kvm: Report proper error on GET_VCPU_MMAP_SIZE failures

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

kvm-all.c

@@ -219,6 +219,7 @@ int kvm_init_vcpu(CPUState *env)
 
     mmap_size = kvm_ioctl(s, KVM_GET_VCPU_MMAP_SIZE, 0);
     if (mmap_size < 0) {
+        ret = mmap_size;
         DPRINTF("KVM_GET_VCPU_MMAP_SIZE failed\n");
         goto err;
     }