Hi Pavel,
On 06/07/15 14:32, Pavel Fedin wrote:
> Hi!
>
>>> Well, as we are about to implement this: yes. But the issue is that MSI
>>> injection and GSI routing code is generic PCI code in userland (at least
>>> in kvmtool, guess in QEMU, too), so I don't want to pull in any kind of
>>> ARM specific code in there. The idea is to always provide the device ID
>>> from the PCI code (for PCI devices it's just the B/D/F triplet), but
>>> only send it to the kernel if needed. Querying a KVM capability is
>>> perfectly fine for this IMO.
>>
>> Yes, I agree.
>
> Actually, we already have this capability, it's KVM_CAP_IRQ_ROUTING. If we have this capability,
> and want to use irqfds with GICv3, we need to set KVM_MSI_VALID_DEVID.
This is the connection that I don't like: We make the decision to
support a flag on a generic KVM interface dependent on some particular
device emulation (for some very specific architecture, also).
> And there is no other way to
> use irqfds with GICv3.
For now: yes, but I fail to see why the GICv3 is so special that is
justifies an extra handling in the KVM interrupt routing code. If it is
special, lets name it explicitly why: we need a device ID.
> Just for example, this is what i have done in qemu:
> --- cut ---
> int kvm_irqchip_add_msi_route(KVMState *s, MSIMessage msg, PCIDevice *dev)
> {
> struct kvm_irq_routing_entry kroute = {};
> int virq;
>
> if (kvm_gsi_direct_mapping()) {
> return kvm_arch_msi_data_to_gsi(msg.data);
> }
>
> if (!kvm_gsi_routing_enabled()) {
> return -ENOSYS;
> }
>
> virq = kvm_irqchip_get_virq(s);
> if (virq < 0) {
> return virq;
> }
>
> kroute.gsi = virq;
> kroute.type = KVM_IRQ_ROUTING_MSI;
> kroute.u.msi.address_lo = (uint32_t)msg.address;
> kroute.u.msi.address_hi = msg.address >> 32;
> kroute.u.msi.data = le32_to_cpu(msg.data);
> kroute.flags = kvm_msi_flags;
> if (kroute.flags & KVM_MSI_VALID_DEVID) {
> kroute.u.msi.devid = (pci_bus_num(dev->bus) << 8) | dev->devfn;
> }
Wouldn't:
if (kvm_vm_check_extension(s, KVM_CAP_MSI_DEVID)) {
kroute.flags = KVM_MSI_VALID_DEVID;
kroute.u.msi.devid = (pci_bus_num(dev->bus) << 8) | dev->devfn;
}
be saner (without a global variable)?
That would make the interface more consistent, with a new flag being
protected by a new capability.
Cheers,
Andre.
> if (kvm_arch_fixup_msi_route(&kroute, msg.address, msg.data)) {
> kvm_irqchip_release_virq(s, virq);
> return -EINVAL;
> }
>
> kvm_add_routing_entry(s, &kroute);
> kvm_irqchip_commit_routes(s);
>
> return virq;
> }
--
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
