static void kvm_io_ioeventfd_del(MemoryRegionSection *section,
bool match_data, uint64_t data, int fd)
{
int r;
r = kvm_set_ioeventfd_pio_word(fd, section->offset_within_address_space,
data, false);
if (r < 0) {
abort();
}
}
static void kvm_io_ioeventfd_add(MemoryRegionSection *section,
bool match_data, uint64_t data, int fd)
{
int r;
assert(match_data && section->size == 2);
r = kvm_set_ioeventfd_pio_word(fd, section->offset_within_address_space,
data, true);
if (r < 0) {
abort();
}
}
static int kvm_check_many_ioeventfds(void)
{
/* Userspace can use ioeventfd for io notification. This requires a host
* that supports eventfd(2) and an I/O thread; since eventfd does not
* support SIGIO it cannot interrupt the vcpu.
*
* Older kernels have a 6 device limit on the KVM io bus. Find out so we
* can avoid creating too many ioeventfds.
*/
#if defined(CONFIG_EVENTFD)
int ioeventfds[7];
int i, ret = 0;
for (i = 0; i < ARRAY_SIZE(ioeventfds); i++) {
ioeventfds[i] = eventfd(0, EFD_CLOEXEC);
if (ioeventfds[i] < 0) {
break;
}
ret = kvm_set_ioeventfd_pio_word(ioeventfds[i], 0, i, true);
if (ret < 0) {
close(ioeventfds[i]);
break;
}
}
/* Decide whether many devices are supported or not */
ret = i == ARRAY_SIZE(ioeventfds);
while (i-- > 0) {
kvm_set_ioeventfd_pio_word(ioeventfds[i], 0, i, false);
close(ioeventfds[i]);
}
return ret;
#else
return 0;
#endif
}
