[PATCH 09/17] xen: bind pirq to vector and event channel

Jeremy Fitzhardinge
2009-05-12T23:28:43Z

Having converting a dev+pin to a gsi, and that gsi to an irq, and
allocated a vector for the irq, we must program the IO APIC to deliver
an interrupt on a pin to the vector, so Xen can deliver it as an event
channel.

Given the pirq, we can get the gsi and vector. We map the gsi to a
specific IO APIC's pin, and set the routing entry.

(We were passing the ACPI triggering and polarity levels directly into
the apic - but they have reversed values. The result was that
all the level-triggered interrupts were edge, and vice-versa.
It's surprising that anything worked at all, but now AHCI works
for me.

Thanks for Gerd Hoffmann for noticing this.)

[ Impact: program IO APICs under Xen ]

Diagnosed-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
arch/x86/xen/apic.c | 2 ++
arch/x86/xen/pci.c | 33 +++++++++++++++++++++++++++++++++
2 files changed, 35 insertions(+), 0 deletions(-)

diff --git a/arch/x86/xen/apic.c b/arch/x86/xen/apic.c
index 8ae563c..35a8af7 100644
--- a/arch/x86/xen/apic.c
+++ b/arch/x86/xen/apic.c
@@ -4,6 +4,7 @@

#include <asm/io_apic.h>
#include <asm/acpi.h>
+#include <asm/hw_irq.h>

#include <asm/xen/hypervisor.h>
#include <asm/xen/hypercall.h>
@@ -13,6 +14,7 @@

static void __init xen_io_apic_init(void)
{
+ enable_IO_APIC();
}

static unsigned int xen_io_apic_read(unsigned apic, unsigned reg)
diff --git a/arch/x86/xen/pci.c b/arch/x86/xen/pci.c
index f450007..af4e898 100644
--- a/arch/x86/xen/pci.c
+++ b/arch/x86/xen/pci.c
@@ -2,6 +2,8 @@
#include <linux/acpi.h>
#include <linux/pci.h>

+#include <asm/mpspec.h>
+#include <asm/io_apic.h>
#include <asm/pci_x86.h>

#include <asm/xen/hypervisor.h>
@@ -11,6 +13,32 @@

#include "xen-ops.h"

+static void xen_set_io_apic_routing(int irq, int trigger, int polarity)
+{
+ int ioapic, ioapic_pin;
+ int vector, gsi;
+ struct IO_APIC_route_entry entry;
+
+ gsi = xen_gsi_from_irq(irq);
+ vector = xen_vector_from_irq(irq);
+
+ ioapic = mp_find_ioapic(gsi);
+ if (ioapic == -1) {
+ printk(KERN_WARNING "xen_set_ioapic_routing: irq %d gsi %d ioapic %d\n",
+ irq, gsi, ioapic);
+ return;
+ }
+
+ ioapic_pin = mp_find_ioapic_pin(ioapic, gsi);
+
+ printk(KERN_INFO "xen_set_ioapic_routing: irq %d gsi %d vector %d ioapic %d pin %d triggering %d polarity %d\n",
+ irq, gsi, vector, ioapic, ioapic_pin, trigger, polarity);
+
+ setup_ioapic_entry(ioapic, -1, &entry, ~0, trigger, polarity, vector,
+ ioapic_pin);
+ ioapic_write_entry(ioapic, ioapic_pin, entry);
+}
+
int xen_register_gsi(u32 gsi, int triggering, int polarity)
{
int irq;
@@ -25,6 +53,11 @@ int xen_register_gsi(u32 gsi, int triggering, int polarity)

printk(KERN_DEBUG "xen: --> irq=%d\n", irq);

+ if (irq > 0)
+ xen_set_io_apic_routing(irq,
+ triggering == ACPI_EDGE_SENSITIVE ? 0 : 1,
+ polarity == ACPI_ACTIVE_HIGH ? 0 : 1);
+
return irq;
}

--
1.6.0.6