commit 58ff6569bc
1 changed files with 3 additions and 7 deletions
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10
arch/arm64/kvm/pmu-emul.c
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@ -461,14 +461,10 @@ static u64 compute_period(struct kvm_pmc *pmc, u64 counter)
{ {
u64 val; u64 val;
if (kvm_pmc_is_64bit(pmc)) { if (kvm_pmc_is_64bit(pmc) && kvm_pmc_has_64bit_overflow(pmc))
if (!kvm_pmc_has_64bit_overflow(pmc)) val = (-counter) & GENMASK(63, 0);
val = -(counter & GENMASK(31, 0)); else
else
val = (-counter) & GENMASK(63, 0);
} else {
val = (-counter) & GENMASK(31, 0); val = (-counter) & GENMASK(31, 0);
}
return val; return val;
} }