[Xen-devel] [PATCH 3/6] x86/shadow: ignore sh_pin() failure in one more case

["Jan Beulich" <JBeulich@xxxxxxxx>]

Following what we've already done in the XSA-250 fix, convert another
sh_pin() caller to no longer fail the higher level operation if pinning
fails, as pinning is a performance optimization only in those places.

Suggested-by: Tim Deegan <tim@xxxxxxx>
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
Would it be worth making sh_pin() return void, by adding a bool
parameter which the other call site in sh_set_toplevel_shadow() could
use to indicate a ref is avalable to be used (instead of aquiring a
new one)? This would allow to drop another domain_crash().

--- a/xen/arch/x86/mm/shadow/multi.c
+++ b/xen/arch/x86/mm/shadow/multi.c
@@ -3925,17 +3925,15 @@ sh_set_toplevel_shadow(struct vcpu *v,
     }
     ASSERT(mfn_valid(smfn));
 
-    /* Pin the shadow and put it (back) on the list of pinned shadows */
-    if ( sh_pin(d, smfn) == 0 )
-    {
-        SHADOW_ERROR("can't pin %#lx as toplevel shadow\n", mfn_x(smfn));
-        domain_crash(d);
-    }
-
     /* Take a ref to this page: it will be released in sh_detach_old_tables()
      * or the next call to set_toplevel_shadow() */
     if ( sh_get_ref(d, smfn, 0) )
+    {
+        /* Pin the shadow and put it (back) on the list of pinned shadows */
+        sh_pin(d, smfn);
+
         new_entry = pagetable_from_mfn(smfn);
+    }
     else
     {
         SHADOW_ERROR("can't install %#lx as toplevel shadow\n", mfn_x(smfn));




_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel