[PATCH v2] kvm: selftests: Add KVM_CAP_MAX_VCPU_ID cap test

[Zeng Guang <guang.zeng@intel.com>]

Basic test coverage of KVM_CAP_MAX_VCPU_ID cap.

This capability can be enabled before vCPU creation and only allowed
to set once. if assigned vcpu id is beyond KVM_CAP_MAX_VCPU_ID
capability, vCPU creation will fail.

Signed-off-by: Zeng Guang <guang.zeng@intel.com>
---
 tools/testing/selftests/kvm/.gitignore        |  1 +
 tools/testing/selftests/kvm/Makefile          |  1 +
 .../kvm/x86_64/max_vcpuid_cap_test.c          | 59 +++++++++++++++++++
 3 files changed, 61 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/x86_64/max_vcpuid_cap_test.c

diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index d1e8f5237469..b860dcfee920 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -22,6 +22,7 @@
 /x86_64/hyperv_cpuid
 /x86_64/hyperv_features
 /x86_64/hyperv_svm_test
+/x86_64/max_vcpuid_cap_test
 /x86_64/mmio_warning_test
 /x86_64/mmu_role_test
 /x86_64/platform_info_test
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 21c2dbd21a81..e92dc78de4d0 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -86,6 +86,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/xen_shinfo_test
 TEST_GEN_PROGS_x86_64 += x86_64/xen_vmcall_test
 TEST_GEN_PROGS_x86_64 += x86_64/sev_migrate_tests
 TEST_GEN_PROGS_x86_64 += x86_64/amx_test
+TEST_GEN_PROGS_x86_64 += x86_64/max_vcpuid_cap_test
 TEST_GEN_PROGS_x86_64 += access_tracking_perf_test
 TEST_GEN_PROGS_x86_64 += demand_paging_test
 TEST_GEN_PROGS_x86_64 += dirty_log_test
diff --git a/tools/testing/selftests/kvm/x86_64/max_vcpuid_cap_test.c b/tools/testing/selftests/kvm/x86_64/max_vcpuid_cap_test.c
new file mode 100644
index 000000000000..2e3d1d236ef0
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/max_vcpuid_cap_test.c
@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * maximum APIC ID capability tests
+ *
+ * Copyright (C) 2022, Intel, Inc.
+ *
+ * Tests for getting/setting maximum APIC ID capability
+ */
+
+#include "kvm_util.h"
+#include "../lib/kvm_util_internal.h"
+
+#define MAX_VCPU_ID	2
+
+int main(int argc, char *argv[])
+{
+	struct kvm_vm *vm;
+	struct kvm_enable_cap cap = { 0 };
+	int ret;
+
+	vm = vm_create(VM_MODE_DEFAULT, 0, O_RDWR);
+
+	/* Get KVM_CAP_MAX_VCPU_ID cap supported in KVM */
+	ret = vm_check_cap(vm, KVM_CAP_MAX_VCPU_ID);
+
+	/* Check failure if set KVM_CAP_MAX_VCPU_ID beyond KVM cap */
+	cap.cap = KVM_CAP_MAX_VCPU_ID;
+	cap.args[0] = ret + 1;
+	ret = ioctl(vm->fd, KVM_ENABLE_CAP, &cap);
+	TEST_ASSERT(ret < 0,
+		    "Unexpected success to enable KVM_CAP_MAX_VCPU_ID"
+		    "beyond KVM cap!\n");
+
+	/* Check success if set KVM_CAP_MAX_VCPU_ID */
+	cap.args[0] = MAX_VCPU_ID;
+	ret = ioctl(vm->fd, KVM_ENABLE_CAP, &cap);
+	TEST_ASSERT(ret == 0,
+		    "Unexpected failure to enable KVM_CAP_MAX_VCPU_ID!\n");
+
+	/* Check success if set KVM_CAP_MAX_VCPU_ID same value */
+	ret = ioctl(vm->fd, KVM_ENABLE_CAP, &cap);
+	TEST_ASSERT(ret == 0,
+		    "Unexpected failure to set KVM_CAP_MAX_VCPU_ID same value\n");
+
+	/* Check failure if set KVM_CAP_MAX_VCPU_ID different value again */
+	cap.args[0] = MAX_VCPU_ID + 1;
+	ret = ioctl(vm->fd, KVM_ENABLE_CAP, &cap);
+	TEST_ASSERT(ret < 0,
+		    "Unexpected success to enable KVM_CAP_MAX_VCPU_ID with"
+		    "different value again\n");
+
+	/* Check failure if create vCPU with id beyond KVM_CAP_MAX_VCPU_ID cap*/
+	ret = ioctl(vm->fd, KVM_CREATE_VCPU, MAX_VCPU_ID);
+	TEST_ASSERT(ret < 0,
+		    "Unexpected success in creating a vCPU with VCPU ID out of range\n");
+
+	kvm_vm_free(vm);
+	return 0;
+}
-- 
2.27.0