xen: events: allocate GSIs and dynamic IRQs from separate IRQ ranges.

[mv-sheeva.git] / drivers / xen / events.c

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 81a53eb6cd1dd6ac6a2b4ab2331bf79e5ea08aa7..06f2e61de69106c3ea498321a80fdf89f454e5b4 100644 (file)
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -376,72 +376,49 @@ static void unmask_evtchn(int port)
        put_cpu();
 }
 
-static int get_nr_hw_irqs(void)
+static int xen_allocate_irq_dynamic(void)
 {
-       int ret = 1;
+       int first = 0;
+       int irq;
 
 #ifdef CONFIG_X86_IO_APIC
-       ret = get_nr_irqs_gsi();
+       /*
+        * For an HVM guest or domain 0 which see "real" (emulated or
+        * actual repectively) GSIs we allocate dynamic IRQs
+        * e.g. those corresponding to event channels or MSIs
+        * etc. from the range above those "real" GSIs to avoid
+        * collisions.
+        */
+       if (xen_initial_domain() || xen_hvm_domain())
+               first = get_nr_irqs_gsi();
 #endif
 
-       return ret;
-}
+retry:
+       irq = irq_alloc_desc_from(first, -1);
 
-static int xen_allocate_irq_dynamic(void)
-{
-       struct irq_data *data;
-       int irq, res;
-       int bottom = get_nr_hw_irqs();
-       int top = nr_irqs-1;
-
-       if (bottom == nr_irqs)
-               goto no_irqs;
-
-       /* This loop starts from the top of IRQ space and goes down.
-        * We need this b/c if we have a PCI device in a Xen PV guest
-        * we do not have an IO-APIC (though the backend might have them)
-        * mapped in. To not have a collision of physical IRQs with the Xen
-        * event channels start at the top of the IRQ space for virtual IRQs.
-        */
-       for (irq = top; irq > bottom; irq--) {
-               data = irq_get_irq_data(irq);
-               /* only 15->0 have init'd desc; handle irq > 16 */
-               if (!data)
-                       break;
-               if (data->chip == &no_irq_chip)
-                       break;
-               if (data->chip != &xen_dynamic_chip)
-                       continue;
-               if (irq_info[irq].type == IRQT_UNBOUND)
-                       return irq;
+       if (irq == -ENOMEM && first > NR_IRQS_LEGACY) {
+               printk(KERN_ERR "Out of dynamic IRQ space and eating into GSI space. You should increase nr_irqs\n");
+               first = max(NR_IRQS_LEGACY, first - NR_IRQS_LEGACY);
+               goto retry;
        }
 
-       if (irq == bottom)
-               goto no_irqs;
-
-       res = irq_alloc_desc_at(irq, -1);
-
-       if (WARN_ON(res != irq))
-               return -1;
+       if (irq < 0)
+               panic("No available IRQ to bind to: increase nr_irqs!\n");
 
        return irq;
-
-no_irqs:
-       panic("No available IRQ to bind to: increase nr_irqs!\n");
-}
-
-static bool identity_mapped_irq(unsigned irq)
-{
-       /* identity map all the hardware irqs */
-       return irq < get_nr_hw_irqs();
 }
 
 static int xen_allocate_irq_gsi(unsigned gsi)
 {
        int irq;
 
-       if (!identity_mapped_irq(gsi) &&
-           (xen_initial_domain() || !xen_pv_domain()))
+       /*
+        * A PV guest has no concept of a GSI (since it has no ACPI
+        * nor access to/knowledge of the physical APICs). Therefore
+        * all IRQs are dynamically allocated from the entire IRQ
+        * space.
+        */
+       if (xen_pv_domain() && !xen_initial_domain())
                return xen_allocate_irq_dynamic();
 
        /* Legacy IRQ descriptors are already allocated by the arch. */