KVM: arm64: Filter out v8.1+ events on v8.0 HW

When running on v8.0 HW, make sure we don't try to advertise
events in the 0x4000-0x403f range.

Cc: stable@vger.kernel.org
Fixes: 88865bec ("KVM: arm64: Mask out filtered events in PCMEID{0,1}_EL1")
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210121105636.1478491-1-maz@kernel.org

arch/arm64/kvm/pmu-emul.c

@@ -788,7 +788,7 @@ u64 kvm_pmu_get_pmceid(struct kvm_vcpu *vcpu, bool pmceid1)
 {
 	unsigned long *bmap = vcpu->kvm->arch.pmu_filter;
 	u64 val, mask = 0;
-	int base, i;
+	int base, i, nr_events;
 
 	if (!pmceid1) {
 		val = read_sysreg(pmceid0_el0);
@@ -801,13 +801,17 @@ u64 kvm_pmu_get_pmceid(struct kvm_vcpu *vcpu, bool pmceid1)
 	if (!bmap)
 		return val;
 
+	nr_events = kvm_pmu_event_mask(vcpu->kvm) + 1;
+
 	for (i = 0; i < 32; i += 8) {
 		u64 byte;
 
 		byte = bitmap_get_value8(bmap, base + i);
 		mask |= byte << i;
-		byte = bitmap_get_value8(bmap, 0x4000 + base + i);
-		mask |= byte << (32 + i);
+		if (nr_events >= (0x4000 + base + 32)) {
+			byte = bitmap_get_value8(bmap, 0x4000 + base + i);
+			mask |= byte << (32 + i);
+		}
 	}
 
 	return val & mask;