[Xen-devel] [PATCH] xen_pt: fix failure of attaching & detaching a PCI device to VM repeatedly

["Jianzhong,Chang" <jianzhongx.chang@xxxxxxxxx>]

From: jianzhong,Chang <jianzhongx.chang@xxxxxxxxx>

Add pci = [ '$VF_BDF', '$VF_BDF', '$VF_BDF'] in
hvm guest configuration file. After the guest boot up,
detach the VFs in sequence by "xl pci-detach $DOMID $VF_BDF",
reattach the VFs by "xl pci-attach $VF_BDF" in sequence.
An error message will be reported like this:
"libxl: error: libxl_qmp.c:287:qmp_handle_error_response: received
an error message from QMP server: Duplicate ID 'pci-pt-07_10.1' for device"

When xen_pt_region_add/del() is called, MemoryRegion
may not belong to the XenPCIPassthroughState.
xen_pt_region_update() checks it but memory_region_ref/unref() does not.
This case causes obj->ref issue and affects the release of related objects.
So, the detection operation is moved from
xen_pt_region_update to xen_pt_region_add/del.

Signed-off-by: Jianzhong,Chang <jianzhongx.chang@xxxxxxxxx>
---
 hw/xen/xen_pt.c |   23 ++++++++++++++++++++---
 1 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/hw/xen/xen_pt.c b/hw/xen/xen_pt.c
index aa96288..95b4970 100644
--- a/hw/xen/xen_pt.c
+++ b/hw/xen/xen_pt.c
@@ -523,6 +523,14 @@ static int xen_pt_bar_from_region(XenPCIPassthroughState 
*s, MemoryRegion *mr)
     }
     return -1;
 }
+static bool xen_pt_region_in_state(XenPCIPassthroughState *s, MemoryRegion *mr)
+{
+    int bar = xen_pt_bar_from_region(s, mr);
+    if (-1 == bar && (!s->msix || &s->msix->mmio != mr)) {
+        return false;
+    }
+    return true;
+}
 
 /*
  * This function checks if an io_region overlaps an io_region from another
@@ -587,9 +595,6 @@ static void xen_pt_region_update(XenPCIPassthroughState *s,
     };
 
     bar = xen_pt_bar_from_region(s, mr);
-    if (bar == -1 && (!s->msix || &s->msix->mmio != mr)) {
-        return;
-    }
 
     if (s->msix && &s->msix->mmio == mr) {
         if (adding) {
@@ -642,6 +647,9 @@ static void xen_pt_region_add(MemoryListener *l, 
MemoryRegionSection *sec)
     XenPCIPassthroughState *s = container_of(l, XenPCIPassthroughState,
                                              memory_listener);
 
+    if (!xen_pt_region_in_state(s, sec->mr)) {
+        return;
+    }
     memory_region_ref(sec->mr);
     xen_pt_region_update(s, sec, true);
 }
@@ -651,6 +659,9 @@ static void xen_pt_region_del(MemoryListener *l, 
MemoryRegionSection *sec)
     XenPCIPassthroughState *s = container_of(l, XenPCIPassthroughState,
                                              memory_listener);
 
+    if (!xen_pt_region_in_state(s, sec->mr)) {
+        return;
+    }
     xen_pt_region_update(s, sec, false);
     memory_region_unref(sec->mr);
 }
@@ -660,6 +671,9 @@ static void xen_pt_io_region_add(MemoryListener *l, 
MemoryRegionSection *sec)
     XenPCIPassthroughState *s = container_of(l, XenPCIPassthroughState,
                                              io_listener);
 
+    if (!xen_pt_region_in_state(s, sec->mr)) {
+        return;
+    }
     memory_region_ref(sec->mr);
     xen_pt_region_update(s, sec, true);
 }
@@ -669,6 +683,9 @@ static void xen_pt_io_region_del(MemoryListener *l, 
MemoryRegionSection *sec)
     XenPCIPassthroughState *s = container_of(l, XenPCIPassthroughState,
                                              io_listener);
 
+    if (!xen_pt_region_in_state(s, sec->mr)) {
+        return;
+    }
     xen_pt_region_update(s, sec, false);
     memory_region_unref(sec->mr);
 }
-- 
1.7.1


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel