From 005339f7deaee639c38d30e5bf2235c292ce3937 Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= <berrange@redhat.com>

Date: Wed, 5 Jan 2022 12:38:47 +0000

Subject: [PATCH 3/3] softmmu: fix device deletion events with -device JSON

 syntax

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RH-Author: Kevin Wolf <kwolf@redhat.com>

RH-MergeRequest: 62: Fix hot unplug of devices created with -device JSON syntax

RH-Commit: [1/1] 980e505ba215b5f9324c107481c5bb257ae03f42 (kmwolf/centos-qemu-kvm)

RH-Bugzilla: 2036669

RH-Acked-by: Daniel P. Berrangé <berrange@redhat.com>

RH-Acked-by: Laurent Vivier <lvivier@redhat.com>

RH-Acked-by: Jano Tomko <None>

The -device JSON syntax impl leaks a reference on the created

DeviceState instance. As a result when you hot-unplug the

device, the device_finalize method won't be called and thus

it will fail to emit the required DEVICE_DELETED event.

A 'json-cli' feature was previously added against the

'device_add' QMP command QAPI schema to indicated to mgmt

apps that -device supported JSON syntax. Given the hotplug

bug that feature flag is not usable for its purpose, so

we add a new 'json-cli-hotplug' feature to indicate the

-device supports JSON without breaking hotplug.

Fixes: 5dacda5167560b3af8eadbce5814f60ba44b467e

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/802

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

Message-Id: <20220105123847.4047954-2-berrange@redhat.com>

Reviewed-by: Laurent Vivier <lvivier@redhat.com>

Tested-by: Ján Tomko <jtomko@redhat.com>

Reviewed-by: Thomas Huth <thuth@redhat.com>

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

(cherry picked from commit 64b4529a432507ee84a924be69a03432639e87ba)

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

---

 qapi/qdev.json                 |  5 ++++-

 softmmu/vl.c                   |  4 +++-

 tests/qtest/device-plug-test.c | 19 +++++++++++++++++++

 3 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/qapi/qdev.json b/qapi/qdev.json

index 69656b14df..26cd10106b 100644

--- a/qapi/qdev.json

+++ b/qapi/qdev.json

@@ -44,6 +44,9 @@

 # @json-cli: If present, the "-device" command line option supports JSON

 #            syntax with a structure identical to the arguments of this

 #            command.

+# @json-cli-hotplug: If present, the "-device" command line option supports JSON

+#                    syntax without the reference counting leak that broke

+#                    hot-unplug

 #

 # Notes:

 #

@@ -74,7 +77,7 @@

 { 'command': 'device_add',

   'data': {'driver': 'str', '*bus': 'str', '*id': 'str'},

   'gen': false, # so we can get the additional arguments

-  'features': ['json-cli'] }

+  'features': ['json-cli', 'json-cli-hotplug'] }

 ##

 # @device_del:

diff --git a/softmmu/vl.c b/softmmu/vl.c

index d46b8fb4ab..b3829e2edd 100644

--- a/softmmu/vl.c

+++ b/softmmu/vl.c

@@ -2690,6 +2690,7 @@ static void qemu_create_cli_devices(void)

     qemu_opts_foreach(qemu_find_opts("device"),

                       device_init_func, NULL, &error_fatal);

     QTAILQ_FOREACH(opt, &device_opts, next) {

+        DeviceState *dev;

         loc_push_restore(&opt->loc);

         /*

          * TODO Eventually we should call qmp_device_add() here to make sure it

@@ -2698,7 +2699,8 @@ static void qemu_create_cli_devices(void)

          * from the start, so call qdev_device_add_from_qdict() directly for

          * now.

          */

-        qdev_device_add_from_qdict(opt->opts, true, &error_fatal);

+        dev = qdev_device_add_from_qdict(opt->opts, true, &error_fatal);

+        object_unref(OBJECT(dev));

         loc_pop(&opt->loc);

     }

     rom_reset_order_override();

diff --git a/tests/qtest/device-plug-test.c b/tests/qtest/device-plug-test.c

index 559d47727a..ad79bd4c14 100644

--- a/tests/qtest/device-plug-test.c

+++ b/tests/qtest/device-plug-test.c

@@ -77,6 +77,23 @@ static void test_pci_unplug_request(void)

     qtest_quit(qtest);

 }

+static void test_pci_unplug_json_request(void)

+{

+    QTestState *qtest = qtest_initf(

+        "-device '{\"driver\": \"virtio-mouse-pci\", \"id\": \"dev0\"}'");

+

+    /*

+     * Request device removal. As the guest is not running, the request won't

+     * be processed. However during system reset, the removal will be

+     * handled, removing the device.

+     */

+    device_del(qtest, "dev0");

+    system_reset(qtest);

+    wait_device_deleted_event(qtest, "dev0");

+

+    qtest_quit(qtest);

+}

+

 static void test_ccw_unplug(void)

 {

     QTestState *qtest = qtest_initf("-device virtio-balloon-ccw,id=dev0");

@@ -145,6 +162,8 @@ int main(int argc, char **argv)

      */

     qtest_add_func("/device-plug/pci-unplug-request",

                    test_pci_unplug_request);

+    qtest_add_func("/device-plug/pci-unplug-json-request",

+                   test_pci_unplug_json_request);

     if (!strcmp(arch, "s390x")) {

         qtest_add_func("/device-plug/ccw-unplug",

-- 

2.27.0