Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752455AbbGFPCQ (ORCPT ); Mon, 6 Jul 2015 11:02:16 -0400 Received: from mail-wi0-f181.google.com ([209.85.212.181]:35809 "EHLO mail-wi0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751307AbbGFPCG (ORCPT ); Mon, 6 Jul 2015 11:02:06 -0400 Message-ID: <559A9854.2090607@linaro.org> Date: Mon, 06 Jul 2015 17:01:40 +0200 From: Eric Auger User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Pavel Fedin , "'Paolo Bonzini'" , "'Andre Przywara'" , "'Christoffer Dall'" CC: eric.auger@st.com, linux-arm-kernel@lists.infradead.org, "'Marc Zyngier'" , kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/7] KVM: api: add kvm_irq_routing_extended_msi References: <1435592237-17924-1-git-send-email-eric.auger@linaro.org> <1435592237-17924-2-git-send-email-eric.auger@linaro.org> <011f01d0b498$6a17aeb0$3e470c10$@samsung.com> <5596503E.6040902@arm.com> <00fd01d0b7b6$f6cf3550$e46d9ff0$@samsung.com> <559A3C9C.6050302@arm.com> <20150706093026.GA11590@cbox> <559A52E6.5050402@arm.com> <20150706103755.GC11590@cbox> <559A6164.1000401@redhat.com> <559A6527.1040107@arm.com> <559A6BBC.2040901@redhat.com> <024301d0b7f0$2b13b410$813b1c30$@samsung.com> In-Reply-To: <024301d0b7f0$2b13b410$813b1c30$@samsung.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3737 Lines: 112 Hi all, On 07/06/2015 03:32 PM, 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. 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; Personally I prefer a capability rather than hardcoding a global variable value in the qemu interrupt controller code. All the more so typically there is KVM GSI routing cap that could/should? be queried instead of hardcoding the value I think. So not sure whether we eventually concluded;-) - introduce a KVM_CAP_MSI_DEVID capability? All OK except Pavel not convinced? - userspaces puts the devid in struct kvm_irq_routing_msi pad field: consensus (we do not intrduce a new kvm_irq_routing_ext_msi) - userspace tells it conveyed a devid by setting A) the kvm_irq_routing_entry's field? B) the kvm_irq_routing_entry's type no consensus. If there is a cap, does it really matter? Best Regards Eric > 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 > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/