[PATCH-4.5 v2 06/10] xen/arm: second irq injection while the first irq is still inflight

[Stefano Stabellini <stefano.stabellini@eu.citrix.com>]

Set GICH_LR_PENDING in the corresponding GICH_LR to inject a second irq
while the first one is still active.
If the first irq is already pending (not active), just clear
GIC_IRQ_GUEST_PENDING because the irq has already been injected and is
already visible by the guest.
If the irq has already been EOI'ed then just clear the GICH_LR right
away and move the interrupt to lr_pending so that it is going to be
reinjected by gic_restore_pending_irqs on return to guest.

If the target cpu is not the current cpu, then set GIC_IRQ_GUEST_PENDING
and send an SGI. The target cpu is going to be interrupted and call
gic_clear_lrs, that is going to take the same actions.

Do not call vgic_vcpu_inject_irq from gic_inject if
evtchn_upcall_pending is set. If we remove that call, we don't need to
special case evtchn_irq in vgic_vcpu_inject_irq anymore.
We also need to force the first injection of evtchn_irq (call
gic_vcpu_inject_irq) from vgic_enable_irqs because evtchn_upcall_pending
is already set by common code on vcpu creation.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
 xen/arch/arm/gic.c        |   82 +++++++++++++++++++++++++--------------------
 xen/arch/arm/vgic.c       |   18 +++++++---
 xen/include/asm-arm/gic.h |    1 +
 3 files changed, 61 insertions(+), 40 deletions(-)

diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
index 5fca5be..0955d48 100644
--- a/xen/arch/arm/gic.c
+++ b/xen/arch/arm/gic.c
@@ -698,51 +698,64 @@ out:
     return;
 }
 
-static void gic_clear_lrs(struct vcpu *v)
+static void _gic_clear_lr(struct vcpu *v, int i)
 {
-    struct pending_irq *p;
-    int i = 0, irq;
+    int irq;
     uint32_t lr;
-    bool_t inflight;
+    struct pending_irq *p;
 
     ASSERT(!local_irq_is_enabled());
 
-    while ((i = find_next_bit((const long unsigned int *) &this_cpu(lr_mask),
-                              nr_lrs, i)) < nr_lrs) {
-        lr = GICH[GICH_LR + i];
-        if ( !(lr & (GICH_LR_PENDING|GICH_LR_ACTIVE)) )
+    lr = GICH[GICH_LR + i];
+    irq = (lr >> GICH_LR_VIRTUAL_SHIFT) & GICH_LR_VIRTUAL_MASK;
+    p = irq_to_pending(v, irq);
+    if ( lr & GICH_LR_ACTIVE )
+    {
+        if ( test_bit(GIC_IRQ_GUEST_ENABLED, &p->status) &&
+             test_and_clear_bit(GIC_IRQ_GUEST_PENDING, &p->status) )
+            GICH[GICH_LR + i] = lr | GICH_LR_PENDING;
+    } else if ( lr & GICH_LR_PENDING ) {
+        clear_bit(GIC_IRQ_GUEST_PENDING, &p->status);
+    } else {
+        spin_lock(&gic.lock);
+
+        GICH[GICH_LR + i] = 0;
+        clear_bit(i, &this_cpu(lr_mask));
+
+        if ( p->desc != NULL )
+            p->desc->status &= ~IRQ_INPROGRESS;
+        clear_bit(GIC_IRQ_GUEST_VISIBLE, &p->status);
+        p->lr = nr_lrs;
+        if ( test_bit(GIC_IRQ_GUEST_PENDING, &p->status) &&
+                test_bit(GIC_IRQ_GUEST_ENABLED, &p->status))
         {
-            inflight = 0;
-            GICH[GICH_LR + i] = 0;
-            clear_bit(i, &this_cpu(lr_mask));
-
-            irq = (lr >> GICH_LR_VIRTUAL_SHIFT) & GICH_LR_VIRTUAL_MASK;
-            spin_lock(&gic.lock);
-            p = irq_to_pending(v, irq);
-            if ( p->desc != NULL )
-                p->desc->status &= ~IRQ_INPROGRESS;
-            clear_bit(GIC_IRQ_GUEST_VISIBLE, &p->status);
-            p->lr = nr_lrs;
-            if ( test_bit(GIC_IRQ_GUEST_PENDING, &p->status) &&
-                    test_bit(GIC_IRQ_GUEST_ENABLED, &p->status))
-            {
-                inflight = 1;
-                gic_add_to_lr_pending(v, irq, p->priority);
-            }
-            spin_unlock(&gic.lock);
-            if ( !inflight )
-            {
-                spin_lock(&v->arch.vgic.lock);
-                list_del_init(&p->inflight);
-                spin_unlock(&v->arch.vgic.lock);
-            }
+            gic_add_to_lr_pending(v, irq, p->priority);
+        } else
+            list_del_init(&p->inflight);
 
-        }
+        spin_unlock(&gic.lock);
+    }
+}
+
+static void gic_clear_lrs(struct vcpu *v)
+{
+    int i = 0;
 
+    while ((i = find_next_bit((const long unsigned int *) &this_cpu(lr_mask),
+                              nr_lrs, i)) < nr_lrs) {
+
+        spin_lock(&v->arch.vgic.lock);
+        _gic_clear_lr(v, i);
+        spin_unlock(&v->arch.vgic.lock);
         i++;
     }
 }
 
+void gic_set_clear_lr(struct vcpu *v, struct pending_irq *p)
+{
+    _gic_clear_lr(v, p->lr);
+}
+
 static void gic_restore_pending_irqs(struct vcpu *v)
 {
     int i;
@@ -801,9 +814,6 @@ void gic_inject(void)
 {
     gic_clear_lrs(current);
 
-    if ( vcpu_info(current, evtchn_upcall_pending) )
-        vgic_vcpu_inject_irq(current, current->domain->arch.evtchn_irq);
-
     gic_restore_pending_irqs(current);
     if (!gic_events_need_delivery())
         gic_inject_irq_stop();
diff --git a/xen/arch/arm/vgic.c b/xen/arch/arm/vgic.c
index da15f4d..210ac39 100644
--- a/xen/arch/arm/vgic.c
+++ b/xen/arch/arm/vgic.c
@@ -387,7 +387,11 @@ static void vgic_enable_irqs(struct vcpu *v, uint32_t r, int n)
         irq = i + (32 * n);
         p = irq_to_pending(v, irq);
         set_bit(GIC_IRQ_GUEST_ENABLED, &p->status);
-        if ( !list_empty(&p->inflight) && !test_bit(GIC_IRQ_GUEST_VISIBLE, &p->status) )
+        if ( irq == v->domain->arch.evtchn_irq &&
+             vcpu_info(current, evtchn_upcall_pending) &&
+             list_empty(&p->inflight) )
+            vgic_vcpu_inject_irq(v, irq);
+        else if ( !list_empty(&p->inflight) && !test_bit(GIC_IRQ_GUEST_VISIBLE, &p->status) )
             gic_set_guest_irq(v, irq, GICH_LR_PENDING, p->priority);
         if ( p->desc != NULL )
             p->desc->handler->enable(p->desc);
@@ -696,10 +700,16 @@ void vgic_vcpu_inject_irq(struct vcpu *v, unsigned int irq)
 
     if ( !list_empty(&n->inflight) )
     {
-        if ( (irq != current->domain->arch.evtchn_irq) ||
-             (!test_bit(GIC_IRQ_GUEST_VISIBLE, &n->status)) )
+        if ( v == current )
+        {
+            set_bit(GIC_IRQ_GUEST_PENDING, &n->status);
+            gic_set_clear_lr(v, n);
+            spin_unlock_irqrestore(&v->arch.vgic.lock, flags);
+            return;
+        } else {
             set_bit(GIC_IRQ_GUEST_PENDING, &n->status);
-        goto out;
+            goto out;
+        }
     }
 
     /* vcpu offline */
diff --git a/xen/include/asm-arm/gic.h b/xen/include/asm-arm/gic.h
index 6fce5c2..6de0d9b 100644
--- a/xen/include/asm-arm/gic.h
+++ b/xen/include/asm-arm/gic.h
@@ -184,6 +184,7 @@ extern void gic_remove_from_queues(struct vcpu *v, unsigned int virtual_irq);
 extern int gic_route_irq_to_guest(struct domain *d,
                                   const struct dt_irq *irq,
                                   const char * devname);
+extern void gic_set_clear_lr(struct vcpu *v, struct pending_irq *p);
 
 /* Accept an interrupt from the GIC and dispatch its handler */
 extern void gic_interrupt(struct cpu_user_regs *regs, int is_fiq);
-- 
1.7.10.4