On Mon, May 11, 2009 at 05:24:25PM -0500, Anthony Liguori wrote: > Michael S. Tsirkin wrote: >> Here's a draft MSI-X support patch. Among missing features: >> save/load support, and command-line flag to control the >> feature. This is on top of qemu-kvm: msi-x is disabled >> without kvm interrupt injection support for now. >> > > What's your impression of how much work would be to get this going on > top of upstream QEMU? > > I'm willing to borrow a few cycles to help out here. I'd really like to > see this series go in via QEMU if possible. It seems that if I just call apic_deliver_irq each time I want to send MSI, things will work. However, large part of the msix code is managing IRQs versus kernel, and I'm not sure it's a wise investment of effort to rip it all out. So IMHO, what's missing is API that abstracts managing irq routes in kvm, specifically abstract this stuff in some way: kvm_get_irq_route_gsi kvm_add_routing_entry kvm_del_routing_entry kvm_commit_irq_routes kvm_set_irq How hard is that? For now, this API could be a stub that just stores the routes somewhere, and set_irq would call the local apic emulation, along the lines of: uint8_t dest = (addr_lo & MSI_ADDR_DEST_ID_MASK) >> MSI_ADDR_DEST_ID_SHIFT; uint8_t vector = (addr_hi & MSI_DATA_VECTOR_MASK) >> MSI_DATA_VECTOR_SHIFT; uint8_t dest_mode = (addr_lo >> MSI_ADDR_DEST_MODE_SHIFT) & 0x1; uint8_t trigger_mode = (data >> MSI_DATA_TRIGGER_SHIFT) & 0x1; uint8_t delivery_mode = (data >> MSI_DATA_DELIVERY_MODE_SHIFT) & 0x7; apic_deliver_irq(dest, dest_mode, delivery_mode, vector, 0, trigger_mode); I would be happy to port my msix code to work on top of this API. Willing to help? -- MST -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
