Re: [PATCH] ui/vdagent: fix windows agent regression

[Lucas Kornicki <lucas.kornicki@nutanix.com>]

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I've tested this patch on windows 11 and windows server 2022. In both 
cases the device stays open after serial reset and clipboard operations 
work. Thanks a lot

Tested-by: Lucas Kornicki <lucas.kornicki@nutanix.com>

On 10/27/25 14:07, marcandre.lureau@redhat.com wrote:
> From: Marc-André Lureau<marcandre.lureau@redhat.com>
>
> Since commit f626116f ("ui/vdagent: factor out clipboard peer
> registration"), the QEMU clipboard serial is reset whenever the vdagent
> chardev receives the guest caps. This triggers a CHR_EVENT_CLOSED which
> is handled by virtio_serial_close() to notify the guest.
>
> The "reconnection logic" is there to reset the agent when a
> client (dbus, spice etc) reconnects, or the agent is restarted.
> It is required to sync the clipboard serials and to prevent races or
> loops due to clipboard managers on both ends (but this is not
> implemented by windows vdagent).
>
> The Unix agent has been reconnecting without resending caps, thus
> working with this approach.
>
> However, the Windows agent does not seem to have a way to handle
> VIRTIO_CONSOLE_PORT_OPEN=0 event and do not receive further data...
>
> Let's not trigger this disconnection/reset logic if the agent does not
> support VD_AGENT_CAP_CLIPBOARD_GRAB_SERIAL.
>
> Fixes: f626116f ("ui/vdagent: factor out clipboard peer registration")
> Signed-off-by: Marc-André Lureau<marcandre.lureau@redhat.com>
> Reported-by: Lucas Kornicki<lucas.kornicki@nutanix.com>
> ---
>   ui/vdagent.c | 20 ++++++++++++++------
>   1 file changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/ui/vdagent.c b/ui/vdagent.c
> index ddb91e75c6..660686c9c0 100644
> --- a/ui/vdagent.c
> +++ b/ui/vdagent.c
> @@ -316,6 +316,15 @@ static bool have_selection(VDAgentChardev *vd)
>       return vd->caps & (1 << VD_AGENT_CAP_CLIPBOARD_SELECTION);
>   }
>   
> +static bool have_clipboard_serial(VDAgentChardev *vd)
> +{
> +#if CHECK_SPICE_PROTOCOL_VERSION(0, 14, 1)
> +    return vd->caps & (1 << VD_AGENT_CAP_CLIPBOARD_GRAB_SERIAL);
> +#else
> +    return false;
> +#endif
> +}
> +
>   static uint32_t type_qemu_to_vdagent(enum QemuClipboardType type)
>   {
>       switch (type) {
> @@ -345,8 +354,7 @@ static void vdagent_send_clipboard_grab(VDAgentChardev *vd,
>           return;
>       }
>   
> -#if CHECK_SPICE_PROTOCOL_VERSION(0, 14, 1)
> -    if (vd->caps & (1 << VD_AGENT_CAP_CLIPBOARD_GRAB_SERIAL)) {
> +    if (have_clipboard_serial(vd)) {
>           if (!info->has_serial) {
>               /* client should win */
>               info->serial = vd->last_serial[info->selection]++;
> @@ -356,7 +364,6 @@ static void vdagent_send_clipboard_grab(VDAgentChardev *vd,
>           data++;
>           msg->size += sizeof(uint32_t);
>       }
> -#endif
>   
>       for (q = 0; q < QEMU_CLIPBOARD_TYPE__COUNT; q++) {
>           type = type_qemu_to_vdagent(q);
> @@ -464,6 +471,9 @@ static void vdagent_clipboard_reset_serial(VDAgentChardev *vd)
>   {
>       Chardev *chr = CHARDEV(vd);
>   
> +    if (!have_clipboard_serial(vd)) {
> +        return;
> +    }
>       /* reopen the agent connection to reset the serial state */
>       qemu_chr_be_event(chr, CHR_EVENT_CLOSED);
>       /* OPENED again after the guest disconnected, see set_fe_open */
> @@ -518,8 +528,7 @@ static void vdagent_clipboard_recv_grab(VDAgentChardev *vd, uint8_t s, uint32_t
>   
>       trace_vdagent_cb_grab_selection(GET_NAME(sel_name, s));
>       info = qemu_clipboard_info_new(&vd->cbpeer, s);
> -#if CHECK_SPICE_PROTOCOL_VERSION(0, 14, 1)
> -    if (vd->caps & (1 << VD_AGENT_CAP_CLIPBOARD_GRAB_SERIAL)) {
> +    if (have_clipboard_serial(vd)) {
>           if (size < sizeof(uint32_t)) {
>               /* this shouldn't happen! */
>               return;
> @@ -537,7 +546,6 @@ static void vdagent_clipboard_recv_grab(VDAgentChardev *vd, uint8_t s, uint32_t
>           data += sizeof(uint32_t);
>           size -= sizeof(uint32_t);
>       }
> -#endif
>       if (size > sizeof(uint32_t) * 10) {
>           /*
>            * spice has 6 types as of 2021. Limiting to 10 entries

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