KVM: selftests: Test vCPU boot IDs above 2^32 and MAX_VCPU_ID

The KVM_SET_BOOT_CPU_ID ioctl missed to reject invalid vCPU IDs. Verify
this no longer works and gets rejected with an appropriate error code.

Signed-off-by: Mathias Krause <minipli@grsecurity.net>
Link: https://lore.kernel.org/r/20240614202859.3597745-6-minipli@grsecurity.net
[sean: add test for MAX_VCPU_ID+1, always do negative test]
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/tools/testing/selftests/kvm/x86_64/set_boot_cpu_id.c b/tools/testing/selftests/kvm/x86_64/set_boot_cpu_id.c
index d691d86e5bc33a55f4c2fc801e3d5a872bf81332..49913784bc82a039fd21eefb03624ca040e3cbf5 100644 (file)
--- a/tools/testing/selftests/kvm/x86_64/set_boot_cpu_id.c
+++ b/tools/testing/selftests/kvm/x86_64/set_boot_cpu_id.c
@@ -33,6 +33,20 @@ static void guest_not_bsp_vcpu(void *arg)
        GUEST_DONE();
 }
 
+static void test_set_invalid_bsp(struct kvm_vm *vm)
+{
+       unsigned long max_vcpu_id = vm_check_cap(vm, KVM_CAP_MAX_VCPU_ID);
+       int r;
+
+       if (max_vcpu_id) {
+               r = __vm_ioctl(vm, KVM_SET_BOOT_CPU_ID, (void *)(max_vcpu_id + 1));
+               TEST_ASSERT(r == -1 && errno == EINVAL, "BSP with ID > MAX should fail");
+       }
+
+       r = __vm_ioctl(vm, KVM_SET_BOOT_CPU_ID, (void *)(1L << 32));
+       TEST_ASSERT(r == -1 && errno == EINVAL, "BSP with ID[63:32]!=0 should fail");
+}
+
 static void test_set_bsp_busy(struct kvm_vcpu *vcpu, const char *msg)
 {
        int r = __vm_ioctl(vcpu->vm, KVM_SET_BOOT_CPU_ID,
@@ -80,6 +94,8 @@ static struct kvm_vm *create_vm(uint32_t nr_vcpus, uint32_t bsp_vcpu_id,
 
        vm = vm_create(nr_vcpus);
 
+       test_set_invalid_bsp(vm);
+
        vm_ioctl(vm, KVM_SET_BOOT_CPU_ID, (void *)(unsigned long)bsp_vcpu_id);
 
        for (i = 0; i < nr_vcpus; i++)