xc_save: use correct size when unmapping live p2m.

Otherwise we unmap a larger region than was mapped when saving 32 bit
guest from 64 bit tools, leading to badness.

The equivalent change was made to the restore code in
18329:ca7dd77d5365

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>

tools/libxc/xc_domain_save.c

@@ -727,7 +727,7 @@ static xen_pfn_t *map_and_save_p2m_table(int xc_handle,
  out:
     
     if ( !success && p2m )
-        munmap(p2m, ROUNDUP(p2m_size * sizeof(xen_pfn_t), PAGE_SHIFT));
+        munmap(p2m, P2M_FLL_ENTRIES * PAGE_SIZE);
 
     if ( live_p2m_frame_list_list )
         munmap(live_p2m_frame_list_list, PAGE_SIZE);
@@ -1608,7 +1608,7 @@ int xc_domain_save(int xc_handle, int io_fd, uint32_t dom, uint32_t max_iters,
         munmap(live_shinfo, PAGE_SIZE);
 
     if ( live_p2m )
-        munmap(live_p2m, ROUNDUP(p2m_size * sizeof(xen_pfn_t), PAGE_SHIFT));
+        munmap(live_p2m, P2M_FLL_ENTRIES * PAGE_SIZE);
 
     if ( live_m2p )
         munmap(live_m2p, M2P_SIZE(max_mfn));