summaryrefslogtreecommitdiffstats
path: root/arch/arm64/kvm/vgic/vgic-v4.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/arm64/kvm/vgic/vgic-v4.c')
-rw-r--r--arch/arm64/kvm/vgic/vgic-v4.c521
1 files changed, 521 insertions, 0 deletions
diff --git a/arch/arm64/kvm/vgic/vgic-v4.c b/arch/arm64/kvm/vgic/vgic-v4.c
new file mode 100644
index 000000000..339a55194
--- /dev/null
+++ b/arch/arm64/kvm/vgic/vgic-v4.c
@@ -0,0 +1,521 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2017 ARM Ltd.
+ * Author: Marc Zyngier <marc.zyngier@arm.com>
+ */
+
+#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_make_vpe_resident().
+ * You must be in a non-preemptible context. On exit, a call to
+ * its_make_vpe_non_resident() 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;
+
+ /* We got the message, no need to fire again */
+ if (!kvm_vgic_global_state.has_gicv4_1 &&
+ !irqd_irq_disabled(&irq_to_desc(irq)->irq_data))
+ disable_irq_nosync(irq);
+
+ /*
+ * The v4.1 doorbell can fire concurrently with the vPE being
+ * made non-resident. Ensure we only update pending_last
+ * *after* the non-residency sequence has completed.
+ */
+ raw_spin_lock(&vcpu->arch.vgic_cpu.vgic_v3.its_vpe.vpe_lock);
+ vcpu->arch.vgic_cpu.vgic_v3.its_vpe.pending_last = true;
+ raw_spin_unlock(&vcpu->arch.vgic_cpu.vgic_v3.its_vpe.vpe_lock);
+
+ kvm_make_request(KVM_REQ_IRQ_PENDING, vcpu);
+ kvm_vcpu_kick(vcpu);
+
+ return IRQ_HANDLED;
+}
+
+static void vgic_v4_sync_sgi_config(struct its_vpe *vpe, struct vgic_irq *irq)
+{
+ vpe->sgi_config[irq->intid].enabled = irq->enabled;
+ vpe->sgi_config[irq->intid].group = irq->group;
+ vpe->sgi_config[irq->intid].priority = irq->priority;
+}
+
+static void vgic_v4_enable_vsgis(struct kvm_vcpu *vcpu)
+{
+ struct its_vpe *vpe = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe;
+ int i;
+
+ /*
+ * With GICv4.1, every virtual SGI can be directly injected. So
+ * let's pretend that they are HW interrupts, tied to a host
+ * IRQ. The SGI code will do its magic.
+ */
+ for (i = 0; i < VGIC_NR_SGIS; i++) {
+ struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, i);
+ struct irq_desc *desc;
+ unsigned long flags;
+ int ret;
+
+ raw_spin_lock_irqsave(&irq->irq_lock, flags);
+
+ if (irq->hw)
+ goto unlock;
+
+ irq->hw = true;
+ irq->host_irq = irq_find_mapping(vpe->sgi_domain, i);
+
+ /* Transfer the full irq state to the vPE */
+ vgic_v4_sync_sgi_config(vpe, irq);
+ desc = irq_to_desc(irq->host_irq);
+ ret = irq_domain_activate_irq(irq_desc_get_irq_data(desc),
+ false);
+ if (!WARN_ON(ret)) {
+ /* Transfer pending state */
+ ret = irq_set_irqchip_state(irq->host_irq,
+ IRQCHIP_STATE_PENDING,
+ irq->pending_latch);
+ WARN_ON(ret);
+ irq->pending_latch = false;
+ }
+ unlock:
+ raw_spin_unlock_irqrestore(&irq->irq_lock, flags);
+ vgic_put_irq(vcpu->kvm, irq);
+ }
+}
+
+static void vgic_v4_disable_vsgis(struct kvm_vcpu *vcpu)
+{
+ int i;
+
+ for (i = 0; i < VGIC_NR_SGIS; i++) {
+ struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, i);
+ struct irq_desc *desc;
+ unsigned long flags;
+ int ret;
+
+ raw_spin_lock_irqsave(&irq->irq_lock, flags);
+
+ if (!irq->hw)
+ goto unlock;
+
+ irq->hw = false;
+ ret = irq_get_irqchip_state(irq->host_irq,
+ IRQCHIP_STATE_PENDING,
+ &irq->pending_latch);
+ WARN_ON(ret);
+
+ desc = irq_to_desc(irq->host_irq);
+ irq_domain_deactivate_irq(irq_desc_get_irq_data(desc));
+ unlock:
+ raw_spin_unlock_irqrestore(&irq->irq_lock, flags);
+ vgic_put_irq(vcpu->kvm, irq);
+ }
+}
+
+void vgic_v4_configure_vsgis(struct kvm *kvm)
+{
+ struct vgic_dist *dist = &kvm->arch.vgic;
+ struct kvm_vcpu *vcpu;
+ unsigned long i;
+
+ lockdep_assert_held(&kvm->arch.config_lock);
+
+ kvm_arm_halt_guest(kvm);
+
+ kvm_for_each_vcpu(i, vcpu, kvm) {
+ if (dist->nassgireq)
+ vgic_v4_enable_vsgis(vcpu);
+ else
+ vgic_v4_disable_vsgis(vcpu);
+ }
+
+ kvm_arm_resume_guest(kvm);
+}
+
+/*
+ * Must be called with GICv4.1 and the vPE unmapped, which
+ * indicates the invalidation of any VPT caches associated
+ * with the vPE, thus we can get the VLPI state by peeking
+ * at the VPT.
+ */
+void vgic_v4_get_vlpi_state(struct vgic_irq *irq, bool *val)
+{
+ struct its_vpe *vpe = &irq->target_vcpu->arch.vgic_cpu.vgic_v3.its_vpe;
+ int mask = BIT(irq->intid % BITS_PER_BYTE);
+ void *va;
+ u8 *ptr;
+
+ va = page_address(vpe->vpt_page);
+ ptr = va + irq->intid / BITS_PER_BYTE;
+
+ *val = !!(*ptr & mask);
+}
+
+int vgic_v4_request_vpe_irq(struct kvm_vcpu *vcpu, int irq)
+{
+ return request_irq(irq, vgic_v4_doorbell_handler, 0, "vcpu", vcpu);
+}
+
+/**
+ * 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. 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 nr_vcpus, ret;
+ unsigned long i;
+
+ lockdep_assert_held(&kvm->arch.config_lock);
+
+ 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_ACCOUNT);
+ 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;
+ unsigned long irq_flags = DB_IRQ_FLAGS;
+
+ /*
+ * 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...
+ *
+ * On GICv4.1, the doorbell is managed in HW and must
+ * be left enabled.
+ */
+ if (kvm_vgic_global_state.has_gicv4_1)
+ irq_flags &= ~IRQ_NOAUTOEN;
+ irq_set_status_flags(irq, irq_flags);
+
+ ret = vgic_v4_request_vpe_irq(vcpu, irq);
+ 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
+ */
+void vgic_v4_teardown(struct kvm *kvm)
+{
+ struct its_vm *its_vm = &kvm->arch.vgic.its_vm;
+ int i;
+
+ lockdep_assert_held(&kvm->arch.config_lock);
+
+ 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_put(struct kvm_vcpu *vcpu)
+{
+ struct its_vpe *vpe = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe;
+
+ if (!vgic_supports_direct_msis(vcpu->kvm) || !vpe->resident)
+ return 0;
+
+ return its_make_vpe_non_resident(vpe, !!vcpu_get_flag(vcpu, IN_WFI));
+}
+
+int vgic_v4_load(struct kvm_vcpu *vcpu)
+{
+ struct its_vpe *vpe = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe;
+ int err;
+
+ if (!vgic_supports_direct_msis(vcpu->kvm) || vpe->resident)
+ return 0;
+
+ if (vcpu_get_flag(vcpu, IN_WFI))
+ 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(vpe->irq, cpumask_of(smp_processor_id()));
+ if (err)
+ return err;
+
+ err = its_make_vpe_resident(vpe, false, vcpu->kvm->arch.vgic.enabled);
+ if (err)
+ return err;
+
+ /*
+ * Now that the VPE is resident, let's get rid of a potential
+ * doorbell interrupt that would still be pending. This is a
+ * GICv4.0 only "feature"...
+ */
+ if (!kvm_vgic_global_state.has_gicv4_1)
+ err = irq_set_irqchip_state(vpe->irq, IRQCHIP_STATE_PENDING, false);
+
+ return err;
+}
+
+void vgic_v4_commit(struct kvm_vcpu *vcpu)
+{
+ struct its_vpe *vpe = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe;
+
+ /*
+ * No need to wait for the vPE to be ready across a shallow guest
+ * exit, as only a vcpu_put will invalidate it.
+ */
+ if (!vpe->ready)
+ its_commit_vpe(vpe);
+}
+
+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;
+ unsigned long flags;
+ 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 the 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;
+ atomic_inc(&map.vpe->vlpi_count);
+
+ /* Transfer pending state */
+ raw_spin_lock_irqsave(&irq->irq_lock, flags);
+ if (irq->pending_latch) {
+ ret = irq_set_irqchip_state(irq->host_irq,
+ IRQCHIP_STATE_PENDING,
+ irq->pending_latch);
+ WARN_RATELIMIT(ret, "IRQ %d", irq->host_irq);
+
+ /*
+ * Clear pending_latch and communicate this state
+ * change via vgic_queue_irq_unlock.
+ */
+ irq->pending_latch = false;
+ vgic_queue_irq_unlock(kvm, irq, flags);
+ } else {
+ raw_spin_unlock_irqrestore(&irq->irq_lock, flags);
+ }
+
+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) {
+ atomic_dec(&irq->target_vcpu->arch.vgic_cpu.vgic_v3.its_vpe.vlpi_count);
+ irq->hw = false;
+ ret = its_unmap_vlpi(virq);
+ }
+
+out:
+ mutex_unlock(&its->its_lock);
+ return ret;
+}