[XEN PATCH v12 5/7] tools/libxc: Allow gsi be mapped into a free pirq

[Jiqian Chen <Jiqian.Chen@xxxxxxx>]

Hypercall PHYSDEVOP_map_pirq support to map a gsi into a specific
pirq or a free pirq, it depends on the parameter pirq(>0 or <0).
But in current xc_physdev_map_pirq, it set *pirq=index when
parameter pirq is <0, it causes to force all cases to be mapped
to a specific pirq. That has some problems, one is caller can't
get a free pirq value, another is that once the pecific pirq was
already mapped to other gsi, then it will fail.

So, change xc_physdev_map_pirq to allow to pass negative parameter
in and then get a free pirq.

There are four caller of xc_physdev_map_pirq in original codes, so
clarify the affect below(just need to clarify the pirq<0 case):

First, pci_add_dm_done->xc_physdev_map_pirq, it pass irq to pirq
parameter, if pirq<0 means irq<0, then it will fail at check
"index < 0" in allocate_and_map_gsi_pirq and get EINVAL, logic is
the same as original code.

Second, domcreate_launch_dm->libxl__arch_domain_map_irq->
xc_physdev_map_pirq, the passed pirq is always >=0, so no affect.

Third, pyxc_physdev_map_pirq->xc_physdev_map_pirq, not sure, so add
the check logic into pyxc_physdev_map_pirq to keep the same behavior.

Fourth, xen_pt_realize->xc_physdev_map_pirq, it wants to allocate a
pirq for gsi, but it isn't necessary to get pirq whose value is equal
with the value of gsi. After this patch, it will get a free pirq, and
it also can work.

Signed-off-by: Jiqian Chen <Jiqian.Chen@xxxxxxx>
Signed-off-by: Huang Rui <ray.huang@xxxxxxx>
Signed-off-by: Jiqian Chen <Jiqian.Chen@xxxxxxx>
---
 tools/libs/ctrl/xc_physdev.c      | 2 +-
 tools/python/xen/lowlevel/xc/xc.c | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/libs/ctrl/xc_physdev.c b/tools/libs/ctrl/xc_physdev.c
index 460a8e779ce8..e9fcd755fa62 100644
--- a/tools/libs/ctrl/xc_physdev.c
+++ b/tools/libs/ctrl/xc_physdev.c
@@ -50,7 +50,7 @@ int xc_physdev_map_pirq(xc_interface *xch,
     map.domid = domid;
     map.type = MAP_PIRQ_TYPE_GSI;
     map.index = index;
-    map.pirq = *pirq < 0 ? index : *pirq;
+    map.pirq = *pirq;
 
     rc = do_physdev_op(xch, PHYSDEVOP_map_pirq, &map, sizeof(map));
 
diff --git a/tools/python/xen/lowlevel/xc/xc.c 
b/tools/python/xen/lowlevel/xc/xc.c
index 9feb12ae2b16..f8c9db7115ee 100644
--- a/tools/python/xen/lowlevel/xc/xc.c
+++ b/tools/python/xen/lowlevel/xc/xc.c
@@ -774,6 +774,8 @@ static PyObject *pyxc_physdev_map_pirq(PyObject *self,
     if ( !PyArg_ParseTupleAndKeywords(args, kwds, "iii", kwd_list,
                                       &dom, &index, &pirq) )
         return NULL;
+    if ( pirq < 0 )
+        pirq = index;
     ret = xc_physdev_map_pirq(xc->xc_handle, dom, index, &pirq);
     if ( ret != 0 )
           return pyxc_error_to_exception(xc->xc_handle);
-- 
2.34.1