From c95026c6979bb6f8dc52a6392318bc16615ace77 Mon Sep 17 00:00:00 2001
From: Jan Synacek <jsynacek@redhat.com>
Date: Wed, 30 Jan 2019 10:36:53 +0100
Subject: [PATCH] rules: implement new memory hotplug policy

Our new policy is based on following motivations (assumptions),
  * we want to allow the system to use hotplugged memory
  * we want memory ballon inflation to work as expected in VMs (going for small
  to big in terms of memory footprint)
  * we want to allow memory hotplug and memory hot-unplug on high-end
  enterprise server (we assume that node0 will have sufficient memory
  resources and marking all memory as movable shouldn't be a problem)

Policy:
  * nevert online memory on s390 (on both physical and z/VM)
  * mark memory as "online_movable" on physical machines
  * mark memory as "online" in VMs

If you have the feeling that all this is very wrong and we shouldn't
encode complex policies in udev rules you are absolutely right. However,
for now, we don't have any better place where to put it. In ideal world
we would have a user-space daemon that would be able to configure the
system wrt. to currently present HW and user-defined policy.

Resolves: #1670728
---
 rules/40-redhat.rules | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/rules/40-redhat.rules b/rules/40-redhat.rules
index 8ac96933c3..17b33682bd 100644
--- a/rules/40-redhat.rules
+++ b/rules/40-redhat.rules
@@ -4,7 +4,15 @@
 SUBSYSTEM=="cpu", ACTION=="add", TEST=="online", ATTR{online}=="0", ATTR{online}="1"
 
 # Memory hotadd request
-SUBSYSTEM=="memory", ACTION=="add", PROGRAM=="/bin/uname -p", RESULT!="s390*", ATTR{state}=="offline", ATTR{state}="online"
+SUBSYSTEM!="memory", GOTO="memory_hotplug_end"
+ACTION!="add", GOTO="memory_hotplug_end"
+PROGRAM="/bin/uname -p", RESULT=="s390*", GOTO="memory_hotplug_end"
+
+ENV{.state}="online"
+PROGRAM="/bin/systemd-detect-virt", RESULT=="none", ENV{.state}="online_movable"
+ATTR{state}=="offline", ATTR{state}="$env{.state}"
+
+LABEL="memory_hotplug_end"
 
 # reload sysctl.conf / sysctl.conf.d settings when the bridge module is loaded
 ACTION=="add", SUBSYSTEM=="module", KERNEL=="bridge", RUN+="/usr/lib/systemd/systemd-sysctl --prefix=/proc/sys/net/bridge"