Michael S. Tsirkin wrote:
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
All these are just games with qemu_irq objects. Should be a lot simpler
in userspace.
kvm_set_irq
qemu_set_irq().
How hard is that?
Should be pretty easy, once you get the hang of qemu_irq.
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);
qemu_set_irq() eventually calls a callback that you specify; just set it
do look up the entry and call apic_deliver_irq.
--
Do not meddle in the internals of kernels, for they are subtle and quick to
panic.
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