3 files changed, 72 insertions, 0 deletions

diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index 6027b5f3d72d..2a9209d18684 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -1,6 +1,7 @@
 /x86_64/cr4_cpuid_sync_test
 /x86_64/evmcs_test
 /x86_64/hyperv_cpuid
+/x86_64/kvm_create_max_vcpus
 /x86_64/platform_info_test
 /x86_64/set_sregs_test
 /x86_64/smm_test
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index f8588cca2bef..6b7b3617d25c 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -20,6 +20,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/evmcs_test
 TEST_GEN_PROGS_x86_64 += x86_64/hyperv_cpuid
 TEST_GEN_PROGS_x86_64 += x86_64/vmx_close_while_nested_test
 TEST_GEN_PROGS_x86_64 += x86_64/smm_test
+TEST_GEN_PROGS_x86_64 += x86_64/kvm_create_max_vcpus
 TEST_GEN_PROGS_x86_64 += dirty_log_test
 TEST_GEN_PROGS_x86_64 += clear_dirty_log_test
 
diff --git a/tools/testing/selftests/kvm/x86_64/kvm_create_max_vcpus.c b/tools/testing/selftests/kvm/x86_64/kvm_create_max_vcpus.c
new file mode 100644
index 000000000000..50e92996f918
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/kvm_create_max_vcpus.c
@@ -0,0 +1,70 @@
+/*
+ * kvm_create_max_vcpus
+ *
+ * Copyright (C) 2019, Google LLC.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
+ *
+ * Test for KVM_CAP_MAX_VCPUS and KVM_CAP_MAX_VCPU_ID.
+ */
+
+#define _GNU_SOURCE /* for program_invocation_short_name */
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "test_util.h"
+
+#include "kvm_util.h"
+#include "asm/kvm.h"
+#include "linux/kvm.h"
+
+void test_vcpu_creation(int first_vcpu_id, int num_vcpus)
+{
+        struct kvm_vm *vm;
+        int i;
+
+        printf("Testing creating %d vCPUs, with IDs %d...%d.\n",
+               num_vcpus, first_vcpu_id, first_vcpu_id + num_vcpus - 1);
+
+        vm = vm_create(VM_MODE_P52V48_4K, DEFAULT_GUEST_PHY_PAGES, O_RDWR);
+
+        for (i = 0; i < num_vcpus; i++) {
+                int vcpu_id = first_vcpu_id + i;
+
+                /* This asserts that the vCPU was created. */
+                vm_vcpu_add(vm, vcpu_id, 0, 0);
+        }
+
+        kvm_vm_free(vm);
+}
+
+int main(int argc, char *argv[])
+{
+        int kvm_max_vcpu_id = kvm_check_cap(KVM_CAP_MAX_VCPU_ID);
+        int kvm_max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
+
+        printf("KVM_CAP_MAX_VCPU_ID: %d\n", kvm_max_vcpu_id);
+        printf("KVM_CAP_MAX_VCPUS: %d\n", kvm_max_vcpus);
+
+        /*
+         * Upstream KVM prior to 4.8 does not support KVM_CAP_MAX_VCPU_ID.
+         * Userspace is supposed to use KVM_CAP_MAX_VCPUS as the maximum ID
+         * in this case.
+         */
+        if (!kvm_max_vcpu_id)
+                kvm_max_vcpu_id = kvm_max_vcpus;
+
+        TEST_ASSERT(kvm_max_vcpu_id >= kvm_max_vcpus,
+                    "KVM_MAX_VCPU_ID (%d) must be at least as large as KVM_MAX_VCPUS (%d).",
+                    kvm_max_vcpu_id, kvm_max_vcpus);
+
+        test_vcpu_creation(0, kvm_max_vcpus);
+
+        if (kvm_max_vcpu_id > kvm_max_vcpus)
+                test_vcpu_creation(
+                        kvm_max_vcpu_id - kvm_max_vcpus, kvm_max_vcpus);
+
+        return 0;
+}