[Xen-changelog] [xen-unstable] x86: Reduce logging about get_page_type() failures.

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir@xxxxxxxxxxxxx>
# Date 1192616273 -3600
# Node ID d994e6d3136de94f50aeb86c4a060ee06ecfbf6d
# Parent  76bf1fcaf01d2d344e4c4c4a127bf20fece77d4a
x86: Reduce logging about get_page_type() failures.

We shouldn't log if the cause could be a recursive-mapping attempt --
we expect a get_page_type() failure in that case.

Based on a patch maintained for NetBSD.

Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
 xen/arch/x86/mm.c |   21 ++++++++++++++-------
 1 files changed, 14 insertions(+), 7 deletions(-)

diff -r 76bf1fcaf01d -r d994e6d3136d xen/arch/x86/mm.c
--- a/xen/arch/x86/mm.c Wed Oct 17 11:12:32 2007 +0100
+++ b/xen/arch/x86/mm.c Wed Oct 17 11:17:53 2007 +0100
@@ -1771,13 +1771,20 @@ int get_page_type(struct page_info *page
         }
         else if ( unlikely((x & (PGT_type_mask|PGT_pae_xen_l2)) != type) )
         {
-            if ( ((x & PGT_type_mask) != PGT_l2_page_table) ||
-                 (type != PGT_l1_page_table) )
-                MEM_LOG("Bad type (saw %" PRtype_info
-                        " != exp %" PRtype_info ") "
-                        "for mfn %lx (pfn %lx)",
-                        x, type, page_to_mfn(page),
-                        get_gpfn_from_mfn(page_to_mfn(page)));
+            /* Don't log failure if it could be a recursive-mapping attempt. */
+            if ( ((x & PGT_type_mask) == PGT_l2_page_table) &&
+                 (type == PGT_l1_page_table) )
+                return 0;
+            if ( ((x & PGT_type_mask) == PGT_l3_page_table) &&
+                 (type == PGT_l2_page_table) )
+                return 0;
+            if ( ((x & PGT_type_mask) == PGT_l4_page_table) &&
+                 (type == PGT_l3_page_table) )
+                return 0;
+            MEM_LOG("Bad type (saw %" PRtype_info " != exp %" PRtype_info ") "
+                    "for mfn %lx (pfn %lx)",
+                    x, type, page_to_mfn(page),
+                    get_gpfn_from_mfn(page_to_mfn(page)));
             return 0;
         }
         else if ( unlikely(!(x & PGT_validated)) )

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