[PATCH v2 4/4] KVM: arm/arm64: vgic: Make vgic_cpu->ap_list_lock a raw_spinlock

From: Julien Thierry
Date: Mon Nov 26 2018 - 13:27:08 EST

vgic_cpu->ap_list_lock must always be taken with interrupts disabled as
it is used in interrupt context.

For configurations such as PREEMPT_RT_FULL, this means that it should
be a raw_spinlock since RT spinlocks are interruptible.

Signed-off-by: Julien Thierry <julien.thierry@xxxxxxx>
Cc: Christoffer Dall <christoffer.dall@xxxxxxx>
Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
---
include/kvm/arm_vgic.h | 2 +-
virt/kvm/arm/vgic/vgic-init.c | 2 +-
virt/kvm/arm/vgic/vgic.c | 43 ++++++++++++++++++++++---------------------
3 files changed, 24 insertions(+), 23 deletions(-)

diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index 32954e1..c36c86f 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -307,7 +307,7 @@ struct vgic_cpu {
unsigned int used_lrs;
struct vgic_irq private_irqs[VGIC_NR_PRIVATE_IRQS];

- spinlock_t ap_list_lock; /* Protects the ap_list */
+ raw_spinlock_t ap_list_lock; /* Protects the ap_list */

/*
* List of IRQs that this VCPU should consider because they are either
diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c
index 330c1ad..dfbfcb1 100644
--- a/virt/kvm/arm/vgic/vgic-init.c
+++ b/virt/kvm/arm/vgic/vgic-init.c
@@ -206,7 +206,7 @@ int kvm_vgic_vcpu_init(struct kvm_vcpu *vcpu)
vgic_cpu->sgi_iodev.base_addr = VGIC_ADDR_UNDEF;

INIT_LIST_HEAD(&vgic_cpu->ap_list_head);
- spin_lock_init(&vgic_cpu->ap_list_lock);
+ raw_spin_lock_init(&vgic_cpu->ap_list_lock);

/*
* Enable and configure all SGIs to be edge-triggered and
diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index 01bd18c..736ae59 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -54,11 +54,11 @@ struct vgic_global kvm_vgic_global_state __ro_after_init = {
* 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);
+ * raw_spin_lock(vcpuX->arch.vgic_cpu.ap_list_lock);
+ * raw_spin_lock(vcpuY->arch.vgic_cpu.ap_list_lock);
*
* Since the VGIC must support injecting virtual interrupts from ISRs, we have
- * to use the spin_lock_irqsave/spin_unlock_irqrestore versions of outer
+ * to use the raw_spin_lock_irqsave/raw_spin_unlock_irqrestore versions of outer
* spinlocks for any lock that may be taken while injecting an interrupt.
*/

@@ -273,7 +273,7 @@ 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));
+ DEBUG_SPINLOCK_BUG_ON(!raw_spin_is_locked(&vgic_cpu->ap_list_lock));

list_sort(NULL, &vgic_cpu->ap_list_head, vgic_irq_cmp);
}
@@ -351,7 +351,7 @@ bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq,

/* someone can do stuff here, which we re-check below */

- spin_lock_irqsave(&vcpu->arch.vgic_cpu.ap_list_lock, flags);
+ raw_spin_lock_irqsave(&vcpu->arch.vgic_cpu.ap_list_lock, flags);
raw_spin_lock(&irq->irq_lock);

/*
@@ -368,7 +368,8 @@ bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq,

if (unlikely(irq->vcpu || vcpu != vgic_target_oracle(irq))) {
raw_spin_unlock(&irq->irq_lock);
- spin_unlock_irqrestore(&vcpu->arch.vgic_cpu.ap_list_lock, flags);
+ raw_spin_unlock_irqrestore(&vcpu->arch.vgic_cpu.ap_list_lock,
+ flags);

raw_spin_lock_irqsave(&irq->irq_lock, flags);
goto retry;
@@ -383,7 +384,7 @@ bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq,
irq->vcpu = vcpu;

raw_spin_unlock(&irq->irq_lock);
- spin_unlock_irqrestore(&vcpu->arch.vgic_cpu.ap_list_lock, flags);
+ raw_spin_unlock_irqrestore(&vcpu->arch.vgic_cpu.ap_list_lock, flags);

kvm_make_request(KVM_REQ_IRQ_PENDING, vcpu);
kvm_vcpu_kick(vcpu);
@@ -597,7 +598,7 @@ static void vgic_prune_ap_list(struct kvm_vcpu *vcpu)
DEBUG_SPINLOCK_BUG_ON(!irqs_disabled());

retry:
- spin_lock(&vgic_cpu->ap_list_lock);
+ raw_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;
@@ -638,7 +639,7 @@ static void vgic_prune_ap_list(struct kvm_vcpu *vcpu)
/* This interrupt looks like it has to be migrated. */

raw_spin_unlock(&irq->irq_lock);
- spin_unlock(&vgic_cpu->ap_list_lock);
+ raw_spin_unlock(&vgic_cpu->ap_list_lock);

/*
* Ensure locking order by always locking the smallest
@@ -652,9 +653,9 @@ static void vgic_prune_ap_list(struct kvm_vcpu *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);
+ raw_spin_lock(&vcpuA->arch.vgic_cpu.ap_list_lock);
+ raw_spin_lock_nested(&vcpuB->arch.vgic_cpu.ap_list_lock,
+ SINGLE_DEPTH_NESTING);
raw_spin_lock(&irq->irq_lock);

/*
@@ -676,8 +677,8 @@ static void vgic_prune_ap_list(struct kvm_vcpu *vcpu)
}

raw_spin_unlock(&irq->irq_lock);
- spin_unlock(&vcpuB->arch.vgic_cpu.ap_list_lock);
- spin_unlock(&vcpuA->arch.vgic_cpu.ap_list_lock);
+ raw_spin_unlock(&vcpuB->arch.vgic_cpu.ap_list_lock);
+ raw_spin_unlock(&vcpuA->arch.vgic_cpu.ap_list_lock);

if (target_vcpu_needs_kick) {
kvm_make_request(KVM_REQ_IRQ_PENDING, target_vcpu);
@@ -687,7 +688,7 @@ static void vgic_prune_ap_list(struct kvm_vcpu *vcpu)
goto retry;
}

- spin_unlock(&vgic_cpu->ap_list_lock);
+ raw_spin_unlock(&vgic_cpu->ap_list_lock);
}

static inline void vgic_fold_lr_state(struct kvm_vcpu *vcpu)
@@ -736,7 +737,7 @@ static int compute_ap_list_depth(struct kvm_vcpu *vcpu,

*multi_sgi = false;

- DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&vgic_cpu->ap_list_lock));
+ DEBUG_SPINLOCK_BUG_ON(!raw_spin_is_locked(&vgic_cpu->ap_list_lock));

list_for_each_entry(irq, &vgic_cpu->ap_list_head, ap_list) {
int w;
@@ -761,7 +762,7 @@ static void vgic_flush_lr_state(struct kvm_vcpu *vcpu)
bool multi_sgi;
u8 prio = 0xff;

- DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&vgic_cpu->ap_list_lock));
+ DEBUG_SPINLOCK_BUG_ON(!raw_spin_is_locked(&vgic_cpu->ap_list_lock));

count = compute_ap_list_depth(vcpu, &multi_sgi);
if (count > kvm_vgic_global_state.nr_lr || multi_sgi)
@@ -872,9 +873,9 @@ void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)

DEBUG_SPINLOCK_BUG_ON(!irqs_disabled());

- spin_lock(&vcpu->arch.vgic_cpu.ap_list_lock);
+ raw_spin_lock(&vcpu->arch.vgic_cpu.ap_list_lock);
vgic_flush_lr_state(vcpu);
- spin_unlock(&vcpu->arch.vgic_cpu.ap_list_lock);
+ raw_spin_unlock(&vcpu->arch.vgic_cpu.ap_list_lock);

if (can_access_vgic_from_kernel())
vgic_restore_state(vcpu);
@@ -915,7 +916,7 @@ int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu)
if (vcpu->arch.vgic_cpu.vgic_v3.its_vpe.pending_last)
return true;

- spin_lock_irqsave(&vgic_cpu->ap_list_lock, flags);
+ raw_spin_lock_irqsave(&vgic_cpu->ap_list_lock, flags);

list_for_each_entry(irq, &vgic_cpu->ap_list_head, ap_list) {
raw_spin_lock(&irq->irq_lock);
@@ -926,7 +927,7 @@ int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu)
break;
}

- spin_unlock_irqrestore(&vgic_cpu->ap_list_lock, flags);
+ raw_spin_unlock_irqrestore(&vgic_cpu->ap_list_lock, flags);

return pending;
}
--
1.9.1