On 2017/9/1 14:49, Quan Xu wrote:
on 2017/8/29 22:39, Borislav Petkov wrote:
On Tue, Aug 29, 2017 at 11:46:37AM +0000, Yang Zhang wrote:
Add poll in do_idle. For UP VM, if there are running task, it will not
goes into idle path, so we only enable poll in SMP VM.

Signed-off-by: Yang Zhang <yang.zhang...@gmail.com>
Signed-off-by: Quan Xu <quan....@gmail.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: "H. Peter Anvin" <h...@zytor.com>
Cc: x...@kernel.org
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Borislav Petkov <b...@alien8.de>
Cc: Kyle Huey <m...@kylehuey.com>
Cc: Andy Lutomirski <l...@kernel.org>
Cc: Len Brown <len.br...@intel.com>
Cc: linux-kernel@vger.kernel.org
---
  arch/x86/kernel/process.c | 7 +++++++
  kernel/sched/idle.c       | 2 ++
  2 files changed, 9 insertions(+)

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 3ca1980..def4113 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -332,6 +332,13 @@ void arch_cpu_idle(void)
      x86_idle();
  }
  +#if defined(CONFIG_SMP) && defined(CONFIG_PARAVIRT)
+void arch_cpu_idle_poll(void)
+{
+    paravirt_idle_poll();
+}
+#endif
So this will get called on any system which has CONFIG_PARAVIRT enabled
*even* if they're not running any guests.

Huh?
     Borislav,
     think twice, it is better to run ander an IF condition, to make sure they are running any guests.

      Quan
Borislav ,
   yes, this will get called on any system which has CONFIG_PARAVIRT enabled.

   but if they are not running any guests,  the callback is paravirt_nop() ,    IIUC which is as similar as the other paravirt_*, such as paravirt_pgd_free()..

 - Quan

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