On 02/03/18 13:53, Andre Przywara wrote:

Hi Andre,

On 26/02/18 16:30, Julien Grall wrote:

On 02/26/2018 04:25 PM, Andre Przywara wrote:

On 26/02/18 15:55, Julien Grall wrote:

On 02/26/2018 03:29 PM, Andre Przywara wrote:
On 13/02/18 16:35, Julien Grall wrote:
diff --git a/xen/arch/arm/vgic/vgic.c b/xen/arch/arm/vgic/vgic.c
index f4f2a04a60..9e7fb1edcb 100644
--- a/xen/arch/arm/vgic/vgic.c
+++ b/xen/arch/arm/vgic/vgic.c
@@ -646,6 +646,38 @@ void gic_inject(void)
     +static int vgic_vcpu_pending_irq(struct vcpu *vcpu)
+    struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+    struct vgic_irq *irq;
+    bool pending = false;
+    unsigned long flags;
+    if ( !vcpu->domain->arch.vgic.enabled )
+        return false;
+    spin_lock_irqsave(&vgic_cpu->ap_list_lock, flags);
+    list_for_each_entry(irq, &vgic_cpu->ap_list_head, ap_list)
+    {
+        spin_lock(&irq->irq_lock);
+        pending = irq_is_pending(irq) && irq->enabled;
+        spin_unlock(&irq->irq_lock);
+        if ( pending )
+            break;
+    }
+    spin_unlock_irqrestore(&vgic_cpu->ap_list_lock, flags);
+    return pending;
+int gic_events_need_delivery(void)

You probably want to rename that function or just expose

Rename to what? I need both functions: vgic_vcpu_pending_irq() is also
called by vgic_kick_vcpus() (later in the series).
And gic_events_need_delivery(void) is the interface that the arch code
expects. Shall I rename this there? To what?

Let me start with it is a bit odd to have a function name 'gic_*' in the
virtual GIC code. So at least renaming to vgic_events_need_delivery
would be an improvement.

Regarding the interface itself, it is ARM specific and not set in stone.
It would not be too bad to use vgic_vcpu_pending_irq(current). Is there
any reason for not doing that?

The two interfaces used for that purpose are different in the two VGICs:
- The old VGIC only works on the current VCPU, since it peeks into the
GICH_ register to learn the priority (regardless of whether this is
really needed or useful).
- The new VGIC can use this function for any VCPU, and we need this
functionality later on (when we iterate over all VCPUs).
So we can't use a function hardwiring "current", that would break
vgic_kick_vcpus() in the new VGIC. And we can't pass a VCPU parameter,
that would not work for the old VGIC.
So I believe having this small wrapper here is the easiest solution.
I will add a patch to rename this function to vgic_pending_irq(),
though, so this one here looks like:
int vgic_pending_irq(void)
     return vgic_vcpu_pending_irq(current);

We can clean this up when the old VGIC gets removed.

Likely no-one in the old vGIC are going to call that function with v != current. This would not be the only place in Xen where a vCPU is taken in parameter but effectively v can only be current. That's where ASSERT(v == current) comes into place.


Julien Grall

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