Re: [Xen-devel] IRQ migration (c/s 20370 + 20465)

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 29.11.10 at 14:14, "Jan Beulich" <JBeulich@xxxxxxxxxx> wrote:
> Edwin, Xiantao,
> 
> I'm observing I/O-APIC IRQs never getting migrated on a system
> using directed EOI. Looking at end_level_ioapic_irq(), I fail
> to see how that case is being handled (other than in the Linux
> implementation, which this code supposedly is a clone of).
> 
> Additionally it seems wasteful to check whether to move the IRQ in
> mask_and_ack_level_ioapic_irq(), as ack_APIC_irq() cannot
> possibly have resulted in clearing any of the IRR bits that
> io_apic_level_ack_pending() is looking at.

Below is a tentative (lightly tested) fix for this. Comments?

Jan

--- a/xen/arch/x86/io_apic.c
+++ b/xen/arch/x86/io_apic.c
@@ -1634,11 +1634,14 @@ static void mask_and_ack_level_ioapic_ir
 
     ack_APIC_irq();
     
+    if ( directed_eoi_enabled )
+        return;
+
     if ((irq_desc[irq].status & IRQ_MOVE_PENDING) &&
        !io_apic_level_ack_pending(irq))
-        move_native_irq(irq);
+        move_masked_irq(irq);
 
-    if (!directed_eoi_enabled && !(v & (1 << (i & 0x1f)))) {
+    if ( !(v & (1 << (i & 0x1f))) ) {
         atomic_inc(&irq_mis_count);
         spin_lock(&ioapic_lock);
         __edge_IO_APIC_irq(irq);
@@ -1654,12 +1657,22 @@ static void end_level_ioapic_irq (unsign
 
     if ( !ioapic_ack_new )
     {
-        if ( irq_desc[irq].status & IRQ_DISABLED )
-            return;
-
         if ( directed_eoi_enabled )
+        {
+            if ( !(irq_desc[irq].status & (IRQ_DISABLED|IRQ_MOVE_PENDING)) )
+            {
+                eoi_IO_APIC_irq(irq);
+                return;
+            }
+
+            mask_IO_APIC_irq(irq);
             eoi_IO_APIC_irq(irq);
-        else
+            if ( (irq_desc[irq].status & IRQ_MOVE_PENDING) &&
+                 !io_apic_level_ack_pending(irq) )
+                move_masked_irq(irq);
+        }
+
+        if ( !(irq_desc[irq].status & IRQ_DISABLED) )
             unmask_IO_APIC_irq(irq);
 
         return;



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