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// 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);
}
}
/* Must be called with the kvm lock held */
void vgic_v4_configure_vsgis(struct kvm *kvm)
{
struct vgic_dist *dist = &kvm->arch.vgic;
struct kvm_vcpu *vcpu;
int i;
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);
}
/**
* 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;
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 = 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_put(struct kvm_vcpu *vcpu, bool need_db)
{
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, need_db);
}
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;
/*
* 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;
}
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 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);
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;
}