vgic.c
/*
* 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 <linux/list_sort.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 = {.gicv3_cpuif = STATIC_KEY_FALSE_INIT,};
/*
* Locking order is always:
* its->cmd_lock (mutex)
* its->its_lock (mutex)
* vgic_cpu->ap_list_lock
* kvm->lpi_list_lock
* vgic_irq->irq_lock
*
* If you need to take multiple locks, always take the upper lock first,
* then the lower ones, e.g. first take the its_lock, then the irq_lock.
* If you are already holding a lock and need to take a higher one, you
* have to drop the lower ranking lock first and re-aquire it after having
* taken the upper one.
*
* 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);
*/
/*
* Iterate over the VM's list of mapped LPIs to find the one with a
* matching interrupt ID and return a reference to the IRQ structure.
*/
static struct vgic_irq *vgic_get_lpi(struct kvm *kvm, u32 intid)
{
struct vgic_dist *dist = &kvm->arch.vgic;
struct vgic_irq *irq = NULL;
spin_lock(&dist->lpi_list_lock);
list_for_each_entry(irq, &dist->lpi_list_head, lpi_list) {
if (irq->intid != intid)
continue;
/*
* This increases the refcount, the caller is expected to
* call vgic_put_irq() later once it's finished with the IRQ.
*/
vgic_get_irq_kref(irq);
goto out_unlock;
}
irq = NULL;
out_unlock:
spin_unlock(&dist->lpi_list_lock);
return irq;
}
/*
* This looks up the virtual interrupt ID to get the corresponding
* struct vgic_irq. It also increases the refcount, so any caller is expected
* to call vgic_put_irq() once it's finished with this IRQ.
*/
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 */
if (intid >= VGIC_MIN_LPI)
return vgic_get_lpi(kvm, intid);
WARN(1, "Looking up struct vgic_irq for reserved INTID");
return NULL;
}
/*
* We can't do anything in here, because we lack the kvm pointer to
* lock and remove the item from the lpi_list. So we keep this function
* empty and use the return value of kref_put() to trigger the freeing.
*/
static void vgic_irq_release(struct kref *ref)
{
}
void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq)
{
struct vgic_dist *dist = &kvm->arch.vgic;
if (irq->intid < VGIC_MIN_LPI)
return;
spin_lock(&dist->lpi_list_lock);
if (!kref_put(&irq->refcount, vgic_irq_release)) {
spin_unlock(&dist->lpi_list_lock);
return;
};
list_del(&irq->lpi_list);
dist->lpi_list_count--;
spin_unlock(&dist->lpi_list_lock);
kfree(irq);
}
/**
* 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;
}
/*
* The order of items in the ap_lists defines how we'll pack things in LRs as
* well, the first items in the list being the first things populated in the
* LRs.
*
* A hard rule is that active interrupts can never be pushed out of the LRs
* (and therefore take priority) since we cannot reliably trap on deactivation
* of IRQs and therefore they have to be present in the LRs.
*
* Otherwise things should be sorted by the priority field and the GIC
* hardware support will take care of preemption of priority groups etc.
*
* Return negative if "a" sorts before "b", 0 to preserve order, and positive
* to sort "b" before "a".
*/
static int vgic_irq_cmp(void *priv, struct list_head *a, struct list_head *b)
{
struct vgic_irq *irqa = container_of(a, struct vgic_irq, ap_list);
struct vgic_irq *irqb = container_of(b, struct vgic_irq, ap_list);
bool penda, pendb;
int ret;
spin_lock(&irqa->irq_lock);
spin_lock_nested(&irqb->irq_lock, SINGLE_DEPTH_NESTING);
if (irqa->active || irqb->active) {
ret = (int)irqb->active - (int)irqa->active;
goto out;
}
penda = irqa->enabled && irqa->pending;
pendb = irqb->enabled && irqb->pending;
if (!penda || !pendb) {
ret = (int)pendb - (int)penda;
goto out;
}
/* Both pending and enabled, sort by priority */
ret = irqa->priority - irqb->priority;
out:
spin_unlock(&irqb->irq_lock);
spin_unlock(&irqa->irq_lock);
return ret;
}
/* Must be called with the ap_list_lock held */
static void vgic_sort_ap_list(struct kvm_vcpu *vcpu)
{
struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&vgic_cpu->ap_list_lock));
list_sort(NULL, &vgic_cpu->ap_list_head, vgic_irq_cmp);
}
/*
* 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;
}
/*
* Grab a reference to the irq to reflect the fact that it is
* now in the ap_list.
*/
vgic_get_irq_kref(irq);
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);
ret = vgic_lazy_init(kvm);
if (ret)
return ret;
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) {
vgic_put_irq(kvm, 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);
vgic_put_irq(kvm, irq);
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);
vgic_put_irq(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);
}
int kvm_vgic_inject_mapped_irq(struct kvm *kvm, int cpuid, unsigned int intid,
bool level)
{
return vgic_update_irq_pending(kvm, cpuid, intid, level, true);
}
int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, u32 virt_irq, u32 phys_irq)
{
struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, virt_irq);
BUG_ON(!irq);
spin_lock(&irq->irq_lock);
irq->hw = true;
irq->hwintid = phys_irq;
spin_unlock(&irq->irq_lock);
vgic_put_irq(vcpu->kvm, irq);
return 0;
}
int kvm_vgic_unmap_phys_irq(struct kvm_vcpu *vcpu, unsigned int virt_irq)
{
struct vgic_irq *irq;
if (!vgic_initialized(vcpu->kvm))
return -EAGAIN;
irq = vgic_get_irq(vcpu->kvm, vcpu, virt_irq);
BUG_ON(!irq);
spin_lock(&irq->irq_lock);
irq->hw = false;
irq->hwintid = 0;
spin_unlock(&irq->irq_lock);
vgic_put_irq(vcpu->kvm, irq);
return 0;
}
/**
* vgic_prune_ap_list - Remove non-relevant interrupts from the list
*
* @vcpu: The VCPU pointer
*
* Go over the list of "interesting" interrupts, and prune those that we
* won't have to consider in the near future.
*/
static void vgic_prune_ap_list(struct kvm_vcpu *vcpu)
{
struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
struct vgic_irq *irq, *tmp;
retry:
spin_lock(&vgic_cpu->ap_list_lock);
list_for_each_entry_safe(irq, tmp, &vgic_cpu->ap_list_head, ap_list) {
struct kvm_vcpu *target_vcpu, *vcpuA, *vcpuB;
spin_lock(&irq->irq_lock);
BUG_ON(vcpu != irq->vcpu);
target_vcpu = vgic_target_oracle(irq);
if (!target_vcpu) {
/*
* We don't need to process this interrupt any
* further, move it off the list.
*/
list_del(&irq->ap_list);
irq->vcpu = NULL;
spin_unlock(&irq->irq_lock);
/*
* This vgic_put_irq call matches the
* vgic_get_irq_kref in vgic_queue_irq_unlock,
* where we added the LPI to the ap_list. As
* we remove the irq from the list, we drop
* also drop the refcount.
*/
vgic_put_irq(vcpu->kvm, irq);
continue;
}
if (target_vcpu == vcpu) {
/* We're on the right CPU */
spin_unlock(&irq->irq_lock);
continue;
}
/* This interrupt looks like it has to be migrated. */
spin_unlock(&irq->irq_lock);
spin_unlock(&vgic_cpu->ap_list_lock);
/*
* Ensure locking order by always locking the smallest
* ID first.
*/
if (vcpu->vcpu_id < target_vcpu->vcpu_id) {
vcpuA = vcpu;
vcpuB = target_vcpu;
} else {
vcpuA = target_vcpu;
vcpuB = vcpu;
}
spin_lock(&vcpuA->arch.vgic_cpu.ap_list_lock);
spin_lock_nested(&vcpuB->arch.vgic_cpu.ap_list_lock,
SINGLE_DEPTH_NESTING);
spin_lock(&irq->irq_lock);
/*
* If the affinity has been preserved, move the
* interrupt around. Otherwise, it means things have
* changed while the interrupt was unlocked, and we
* need to replay this.
*
* In all cases, we cannot trust the list not to have
* changed, so we restart from the beginning.
*/
if (target_vcpu == vgic_target_oracle(irq)) {
struct vgic_cpu *new_cpu = &target_vcpu->arch.vgic_cpu;
list_del(&irq->ap_list);
irq->vcpu = target_vcpu;
list_add_tail(&irq->ap_list, &new_cpu->ap_list_head);
}
spin_unlock(&irq->irq_lock);
spin_unlock(&vcpuB->arch.vgic_cpu.ap_list_lock);
spin_unlock(&vcpuA->arch.vgic_cpu.ap_list_lock);
goto retry;
}
spin_unlock(&vgic_cpu->ap_list_lock);
}
static inline void vgic_process_maintenance_interrupt(struct kvm_vcpu *vcpu)
{
if (kvm_vgic_global_state.type == VGIC_V2)
vgic_v2_process_maintenance(vcpu);
else
vgic_v3_process_maintenance(vcpu);
}
static inline void vgic_fold_lr_state(struct kvm_vcpu *vcpu)
{
if (kvm_vgic_global_state.type == VGIC_V2)
vgic_v2_fold_lr_state(vcpu);
else
vgic_v3_fold_lr_state(vcpu);
}
/* Requires the irq_lock to be held. */
static inline void vgic_populate_lr(struct kvm_vcpu *vcpu,
struct vgic_irq *irq, int lr)
{
DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&irq->irq_lock));
if (kvm_vgic_global_state.type == VGIC_V2)
vgic_v2_populate_lr(vcpu, irq, lr);
else
vgic_v3_populate_lr(vcpu, irq, lr);
}
static inline void vgic_clear_lr(struct kvm_vcpu *vcpu, int lr)
{
if (kvm_vgic_global_state.type == VGIC_V2)
vgic_v2_clear_lr(vcpu, lr);
else
vgic_v3_clear_lr(vcpu, lr);
}
static inline void vgic_set_underflow(struct kvm_vcpu *vcpu)
{
if (kvm_vgic_global_state.type == VGIC_V2)
vgic_v2_set_underflow(vcpu);
else
vgic_v3_set_underflow(vcpu);
}
/* Requires the ap_list_lock to be held. */
static int compute_ap_list_depth(struct kvm_vcpu *vcpu)
{
struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
struct vgic_irq *irq;
int count = 0;
DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&vgic_cpu->ap_list_lock));
list_for_each_entry(irq, &vgic_cpu->ap_list_head, ap_list) {
spin_lock(&irq->irq_lock);
/* GICv2 SGIs can count for more than one... */
if (vgic_irq_is_sgi(irq->intid) && irq->source)
count += hweight8(irq->source);
else
count++;
spin_unlock(&irq->irq_lock);
}
return count;
}
/* Requires the VCPU's ap_list_lock to be held. */
static void vgic_flush_lr_state(struct kvm_vcpu *vcpu)
{
struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
struct vgic_irq *irq;
int count = 0;
DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&vgic_cpu->ap_list_lock));
if (compute_ap_list_depth(vcpu) > kvm_vgic_global_state.nr_lr) {
vgic_set_underflow(vcpu);
vgic_sort_ap_list(vcpu);
}
list_for_each_entry(irq, &vgic_cpu->ap_list_head, ap_list) {
spin_lock(&irq->irq_lock);
if (unlikely(vgic_target_oracle(irq) != vcpu))
goto next;
/*
* If we get an SGI with multiple sources, try to get
* them in all at once.
*/
do {
vgic_populate_lr(vcpu, irq, count++);
} while (irq->source && count < kvm_vgic_global_state.nr_lr);
next:
spin_unlock(&irq->irq_lock);
if (count == kvm_vgic_global_state.nr_lr)
break;
}
vcpu->arch.vgic_cpu.used_lrs = count;
/* Nuke remaining LRs */
for ( ; count < kvm_vgic_global_state.nr_lr; count++)
vgic_clear_lr(vcpu, count);
}
/* Sync back the hardware VGIC state into our emulation after a guest's run. */
void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
{
if (unlikely(!vgic_initialized(vcpu->kvm)))
return;
vgic_process_maintenance_interrupt(vcpu);
vgic_fold_lr_state(vcpu);
vgic_prune_ap_list(vcpu);
}
/* Flush our emulation state into the GIC hardware before entering the guest. */
void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
{
if (unlikely(!vgic_initialized(vcpu->kvm)))
return;
spin_lock(&vcpu->arch.vgic_cpu.ap_list_lock);
vgic_flush_lr_state(vcpu);
spin_unlock(&vcpu->arch.vgic_cpu.ap_list_lock);
}
int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu)
{
struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
struct vgic_irq *irq;
bool pending = false;
if (!vcpu->kvm->arch.vgic.enabled)
return false;
spin_lock(&vgic_cpu->ap_list_lock);
list_for_each_entry(irq, &vgic_cpu->ap_list_head, ap_list) {
spin_lock(&irq->irq_lock);
pending = irq->pending && irq->enabled;
spin_unlock(&irq->irq_lock);
if (pending)
break;
}
spin_unlock(&vgic_cpu->ap_list_lock);
return pending;
}
void vgic_kick_vcpus(struct kvm *kvm)
{
struct kvm_vcpu *vcpu;
int c;
/*
* We've injected an interrupt, time to find out who deserves
* a good kick...
*/
kvm_for_each_vcpu(c, vcpu, kvm) {
if (kvm_vgic_vcpu_pending_irq(vcpu))
kvm_vcpu_kick(vcpu);
}
}
bool kvm_vgic_map_is_active(struct kvm_vcpu *vcpu, unsigned int virt_irq)
{
struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, virt_irq);
bool map_is_active;
spin_lock(&irq->irq_lock);
map_is_active = irq->hw && irq->active;
spin_unlock(&irq->irq_lock);
vgic_put_irq(vcpu->kvm, irq);
return map_is_active;
}