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Subject[PATCH v2] Use PHYSDEVOP_get_free_pirq to implement find_unbound_pirq
Use PHYSDEVOP_get_free_pirq to implement find_unbound_pirq

Use the new hypercall PHYSDEVOP_get_free_pirq to ask Xen to allocate a
pirq. Remove the unsupported PHYSDEVOP_get_nr_pirqs hypercall to get the
amount of pirq available.

Changes since v1:

- if PHYSDEVOP_get_free_pirq is not implemented, start pirq allocation
from 0 instead of 16. The pirq number 16 is not actually meaningful for
Xen.

- Remove nr_pirqs, it is not needed anymore. Add a comment to specify
that we don't actually know the upper limit of the pirq number range.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>


diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 2811bb9..072af50 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -105,7 +105,6 @@ struct irq_info

static struct irq_info *irq_info;
static int *pirq_to_irq;
-static int nr_pirqs;

static int *evtchn_to_irq;
struct cpu_evtchn_s {
@@ -385,12 +384,17 @@ static int get_nr_hw_irqs(void)
return ret;
}

-/* callers of this function should make sure that PHYSDEVOP_get_nr_pirqs
- * succeeded otherwise nr_pirqs won't hold the right value */
-static int find_unbound_pirq(void)
+static int find_unbound_pirq(int type)
{
- int i;
- for (i = nr_pirqs-1; i >= 0; i--) {
+ int rc, i;
+ struct physdev_get_free_pirq op_get_free_pirq;
+ op_get_free_pirq.type = type;
+
+ rc = HYPERVISOR_physdev_op(PHYSDEVOP_get_free_pirq, &op_get_free_pirq);
+ if (!rc)
+ return op_get_free_pirq.pirq;
+
+ for (i = 0; i <= nr_irqs-1; i++) {
if (pirq_to_irq[i] < 0)
return i;
}
@@ -611,9 +615,9 @@ int xen_map_pirq_gsi(unsigned pirq, unsigned gsi, int shareable, char *name)

spin_lock(&irq_mapping_update_lock);

- if ((pirq > nr_pirqs) || (gsi > nr_irqs)) {
+ if ((pirq > nr_irqs) || (gsi > nr_irqs)) {
printk(KERN_WARNING "xen_map_pirq_gsi: %s %s is incorrect!\n",
- pirq > nr_pirqs ? "nr_pirqs" :"",
+ pirq > nr_irqs ? "nr_pirqs" :"",
gsi > nr_irqs ? "nr_irqs" : "");
goto out;
}
@@ -672,7 +676,7 @@ void xen_allocate_pirq_msi(char *name, int *irq, int *pirq)
if (*irq == -1)
goto out;

- *pirq = find_unbound_pirq();
+ *pirq = find_unbound_pirq(MAP_PIRQ_TYPE_MSI);
if (*pirq == -1)
goto out;

@@ -1506,26 +1510,17 @@ void xen_callback_vector(void) {}

void __init xen_init_IRQ(void)
{
- int i, rc;
- struct physdev_nr_pirqs op_nr_pirqs;
+ int i;

cpu_evtchn_mask_p = kcalloc(nr_cpu_ids, sizeof(struct cpu_evtchn_s),
GFP_KERNEL);
irq_info = kcalloc(nr_irqs, sizeof(*irq_info), GFP_KERNEL);

- rc = HYPERVISOR_physdev_op(PHYSDEVOP_get_nr_pirqs, &op_nr_pirqs);
- if (rc < 0) {
- nr_pirqs = nr_irqs;
- if (rc != -ENOSYS)
- printk(KERN_WARNING "PHYSDEVOP_get_nr_pirqs returned rc=%d\n", rc);
- } else {
- if (xen_pv_domain() && !xen_initial_domain())
- nr_pirqs = max((int)op_nr_pirqs.nr_pirqs, nr_irqs);
- else
- nr_pirqs = op_nr_pirqs.nr_pirqs;
- }
- pirq_to_irq = kcalloc(nr_pirqs, sizeof(*pirq_to_irq), GFP_KERNEL);
- for (i = 0; i < nr_pirqs; i++)
+ /* We are using nr_irqs as the maximum number of pirq available but
+ * that number is actually chosen by Xen and we don't know exactly
+ * what it is. Be careful choosing high pirq numbers. */
+ pirq_to_irq = kcalloc(nr_irqs, sizeof(*pirq_to_irq), GFP_KERNEL);
+ for (i = 0; i < nr_irqs; i++)
pirq_to_irq[i] = -1;

evtchn_to_irq = kcalloc(NR_EVENT_CHANNELS, sizeof(*evtchn_to_irq),
diff --git a/include/xen/interface/physdev.h b/include/xen/interface/physdev.h
index 2b2c66c..534cac8 100644
--- a/include/xen/interface/physdev.h
+++ b/include/xen/interface/physdev.h
@@ -188,6 +188,16 @@ struct physdev_nr_pirqs {
uint32_t nr_pirqs;
};

+/* type is MAP_PIRQ_TYPE_GSI or MAP_PIRQ_TYPE_MSI
+ * the hypercall returns a free pirq */
+#define PHYSDEVOP_get_free_pirq 23
+struct physdev_get_free_pirq {
+ /* IN */
+ int type;
+ /* OUT */
+ uint32_t pirq;
+};
+
/*
* Notify that some PIRQ-bound event channels have been unmasked.
* ** This command is obsolete since interface version 0x00030202 and is **

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