Jan Beulich
2010-Dec-01 10:42 UTC
[Xen-devel] [PATCH] 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@novell.com>
--- 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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