File 24189-x86-p2m-pod-locking.patch of Package xen

# HG changeset patch
# User Andres Lagar-Cavilla <andres@lagarcavilla.org>
# Date 1322148057 0
# Node ID 7da681c490e0a8a2b3f1fb311d254dc7ce618a43
# Parent  b082fdc52ad7607d93b59148fb289aafe21f294b
x86/mm/p2m: fix pod locking

The path p2m-lookup -> p2m-pt->get_entry -> 1GB PoD superpage ->
pod_demand_populate ends in the pod code performing a p2m_set_entry with
no locks held (in order to split the 1GB superpage into 512 2MB ones)

Further, it calls p2m_unlock after that, which will break the spinlock.

This patch attempts to fix that.

Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Acked-by: George Dunlap <george.dunlap@eu.citrix.com>
Acked-by: Tim Deegan <tim@xen.org>
Committed-by: Tim Deegan <tim@xen.org>

--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -1244,7 +1244,6 @@ p2m_pod_demand_populate(struct p2m_domai
         set_p2m_entry(p2m, gfn_aligned, _mfn(POPULATE_ON_DEMAND_MFN), 9,
                       p2m_populate_on_demand, p2m->default_access);
         audit_p2m(p2m, 1);
-        p2m_unlock(p2m);
         return 0;
     }
 
@@ -1602,7 +1601,8 @@ pod_retry_l3:
             {
                 if ( q != p2m_query )
                 {
-                    if ( !p2m_pod_demand_populate(p2m, gfn, 18, q) )
+                    if ( !p2m_pod_check_and_populate(p2m, gfn,
+                              (l1_pgentry_t *) &l3e, 18, q) )
                         goto pod_retry_l3;
                 }
                 else
@@ -1733,7 +1733,8 @@ static mfn_t p2m_gfn_to_mfn_current(stru
                 /* The read has succeeded, so we know that mapping exists */
                 if ( q != p2m_query )
                 {
-                    if ( !p2m_pod_demand_populate(p2m, gfn, 18, q) )
+                    if ( !p2m_pod_check_and_populate(p2m, gfn,
+                              (l1_pgentry_t *) &l3e, 18, q) )
                         goto pod_retry_l3;
                     p2mt = p2m_invalid;
                     printk("%s: Allocate 1GB failed!\n", __func__);