From d2f2c20a6dc0f5c6fbab7d7ca8dc8f636a72abdb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafa=C3=ABl=20Kooi?=
 <48814281+RA-Kooi@users.noreply.github.com>
Date: Mon, 22 Jan 2024 17:04:07 +0100
Subject: [PATCH 1/3] id128-util: Attempt to read UUID from
 /sys/hypervisor/uuid

When using the Xen hypervisor the virtual machine UUID is exposed here.
This is useful when one needs stable IPv4 address assignment, e.g. for a
set of RAM nodes that are built from a template.
---
 src/libsystemd/sd-id128/id128-util.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/libsystemd/sd-id128/id128-util.c b/src/libsystemd/sd-id128/id128-util.c
index 5808cea757..a73bc1fa54 100644
--- a/src/libsystemd/sd-id128/id128-util.c
+++ b/src/libsystemd/sd-id128/id128-util.c
@@ -234,6 +234,8 @@ int id128_get_product(sd_id128_t *ret) {
         r = id128_read("/sys/class/dmi/id/product_uuid", ID128_FORMAT_UUID, &uuid);
         if (r == -ENOENT)
                 r = id128_read("/proc/device-tree/vm,uuid", ID128_FORMAT_UUID, &uuid);
+        if (r == -ENOENT)
+                r = id128_read("/sys/hypervisor/uuid", ID128_FORMAT_UUID, &uuid);
         if (r < 0)
                 return r;
 

From 98d550baa9086a0c5d531a67d263357270ebadf0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafa=C3=ABl=20Kooi?=
 <48814281+RA-Kooi@users.noreply.github.com>
Date: Mon, 22 Jan 2024 17:13:21 +0100
Subject: [PATCH 2/3] machine-id-setup: Generate stable machine IDs based on
 Xen hypervisor UUID

---
 src/shared/machine-id-setup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/shared/machine-id-setup.c b/src/shared/machine-id-setup.c
index 833c98b88e..94425d6a73 100644
--- a/src/shared/machine-id-setup.c
+++ b/src/shared/machine-id-setup.c
@@ -78,7 +78,7 @@ static int generate_machine_id(const char *root, sd_id128_t *ret) {
                                 return 0;
                         }
 
-                } else if (IN_SET(detect_vm(), VIRTUALIZATION_KVM, VIRTUALIZATION_AMAZON, VIRTUALIZATION_QEMU)) {
+                } else if (IN_SET(detect_vm(), VIRTUALIZATION_KVM, VIRTUALIZATION_AMAZON, VIRTUALIZATION_QEMU, VIRTUALIZATION_XEN)) {
 
                         /* If we are not running in a container, see if we are running in a VM that provides
                          * a system UUID via the SMBIOS/DMI interfaces.  Such environments include QEMU/KVM

From 9fe1f1ca95c57c6fc453ba31f363f8b3230cebeb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafa=C3=ABl=20Kooi?=
 <48814281+RA-Kooi@users.noreply.github.com>
Date: Wed, 24 Jan 2024 02:19:00 +0100
Subject: [PATCH 3/3] man: Describe how machine ID is initialized on Xen

---
 man/machine-id.xml | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/man/machine-id.xml b/man/machine-id.xml
index 833b4f0841..4ee100b473 100644
--- a/man/machine-id.xml
+++ b/man/machine-id.xml
@@ -101,7 +101,8 @@
     to use the D-Bus machine ID from <filename>/var/lib/dbus/machine-id</filename>, the
     value of the kernel command line option <varname>container_uuid</varname>, the KVM DMI
     <filename>product_uuid</filename> or the devicetree <filename>vm,uuid</filename>
-    (on KVM systems), and finally a randomly generated UUID.</para>
+    (on KVM systems), the Xen hypervisor <filename>uuid</filename>, and finally a randomly
+    generated UUID.</para>
 
     <para>After the machine ID is established,
     <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>