KVM: arm64: Only apply PMCR_EL0.P to the guest range of counters

An important distinction from other registers affected by HPMN is that
PMCR_EL0 only affects the guest range of counters, regardless of the EL
from which it is accessed. Ensure that PMCR_EL0.P is always applied to
'guest' counters by manually computing the mask rather than deriving it
from the current context.

Reviewed-by: Marc Zyngier <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Oliver Upton <[e-mail]>

arch/arm64/kvm/pmu-emul.c

···
 		kvm_pmu_set_counter_value(vcpu, ARMV8_PMU_CYCLE_IDX, 0);
 
 	if (val & ARMV8_PMU_PMCR_P) {
-		unsigned long mask = kvm_pmu_accessible_counter_mask(vcpu);
-		mask &= ~BIT(ARMV8_PMU_CYCLE_IDX);
+		/*
+		 * Unlike other PMU sysregs, the controls in PMCR_EL0 always apply
+		 * to the 'guest' range of counters and never the 'hyp' range.
+		 */
+		unsigned long mask = kvm_pmu_implemented_counter_mask(vcpu) &
+				     ~kvm_pmu_hyp_counter_mask(vcpu) &
+				     ~BIT(ARMV8_PMU_CYCLE_IDX);
+
 		for_each_set_bit(i, &mask, 32)
 			kvm_pmu_set_pmc_value(kvm_vcpu_idx_to_pmc(vcpu, i), 0, true);
 	}