check-cap-upm.c

#define _GNU_SOURCE
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <linux/kvm.h>
#include <sys/ioctl.h>

#define KVM_CAP_UNMAPPED_PRIVATE_MEM 240

int main(void)
{
        int exit_code = 1;
        int ret;
        int kvm;
        int vm;

        kvm = open("/dev/kvm", O_RDWR | O_CLOEXEC);
        if (kvm == -1) {
                perror("open");
                goto err;
        }

        ret = ioctl(kvm, KVM_GET_API_VERSION, NULL);
        if (ret == -1) {
                perror("ioctl");
                goto err_kvm;
        }

        if (ret != 12) {
                fprintf(stderr, "Expected KVM API 12 != %d", ret);
                goto err_kvm;
        }

        vm = ioctl(kvm, KVM_CREATE_VM, 0UL);
        if (vm == -1) {
                perror("ioctl");
                goto err_kvm;
        }

        ret = ioctl(vm, KVM_CHECK_EXTENSION, KVM_CAP_UNMAPPED_PRIVATE_MEM);
        if (ret == -1) {
                perror("ioctl");
                goto err_vm;
        }

        printf("%d\n", ret);
        exit_code = 0;

err_vm:
        close(vm);

err_kvm:
        close(kvm);

err:
        exit(exit_code);
}