Messages in this thread | | | From | Pavel Fedin <> | Subject | RE: [PATCH 1/7] KVM: api: add kvm_irq_routing_extended_msi | Date | Mon, 06 Jul 2015 16:32:12 +0300 |
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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. And there is no other way to use irqfds with GICv3. 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; }
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; } --- cut ---
ITS code in qemu just does:
---cut --- msi_supported = true; kvm_msi_flags = KVM_MSI_VALID_DEVID; kvm_msi_via_irqfd_allowed = kvm_has_gsi_routing(); kvm_gsi_routing_allowed = kvm_msi_via_irqfd_allowed; --- cut ---
I set KVM_MSI_VALID_DEVID unconditionally here just because it will never be checked if kvm_msi_via_irqfd_allowed is false, it's just qemu specifics. The more canonical form would perhaps be: --- cut --- if (kvm_has_gsi_routing()) { kvm_msi_flags = KVM_MSI_VALID_DEVID; kvm_gsi_routing_allowed = true; kvm_msi_via_irqfd_allowed = true; } --- cut ---
I can post my sets as RFCs to qemu mailing list, if you want to take a look at the whole change set.
Kind regards, Pavel Fedin Expert Engineer Samsung Electronics Research center Russia
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