Paul Brook wrote: >> Instead of writing directly, let's abstract it behind a qemu_set_irq(). >> This is easier for device authors. The default implementation of the >> irq callback could write to apic memory, while for kvm we can directly >> trigger the interrupt via the kvm APIs. >> > > I'm still not convinced. > > A tight coupling between PCI devices and the APIC is just going to cause us > problems later one. I'm going to come back to the fact that these are memory > writes so once we get IOMMU support they will presumably be subject to > remapping by that, just like any other memory access. > I'm not suggesting the qemu_irq will extend all the way to the apic. Think of it as connecting the device core with its interrupt unit. > Even ignoring that, qemu_irq isn't really the right interface. A MSI is a one- > off event, not a level state. OTOH stl_phys is exactly the right interface. > The qemu_irq callback should do an stl_phys(). The device is happy since it's using the same API it uses for non-MSI. The APIC is happy since it isn't connected directly to the device. stl_phys() is happy since it sees more traffic and can serve more ads. kvm is happy since it can hijack the callback to throw the interrupt directly into the kernel. > The KVM interface should be contained within the APIC implementation. > Tricky, but doable. -- error compiling committee.c: too many arguments to function _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/virtualization
