[Xen-devel] [PATCH for-4.12 V2] x86/p2m: fix p2m_finish_type_change()

[Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>]

finish_type_change() returns a negative int on error, but the
current code checks if ( !rc ). We also need to treat
finish_type_change()'s return codes cumulatively in the
success case (don't overwrite a 1 returned while processing
the hostp2m if processing an altp2m returns 0).

The breakage was introduced by commit 0fb4b58c8b
("x86/altp2m: fix display frozen when switching to a new view
early").

Properly indent the out: label while at it.

Signed-off-by: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>

---
Changes since V1:
 - Updated description.
 - Now treating finish_type_change()'s return value cumulatively
   for the success case.
---
 xen/arch/x86/mm/p2m.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 5451f16..91f412f 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -1176,7 +1176,7 @@ int p2m_finish_type_change(struct domain *d,
 
     rc = finish_type_change(hostp2m, first_gfn, max_nr);
 
-    if ( !rc )
+    if ( rc < 0 )
         goto out;
 
 #ifdef CONFIG_HVM
@@ -1188,18 +1188,24 @@ int p2m_finish_type_change(struct domain *d,
             if ( d->arch.altp2m_eptp[i] != mfn_x(INVALID_MFN) )
             {
                 struct p2m_domain *altp2m = d->arch.altp2m_p2m[i];
+                int rc1;
 
                 p2m_lock(altp2m);
-                rc = finish_type_change(altp2m, first_gfn, max_nr);
+                rc1 = finish_type_change(altp2m, first_gfn, max_nr);
                 p2m_unlock(altp2m);
 
-                if ( !rc )
+                if ( rc1 < 0 )
+                {
+                    rc = rc1;
                     goto out;
+                }
+
+                rc = max(rc, rc1);
             }
     }
 #endif
 
-out:
+ out:
     p2m_unlock(hostp2m);
 
     return rc;
-- 
2.7.4


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