[Xen-changelog] [xen-unstable] x86: fix IRQ migration when using directed EOI (broken with c/s 20465)

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir@xxxxxxx>
# Date 1291234227 0
# Node ID 62bf12040b0f4d802dc7e1cd61294776c8a41a89
# Parent  8420b82c22c2cad54860ffdbe8bcec21c65c86be
x86: fix IRQ migration when using directed EOI (broken with c/s 20465)

In directed-EOI mode, there is no chance to do the migration in
mask_and_ack_level_ioapic_irq(), as the remote IRR bit can't possibly
be clear after issuing the EOI to the LAPIC. Consequently, there's no
point to even try. Instead, migration must be done in
end_level_ioapic_irq(), and it requires masking the interrupt source
prior to issuing the EOI to the IO-APIC.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
---
 xen/arch/x86/io_apic.c |   27 ++++++++++++++++++++-------
 1 files changed, 20 insertions(+), 7 deletions(-)

diff -r 8420b82c22c2 -r 62bf12040b0f xen/arch/x86/io_apic.c
--- a/xen/arch/x86/io_apic.c    Tue Nov 30 11:34:08 2010 +0000
+++ b/xen/arch/x86/io_apic.c    Wed Dec 01 20:10:27 2010 +0000
@@ -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);
-
-    if (!directed_eoi_enabled && !(v & (1 << (i & 0x1f)))) {
+        move_masked_irq(irq);
+
+    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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