On Wed, 2023-01-11 at 11:25 -0500, Michael S. Tsirkin wrote: > On Wed, Jan 11, 2023 at 02:41:58PM +0000, David Woodhouse wrote: > > This allows drivers to register a callback on a qemu_irq, which is > > invoked when a level-triggered IRQ is acked on the irqchip. > > > > This allows us to simulate level-triggered interrupts more efficiently, > > by resampling the state of the interrupt only when it actually matters. > > I think we tried this with vfio and had to give up on this. > I don't remember the details though. Alex probably does?
Hm, not sure why there would be any insurmountable problems. I've seen this working at scale in a different VMM with split-irqchip and PCI INTX + Xen event channel support. And it's what the kernel does internally, and exposes through its dual- eventfd APIs in both KVM IRQ routing and VFIO interrupts. That said, I don't care *that* much. I can live with the way I've done it for the Xen support, by polling the status on a vCPU0 vmexit. Looking at the VFIO code made me throw up in my mouth a little bit, but I just won't do that again... :)
smime.p7s
Description: S/MIME cryptographic signature
