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Message-ID: <467932B4.6030800@redhat.com>
Date: Wed, 20 Jun 2007 15:59:16 +0200
From: Michal Schmidt <mschmidt@...hat.com>
To: Ingo Molnar <mingo@...hat.com>
CC: Steven Rostedt <srostedt@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>,
linux-rt-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH -rt] irq nobody cared workaround for i386
Michal Schmidt wrote:
> Steven Rostedt wrote:
>
>> This is the final "design" for the nobody cared bug. For all IO-APICS
>> other than the first one (the chained IO-APICS) we use the PCIX version
>> of the mask and unmask interrupt routines. This changes the interrupt
>> from level to edge for mask and edge to level for unmask. This keeps the
>> PCI-E from thinking it's in legacy mode and assert an old fashion INT#
>> interrupt which might spread to other interrupts.
>>
>>
>>
>
> Here's a port of the workaround to i386. I tested it successfully on IBM
> LS21.
> Notice I had to disable the quirk handling in ack_ioapic_quirk_irq. The
> code path was triggering on LS21 and because it plays with the Interrupt
> Mask bit, it produced the doubled interrupts again. I don't like it and
> I need to think about a solution which would handle both quirks correctly.
>
I came to the conclusion that the IO-APICs which need the fix for the
nobody cared bug don't have the issue ack_ioapic_quirk_irq is designed
to work-around. It should be safe simply to use the normal
ack_ioapic_irq as the .eoi method in pcix_ioapic_chip.
So this is the port of Steven's fix for the nobody cared bug to i386. It
works fine on IBM LS21 I have access to.
Signed-off-by: Michal Schmidt <mschmidt@...hat.com>
--- arch/i386/kernel/io_apic.c.orig 2007-06-19 08:40:05.000000000 -0400
+++ arch/i386/kernel/io_apic.c 2007-06-20 09:03:55.000000000 -0400
@@ -261,6 +261,18 @@ static void __unmask_IO_APIC_irq (unsign
__modify_IO_APIC_irq(irq, 0, 0x00010000);
}
+/* trigger = 0 (edge mode) */
+static void __pcix_mask_IO_APIC_irq (unsigned int irq)
+{
+ __modify_IO_APIC_irq(irq, 0, 0x00008000);
+}
+
+/* mask = 0, trigger = 1 (level mode) */
+static void __pcix_unmask_IO_APIC_irq (unsigned int irq)
+{
+ __modify_IO_APIC_irq(irq, 0x00008000, 0x00010000);
+}
+
static void mask_IO_APIC_irq (unsigned int irq)
{
unsigned long flags;
@@ -279,6 +291,24 @@ static void unmask_IO_APIC_irq (unsigned
spin_unlock_irqrestore(&ioapic_lock, flags);
}
+static void pcix_mask_IO_APIC_irq (unsigned int irq)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&ioapic_lock, flags);
+ __pcix_mask_IO_APIC_irq(irq);
+ spin_unlock_irqrestore(&ioapic_lock, flags);
+}
+
+static void pcix_unmask_IO_APIC_irq (unsigned int irq)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&ioapic_lock, flags);
+ __pcix_unmask_IO_APIC_irq(irq);
+ spin_unlock_irqrestore(&ioapic_lock, flags);
+}
+
static void clear_IO_APIC_pin(unsigned int apic, unsigned int pin)
{
struct IO_APIC_route_entry entry;
@@ -1257,22 +1287,27 @@ static int assign_irq_vector(int irq)
return vector;
}
+
static struct irq_chip ioapic_chip;
+static struct irq_chip pcix_ioapic_chip;
#define IOAPIC_AUTO -1
#define IOAPIC_EDGE 0
#define IOAPIC_LEVEL 1
-static void ioapic_register_intr(int irq, int vector, unsigned long trigger)
+static void ioapic_register_intr(int irq, int vector, unsigned long trigger,
+ int pcix)
{
+ struct irq_chip *chip = pcix ? &pcix_ioapic_chip : &ioapic_chip;
+
if ((trigger == IOAPIC_AUTO && IO_APIC_irq_trigger(irq)) ||
trigger == IOAPIC_LEVEL)
- set_irq_chip_and_handler_name(irq, &ioapic_chip,
- handle_fasteoi_irq, "fasteoi");
- else {
- set_irq_chip_and_handler_name(irq, &ioapic_chip,
- handle_edge_irq, "edge");
- }
+ set_irq_chip_and_handler_name(irq, chip, handle_fasteoi_irq,
+ pcix ? "pcix-fasteoi" : "fasteoi");
+ else
+ set_irq_chip_and_handler_name(irq, chip, handle_edge_irq,
+ pcix ? "pcix-edge" : "edge");
+
set_intr_gate(vector, interrupt[irq]);
}
@@ -1336,7 +1371,7 @@ static void __init setup_IO_APIC_irqs(vo
if (IO_APIC_IRQ(irq)) {
vector = assign_irq_vector(irq);
entry.vector = vector;
- ioapic_register_intr(irq, vector, IOAPIC_AUTO);
+ ioapic_register_intr(irq, vector, IOAPIC_AUTO, apic>0);
if (!apic && (irq < 16))
disable_8259A_irq(irq);
@@ -2058,6 +2093,18 @@ static struct irq_chip ioapic_chip __rea
.retrigger = ioapic_retrigger_irq,
};
+static struct irq_chip pcix_ioapic_chip __read_mostly = {
+ .name = "IO-APIC",
+ .startup = startup_ioapic_irq,
+ .mask = pcix_mask_IO_APIC_irq,
+ .unmask = pcix_unmask_IO_APIC_irq,
+ .ack = ack_ioapic_irq,
+ .eoi = ack_ioapic_irq,
+#ifdef CONFIG_SMP
+ .set_affinity = set_ioapic_affinity_irq,
+#endif
+ .retrigger = ioapic_retrigger_irq,
+};
static inline void init_IO_APIC_traps(void)
{
@@ -2858,7 +2905,7 @@ int io_apic_set_pci_routing (int ioapic,
mp_ioapics[ioapic].mpc_apicid, pin, entry.vector, irq,
edge_level, active_high_low);
- ioapic_register_intr(irq, entry.vector, edge_level);
+ ioapic_register_intr(irq, entry.vector, edge_level, ioapic>0);
if (!ioapic && (irq < 16))
disable_8259A_irq(irq);
-
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