[RFC PATCH V4 09/18] Add evtchn_extended in struct domain

[Wei Liu <wei.liu2@citrix.com>]

This field is a bitmap of currently in use extended event channel ABI, which
can have 0 (no extended event channel in use) or 1 bit set. It is manipulated
by hypervisor only, so if anything goes wrong it is a bug.

The default event channel ABI is EVTCHN_EXTENDED_NONE, which means no extended
event channel is used.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
 xen/common/event_channel.c |    8 +++++++-
 xen/include/xen/event.h    |   12 +++++++++++-
 xen/include/xen/sched.h    |    1 +
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/xen/common/event_channel.c b/xen/common/event_channel.c
index 6b23157..99af57e 100644
--- a/xen/common/event_channel.c
+++ b/xen/common/event_channel.c
@@ -988,6 +988,12 @@ out:
     return rc;
 }
 
+static void __set_evtchn_abi(struct domain *d, uint64_t abi)
+{
+    d->evtchn_extended = abi;
+    /* This must go after setting ABI */
+    d->max_evtchns = max_evtchns(d);
+}
 
 long do_event_channel_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
 {
@@ -1205,7 +1211,7 @@ int evtchn_init(struct domain *d)
 
     if ( d->evtchn == NULL )
         return -ENOMEM;
-    d->max_evtchns = max_evtchns(d);
+    __set_evtchn_abi(d, EVTCHN_EXTENDED_NONE);
 
     spin_lock_init(&d->event_lock);
     if ( get_free_port(d) != 0 )
diff --git a/xen/include/xen/event.h b/xen/include/xen/event.h
index fbbe9dc..f5a49a9 100644
--- a/xen/include/xen/event.h
+++ b/xen/include/xen/event.h
@@ -14,6 +14,7 @@
 #include <xen/softirq.h>
 #include <asm/bitops.h>
 #include <asm/event.h>
+#include <public/event_channel.h>
 
 #ifndef CONFIG_COMPAT
 #define BITS_PER_EVTCHN_WORD(d) BITS_PER_XEN_ULONG
@@ -22,7 +23,16 @@
 #endif
 static inline unsigned int max_evtchns(struct domain *d)
 {
-    return BITS_PER_EVTCHN_WORD(d) * BITS_PER_EVTCHN_WORD(d);
+    unsigned int ret = 0;
+    switch ( d->evtchn_extended )
+    {
+    case EVTCHN_EXTENDED_NONE:
+        ret = BITS_PER_EVTCHN_WORD(d) * BITS_PER_EVTCHN_WORD(d);
+        break;
+    default:
+        BUG();
+    }
+    return ret;
 }
 
 #define EVTCHNS_PER_BUCKET 128
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index ad0f042..8bdf5ec 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -218,6 +218,7 @@ struct domain
     struct evtchn  **evtchn;
     spinlock_t       event_lock;
     unsigned int     max_evtchns;
+    unsigned int     evtchn_extended;
 
     struct grant_table *grant_table;
 
-- 
1.7.10.4