Re: [Xen-devel] [PATCH] libxc: correctly unmap pages after core-dumping a pv guest

[Markus Groà <gross@xxxxxxxxxxxxx>]

Hi,

while implementing core dumping functionality for the libxl driver
of libvirt, I discovered an issue with mapping pages of a pv guest.

After dumping the core of a pv guest the domain was not cleared up
properly and some pages were not unmapped. This issue is similar
to the one reported here:
http://lists.xensource.com/archives/html/xen-devel/2011-05/msg01314.html

In xc_domain_dumpcore_via_callback in the file xc_core.c the function
xc_core_arch_map_p2m is called to map P2M_FL_ENTRIES pages to the  
variable p2m.
But to unmap the pages later, the dinfo->p2m_size has to be set accordingly.
This was not done, instead a variable named p2m_size was set.
This way P2M_FL_ENTRIES was always zero and the pages were left mapped.

The following patch fixes this.

Best regards,
Markus

Signed-off-by: Markus Groà <gross <at> univention.de>

diff -r 7c7ef1b6f4e5 tools/libxc/xc_core.c
--- a/tools/libxc/xc_core.c     Tue Apr 26 14:11:18 2011 +0100
+++ b/tools/libxc/xc_core.c     Mon May 23 13:36:23 2011 +0200
@@ -468,7 +468,6 @@

     int auto_translated_physmap;
     xen_pfn_t *p2m = NULL;
-    unsigned long p2m_size = 0;
     struct xen_dumpcore_p2m *p2m_array = NULL;

     uint64_t *pfn_array = NULL;
@@ -569,7 +568,7 @@
         }

         sts = xc_core_arch_map_p2m(xch, dinfo->guest_width, &info,  
live_shinfo,
-                                   &p2m, &p2m_size);
+                                   &p2m, &dinfo->p2m_size);
         if ( sts != 0 )
             goto out;
     }


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