ia64: why is mmio bus access lockless?

Hi,
arch/ia64/kvm/kvm-ia64.c does this:

       mmio_dev = vcpu_find_mmio_dev(vcpu, p->addr, p->size, !p->dir);
       if (mmio_dev) {
               if (!p->dir)
                       kvm_iodevice_write(mmio_dev, p->addr, p->size,
                                               &p->data);
               else
                       kvm_iodevice_read(mmio_dev, p->addr, p->size,
                                               &p->data);

without holding kvm lock.

I know that find/read/write on the bus require locking on x86 - are they safe to do without locking on ia64?

MST

Hi, Michael
Since only virtual ioapic uses the lock-less logic, so it shouldn't introduce the issues. Anyway, it should be safer to add the lock considering its semantic and future usage models. Would you like to prepare a patch to enhance it ? Thanks!
Xiantao