On Mon, May 12, 2014 at 12:14:25PM +0200, Paolo Bonzini wrote: > Il 12/05/2014 12:08, Michael S. Tsirkin ha scritto: > >On Mon, May 12, 2014 at 11:57:32AM +0200, Paolo Bonzini wrote: > >>Perhaps we can check for cases where only the address is changing, > >>and poke at an existing struct kvm_kernel_irq_routing_entry without > >>doing any RCU synchronization? > > > >I suspect interrupts can get lost then: e.g. if address didn't match any > >cpus, now it matches some. No? > > Can you explain the problem more verbosely? :) > > Multiple writers would still be protected by the mutex, so you > cannot have an "in-place update" writer racing with a "copy the > array" writer. > > Paolo
I am not sure really. I'm worried about reader vs writer. If reader sees a stale msi value msi will be sent to a wrong address.
