[PATCH v5 0/2] Fix and re-enable GTK clipboard

[PATCH v5 0/2] Fix and re-enable GTK clipboard

[Jindřich Makovička]

The following patches change blocking clipboard retrieval function
calls in gtk-clipboard.c to non-blocking variants using callbacks to
avoid UI lockup. It is a follow-up to the patch proposed in the GitLab
issue

https://gitlab.com/qemu-project/qemu/-/work_items/1150

This version adds a similar change to gd_clipboard_request that also
uses the blocking clipboard API.

The second patch removes the gtk-clipboard compile flag, keeping the
GTK clipboard always compiled in. By default, clipboard is off,
can be enabled by -display gtk,clipboard=on .

Signed-off-by: Jindrich Makovicka <makovick@gmail.com>
---
Changes in v5:
- Runtime option added, clipboard still off by default
- Link to v4: https://lore.kernel.org/qemu-devel/20260427-gtk-clipboard-v4-0-176ad9919931@gmail.com

Changes in v4:
- Replace gtk_clipboard_request_contents with
  gtk_clipboard_request_targets which can utilize GTK's target cache
- Link to v3: https://lore.kernel.org/qemu-devel/20260426-gtk-clipboard-v3-0-09555aaeda34@gmail.com

Changes in v3:
- Use gtk_clipboard_request_contents to avoid text conversion
  when we only need to check if the text is available.
- Link to v2: https://lore.kernel.org/qemu-devel/20260425-gtk-clipboard-v2-0-b098f3cf69cc@gmail.com

Changes in v2:
- Removed forgotten gtk-clipboard comment in meson_options.txt
- Link to v1: https://lore.kernel.org/qemu-devel/20260425-gtk-clipboard-v1-0-6bd99e708e14@gmail.com

---
Jindřich Makovička (2):
      ui/gtk: Use non-blocking clipboard retrieval
      ui/gtk: Turn clipboard flag into runtime option

 meson.build        |  4 ----
 meson_options.txt  |  7 -------
 qapi/ui.json       |  6 +++++-
 qemu-options.hx    |  9 ++++++---
 ui/gtk-clipboard.c | 53 ++++++++++++++++++++++++++++++++++++++++-------------
 ui/gtk.c           |  8 +++++---
 ui/meson.build     |  4 +---
 7 files changed, 57 insertions(+), 34 deletions(-)
---
base-commit: aa15257174da180c6a8a9d58f87319cfe61c5520
change-id: 20260425-gtk-clipboard-fdf99db13ac0

Best regards,
-- 
Jindrich Makovicka

[PATCH v5 1/2] ui/gtk: Use non-blocking clipboard retrieval

[Jindřich Makovička]

Signed-off-by: Jindrich Makovicka <makovick@gmail.com>
---
 ui/gtk-clipboard.c | 53 ++++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 40 insertions(+), 13 deletions(-)

diff --git a/ui/gtk-clipboard.c b/ui/gtk-clipboard.c
index 65d89ec601..463ed4e905 100644
--- a/ui/gtk-clipboard.c
+++ b/ui/gtk-clipboard.c
@@ -136,26 +136,55 @@ static void gd_clipboard_notify(Notifier *notifier, void *data)
     }
 }
 
+static void
+gd_clipboard_request_text_received_callback(GtkClipboard *clipboard,
+                                            const gchar *text,
+                                            gpointer data)
+{
+    QemuClipboardInfo *info = (QemuClipboardInfo *)data;
+
+    if (text) {
+        qemu_clipboard_set_data(info->owner, info, QEMU_CLIPBOARD_TYPE_TEXT,
+                                strlen(text), text, true);
+    }
+    qemu_clipboard_info_unref(info);
+}
+
 static void gd_clipboard_request(QemuClipboardInfo *info,
                                  QemuClipboardType type)
 {
     GtkDisplayState *gd = container_of(info->owner, GtkDisplayState, cbpeer);
-    char *text;
 
     switch (type) {
     case QEMU_CLIPBOARD_TYPE_TEXT:
-        text = gtk_clipboard_wait_for_text(gd->gtkcb[info->selection]);
-        if (text) {
-            qemu_clipboard_set_data(&gd->cbpeer, info, type,
-                                    strlen(text), text, true);
-            g_free(text);
-        }
+        qemu_clipboard_info_ref(info);
+        gtk_clipboard_request_text(gd->gtkcb[info->selection],
+                                   gd_clipboard_request_text_received_callback,
+                                   info);
         break;
     default:
         break;
     }
 }
 
+static void gd_clipboard_owner_change_targets_received_callback(
+    GtkClipboard *clipboard,
+    GdkAtom *targets,
+    gint n_targets,
+    gpointer data)
+{
+    QemuClipboardInfo *info = (QemuClipboardInfo *)data;
+
+    if (n_targets) {
+        if (gtk_targets_include_text(targets, n_targets)) {
+            info->types[QEMU_CLIPBOARD_TYPE_TEXT].available = true;
+        }
+    }
+
+    qemu_clipboard_update(info);
+    qemu_clipboard_info_unref(info);
+}
+
 static void gd_owner_change(GtkClipboard *clipboard,
                             GdkEvent *event,
                             gpointer data)
@@ -173,12 +202,10 @@ static void gd_owner_change(GtkClipboard *clipboard,
     switch (event->owner_change.reason) {
     case GDK_OWNER_CHANGE_NEW_OWNER:
         info = qemu_clipboard_info_new(&gd->cbpeer, s);
-        if (gtk_clipboard_wait_is_text_available(clipboard)) {
-            info->types[QEMU_CLIPBOARD_TYPE_TEXT].available = true;
-        }
-
-        qemu_clipboard_update(info);
-        qemu_clipboard_info_unref(info);
+        gtk_clipboard_request_targets(
+            clipboard,
+            gd_clipboard_owner_change_targets_received_callback,
+            info);
         break;
     default:
         qemu_clipboard_peer_release(&gd->cbpeer, s);

-- 
2.53.0

[PATCH v5 2/2] ui/gtk: Turn clipboard flag into runtime option

[Jindřich Makovička]

- Compile the GTK clipboard support unconditionally

- Introduce GTK clipboard option, defaulting to off

Signed-off-by: Jindrich Makovicka <makovick@gmail.com>
---
 meson.build       | 4 ----
 meson_options.txt | 7 -------
 qapi/ui.json      | 6 +++++-
 qemu-options.hx   | 9 ++++++---
 ui/gtk.c          | 8 +++++---
 ui/meson.build    | 4 +---
 6 files changed, 17 insertions(+), 21 deletions(-)

diff --git a/meson.build b/meson.build
index 096303f021..761c0436a3 100644
--- a/meson.build
+++ b/meson.build
@@ -1932,7 +1932,6 @@ endif
 gtk = not_found
 gtkx11 = not_found
 vte = not_found
-have_gtk_clipboard = get_option('gtk_clipboard').enabled()
 
 if get_option('gtk') \
              .disable_auto_if(not have_system) \
@@ -1954,8 +1953,6 @@ if get_option('gtk') \
                        method: 'pkg-config',
                        required: get_option('vte'))
     endif
-  elif have_gtk_clipboard
-    error('GTK clipboard requested, but GTK not found')
   endif
 endif
 
@@ -2475,7 +2472,6 @@ if glusterfs.found()
 endif
 config_host_data.set('CONFIG_GTK', gtk.found())
 config_host_data.set('CONFIG_VTE', vte.found())
-config_host_data.set('CONFIG_GTK_CLIPBOARD', have_gtk_clipboard)
 config_host_data.set('CONFIG_HEXAGON_IDEF_PARSER', get_option('hexagon_idef_parser'))
 config_host_data.set('CONFIG_LIBATTR', have_old_libattr)
 config_host_data.set('CONFIG_LIBCAP_NG', libcap_ng.found())
diff --git a/meson_options.txt b/meson_options.txt
index 31d5916cfc..286461129b 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -262,13 +262,6 @@ option('vnc_sasl', type : 'feature', value : 'auto',
        description: 'SASL authentication for VNC server')
 option('vte', type : 'feature', value : 'auto',
        description: 'vte support for the gtk UI')
-
-# GTK Clipboard implementation is disabled by default, since it may cause hangs
-# of the guest VCPUs. See gitlab issue 1150:
-# https://gitlab.com/qemu-project/qemu/-/issues/1150
-
-option('gtk_clipboard', type: 'feature', value : 'disabled',
-       description: 'clipboard support for the gtk UI (EXPERIMENTAL, MAY HANG)')
 option('xkbcommon', type : 'feature', value : 'auto',
        description: 'xkbcommon support')
 option('zstd', type : 'feature', value : 'auto',
diff --git a/qapi/ui.json b/qapi/ui.json
index e3da77632a..b2c42a7f57 100644
--- a/qapi/ui.json
+++ b/qapi/ui.json
@@ -1319,6 +1319,9 @@
 #
 # GTK display options.
 #
+# @clipboard: Enable host-guest clipboard sharing.  Defaults to "off".
+#     (Since 11.1)
+#
 # @grab-on-hover: Grab keyboard input on mouse hover.
 #
 # @zoom-to-fit: Zoom guest display to fit into the host window.  When
@@ -1344,7 +1347,8 @@
 # Since: 2.12
 ##
 { 'struct'  : 'DisplayGTK',
-  'data'    : { '*grab-on-hover'     : 'bool',
+  'data'    : { '*clipboard'         : 'bool',
+                '*grab-on-hover'     : 'bool',
                 '*zoom-to-fit'       : 'bool',
                 '*show-tabs'         : 'bool',
                 '*show-menubar'      : 'bool',
diff --git a/qemu-options.hx b/qemu-options.hx
index 21972f8326..e780bc2ac0 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2209,9 +2209,9 @@ DEF("display", HAS_ARG, QEMU_OPTION_display,
     "            [,window-close=on|off]\n"
 #endif
 #if defined(CONFIG_GTK)
-    "-display gtk[,full-screen=on|off][,gl=on|off][,grab-on-hover=on|off]\n"
-    "            [,show-tabs=on|off][,show-cursor=on|off][,window-close=on|off]\n"
-    "            [,show-menubar=on|off][,zoom-to-fit=on|off]\n"
+    "-display gtk[,clipboard=on|off][,full-screen=on|off][,gl=on|off]\n"
+    "            [,grab-on-hover=on|off][,show-tabs=on|off][,show-cursor=on|off]\n"
+    "            [,window-close=on|off][,show-menubar=on|off][,zoom-to-fit=on|off]\n"
 #endif
 #if defined(CONFIG_VNC)
     "-display vnc=<display>[,<optargs>]\n"
@@ -2295,6 +2295,9 @@ SRST
         drop-down menus and other UI elements to configure and control
         the VM during runtime. Valid parameters are:
 
+        ``clipboard=on|off`` : Enable host-guest clipboard sharing,
+                               defaults to "off"
+
         ``full-screen=on|off`` : Start in fullscreen mode
 
         ``gl=on|off`` : Use OpenGL for displaying
diff --git a/ui/gtk.c b/ui/gtk.c
index 9ebe7e8df0..ab5f1ef7aa 100644
--- a/ui/gtk.c
+++ b/ui/gtk.c
@@ -2601,9 +2601,11 @@ static void gtk_display_init(DisplayState *ds, DisplayOptions *opts)
         opts->u.gtk.show_tabs) {
         gtk_menu_item_activate(GTK_MENU_ITEM(s->show_tabs_item));
     }
-#ifdef CONFIG_GTK_CLIPBOARD
-    gd_clipboard_init(s);
-#endif /* CONFIG_GTK_CLIPBOARD */
+
+    if (opts->u.gtk.has_clipboard &&
+        opts->u.gtk.clipboard) {
+        gd_clipboard_init(s);
+    }
 
     /* GTK's event polling must happen on the main thread. */
     qemu_main = NULL;
diff --git a/ui/meson.build b/ui/meson.build
index 4e533d3046..6405e21d5d 100644
--- a/ui/meson.build
+++ b/ui/meson.build
@@ -111,9 +111,7 @@ if gtk.found()
 
   gtk_ss = ss.source_set()
   gtk_ss.add(gtk, vte, pixman, files('gtk.c'))
-  if have_gtk_clipboard
-    gtk_ss.add(files('gtk-clipboard.c'))
-  endif
+  gtk_ss.add(files('gtk-clipboard.c'))
   gtk_ss.add(when: x11, if_true: files('x_keymap.c'))
   gtk_ss.add(when: opengl, if_true: files('gtk-gl-area.c'))
   gtk_ss.add(when: [x11, opengl], if_true: files('gtk-egl.c'))

-- 
2.53.0

Re: [PATCH v5 2/2] ui/gtk: Turn clipboard flag into runtime option

[Daniel P. Berrangé]

On Mon, Apr 27, 2026 at 10:06:44PM +0200, Jindřich Makovička wrote:
> - Compile the GTK clipboard support unconditionally
> 
> - Introduce GTK clipboard option, defaulting to off
> 
> Signed-off-by: Jindrich Makovicka <makovick@gmail.com>
> ---
>  meson.build       | 4 ----
>  meson_options.txt | 7 -------
>  qapi/ui.json      | 6 +++++-
>  qemu-options.hx   | 9 ++++++---
>  ui/gtk.c          | 8 +++++---
>  ui/meson.build    | 4 +---
>  6 files changed, 17 insertions(+), 21 deletions(-)

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

Re: [PATCH v5 2/2] ui/gtk: Turn clipboard flag into runtime option

[Markus Armbruster]

Jindřich Makovička <makovick@gmail.com> writes:

> - Compile the GTK clipboard support unconditionally
>
> - Introduce GTK clipboard option, defaulting to off

Should the patch be split?

> Signed-off-by: Jindrich Makovicka <makovick@gmail.com>

[...]

> diff --git a/qapi/ui.json b/qapi/ui.json
> index e3da77632a..b2c42a7f57 100644
> --- a/qapi/ui.json
> +++ b/qapi/ui.json
> @@ -1319,6 +1319,9 @@
>  #
>  # GTK display options.
>  #
> +# @clipboard: Enable host-guest clipboard sharing.  Defaults to "off".
> +#     (Since 11.1)
> +#

Educate ignorant me: what does it mean to share the clipboard?

>  # @grab-on-hover: Grab keyboard input on mouse hover.
>  #
>  # @zoom-to-fit: Zoom guest display to fit into the host window.  When
> @@ -1344,7 +1347,8 @@
>  # Since: 2.12
>  ##
>  { 'struct'  : 'DisplayGTK',
> -  'data'    : { '*grab-on-hover'     : 'bool',
> +  'data'    : { '*clipboard'         : 'bool',
> +                '*grab-on-hover'     : 'bool',
>                  '*zoom-to-fit'       : 'bool',
>                  '*show-tabs'         : 'bool',
>                  '*show-menubar'      : 'bool',
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 21972f8326..e780bc2ac0 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -2209,9 +2209,9 @@ DEF("display", HAS_ARG, QEMU_OPTION_display,
>      "            [,window-close=on|off]\n"
>  #endif
>  #if defined(CONFIG_GTK)
> -    "-display gtk[,full-screen=on|off][,gl=on|off][,grab-on-hover=on|off]\n"
> -    "            [,show-tabs=on|off][,show-cursor=on|off][,window-close=on|off]\n"
> -    "            [,show-menubar=on|off][,zoom-to-fit=on|off]\n"
> +    "-display gtk[,clipboard=on|off][,full-screen=on|off][,gl=on|off]\n"
> +    "            [,grab-on-hover=on|off][,show-tabs=on|off][,show-cursor=on|off]\n"
> +    "            [,window-close=on|off][,show-menubar=on|off][,zoom-to-fit=on|off]\n"
>  #endif
>  #if defined(CONFIG_VNC)
>      "-display vnc=<display>[,<optargs>]\n"
> @@ -2295,6 +2295,9 @@ SRST
>          drop-down menus and other UI elements to configure and control
>          the VM during runtime. Valid parameters are:
>  
> +        ``clipboard=on|off`` : Enable host-guest clipboard sharing,
> +                               defaults to "off"
> +
>          ``full-screen=on|off`` : Start in fullscreen mode
>  
>          ``gl=on|off`` : Use OpenGL for displaying

[...]

Re: [PATCH v5 2/2] ui/gtk: Turn clipboard flag into runtime option

[Daniel P. Berrangé]

On Tue, Apr 28, 2026 at 09:30:37AM +0200, Markus Armbruster wrote:
> Jindřich Makovička <makovick@gmail.com> writes:
> 
> > - Compile the GTK clipboard support unconditionally
> >
> > - Introduce GTK clipboard option, defaulting to off
> 
> Should the patch be split?
> 
> > Signed-off-by: Jindrich Makovicka <makovick@gmail.com>
> 
> [...]
> 
> > diff --git a/qapi/ui.json b/qapi/ui.json
> > index e3da77632a..b2c42a7f57 100644
> > --- a/qapi/ui.json
> > +++ b/qapi/ui.json
> > @@ -1319,6 +1319,9 @@
> >  #
> >  # GTK display options.
> >  #
> > +# @clipboard: Enable host-guest clipboard sharing.  Defaults to "off".
> > +#     (Since 11.1)
> > +#
> 
> Educate ignorant me: what does it mean to share the clipboard?

Conceptually the intent is to create a single logical clipboard
spanning the host & guest. IOW, if the guest copies data into
its clipboard that is made available to the host clipboard, and
vica-verca.

Re: [PATCH v5 2/2] ui/gtk: Turn clipboard flag into runtime option

[Markus Armbruster]

Daniel P. Berrangé <berrange@redhat.com> writes:

> On Tue, Apr 28, 2026 at 09:30:37AM +0200, Markus Armbruster wrote:
>> Jindřich Makovička <makovick@gmail.com> writes:
>> 
>> > - Compile the GTK clipboard support unconditionally
>> >
>> > - Introduce GTK clipboard option, defaulting to off
>> 
>> Should the patch be split?
>> 
>> > Signed-off-by: Jindrich Makovicka <makovick@gmail.com>
>> 
>> [...]
>> 
>> > diff --git a/qapi/ui.json b/qapi/ui.json
>> > index e3da77632a..b2c42a7f57 100644
>> > --- a/qapi/ui.json
>> > +++ b/qapi/ui.json
>> > @@ -1319,6 +1319,9 @@
>> >  #
>> >  # GTK display options.
>> >  #
>> > +# @clipboard: Enable host-guest clipboard sharing.  Defaults to "off".
>> > +#     (Since 11.1)
>> > +#
>> 
>> Educate ignorant me: what does it mean to share the clipboard?
>
> Conceptually the intent is to create a single logical clipboard
> spanning the host & guest. IOW, if the guest copies data into
> its clipboard that is made available to the host clipboard, and
> vica-verca.

Thanks!  Could the description text explain that without getting too
verbose?

Re: [PATCH v5 0/2] Fix and re-enable GTK clipboard

[Marc-André Lureau]

Hi

On Tue, Apr 28, 2026 at 12:06 AM Jindřich Makovička <makovick@gmail.com> wrote:
>
> The following patches change blocking clipboard retrieval function
> calls in gtk-clipboard.c to non-blocking variants using callbacks to
> avoid UI lockup. It is a follow-up to the patch proposed in the GitLab
> issue
>
> https://gitlab.com/qemu-project/qemu/-/work_items/1150
>
> This version adds a similar change to gd_clipboard_request that also
> uses the blocking clipboard API.
>
> The second patch removes the gtk-clipboard compile flag, keeping the
> GTK clipboard always compiled in. By default, clipboard is off,
> can be enabled by -display gtk,clipboard=on .
>
> Signed-off-by: Jindrich Makovicka <makovick@gmail.com>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

> ---
> Changes in v5:
> - Runtime option added, clipboard still off by default
> - Link to v4: https://lore.kernel.org/qemu-devel/20260427-gtk-clipboard-v4-0-176ad9919931@gmail.com
>
> Changes in v4:
> - Replace gtk_clipboard_request_contents with
>   gtk_clipboard_request_targets which can utilize GTK's target cache
> - Link to v3: https://lore.kernel.org/qemu-devel/20260426-gtk-clipboard-v3-0-09555aaeda34@gmail.com
>
> Changes in v3:
> - Use gtk_clipboard_request_contents to avoid text conversion
>   when we only need to check if the text is available.
> - Link to v2: https://lore.kernel.org/qemu-devel/20260425-gtk-clipboard-v2-0-b098f3cf69cc@gmail.com
>
> Changes in v2:
> - Removed forgotten gtk-clipboard comment in meson_options.txt
> - Link to v1: https://lore.kernel.org/qemu-devel/20260425-gtk-clipboard-v1-0-6bd99e708e14@gmail.com
>
> ---
> Jindřich Makovička (2):
>       ui/gtk: Use non-blocking clipboard retrieval
>       ui/gtk: Turn clipboard flag into runtime option
>
>  meson.build        |  4 ----
>  meson_options.txt  |  7 -------
>  qapi/ui.json       |  6 +++++-
>  qemu-options.hx    |  9 ++++++---
>  ui/gtk-clipboard.c | 53 ++++++++++++++++++++++++++++++++++++++++-------------
>  ui/gtk.c           |  8 +++++---
>  ui/meson.build     |  4 +---
>  7 files changed, 57 insertions(+), 34 deletions(-)
> ---
> base-commit: aa15257174da180c6a8a9d58f87319cfe61c5520
> change-id: 20260425-gtk-clipboard-fdf99db13ac0
>
> Best regards,
> --
> Jindrich Makovicka
>