Release 4.17 virt/kvm/arm/vgic/vgic-v4.c
/*
* 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;
}
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/**
* 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 = 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;
}
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/**
* 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;
}
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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);
}
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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;
}
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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);
}
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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;
}
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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;
}
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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);
}
}
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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);
}
}
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