kvm memslot questions

jack.chen
2016-12-12T09:18:44Z

hello,now I want to know which GFN of VM is available,so I set
kvm_userspace_mem->flags |= 0x1; in kvm_vm_ioctl function ,so KVM can
create dirty_bitmap for slots
case KVM_SET_USER_MEMORY_REGION: {
struct kvm_userspace_memory_region kvm_userspace_mem;

……
kvm_userspace_mem->flags |= 0x1;
r = kvm_vm_ioctl_set_memory_region(kvm, &kvm_userspace_mem);
break;

and I have 2 questions:
1.
if corresponding bit is setted,the GFN is used by VM,other than it is
available!right?
2、
how to check wheather the bit is 1 or not,the test_bit function
returns -1 to me,I do not know if I use wrong function!
thanks in advance!!!