[Xen-devel] [PATCH v2 22/22] mini-os: support idle for HVMlite

[Juergen Gross <jgross@xxxxxxxx>]

Instead of calling HYPERVISOR_sched_op(SCHEDOP_block, 0) we need to use
the "hlt" instruction with interrupts enabled to switch to idle when
running as HVMlite domain.

This requires to setup a new timer in the timer handler as there is no
guarantee the original timer event we are waiting for won't fire
between enabling interrupts and calling "hlt".

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>
---
 arch/x86/time.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/arch/x86/time.c b/arch/x86/time.c
index af45e56..3658142 100644
--- a/arch/x86/time.c
+++ b/arch/x86/time.c
@@ -212,17 +212,20 @@ void block_domain(s_time_t until)
     if(monotonic_clock() < until)
     {
         HYPERVISOR_set_timer_op(until);
+#ifdef CONFIG_PARAVIRT
         HYPERVISOR_sched_op(SCHEDOP_block, 0);
+#else
+        local_irq_enable();
+        asm volatile ( "hlt" : : : "memory" );
+#endif
         local_irq_disable();
+        HYPERVISOR_set_timer_op(0);
     }
 }
 
-
-/*
- * Just a dummy
- */
 static void timer_handler(evtchn_port_t ev, struct pt_regs *regs, void *ign)
 {
+    HYPERVISOR_set_timer_op(monotonic_clock() + MILLISECS(1));
 }
 
 
-- 
2.6.6


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