From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mathieu Desnoyers <mathieu.desnoyers-vg+e7yoeK/dWk0Htik3J/w@public.gmane.org>
Subject: [RFC PATCH 0/2] x86: Fix missing core serialization on migration
Date: Fri, 10 Nov 2017 16:12:47 -0500
Message-ID: <20171110211249.10742-1-mathieu.desnoyers@efficios.com>
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To: Andy Lutomirski <luto-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>, "Paul E . McKenney" <paulmck-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>, Boqun Feng <boqun.feng-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Andrew Hunter <ahh-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Maged Michael <maged.michael-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Avi Kivity <avi-VrcmuVmyx1hWk0Htik3J/w@public.gmane.org>, Benjamin Herrenschmidt <benh-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>, Paul Mackerras <paulus-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org>, Michael Ellerman <mpe-Gsx/Oe8HsFggBc27wqDAHg@public.gmane.org>, Dave Watson <davejwatson-b10kYP2dOMg@public.gmane.org>, Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>, Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, "H . Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>, Andrea Parri <parri.andrea-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Russell King <linux-I+IVW8TIWO2tmTQ+vhA3Yw@public.gmane.org>, Greg Hackmann <ghackmann-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>, David Sehr <sehr-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Linus
List-Id: linux-api@vger.kernel.org

x86 can return to user-space through sysexit and sysretq, which are not
core serializing. This breaks expectations from user-space about
sequential consistency from a single-threaded self-modifying program
point of view in specific migration patterns.

Feedback is welcome,

Thanks,

Mathieu

Mathieu Desnoyers (2):
  x86: Introduce sync_core_before_usermode
  Fix: x86: Add missing core serializing instruction on migration

 arch/x86/Kconfig                 |  1 +
 arch/x86/include/asm/processor.h | 10 ++++++++++
 include/linux/processor.h        |  6 ++++++
 kernel/sched/core.c              |  7 +++++++
 kernel/sched/sched.h             |  1 +
 5 files changed, 25 insertions(+)

-- 
2.11.0