1 files changed, 364 insertions, 0 deletions
diff --git a/virt/kvm/arm/vgic/vgic-v4.c b/virt/kvm/arm/vgic/vgic-v4.c
new file mode 100644
index 000000000000..53c324aa44ef
--- /dev/null
+++ b/virt/kvm/arm/vgic/vgic-v4.c
@@ -0,0 +1,364 @@
+/*
+ * Copyright (C) 2017 ARM Ltd.
+ * Author: Marc Zyngier <marc.zyngier@arm.com>
+ *
+ * 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 <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
+#include <linux/kvm_host.h>
+#include <linux/irqchip/arm-gic-v3.h>
+
+#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 (!vgic_supports_direct_msis(kvm))
+		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 = kzalloc(sizeof(*dist->its_vm.vpes) * nr_vcpus,
+				    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));
+	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);
+	}
+}