From eb98192576315d3f4c6c990d589ab398e7091782 Mon Sep 17 00:00:00 2001 From: Emanuele Giuseppe Esposito Date: Mon, 9 Jan 2023 08:06:05 -0500 Subject: KVM: selftests: Verify APIC_ID is set when forcing x2APIC=>xAPIC transition Add a sub-test to verify that KVM stuffs the APIC_ID when userspace forces a transition from x2APIC to xAPIC without first disabling the APIC. Such a transition is architecturally disallowed (WRMSR will #GP), but needs to be handled by KVM to allow userspace to emulate RESET (ignoring that userspace should also stuff local APIC state on RESET). Signed-off-by: Emanuele Giuseppe Esposito Link: https://lore.kernel.org/r/20230109130605.2013555-3-eesposit@redhat.com Co-developed-by: Sean Christopherson Signed-off-by: Sean Christopherson --- .../selftests/kvm/x86_64/xapic_state_test.c | 55 ++++++++++++++++++++++ 1 file changed, 55 insertions(+) (limited to 'tools/testing') diff --git a/tools/testing/selftests/kvm/x86_64/xapic_state_test.c b/tools/testing/selftests/kvm/x86_64/xapic_state_test.c index d7d37dae3eeb..396c13f42457 100644 --- a/tools/testing/selftests/kvm/x86_64/xapic_state_test.c +++ b/tools/testing/selftests/kvm/x86_64/xapic_state_test.c @@ -132,6 +132,59 @@ static void test_icr(struct xapic_vcpu *x) __test_icr(x, -1ull & ~APIC_DM_FIXED_MASK); } +static void __test_apic_id(struct kvm_vcpu *vcpu, uint64_t apic_base) +{ + uint32_t apic_id, expected; + struct kvm_lapic_state xapic; + + vcpu_set_msr(vcpu, MSR_IA32_APICBASE, apic_base); + + vcpu_ioctl(vcpu, KVM_GET_LAPIC, &xapic); + + expected = apic_base & X2APIC_ENABLE ? vcpu->id : vcpu->id << 24; + apic_id = *((u32 *)&xapic.regs[APIC_ID]); + + TEST_ASSERT(apic_id == expected, + "APIC_ID not set back to %s format; wanted = %x, got = %x", + (apic_base & X2APIC_ENABLE) ? "x2APIC" : "xAPIC", + expected, apic_id); +} + +/* + * Verify that KVM switches the APIC_ID between xAPIC and x2APIC when userspace + * stuffs MSR_IA32_APICBASE. Setting the APIC_ID when x2APIC is enabled and + * when the APIC transitions for DISABLED to ENABLED is architectural behavior + * (on Intel), whereas the x2APIC => xAPIC transition behavior is KVM ABI since + * attempted to transition from x2APIC to xAPIC without disabling the APIC is + * architecturally disallowed. + */ +static void test_apic_id(void) +{ + const uint32_t NR_VCPUS = 3; + struct kvm_vcpu *vcpus[NR_VCPUS]; + uint64_t apic_base; + struct kvm_vm *vm; + int i; + + vm = vm_create_with_vcpus(NR_VCPUS, NULL, vcpus); + vm_enable_cap(vm, KVM_CAP_X2APIC_API, KVM_X2APIC_API_USE_32BIT_IDS); + + for (i = 0; i < NR_VCPUS; i++) { + apic_base = vcpu_get_msr(vcpus[i], MSR_IA32_APICBASE); + + TEST_ASSERT(apic_base & MSR_IA32_APICBASE_ENABLE, + "APIC not in ENABLED state at vCPU RESET"); + TEST_ASSERT(!(apic_base & X2APIC_ENABLE), + "APIC not in xAPIC mode at vCPU RESET"); + + __test_apic_id(vcpus[i], apic_base); + __test_apic_id(vcpus[i], apic_base | X2APIC_ENABLE); + __test_apic_id(vcpus[i], apic_base); + } + + kvm_vm_free(vm); +} + int main(int argc, char *argv[]) { struct xapic_vcpu x = { @@ -157,4 +210,6 @@ int main(int argc, char *argv[]) virt_pg_map(vm, APIC_DEFAULT_GPA, APIC_DEFAULT_GPA); test_icr(&x); kvm_vm_free(vm); + + test_apic_id(); } -- cgit v1.2.3