On 10/6/2015 9:49 PM, Stefano Stabellini wrote:
On Tue, 6 Oct 2015, Paolo Bonzini wrote:
On 05/10/2015 18:53, Stefano Stabellini wrote:
This patch is to fix the issue via moving MSIX MMIO memory region into
struct XenPCIPassthroughState and free it together with pt device's obj.
Given that all the MSI-X related info are in XenPTMSIX, I would prefer
to keep the mmio memory region there, if possible.
Couldn't you just unhook msix->mmio from XenPCIPassthroughState's object
in xen_pt_msix_delete? Calling object_property_del_child or
object_unparent?
This is the right thing to do, but there are two separate things to fix.
One is the use-after-free of msix->mmio, the other is that freeing
s->msix and in general xen_pt_config_delete should be done from the
.instance_finalize callback. This is documented in docs/memory.txt.
This is an attempt at a patch (not even compiled):
diff --git a/hw/xen/xen_pt_msi.c b/hw/xen/xen_pt_msi.c
index e3d7194..e476bac 100644
--- a/hw/xen/xen_pt_msi.c
+++ b/hw/xen/xen_pt_msi.c
@@ -610,7 +610,7 @@ error_out:
return rc;
}
-void xen_pt_msix_delete(XenPCIPassthroughState *s)
+void xen_pt_msix_unmap(XenPCIPassthroughState *s)
{
XenPTMSIX *msix = s->msix;
@@ -627,6 +627,17 @@ void xen_pt_msix_delete(XenPCIPassthroughState *s)
}
memory_region_del_subregion(&s->bar[msix->bar_index], &msix->mmio);
+}
+
+void xen_pt_msix_delete(XenPCIPassthroughState *s)
+{
+ XenPTMSIX *msix = s->msix;
+
+ if (!msix) {
+ return;
+ }
+
+ object_unparent(&msix->mmio);
g_free(s->msix);
s->msix = NULL;
where xen_pt_config_unmap would be called from xen_pt_destroy, and the call
to xen_pt_config_delete would be moved to xen_pci_passthrough_info's
instance_finalize member.
Thanks for the explanation and the code. It makes sense to me.
Lan, could you please write up a patch based on this approach and test
it?
Sure. I will update patch following the guide. Thanks Paolo & Stefano.
