Allow domains to set a shutdown code without actually shutting down

Useful for Windows guests, since the PV drivers are notified that
the domain is about to crash just before the crash dump gets written.

Signed-off-by: Tim Deegan <Tim.Deegan@citrix.com>
Signed-off-by: Keir Fraser <keir.fraser@citrix.com>
xen-unstable changeset:   21510:2dffb2585516
xen-unstable date:        Fri Jun 04 09:33:11 2010 +0100

4 files changed, 39 insertions, 4 deletions

diff --git a/xen/common/domain.c b/xen/common/domain.c
index 2cd3b59ca7..ab41187d79 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -231,11 +231,13 @@ struct domain *domain_create(
     atomic_set(&d->refcnt, 1);
     spin_lock_init_prof(d, domain_lock);
     spin_lock_init_prof(d, page_alloc_lock);
-    spin_lock_init(&d->shutdown_lock);
     spin_lock_init(&d->hypercall_deadlock_mutex);
     INIT_PAGE_LIST_HEAD(&d->page_list);
     INIT_PAGE_LIST_HEAD(&d->xenpage_list);
 
+    spin_lock_init(&d->shutdown_lock);
+    d->shutdown_code = -1;
+
     if ( domcr_flags & DOMCRF_hvm )
         d->is_hvm = 1;
 
@@ -483,11 +485,15 @@ void domain_shutdown(struct domain *d, u8 reason)
 {
     struct vcpu *v;
 
+    spin_lock(&d->shutdown_lock);
+
+    if ( d->shutdown_code == -1 )
+        d->shutdown_code = reason;
+    reason = d->shutdown_code;
+
     if ( d->domain_id == 0 )
         dom0_shutdown(reason);
 
-    spin_lock(&d->shutdown_lock);
-
     if ( d->is_shutting_down )
     {
         spin_unlock(&d->shutdown_lock);
@@ -495,7 +501,6 @@ void domain_shutdown(struct domain *d, u8 reason)
     }
 
     d->is_shutting_down = 1;
-    d->shutdown_code = reason;
 
     smp_mb(); /* set shutdown status /then/ check for per-cpu deferrals */
 
@@ -527,6 +532,7 @@ void domain_resume(struct domain *d)
     spin_lock(&d->shutdown_lock);
 
     d->is_shutting_down = d->is_shut_down = 0;
+    d->shutdown_code = -1;
 
     for_each_vcpu ( d, v )
     {
diff --git a/xen/common/schedule.c b/xen/common/schedule.c
index 70289041d2..2534957a8c 100644
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -650,6 +650,27 @@ ret_t do_sched_op(int cmd, XEN_GUEST_HANDLE(void) arg)
         break;
     }
 
+    case SCHEDOP_shutdown_code:
+    {
+        struct sched_shutdown sched_shutdown;
+        struct domain *d = current->domain;
+
+        ret = -EFAULT;
+        if ( copy_from_guest(&sched_shutdown, arg, 1) )
+            break;
+
+        TRACE_3D(TRC_SCHED_SHUTDOWN_CODE,
+                 d->domain_id, current->vcpu_id, sched_shutdown.reason);
+
+        spin_lock(&d->shutdown_lock);
+        if ( d->shutdown_code == -1 )
+            d->shutdown_code = (u8)sched_shutdown.reason;
+        spin_unlock(&d->shutdown_lock);
+
+        ret = 0;
+        break;
+    }
+
     case SCHEDOP_poll:
     {
         struct sched_poll sched_poll;
diff --git a/xen/include/public/sched.h b/xen/include/public/sched.h
index 2227a95be6..e498c3c501 100644
--- a/xen/include/public/sched.h
+++ b/xen/include/public/sched.h
@@ -99,6 +99,13 @@ typedef struct sched_remote_shutdown sched_remote_shutdown_t;
 DEFINE_XEN_GUEST_HANDLE(sched_remote_shutdown_t);
 
 /*
+ * Latch a shutdown code, so that when the domain later shuts down it
+ * reports this code to the control tools.
+ * @arg == as for SCHEDOP_shutdown.
+ */
+#define SCHEDOP_shutdown_code 5
+
+/*
  * Reason codes for SCHEDOP_shutdown. These may be interpreted by control
  * software to determine the appropriate action. For the most part, Xen does
  * not care about the shutdown code.
diff --git a/xen/include/public/trace.h b/xen/include/public/trace.h
index 9385cb75ff..1863952071 100644
--- a/xen/include/public/trace.h
+++ b/xen/include/public/trace.h
@@ -78,6 +78,7 @@
 #define TRC_SCHED_DOM_TIMER_FN   (TRC_SCHED_VERBOSE + 13)
 #define TRC_SCHED_SWITCH_INFPREV (TRC_SCHED_VERBOSE + 14)
 #define TRC_SCHED_SWITCH_INFNEXT (TRC_SCHED_VERBOSE + 15)
+#define TRC_SCHED_SHUTDOWN_CODE  (TRC_SCHED_VERBOSE + 16)
 
 #define TRC_MEM_PAGE_GRANT_MAP      (TRC_MEM + 1)
 #define TRC_MEM_PAGE_GRANT_UNMAP    (TRC_MEM + 2)