[RFC v2 1/9] KVM: ARM: VGIC: fix multiple injection of level sensitive forwarded IRQ

Eric Auger
2014-09-01T12:52:40Z

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.

Signed-off-by: Eric Auger <eric.auger@linaro.org>

---

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.

v1 -> v2:
- fix vgic state bypass in vgic_queue_hwirq
---
virt/kvm/arm/vgic.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 0007300..8ef495b 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1259,7 +1259,9 @@ static bool vgic_queue_sgi(struct kvm_vcpu *vcpu, int irq)

static bool vgic_queue_hwirq(struct kvm_vcpu *vcpu, int irq)
{
- if (vgic_irq_is_queued(vcpu, irq))
+ bool is_forwarded = (vgic_get_phys_irq(vcpu, irq) > 0);
+
+ if (vgic_irq_is_queued(vcpu, irq) && !is_forwarded)
return true; /* level interrupt, already queued */

if (vgic_queue_irq(vcpu, 0, irq)) {
@@ -1517,14 +1519,18 @@ 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 +1563,8 @@ 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