[PATCH v3 06/14] KVM: arm64: PMU: Only narrow counters that are not 64bit wide

Marc Zyngier
2022-11-07T08:55:11Z

The current PMU emulation sometimes narrows counters to 32bit
if the counter isn't the cycle counter. As this is going to
change with PMUv3p5 where the counters are all 64bit, fix
the couple of cases where this happens unconditionally.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/kvm/pmu-emul.c | 14 ++++++--------
1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index 39a04ae424d1..8f6462cbc408 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -151,20 +151,17 @@ static void kvm_pmu_release_perf_event(struct kvm_pmc *pmc)
*/
static void kvm_pmu_stop_counter(struct kvm_vcpu *vcpu, struct kvm_pmc *pmc)
{
- u64 counter, reg, val;
+ u64 reg, val;

if (!pmc->perf_event)
return;

- counter = kvm_pmu_get_counter_value(vcpu, pmc->idx);
+ val = kvm_pmu_get_counter_value(vcpu, pmc->idx);

- if (pmc->idx == ARMV8_PMU_CYCLE_IDX) {
+ if (pmc->idx == ARMV8_PMU_CYCLE_IDX)
reg = PMCCNTR_EL0;
- val = counter;
- } else {
+ else
reg = PMEVCNTR0_EL0 + pmc->idx;
- val = lower_32_bits(counter);
- }

__vcpu_sys_reg(vcpu, reg) = val;

@@ -416,7 +413,8 @@ static void kvm_pmu_counter_increment(struct kvm_vcpu *vcpu,

/* Increment this counter */
reg = __vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + i) + 1;
- reg = lower_32_bits(reg);
+ if (!kvm_pmu_idx_is_64bit(vcpu, i))
+ reg = lower_32_bits(reg);
__vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + i) = reg;

/* No overflow? move on */
--
2.34.1