/*
* Copyright (C) 2015, 2016 ARM Ltd.
*
* 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/kvm.h>
#include <linux/kvm_host.h>
#include "vgic.h"
#define CREATE_TRACE_POINTS
#include "../trace.h"
#ifdef CONFIG_DEBUG_SPINLOCK
#define DEBUG_SPINLOCK_BUG_ON(p) BUG_ON(p)
#else
#define DEBUG_SPINLOCK_BUG_ON(p)
#endif
struct vgic_global __section(.hyp.text) kvm_vgic_global_state;
/*
* Locking order is always:
* vgic_cpu->ap_list_lock
* vgic_irq->irq_lock
*
* (that is, always take the ap_list_lock before the struct vgic_irq lock).
*
* When taking more than one ap_list_lock at the same time, always take the
* lowest numbered VCPU's ap_list_lock first, so:
* vcpuX->vcpu_id < vcpuY->vcpu_id:
* spin_lock(vcpuX->arch.vgic_cpu.ap_list_lock);
* spin_lock(vcpuY->arch.vgic_cpu.ap_list_lock);
*/
struct vgic_irq *vgic_get_irq(struct kvm *kvm, struct kvm_vcpu *vcpu,
u32 intid)
{
/* SGIs and PPIs */
if (intid <= VGIC_MAX_PRIVATE)
return &vcpu->arch.vgic_cpu.private_irqs[intid];
/* SPIs */
if (intid <= VGIC_MAX_SPI)
return &kvm->arch.vgic.spis[intid - VGIC_NR_PRIVATE_IRQS];
/* LPIs are not yet covered */
if (intid >= VGIC_MIN_LPI)
return NULL;
WARN(1, "Looking up struct vgic_irq for reserved INTID");
return NULL;
}
/**
* kvm_vgic_target_oracle - compute the target vcpu for an irq
*
* @irq: The irq to route. Must be already locked.
*
* Based on the current state of the interrupt (enabled, pending,
* active, vcpu and target_vcpu), compute the next vcpu this should be
* given to. Return NULL if this shouldn't be injected at all.
*
* Requires the IRQ lock to be held.
*/
static struct kvm_vcpu *vgic_target_oracle(struct vgic_irq *irq)
{
DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&irq->irq_lock));
/* If the interrupt is active, it must stay on the current vcpu */
if (irq->active)
return irq->vcpu ? : irq->target_vcpu;
/*
* If the IRQ is not active but enabled and pending, we should direct
* it to its configured target VCPU.
* If the distributor is disabled, pending interrupts shouldn't be
* forwarded.
*/
if (irq->enabled && irq->pending) {
if (unlikely(irq->target_vcpu &&
!irq->target_vcpu->kvm->arch.vgic.enabled))
return NULL;
return irq->target_vcpu;
}
/* If neither active nor pending and enabled, then this IRQ should not
* be queued to any VCPU.
*/
return NULL;
}
/*
* Only valid injection if changing level for level-triggered IRQs or for a
* rising edge.
*/
static bool vgic_validate_injection(struct vgic_irq *irq, bool level)
{
switch (irq->config) {
case VGIC_CONFIG_LEVEL:
return irq->line_level != level;
case VGIC_CONFIG_EDGE:
return level;
}
return false;
}
/*
* Check whether an IRQ needs to (and can) be queued to a VCPU's ap list.
* Do the queuing if necessary, taking the right locks in the right order.
* Returns true when the IRQ was queued, false otherwise.
*
* Needs to be entered with the IRQ lock already held, but will return
* with all locks dropped.
*/
bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq)
{
struct kvm_vcpu *vcpu;
DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&irq->irq_lock));
retry:
vcpu = vgic_target_oracle(irq);
if (irq->vcpu || !vcpu) {
/*
* If this IRQ is already on a VCPU's ap_list, then it
* cannot be moved or modified and there is no more work for
* us to do.
*
* Otherwise, if the irq is not pending and enabled, it does
* not need to be inserted into an ap_list and there is also
* no more work for us to do.
*/
spin_unlock(&irq->irq_lock);
return false;
}
/*
* We must unlock the irq lock to take the ap_list_lock where
* we are going to insert this new pending interrupt.
*/
spin_unlock(&irq->irq_lock);
/* someone can do stuff here, which we re-check below */
spin_lock(&vcpu->arch.vgic_cpu.ap_list_lock);
spin_lock(&irq->irq_lock);
/*
* Did something change behind our backs?
*
* There are two cases:
* 1) The irq lost its pending state or was disabled behind our
* backs and/or it was queued to another VCPU's ap_list.
* 2) Someone changed the affinity on this irq behind our
* backs and we are now holding the wrong ap_list_lock.
*
* In both cases, drop the locks and retry.
*/
if (unlikely(irq->vcpu || vcpu != vgic_target_oracle(irq))) {
spin_unlock(&irq->irq_lock);
spin_unlock(&vcpu->arch.vgic_cpu.ap_list_lock);
spin_lock(&irq->irq_lock);
goto retry;
}
list_add_tail(&irq->ap_list, &vcpu->arch.vgic_cpu.ap_list_head);
irq->vcpu = vcpu;
spin_unlock(&irq->irq_lock);
spin_unlock(&vcpu->arch.vgic_cpu.ap_list_lock);
kvm_vcpu_kick(vcpu);
return true;
}
static int vgic_update_irq_pending(struct kvm *kvm, int cpuid,
unsigned int intid, bool level,
bool mapped_irq)
{
struct kvm_vcpu *vcpu;
struct vgic_irq *irq;
int ret;
trace_vgic_update_irq_pending(cpuid, intid, level);
vcpu = kvm_get_vcpu(kvm, cpuid);
if (!vcpu && intid < VGIC_NR_PRIVATE_IRQS)
return -EINVAL;
irq = vgic_get_irq(kvm, vcpu, intid);
if (!irq)
return -EINVAL;
if (irq->hw != mapped_irq)
return -EINVAL;
spin_lock(&irq->irq_lock);
if (!vgic_validate_injection(irq, level)) {
/* Nothing to see here, move along... */
spin_unlock(&irq->irq_lock);
return 0;
}
if (irq->config == VGIC_CONFIG_LEVEL) {
irq->line_level = level;
irq->pending = level || irq->soft_pending;
} else {
irq->pending = true;
}
vgic_queue_irq_unlock(kvm, irq);
return 0;
}
/**
* kvm_vgic_inject_irq - Inject an IRQ from a device to the vgic
* @kvm: The VM structure pointer
* @cpuid: The CPU for PPIs
* @intid: The INTID to inject a new state to.
* @level: Edge-triggered: true: to trigger the interrupt
* false: to ignore the call
* Level-sensitive true: raise the input signal
* false: lower the input signal
*
* The VGIC is not concerned with devices being active-LOW or active-HIGH for
* level-sensitive interrupts. You can think of the level parameter as 1
* being HIGH and 0 being LOW and all devices being active-HIGH.
*/
int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
bool level)
{
return vgic_update_irq_pending(kvm, cpuid, intid, level, false);
}
