Listing 3. Our First Virtual Machine Launcher (launcher.c)

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <libkvm.h>

/* callback definitions as shown in Listing 2 go here */

void load_file(void *mem, const char *filename)
{
    int  fd;
    int  nr;

    fd = open(filename, O_RDONLY);
    if (fd == -1) {
        fprintf(stderr, "Cannot open %s", filename);
        perror("open");
        exit(1);
    }
    while ((nr = read(fd, mem, 4096)) != -1  &&  nr != 0)
        mem += nr;

    if (nr == -1) {
        perror("read");
        exit(1);
    }
    close(fd);
}

#define MEMORY_SIZE     (0x1000000)     /* 16 Mb */
#define FIRST_VCPU      (0)

int main(int argc, char *argv[])
{
    kvm_context_t  kvm;
    void           *memory_area;

    /* Second argument is an opaque, we don't use it yet */
    kvm = kvm_init(&my_callbacks, NULL);
    if (!kvm) {
        fprintf(stderr, "KVM init failed");
        exit(1);
    }
    if (kvm_create(kvm, MEMORY_SIZE, &memory_area) != 0) {
        fprintf(stderr, "VM creation failed");
        exit(1);
    }
#ifndef KVM_VERSION_LESS_THAN_65
    if (kvm_create_vcpu(kvm, FIRST_VCPU)) {
        fprintf(stderr, "VCPU creation failed");
        exit(1);
    }
#endif
    memory_area = kvm_create_phys_mem(kvm, 0, MEMORY_SIZE, 0, 1);
    load_file(memory_area + 0xf0000, argv[1]);

    kvm_run(kvm, FIRST_VCPU);

    return 0;
}