[PATCH v8 4/5] KVM: arm/arm64: remove coarse grain dist locking at kvm_vgic_sync_hwstate

Eric Auger
2015-01-19T16:43:12Z

To prepare for irqfd addition, coarse grain locking is removed at
kvm_vgic_sync_hwstate level and finer grain locking is introduced in
vgic_process_maintenance only.

Signed-off-by: Eric Auger <eric.auger@linaro.org>
---
virt/kvm/arm/vgic.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index c84f53df..18060ea 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1447,6 +1447,7 @@ epilog:
static bool vgic_process_maintenance(struct kvm_vcpu *vcpu)
{
u32 status = vgic_get_interrupt_status(vcpu);
+ struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
bool level_pending = false;

kvm_debug("STATUS = %08x\n", status);
@@ -1464,6 +1465,7 @@ static bool vgic_process_maintenance(struct kvm_vcpu *vcpu)
struct vgic_lr vlr = vgic_get_lr(vcpu, lr);
WARN_ON(vgic_irq_is_edge(vcpu, vlr.irq));

+ spin_lock(&dist->lock);
vgic_irq_clear_queued(vcpu, vlr.irq);
WARN_ON(vlr.state & LR_STATE_MASK);
vlr.state = 0;
@@ -1491,6 +1493,8 @@ static bool vgic_process_maintenance(struct kvm_vcpu *vcpu)
vgic_cpu_irq_clear(vcpu, vlr.irq);
}

+ spin_unlock(&dist->lock);
+
/*
* Despite being EOIed, the LR may not have
* been marked as empty.
@@ -1505,10 +1509,7 @@ static bool vgic_process_maintenance(struct kvm_vcpu *vcpu)
return level_pending;
}

-/*
- * Sync back the VGIC state after a guest run. The distributor lock is
- * needed so we don't get preempted in the middle of the state processing.
- */
+/* Sync back the VGIC state after a guest run */
static void __kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
{
struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
@@ -1555,14 +1556,10 @@ void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)

void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
{
- struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
-
if (!irqchip_in_kernel(vcpu->kvm))
return;

- spin_lock(&dist->lock);
__kvm_vgic_sync_hwstate(vcpu);
- spin_unlock(&dist->lock);
}

int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu)
--
1.9.1