/* * Copyright (C) 2017 ARM Ltd. * Author: Marc Zyngier * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see . */ #include #include #include #include #include #include "vgic.h" /* * How KVM uses GICv4 (insert rude comments here): * * The vgic-v4 layer acts as a bridge between several entities: * - The GICv4 ITS representation offered by the ITS driver * - VFIO, which is in charge of the PCI endpoint * - The virtual ITS, which is the only thing the guest sees * * The configuration of VLPIs is triggered by a callback from VFIO, * instructing KVM that a PCI device has been configured to deliver * MSIs to a vITS. * * kvm_vgic_v4_set_forwarding() is thus called with the routing entry, * and this is used to find the corresponding vITS data structures * (ITS instance, device, event and irq) using a process that is * extremely similar to the injection of an MSI. * * At this stage, we can link the guest's view of an LPI (uniquely * identified by the routing entry) and the host irq, using the GICv4 * driver mapping operation. Should the mapping succeed, we've then * successfully upgraded the guest's LPI to a VLPI. We can then start * with updating GICv4's view of the property table and generating an * INValidation in order to kickstart the delivery of this VLPI to the * guest directly, without software intervention. Well, almost. * * When the PCI endpoint is deconfigured, this operation is reversed * with VFIO calling kvm_vgic_v4_unset_forwarding(). * * Once the VLPI has been mapped, it needs to follow any change the * guest performs on its LPI through the vITS. For that, a number of * command handlers have hooks to communicate these changes to the HW: * - Any invalidation triggers a call to its_prop_update_vlpi() * - The INT command results in a irq_set_irqchip_state(), which * generates an INT on the corresponding VLPI. * - The CLEAR command results in a irq_set_irqchip_state(), which * generates an CLEAR on the corresponding VLPI. * - DISCARD translates into an unmap, similar to a call to * kvm_vgic_v4_unset_forwarding(). * - MOVI is translated by an update of the existing mapping, changing * the target vcpu, resulting in a VMOVI being generated. * - MOVALL is translated by a string of mapping updates (similar to * the handling of MOVI). MOVALL is horrible. * * Note that a DISCARD/MAPTI sequence emitted from the guest without * reprogramming the PCI endpoint after MAPTI does not result in a * VLPI being mapped, as there is no callback from VFIO (the guest * will get the interrupt via the normal SW injection). Fixing this is * not trivial, and requires some horrible messing with the VFIO * internals. Not fun. Don't do that. * * Then there is the scheduling. Each time a vcpu is about to run on a * physical CPU, KVM must tell the corresponding redistributor about * it. And if we've migrated our vcpu from one CPU to another, we must * tell the ITS (so that the messages reach the right redistributor). * This is done in two steps: first issue a irq_set_affinity() on the * irq corresponding to the vcpu, then call its_schedule_vpe(). You * must be in a non-preemptible context. On exit, another call to * its_schedule_vpe() tells the redistributor that we're done with the * vcpu. * * Finally, the doorbell handling: Each vcpu is allocated an interrupt * which will fire each time a VLPI is made pending whilst the vcpu is * not running. Each time the vcpu gets blocked, the doorbell * interrupt gets enabled. When the vcpu is unblocked (for whatever * reason), the doorbell interrupt is disabled. */ #define DB_IRQ_FLAGS (IRQ_NOAUTOEN | IRQ_DISABLE_UNLAZY | IRQ_NO_BALANCING) static irqreturn_t vgic_v4_doorbell_handler(int irq, void *info) { struct kvm_vcpu *vcpu = info; vcpu->arch.vgic_cpu.vgic_v3.its_vpe.pending_last = true; kvm_make_request(KVM_REQ_IRQ_PENDING, vcpu); kvm_vcpu_kick(vcpu); return IRQ_HANDLED; } /** * vgic_v4_init - Initialize the GICv4 data structures * @kvm: Pointer to the VM being initialized * * We may be called each time a vITS is created, or when the * vgic is initialized. This relies on kvm->lock to be * held. In both cases, the number of vcpus should now be * fixed. */ int vgic_v4_init(struct kvm *kvm) { struct vgic_dist *dist = &kvm->arch.vgic; struct kvm_vcpu *vcpu; int i, nr_vcpus, ret; if (!kvm_vgic_global_state.has_gicv4) return 0; /* Nothing to see here... move along. */ if (dist->its_vm.vpes) return 0; nr_vcpus = atomic_read(&kvm->online_vcpus); dist->its_vm.vpes = kcalloc(nr_vcpus, sizeof(*dist->its_vm.vpes), GFP_KERNEL); if (!dist->its_vm.vpes) return -ENOMEM; dist->its_vm.nr_vpes = nr_vcpus; kvm_for_each_vcpu(i, vcpu, kvm) dist->its_vm.vpes[i] = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe; ret = its_alloc_vcpu_irqs(&dist->its_vm); if (ret < 0) { kvm_err("VPE IRQ allocation failure\n"); kfree(dist->its_vm.vpes); dist->its_vm.nr_vpes = 0; dist->its_vm.vpes = NULL; return ret; } kvm_for_each_vcpu(i, vcpu, kvm) { int irq = dist->its_vm.vpes[i]->irq; /* * Don't automatically enable the doorbell, as we're * flipping it back and forth when the vcpu gets * blocked. Also disable the lazy disabling, as the * doorbell could kick us out of the guest too * early... */ irq_set_status_flags(irq, DB_IRQ_FLAGS); ret = request_irq(irq, vgic_v4_doorbell_handler, 0, "vcpu", vcpu); if (ret) { kvm_err("failed to allocate vcpu IRQ%d\n", irq); /* * Trick: adjust the number of vpes so we know * how many to nuke on teardown... */ dist->its_vm.nr_vpes = i; break; } } if (ret) vgic_v4_teardown(kvm); return ret; } /** * vgic_v4_teardown - Free the GICv4 data structures * @kvm: Pointer to the VM being destroyed * * Relies on kvm->lock to be held. */ void vgic_v4_teardown(struct kvm *kvm) { struct its_vm *its_vm = &kvm->arch.vgic.its_vm; int i; if (!its_vm->vpes) return; for (i = 0; i < its_vm->nr_vpes; i++) { struct kvm_vcpu *vcpu = kvm_get_vcpu(kvm, i); int irq = its_vm->vpes[i]->irq; irq_clear_status_flags(irq, DB_IRQ_FLAGS); free_irq(irq, vcpu); } its_free_vcpu_irqs(its_vm); kfree(its_vm->vpes); its_vm->nr_vpes = 0; its_vm->vpes = NULL; } int vgic_v4_sync_hwstate(struct kvm_vcpu *vcpu) { if (!vgic_supports_direct_msis(vcpu->kvm)) return 0; return its_schedule_vpe(&vcpu->arch.vgic_cpu.vgic_v3.its_vpe, false); } int vgic_v4_flush_hwstate(struct kvm_vcpu *vcpu) { int irq = vcpu->arch.vgic_cpu.vgic_v3.its_vpe.irq; int err; if (!vgic_supports_direct_msis(vcpu->kvm)) return 0; /* * Before making the VPE resident, make sure the redistributor * corresponding to our current CPU expects us here. See the * doc in drivers/irqchip/irq-gic-v4.c to understand how this * turns into a VMOVP command at the ITS level. */ err = irq_set_affinity(irq, cpumask_of(smp_processor_id())); if (err) return err; err = its_schedule_vpe(&vcpu->arch.vgic_cpu.vgic_v3.its_vpe, true); if (err) return err; /* * Now that the VPE is resident, let's get rid of a potential * doorbell interrupt that would still be pending. */ err = irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING, false); return err; } static struct vgic_its *vgic_get_its(struct kvm *kvm, struct kvm_kernel_irq_routing_entry *irq_entry) { struct kvm_msi msi = (struct kvm_msi) { .address_lo = irq_entry->msi.address_lo, .address_hi = irq_entry->msi.address_hi, .data = irq_entry->msi.data, .flags = irq_entry->msi.flags, .devid = irq_entry->msi.devid, }; return vgic_msi_to_its(kvm, &msi); } int kvm_vgic_v4_set_forwarding(struct kvm *kvm, int virq, struct kvm_kernel_irq_routing_entry *irq_entry) { struct vgic_its *its; struct vgic_irq *irq; struct its_vlpi_map map; int ret; if (!vgic_supports_direct_msis(kvm)) return 0; /* * Get the ITS, and escape early on error (not a valid * doorbell for any of our vITSs). */ its = vgic_get_its(kvm, irq_entry); if (IS_ERR(its)) return 0; mutex_lock(&its->its_lock); /* Perform then actual DevID/EventID -> LPI translation. */ ret = vgic_its_resolve_lpi(kvm, its, irq_entry->msi.devid, irq_entry->msi.data, &irq); if (ret) goto out; /* * Emit the mapping request. If it fails, the ITS probably * isn't v4 compatible, so let's silently bail out. Holding * the ITS lock should ensure that nothing can modify the * target vcpu. */ map = (struct its_vlpi_map) { .vm = &kvm->arch.vgic.its_vm, .vpe = &irq->target_vcpu->arch.vgic_cpu.vgic_v3.its_vpe, .vintid = irq->intid, .properties = ((irq->priority & 0xfc) | (irq->enabled ? LPI_PROP_ENABLED : 0) | LPI_PROP_GROUP1), .db_enabled = true, }; ret = its_map_vlpi(virq, &map); if (ret) goto out; irq->hw = true; irq->host_irq = virq; out: mutex_unlock(&its->its_lock); return ret; } int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int virq, struct kvm_kernel_irq_routing_entry *irq_entry) { struct vgic_its *its; struct vgic_irq *irq; int ret; if (!vgic_supports_direct_msis(kvm)) return 0; /* * Get the ITS, and escape early on error (not a valid * doorbell for any of our vITSs). */ its = vgic_get_its(kvm, irq_entry); if (IS_ERR(its)) return 0; mutex_lock(&its->its_lock); ret = vgic_its_resolve_lpi(kvm, its, irq_entry->msi.devid, irq_entry->msi.data, &irq); if (ret) goto out; WARN_ON(!(irq->hw && irq->host_irq == virq)); if (irq->hw) { irq->hw = false; ret = its_unmap_vlpi(virq); } out: mutex_unlock(&its->its_lock); return ret; } void kvm_vgic_v4_enable_doorbell(struct kvm_vcpu *vcpu) { if (vgic_supports_direct_msis(vcpu->kvm)) { int irq = vcpu->arch.vgic_cpu.vgic_v3.its_vpe.irq; if (irq) enable_irq(irq); } } void kvm_vgic_v4_disable_doorbell(struct kvm_vcpu *vcpu) { if (vgic_supports_direct_msis(vcpu->kvm)) { int irq = vcpu->arch.vgic_cpu.vgic_v3.its_vpe.irq; if (irq) disable_irq(irq); } }