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| author | Michal Luczaj <mhal@rbox.co> | 2024-08-02 23:29:41 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2024-08-13 19:01:46 +0300 |
| commit | 238d3d63d1e27c8d9733b48f7b682fc6aba86672 (patch) | |
| tree | c55f97dbefa9ad9564d01abe278964ff89de13ea /tools | |
| parent | 4b7c3f6d04bd53f2e5b228b6821fb8f5d1ba3071 (diff) | |
| download | linux-238d3d63d1e27c8d9733b48f7b682fc6aba86672.tar.xz | |
KVM: selftests: Add a testcase to verify x2APIC is fully readonly
Add a test to verify that userspace can't change a vCPU's x2APIC ID by
abusing KVM_SET_LAPIC. KVM models the x2APIC ID (and x2APIC LDR) as
readonly, and silently ignores userspace attempts to change the x2APIC ID
for backwards compatibility.
Signed-off-by: Michal Luczaj <mhal@rbox.co>
[sean: write changelog, add to existing test]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20240802202941.344889-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/testing/selftests/kvm/x86_64/xapic_state_test.c | 28 |
1 files changed, 28 insertions, 0 deletions
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 69849acd95b0..618cd2442390 100644 --- a/tools/testing/selftests/kvm/x86_64/xapic_state_test.c +++ b/tools/testing/selftests/kvm/x86_64/xapic_state_test.c @@ -184,6 +184,33 @@ static void test_apic_id(void) kvm_vm_free(vm); } +static void test_x2apic_id(void) +{ + struct kvm_lapic_state lapic = {}; + struct kvm_vcpu *vcpu; + struct kvm_vm *vm; + int i; + + vm = vm_create_with_one_vcpu(&vcpu, NULL); + vcpu_set_msr(vcpu, MSR_IA32_APICBASE, MSR_IA32_APICBASE_ENABLE | X2APIC_ENABLE); + + /* + * Try stuffing a modified x2APIC ID, KVM should ignore the value and + * always return the vCPU's default/readonly x2APIC ID. + */ + for (i = 0; i <= 0xff; i++) { + *(u32 *)(lapic.regs + APIC_ID) = i << 24; + *(u32 *)(lapic.regs + APIC_SPIV) = APIC_SPIV_APIC_ENABLED; + vcpu_ioctl(vcpu, KVM_SET_LAPIC, &lapic); + + vcpu_ioctl(vcpu, KVM_GET_LAPIC, &lapic); + TEST_ASSERT(*((u32 *)&lapic.regs[APIC_ID]) == vcpu->id << 24, + "x2APIC ID should be fully readonly"); + } + + kvm_vm_free(vm); +} + int main(int argc, char *argv[]) { struct xapic_vcpu x = { @@ -211,4 +238,5 @@ int main(int argc, char *argv[]) kvm_vm_free(vm); test_apic_id(); + test_x2apic_id(); } |