From: H. Peter Anvin <hpa@linux.intel.com>
Date: Tue, 9 Sep 2014 16:09:08 +0000 (+0200)
Subject: x86, idle: add barriers to CLFLUSH workaround
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~4432
X-Git-Url: https://dgit.raspbian.org/%22http:/www.example.com/cgi/%22https://%22%22/%22http:/www.example.com/cgi/%22https:/%22%22?a=commitdiff_plain;h=48d32458bcd453e31b458bca868a079a6d0a38af;p=xen.git

x86, idle: add barriers to CLFLUSH workaround

... since the documentation is explicit that CLFLUSH is only ordered
with respect to MFENCE.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---

diff --git a/xen/arch/x86/acpi/cpu_idle.c b/xen/arch/x86/acpi/cpu_idle.c
index b05fb39182..136c0b6373 100644
--- a/xen/arch/x86/acpi/cpu_idle.c
+++ b/xen/arch/x86/acpi/cpu_idle.c
@@ -336,7 +336,11 @@ void mwait_idle_with_hints(unsigned int eax, unsigned int ecx)
     s_time_t expires = per_cpu(timer_deadline, cpu);
 
     if ( boot_cpu_has(X86_FEATURE_CLFLUSH_MONITOR) )
+    {
+        mb();
         clflush((void *)&mwait_wakeup(cpu));
+        mb();
+    }
 
     __monitor((void *)&mwait_wakeup(cpu), 0, 0);
     smp_mb();