[Xen-devel] [PATCH] libxc: fix HVM core dump

[Wei Liu <wei.liu2@xxxxxxxxxx>]

f969bc9fc96 forbid get_address_size call on HVM guests, because that
didn't make sense. It broke core dump functionality on HVM because
libxc unconditionally asked for guest width.

Only issue the call when necessary in libxc.

Reported-by: Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>

Juergen, this is probably too late for 4.12, but you can at least add
a release note somewhere.

Ian, please backport this to 4.12.
---
 tools/libxc/xc_core.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/tools/libxc/xc_core.c b/tools/libxc/xc_core.c
index e581905ba9..c825b5b0a0 100644
--- a/tools/libxc/xc_core.c
+++ b/tools/libxc/xc_core.c
@@ -459,12 +459,6 @@ xc_domain_dumpcore_via_callback(xc_interface *xch,
     struct xc_core_section_headers *sheaders = NULL;
     Elf64_Shdr *shdr;
  
-    if ( xc_domain_get_guest_width(xch, domid, &dinfo->guest_width) != 0 )
-    {
-        PERROR("Could not get address size for domain");
-        return sts;
-    }
-
     xc_core_arch_context_init(&arch_ctxt);
     if ( (dump_mem_start = malloc(DUMP_INCREMENT*PAGE_SIZE)) == NULL )
     {
@@ -487,6 +481,13 @@ xc_domain_dumpcore_via_callback(xc_interface *xch,
     }
     auto_translated_physmap = xc_core_arch_auto_translated_physmap(&info);
 
+    if ( !auto_translated_physmap &&
+         xc_domain_get_guest_width(xch, domid, &dinfo->guest_width) != 0 )
+    {
+        PERROR("Could not get address size for domain");
+        goto out;
+    }
+
     if ( domid != info.domid )
     {
         PERROR("Domain %d does not exist", domid);
@@ -742,7 +743,10 @@ xc_domain_dumpcore_via_callback(xc_interface *xch,
         goto out;
 
     /* elf note section: xen version */
-    sts = elfnote_dump_xen_version(xch, args, dump_rtn, dinfo->guest_width);
+    sts = elfnote_dump_xen_version(xch, args, dump_rtn,
+                                   auto_translated_physmap ?
+                                   sizeof(unsigned long):
+                                   dinfo->guest_width);
     if ( sts != 0 )
         goto out;
 
-- 
2.20.1


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