[RFC v2 2/4] KVM: arm: vgic: fix state machine for forwarded IRQ

Eric Auger
2015-02-11T08:23:23Z

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 follows those principles:
- A forwarded IRQ only can be sampled when it is pending
- when queueing the IRQ (programming the LR), the pending state is removed
as for edge sensitive IRQs
- an injection of a forwarded IRQ is considered always valid since
coming from the HW and level always is 1.

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

---

v1 -> v2:
- integration in new vgic_can_sample_irq
- remove the pending state when programming the LR
---
virt/kvm/arm/vgic.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index cd00cf2..433ecba 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -361,7 +361,10 @@ static void vgic_cpu_irq_clear(struct kvm_vcpu *vcpu, int irq)

static bool vgic_can_sample_irq(struct kvm_vcpu *vcpu, int irq)
{
- return vgic_irq_is_edge(vcpu, irq) || !vgic_irq_is_queued(vcpu, irq);
+ bool is_forwarded = (vgic_get_phys_irq(vcpu, irq) >= 0);
+
+ return vgic_irq_is_edge(vcpu, irq) || !vgic_irq_is_queued(vcpu, irq) ||
+ (is_forwarded && vgic_dist_irq_is_pending(vcpu, irq));
}

static u32 mmio_data_read(struct kvm_exit_mmio *mmio, u32 mask)
@@ -1296,6 +1299,7 @@ static bool vgic_queue_irq(struct kvm_vcpu *vcpu, u8 sgi_source_id, int irq)
struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
struct vgic_lr vlr;
int lr;
+ bool is_forwarded = (vgic_get_phys_irq(vcpu, irq) >= 0);

/* Sanitize the input... */
BUG_ON(sgi_source_id & ~7);
@@ -1331,7 +1335,7 @@ static bool vgic_queue_irq(struct kvm_vcpu *vcpu, u8 sgi_source_id, int irq)
vlr.irq = irq;
vlr.source = sgi_source_id;
vlr.state = LR_STATE_PENDING;
- if (!vgic_irq_is_edge(vcpu, irq))
+ if (!vgic_irq_is_edge(vcpu, irq) && !is_forwarded)
vlr.state |= LR_EOI_INT;

vgic_set_lr(vcpu, lr, vlr);
@@ -1372,11 +1376,12 @@ static bool vgic_queue_sgi(struct kvm_vcpu *vcpu, int irq)

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

if (vgic_queue_irq(vcpu, 0, irq)) {
- if (vgic_irq_is_edge(vcpu, irq)) {
+ if (vgic_irq_is_edge(vcpu, irq) || is_forwarded) {
vgic_dist_irq_clear_pending(vcpu, irq);
vgic_cpu_irq_clear(vcpu, irq);
} else {
@@ -1626,14 +1631,17 @@ static int 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 (!vgic_validate_injection(vcpu, irq_num, level) && !is_forwarded) {
ret = false;
goto out;
}
--
1.9.1