RE: ia64: why is mmio bus access lockless?

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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


Michael S. Tsirkin wrote:
> 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?

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