[Xen-devel] [PATCH 2/4] x86/PoD: Identify when a domain has already been killed from PoD exhaustion

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

p2m_pod_demand_populate() can be entered repeatedly during a single path
through the hypervisor, e.g. on a toolstack batch map operation.

The domain might be crashed, but the interface currently lacks a way of
passing an error back through the generic p2m layer.

Longterm the p2m layer needs reworking to allow errors to be returned, but in
the short term, avoid repeatedly re-sweeping the domain after it has already
been crashed from PoD exhaustion.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
---
 xen/arch/x86/mm/p2m-pod.c | 3 ++-
 xen/include/asm-x86/p2m.h | 2 ++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/mm/p2m-pod.c b/xen/arch/x86/mm/p2m-pod.c
index be15cf3..6fb054f 100644
--- a/xen/arch/x86/mm/p2m-pod.c
+++ b/xen/arch/x86/mm/p2m-pod.c
@@ -1048,7 +1048,7 @@ p2m_pod_demand_populate(struct p2m_domain *p2m, unsigned 
long gfn,
     /* This check is done with the pod lock held.  This will make sure that
      * even if d->is_dying changes under our feet, p2m_pod_empty_cache() 
      * won't start until we're done. */
-    if ( unlikely(d->is_dying) )
+    if ( unlikely(d->is_dying) || p2m->pod.dead )
         goto out_fail;
 
     
@@ -1129,6 +1129,7 @@ p2m_pod_demand_populate(struct p2m_domain *p2m, unsigned 
long gfn,
     pod_unlock(p2m);
     return 0;
 out_of_memory:
+    p2m->pod.dead = 1;
     pod_unlock(p2m);
 
     printk("%s: Dom%d out of PoD memory! (tot=%"PRIu32" ents=%ld dom%d)\n",
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index d748557..6faf9d6 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -308,6 +308,8 @@ struct p2m_domain {
         } mrp;
         mm_lock_t        lock;         /* Locking of private pod structs,   *
                                         * not relying on the p2m lock.      */
+        bool_t           dead;         /* Emergency sweep has failed and    *
+                                        * the domain has been crashed.      */
     } pod;
     union {
         struct ept_data ept;
-- 
2.1.4


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel