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xen: events: assume PHYSDEVOP_get_free_pirq exists

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The find_unbound_pirq is called only from xen_allocate_pirq_msi and
only if alloc_pirq is true. The only caller which does this is
xen_hvm_setup_msi_irqs. The use of this function is gated, in
pci_xen_hvm_init, on XENFEAT_hvm_pirqs.

The PHYSDEVOP_get_free_pirq interfaces was added to the hypervisor in
22410:be96f6058c05 while XENFEAT_hvm_pirqs was added a couple of
minutes prior in 22409:6663214f06ac. Therefore we do not need to
concern ourselves with hypervisors which support XENFEAT_hvm_pirqs but
not PHYSDEVOP_get_free_pirq.

This eliminates the fallback path in find_unbound_pirq which walks to
pirq_to_irq array looking for a free pirq. Unlike the
PHYSDEVOP_get_free_pirq interface this fallback only looks up a free
pirq but does not reserve it. Removing this fallback will simplify
locking in the future.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Ian Campbell 2011-02-18 16:43:31 +00:00 committed by Konrad Rzeszutek Wilk
parent 9a626612c2
commit 5cad61a6ba
1 changed files with 6 additions and 9 deletions
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15
drivers/xen/events.c
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@ -649,19 +649,16 @@ int xen_map_pirq_gsi(unsigned pirq, unsigned gsi, int shareable, char *name)
static int find_unbound_pirq(int type)
{
int rc, i;
int rc;
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; i++) {
if (pirq_to_irq[i] < 0)
return i;
}
return -1;
WARN_ONCE(rc == -ENOSYS,
"hypervisor does not support the PHYSDEVOP_get_free_pirq interface\n");
return rc ? -1 : op_get_free_pirq.pirq;
}
int xen_allocate_pirq_msi(char *name, int *pirq, int alloc_pirq)