[PATCH 2/2] KVM: selftests: Verify that KVM returns the configured APIC bus frequency

From: Sean Christopherson

Date: Fri May 22 2026 - 13:56:17 EST


Add checks in the APIC bus clock test to verify that querying
KVM_CAP_X86_APIC_BUS_CYCLES_NS on the VM after changing the frequency
returns the VM's actual APIC bus frequency, not KVM's default. For
giggles, verify that KVM still returns its default frequency for the
system-scoped check.

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
tools/testing/selftests/kvm/x86/apic_bus_clock_test.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/tools/testing/selftests/kvm/x86/apic_bus_clock_test.c b/tools/testing/selftests/kvm/x86/apic_bus_clock_test.c
index 404f0028e110..0c84c27ea584 100644
--- a/tools/testing/selftests/kvm/x86/apic_bus_clock_test.c
+++ b/tools/testing/selftests/kvm/x86/apic_bus_clock_test.c
@@ -137,6 +137,10 @@ static void run_apic_bus_clock_test(u64 apic_hz, u64 delay_ms,
vm_enable_cap(vm, KVM_CAP_X86_APIC_BUS_CYCLES_NS,
NSEC_PER_SEC / apic_hz);

+ TEST_ASSERT_EQ(kvm_check_cap(KVM_CAP_X86_APIC_BUS_CYCLES_NS), 1);
+ TEST_ASSERT_EQ(vm_check_cap(vm, KVM_CAP_X86_APIC_BUS_CYCLES_NS),
+ NSEC_PER_SEC / apic_hz);
+
vcpu = vm_vcpu_add(vm, 0, apic_guest_code);
vcpu_args_set(vcpu, 2, apic_hz, delay_ms);

--
2.54.0.794.g4f17f83d09-goog