[RFC v3 03/24] target/arm: Add confidential guest support

[Mathieu Poirier <mathieu.poirier@linaro.org>]

From: Jean-Philippe Brucker <jean-philippe@linaro.org>

Add a new RmeGuest object, inheriting from ConfidentialGuestSupport, to
support the Arm Realm Management Extension (RME). It is instantiated by
passing on the command-line:

  -M virt,confidential-guest-support=<id>
  -object rme-guest,id=<id>

This is only the skeleton. Support will be added in following patches.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
 docs/system/confidential-guest-support.rst |  1 +
 qapi/qom.json                              | 13 +++++++
 target/arm/kvm-rme.c                       | 42 ++++++++++++++++++++++
 target/arm/meson.build                     |  5 ++-
 4 files changed, 60 insertions(+), 1 deletion(-)
 create mode 100644 target/arm/kvm-rme.c

diff --git a/docs/system/confidential-guest-support.rst b/docs/system/confidential-guest-support.rst
index 562a7c3c2852..abb56923ad13 100644
--- a/docs/system/confidential-guest-support.rst
+++ b/docs/system/confidential-guest-support.rst
@@ -42,5 +42,6 @@ Currently supported confidential guest mechanisms are:
 * POWER Protected Execution Facility (PEF) (see :ref:`power-papr-protected-execution-facility-pef`)
 * s390x Protected Virtualization (PV) (see :doc:`s390x/protvirt`)
 * AWS Nitro Enclaves (see :doc:`nitro`)
+* Arm Realm Management Extension (RME)
 
 Other mechanisms may be supported in future.
diff --git a/qapi/qom.json b/qapi/qom.json
index 037c07879986..edc902c88c36 100644
--- a/qapi/qom.json
+++ b/qapi/qom.json
@@ -1216,6 +1216,17 @@
   'data': { '*cpu-affinity': ['uint16'],
             '*node-affinity': ['uint16'] } }
 
+##
+# @RmeGuestProperties:
+#
+# Properties for rme-guest objects.
+#
+# Since: 11.0
+##
+{ 'struct': 'RmeGuestProperties',
+  'base': 'ConfidentialGuestSupportProperties',
+  'data': {} }
+
 ##
 # @ObjectType:
 #
@@ -1272,6 +1283,7 @@
     { 'name': 'pr-manager-helper',
       'if': 'CONFIG_LINUX' },
     'qtest',
+    'rme-guest',
     'rng-builtin',
     'rng-egd',
     { 'name': 'rng-random',
@@ -1351,6 +1363,7 @@
       'pr-manager-helper':          { 'type': 'PrManagerHelperProperties',
                                       'if': 'CONFIG_LINUX' },
       'qtest':                      'QtestProperties',
+      'rme-guest':                  'RmeGuestProperties',
       'rng-builtin':                'RngProperties',
       'rng-egd':                    'RngEgdProperties',
       'rng-random':                 { 'type': 'RngRandomProperties',
diff --git a/target/arm/kvm-rme.c b/target/arm/kvm-rme.c
new file mode 100644
index 000000000000..42e1d1e7b859
--- /dev/null
+++ b/target/arm/kvm-rme.c
@@ -0,0 +1,42 @@
+/*
+ * QEMU Arm RME support
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * Copyright Linaro 2026
+ */
+
+#include "qemu/osdep.h"
+
+#include "hw/core/boards.h"
+#include "hw/core/cpu.h"
+#include "kvm_arm.h"
+#include "migration/blocker.h"
+#include "qapi/error.h"
+#include "qom/object_interfaces.h"
+#include "system/confidential-guest-support.h"
+#include "system/kvm.h"
+#include "system/runstate.h"
+
+#define TYPE_RME_GUEST "rme-guest"
+OBJECT_DECLARE_SIMPLE_TYPE(RmeGuest, RME_GUEST)
+
+struct RmeGuest {
+    ConfidentialGuestSupport parent_obj;
+};
+
+OBJECT_DEFINE_SIMPLE_TYPE_WITH_INTERFACES(RmeGuest, rme_guest, RME_GUEST,
+                                          CONFIDENTIAL_GUEST_SUPPORT,
+                                          { TYPE_USER_CREATABLE }, { })
+
+static void rme_guest_class_init(ObjectClass *oc, const void *data)
+{
+}
+
+static void rme_guest_init(Object *obj)
+{
+}
+
+static void rme_guest_finalize(Object *obj)
+{
+}
diff --git a/target/arm/meson.build b/target/arm/meson.build
index 4723f9f170ad..544df5c84d79 100644
--- a/target/arm/meson.build
+++ b/target/arm/meson.build
@@ -20,7 +20,10 @@ arm_common_ss.add(files(
 arm_common_system_ss.add(files(
   'arm-qmp-cmds.c',
 ))
-arm_system_ss.add(when: 'CONFIG_KVM', if_true: files('hyp_gdbstub.c', 'kvm.c'))
+arm_system_ss.add(when: 'CONFIG_KVM', if_true: files(
+  'hyp_gdbstub.c',
+  'kvm.c',
+  'kvm-rme.c'))
 arm_system_ss.add(when: 'CONFIG_HVF', if_true: files('hyp_gdbstub.c'))
 
 arm_user_ss.add(files('cpu.c'))
-- 
2.43.0