1 files changed, 96 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/kvm_create_max_vcpus.c b/tools/testing/selftests/kvm/kvm_create_max_vcpus.c
new file mode 100644
index 000000000..aa3795cd7
--- /dev/null
+++ b/tools/testing/selftests/kvm/kvm_create_max_vcpus.c
@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * kvm_create_max_vcpus
+ *
+ * Copyright (C) 2019, Google LLC.
+ *
+ * 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 <sys/resource.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;
+
+	pr_info("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_DEFAULT, DEFAULT_GUEST_PHY_PAGES, O_RDWR);
+
+	for (i = first_vcpu_id; i < first_vcpu_id + num_vcpus; i++)
+		/* This asserts that the vCPU was created. */
+		vm_vcpu_add(vm, i);
+
+	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);
+	/*
+	 * Number of file descriptors reqired, KVM_CAP_MAX_VCPUS for vCPU fds +
+	 * an arbitrary number for everything else.
+	 */
+	int nr_fds_wanted = kvm_max_vcpus + 100;
+	struct rlimit rl;
+
+	pr_info("KVM_CAP_MAX_VCPU_ID: %d\n", kvm_max_vcpu_id);
+	pr_info("KVM_CAP_MAX_VCPUS: %d\n", kvm_max_vcpus);
+
+	/*
+	 * Check that we're allowed to open nr_fds_wanted file descriptors and
+	 * try raising the limits if needed.
+	 */
+	TEST_ASSERT(!getrlimit(RLIMIT_NOFILE, &rl), "getrlimit() failed!");
+
+	if (rl.rlim_cur < nr_fds_wanted) {
+		rl.rlim_cur = nr_fds_wanted;
+		if (rl.rlim_max < nr_fds_wanted) {
+			int old_rlim_max = rl.rlim_max;
+			rl.rlim_max = nr_fds_wanted;
+
+			int r = setrlimit(RLIMIT_NOFILE, &rl);
+			if (r < 0) {
+				printf("RLIMIT_NOFILE hard limit is too low (%d, wanted %d)\n",
+				       old_rlim_max, nr_fds_wanted);
+				exit(KSFT_SKIP);
+			}
+		} else {
+			TEST_ASSERT(!setrlimit(RLIMIT_NOFILE, &rl), "setrlimit() failed!");
+		}
+	}
+
+	/*
+	 * 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;
+}