1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * kvm_create_max_vcpus
4 *
5 * Copyright (C) 2019, Google LLC.
6 *
7 * Test for KVM_CAP_MAX_VCPUS and KVM_CAP_MAX_VCPU_ID.
8 */
9
10#define _GNU_SOURCE /* for program_invocation_short_name */
11#include <fcntl.h>
12#include <stdio.h>
13#include <stdlib.h>
14#include <string.h>
15#include <sys/resource.h>
16
17#include "test_util.h"
18
19#include "kvm_util.h"
20#include "asm/kvm.h"
21#include "linux/kvm.h"
22
23void test_vcpu_creation(int first_vcpu_id, int num_vcpus)
24{
25 struct kvm_vm *vm;
26 int i;
27
28 pr_info("Testing creating %d vCPUs, with IDs %d...%d.\n",
29 num_vcpus, first_vcpu_id, first_vcpu_id + num_vcpus - 1);
30
31 vm = vm_create_barebones();
32
33 for (i = first_vcpu_id; i < first_vcpu_id + num_vcpus; i++)
34 /* This asserts that the vCPU was created. */
35 __vm_vcpu_add(vm, i);
36
37 kvm_vm_free(vm);
38}
39
40int main(int argc, char *argv[])
41{
42 int kvm_max_vcpu_id = kvm_check_cap(KVM_CAP_MAX_VCPU_ID);
43 int kvm_max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
44 /*
45 * Number of file descriptors reqired, KVM_CAP_MAX_VCPUS for vCPU fds +
46 * an arbitrary number for everything else.
47 */
48 int nr_fds_wanted = kvm_max_vcpus + 100;
49 struct rlimit rl;
50
51 pr_info("KVM_CAP_MAX_VCPU_ID: %d\n", kvm_max_vcpu_id);
52 pr_info("KVM_CAP_MAX_VCPUS: %d\n", kvm_max_vcpus);
53
54 /*
55 * Check that we're allowed to open nr_fds_wanted file descriptors and
56 * try raising the limits if needed.
57 */
58 TEST_ASSERT(!getrlimit(RLIMIT_NOFILE, &rl), "getrlimit() failed!");
59
60 if (rl.rlim_cur < nr_fds_wanted) {
61 rl.rlim_cur = nr_fds_wanted;
62 if (rl.rlim_max < nr_fds_wanted) {
63 int old_rlim_max = rl.rlim_max;
64 rl.rlim_max = nr_fds_wanted;
65
66 int r = setrlimit(RLIMIT_NOFILE, &rl);
67 __TEST_REQUIRE(r >= 0,
68 "RLIMIT_NOFILE hard limit is too low (%d, wanted %d)",
69 old_rlim_max, nr_fds_wanted);
70 } else {
71 TEST_ASSERT(!setrlimit(RLIMIT_NOFILE, &rl), "setrlimit() failed!");
72 }
73 }
74
75 /*
76 * Upstream KVM prior to 4.8 does not support KVM_CAP_MAX_VCPU_ID.
77 * Userspace is supposed to use KVM_CAP_MAX_VCPUS as the maximum ID
78 * in this case.
79 */
80 if (!kvm_max_vcpu_id)
81 kvm_max_vcpu_id = kvm_max_vcpus;
82
83 TEST_ASSERT(kvm_max_vcpu_id >= kvm_max_vcpus,
84 "KVM_MAX_VCPU_IDS (%d) must be at least as large as KVM_MAX_VCPUS (%d).",
85 kvm_max_vcpu_id, kvm_max_vcpus);
86
87 test_vcpu_creation(first_vcpu_id: 0, num_vcpus: kvm_max_vcpus);
88
89 if (kvm_max_vcpu_id > kvm_max_vcpus)
90 test_vcpu_creation(
91 first_vcpu_id: kvm_max_vcpu_id - kvm_max_vcpus, num_vcpus: kvm_max_vcpus);
92
93 return 0;
94}
95

source code of linux/tools/testing/selftests/kvm/kvm_create_max_vcpus.c