[RFC 1/9] KVM: ARM: VGIC: fix multiple injection of level sensitive forwarded IRQ

Eric Auger
2014-08-25T13:31:55Z

Fix multiple injection of level sensitive forwarded IRQs.
With current code, the second injection fails since the state bitmaps
are not reset (process_maintenance is not called anymore).
New implementation consists in fully bypassing the vgic state
management for forwarded IRQ (checks are ignored in
vgic_update_irq_pending). This obviously assumes the forwarded IRQ is
injected from kernel side.

---
It was attempted to reset the states in __kvm_vgic_sync_hwstate, checking
the emptied LR of forwarded IRQ. However surprisingly this solution does
not seem to work. Some times, a new forwarded IRQ injection is observed
while the LR of the previous instance was not observed as empty.

Signed-off-by: Eric Auger <eric.auger@linaro.org>
---
include/kvm/arm_vgic.h | 1 +
virt/kvm/arm/vgic.c | 9 +++++++--
2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index 743020f..3da244f 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -177,6 +177,7 @@ struct vgic_dist {
unsigned long irq_pending_on_cpu;

struct rb_root irq_phys_map;
+ spinlock_t rb_tree_lock;
#endif
};

diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 0007300..195c10c 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1517,14 +1517,18 @@ static bool vgic_update_irq_pending(struct kvm *kvm, int cpuid,
int edge_triggered, level_triggered;
int enabled;
bool ret = true;
+ bool is_forwarded;

spin_lock(&dist->lock);

vcpu = kvm_get_vcpu(kvm, cpuid);
+ is_forwarded = (vgic_get_phys_irq(vcpu, irq_num) >0);
+
edge_triggered = vgic_irq_is_edge(vcpu, irq_num);
level_triggered = !edge_triggered;

- if (!vgic_validate_injection(vcpu, irq_num, level)) {
+ if (!is_forwarded &&
+ !vgic_validate_injection(vcpu, irq_num, level)) {
ret = false;
goto out;
}
@@ -1557,7 +1561,8 @@ static bool vgic_update_irq_pending(struct kvm *kvm, int cpuid,
goto out;
}

- if (level_triggered && vgic_irq_is_queued(vcpu, irq_num)) {
+ if (!is_forwarded &&
+ level_triggered && vgic_irq_is_queued(vcpu, irq_num)) {
/*
* Level interrupt in progress, will be picked up
* when EOId.
--
1.9.1