[PATCH v3 0/9] virtio-console: notify about the terminal size

[PATCH v3 0/9] virtio-console: notify about the terminal size

[Szymon Lukasz]

The goal of this series is to have a resizable terminal into a guest
without having to set up networking and using, e.g. ssh.

The virtio spec allows a virtio-console device to notify the guest about
terminal resizes in the host. Linux Kernel implements the driver part of
the spec. This series implement the device part in QEMU.

This series adds support for a resizable terminal if a virtio console
device is connected to the stdio backend. 

This series also introduces resize messages that can be sent over QMP to
notify QEMU about the size of the terminal connented to some chardev.
In the libvirt setting, it will allow to implement a resizable terminal 
for virsh console and other libvirt clients.


v3:
add resize messages over QMP, as suggested by Daniel

v2:
fix adding a new virtio feature bit to the virtio console device

Szymon Lukasz (9):
  chardev: add cols, rows fields
  chardev: add CHR_EVENT_RESIZE
  chardev: add qemu_chr_resize()
  char-mux: add support for the terminal size
  main-loop: change the handling of SIGWINCH
  char-stdio: add support for the terminal size
  qmp: add chardev-resize command
  virtio-serial-bus: add terminal resize messages
  virtio-console: notify the guest about terminal resizes

 backends/cryptodev-vhost-user.c   |  1 +
 chardev/char-fe.c                 | 13 +++++++
 chardev/char-mux.c                | 18 ++++++++-
 chardev/char-stdio.c              | 29 ++++++++++++++
 chardev/char.c                    | 26 +++++++++++++
 hw/block/vhost-user-blk.c         |  1 +
 hw/char/terminal3270.c            |  1 +
 hw/char/trace-events              |  1 +
 hw/char/virtio-console.c          | 63 +++++++++++++++++++++++++++++--
 hw/char/virtio-serial-bus.c       | 42 ++++++++++++++++++++-
 hw/core/machine.c                 |  1 +
 hw/ipmi/ipmi_bmc_extern.c         |  1 +
 hw/usb/ccid-card-passthru.c       |  1 +
 hw/usb/dev-serial.c               |  1 +
 hw/usb/redirect.c                 |  1 +
 include/chardev/char-fe.h         | 10 +++++
 include/chardev/char.h            |  7 ++++
 include/hw/virtio/virtio-serial.h |  5 +++
 include/qemu/main-loop.h          |  4 ++
 monitor/hmp.c                     |  1 +
 monitor/qmp.c                     |  1 +
 net/vhost-user.c                  |  1 +
 qapi/char.json                    | 25 ++++++++++++
 ui/curses.c                       | 11 +++---
 util/main-loop.c                  | 21 +++++++++++
 25 files changed, 274 insertions(+), 12 deletions(-)

-- 
2.27.0

[PATCH v3 1/9] chardev: add cols, rows fields

[Szymon Lukasz]

These fields should be interpreted as the size of the terminal connected
to a given chardev.

Signed-off-by: Szymon Lukasz <noh4hss@gmail.com>
---
 chardev/char-fe.c         | 13 +++++++++++++
 include/chardev/char-fe.h | 10 ++++++++++
 include/chardev/char.h    |  1 +
 3 files changed, 24 insertions(+)

diff --git a/chardev/char-fe.c b/chardev/char-fe.c
index f3530a90e6..27f95bfcdf 100644
--- a/chardev/char-fe.c
+++ b/chardev/char-fe.c
@@ -336,6 +336,19 @@ void qemu_chr_fe_set_echo(CharBackend *be, bool echo)
     }
 }
 
+void qemu_chr_fe_get_winsize(CharBackend *be, uint16_t *cols, uint16_t *rows)
+{
+    Chardev *chr = be->chr;
+
+    if (chr) {
+        *cols = chr->cols;
+        *rows = chr->rows;
+    } else {
+        *cols = 0;
+        *rows = 0;
+    }
+}
+
 void qemu_chr_fe_set_open(CharBackend *be, int fe_open)
 {
     Chardev *chr = be->chr;
diff --git a/include/chardev/char-fe.h b/include/chardev/char-fe.h
index a553843364..3672b0d97d 100644
--- a/include/chardev/char-fe.h
+++ b/include/chardev/char-fe.h
@@ -154,6 +154,16 @@ int qemu_chr_fe_wait_connected(CharBackend *be, Error **errp);
  */
 void qemu_chr_fe_set_echo(CharBackend *be, bool echo);
 
+/**
+ * qemu_chr_fe_get_winsize:
+ * @cols: the address for storing columns
+ * @rows: the address for storing rows
+ *
+ * Get the size of the terminal connected to the chardev backend.
+ * Returns *cols = *rows = 0, if no associated Chardev.
+ */
+void qemu_chr_fe_get_winsize(CharBackend *be, uint16_t *cols, uint16_t *rows);
+
 /**
  * qemu_chr_fe_set_open:
  *
diff --git a/include/chardev/char.h b/include/chardev/char.h
index 00589a6025..0cea33cb9a 100644
--- a/include/chardev/char.h
+++ b/include/chardev/char.h
@@ -65,6 +65,7 @@ struct Chardev {
     char *filename;
     int logfd;
     int be_open;
+    uint16_t cols, rows;
     GSource *gsource;
     GMainContext *gcontext;
     DECLARE_BITMAP(features, QEMU_CHAR_FEATURE_LAST);
-- 
2.27.0

[PATCH v3 2/9] chardev: add CHR_EVENT_RESIZE

[Szymon Lukasz]

Add a new chardev event, CHR_EVENT_RESIZE, which a backend should
trigger if detects the size of the connected terminal changed.

Signed-off-by: Szymon Lukasz <noh4hss@gmail.com>
---
 backends/cryptodev-vhost-user.c | 1 +
 chardev/char.c                  | 1 +
 hw/block/vhost-user-blk.c       | 1 +
 hw/char/terminal3270.c          | 1 +
 hw/char/virtio-console.c        | 1 +
 hw/ipmi/ipmi_bmc_extern.c       | 1 +
 hw/usb/ccid-card-passthru.c     | 1 +
 hw/usb/dev-serial.c             | 1 +
 hw/usb/redirect.c               | 1 +
 include/chardev/char.h          | 4 ++++
 monitor/hmp.c                   | 1 +
 monitor/qmp.c                   | 1 +
 net/vhost-user.c                | 1 +
 13 files changed, 16 insertions(+)

diff --git a/backends/cryptodev-vhost-user.c b/backends/cryptodev-vhost-user.c
index 8b8cbc4223..bbf8ad426a 100644
--- a/backends/cryptodev-vhost-user.c
+++ b/backends/cryptodev-vhost-user.c
@@ -174,6 +174,7 @@ static void cryptodev_vhost_user_event(void *opaque, QEMUChrEvent event)
     case CHR_EVENT_BREAK:
     case CHR_EVENT_MUX_IN:
     case CHR_EVENT_MUX_OUT:
+    case CHR_EVENT_RESIZE:
         /* Ignore */
         break;
     }
diff --git a/chardev/char.c b/chardev/char.c
index e3051295ac..904f8bf6e3 100644
--- a/chardev/char.c
+++ b/chardev/char.c
@@ -74,6 +74,7 @@ void qemu_chr_be_event(Chardev *s, QEMUChrEvent event)
     case CHR_EVENT_BREAK:
     case CHR_EVENT_MUX_IN:
     case CHR_EVENT_MUX_OUT:
+    case CHR_EVENT_RESIZE:
         /* Ignore */
         break;
     }
diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
index a00b854736..1a656a27c3 100644
--- a/hw/block/vhost-user-blk.c
+++ b/hw/block/vhost-user-blk.c
@@ -403,6 +403,7 @@ static void vhost_user_blk_event(void *opaque, QEMUChrEvent event)
     case CHR_EVENT_BREAK:
     case CHR_EVENT_MUX_IN:
     case CHR_EVENT_MUX_OUT:
+    case CHR_EVENT_RESIZE:
         /* Ignore */
         break;
     }
diff --git a/hw/char/terminal3270.c b/hw/char/terminal3270.c
index 2c47ebf007..eadccbb617 100644
--- a/hw/char/terminal3270.c
+++ b/hw/char/terminal3270.c
@@ -169,6 +169,7 @@ static void chr_event(void *opaque, QEMUChrEvent event)
     case CHR_EVENT_BREAK:
     case CHR_EVENT_MUX_IN:
     case CHR_EVENT_MUX_OUT:
+    case CHR_EVENT_RESIZE:
         /* Ignore */
         break;
     }
diff --git a/hw/char/virtio-console.c b/hw/char/virtio-console.c
index 4f46753ea3..97b9240ef5 100644
--- a/hw/char/virtio-console.c
+++ b/hw/char/virtio-console.c
@@ -165,6 +165,7 @@ static void chr_event(void *opaque, QEMUChrEvent event)
     case CHR_EVENT_BREAK:
     case CHR_EVENT_MUX_IN:
     case CHR_EVENT_MUX_OUT:
+    case CHR_EVENT_RESIZE:
         /* Ignore */
         break;
     }
diff --git a/hw/ipmi/ipmi_bmc_extern.c b/hw/ipmi/ipmi_bmc_extern.c
index f9a13e0a44..9562584309 100644
--- a/hw/ipmi/ipmi_bmc_extern.c
+++ b/hw/ipmi/ipmi_bmc_extern.c
@@ -439,6 +439,7 @@ static void chr_event(void *opaque, QEMUChrEvent event)
     case CHR_EVENT_BREAK:
     case CHR_EVENT_MUX_IN:
     case CHR_EVENT_MUX_OUT:
+    case CHR_EVENT_RESIZE:
         /* Ignore */
         break;
     }
diff --git a/hw/usb/ccid-card-passthru.c b/hw/usb/ccid-card-passthru.c
index bb325dbc4a..3c26b16ed0 100644
--- a/hw/usb/ccid-card-passthru.c
+++ b/hw/usb/ccid-card-passthru.c
@@ -321,6 +321,7 @@ static void ccid_card_vscard_event(void *opaque, QEMUChrEvent event)
     case CHR_EVENT_MUX_IN:
     case CHR_EVENT_MUX_OUT:
     case CHR_EVENT_CLOSED:
+    case CHR_EVENT_RESIZE:
         /* Ignore */
         break;
     }
diff --git a/hw/usb/dev-serial.c b/hw/usb/dev-serial.c
index 7e50e3ba47..e8e960d0e6 100644
--- a/hw/usb/dev-serial.c
+++ b/hw/usb/dev-serial.c
@@ -507,6 +507,7 @@ static void usb_serial_event(void *opaque, QEMUChrEvent event)
             break;
         case CHR_EVENT_MUX_IN:
         case CHR_EVENT_MUX_OUT:
+        case CHR_EVENT_RESIZE:
             /* Ignore */
             break;
     }
diff --git a/hw/usb/redirect.c b/hw/usb/redirect.c
index 417a60a2e6..b716c4fdd7 100644
--- a/hw/usb/redirect.c
+++ b/hw/usb/redirect.c
@@ -1383,6 +1383,7 @@ static void usbredir_chardev_event(void *opaque, QEMUChrEvent event)
     case CHR_EVENT_BREAK:
     case CHR_EVENT_MUX_IN:
     case CHR_EVENT_MUX_OUT:
+    case CHR_EVENT_RESIZE:
         /* Ignore */
         break;
     }
diff --git a/include/chardev/char.h b/include/chardev/char.h
index 0cea33cb9a..42203e9fa4 100644
--- a/include/chardev/char.h
+++ b/include/chardev/char.h
@@ -22,6 +22,10 @@ typedef enum {
     CHR_EVENT_OPENED, /* new connection established */
     CHR_EVENT_MUX_IN, /* mux-focus was set to this terminal */
     CHR_EVENT_MUX_OUT, /* mux-focus will move on */
+    CHR_EVENT_RESIZE, /*
+                       * the size of the terminal connected to
+                       * the chardev changed
+                       */
     CHR_EVENT_CLOSED /* connection closed.  NOTE: currently this event
                       * is only bound to the read port of the chardev.
                       * Normally the read port and write port of a
diff --git a/monitor/hmp.c b/monitor/hmp.c
index d598dd02bb..020be03d61 100644
--- a/monitor/hmp.c
+++ b/monitor/hmp.c
@@ -1373,6 +1373,7 @@ static void monitor_event(void *opaque, QEMUChrEvent event)
         break;
 
     case CHR_EVENT_BREAK:
+    case CHR_EVENT_RESIZE:
         /* Ignored */
         break;
     }
diff --git a/monitor/qmp.c b/monitor/qmp.c
index d433ceae5b..58aecb475b 100644
--- a/monitor/qmp.c
+++ b/monitor/qmp.c
@@ -371,6 +371,7 @@ static void monitor_qmp_event(void *opaque, QEMUChrEvent event)
     case CHR_EVENT_BREAK:
     case CHR_EVENT_MUX_IN:
     case CHR_EVENT_MUX_OUT:
+    case CHR_EVENT_RESIZE:
         /* Ignore */
         break;
     }
diff --git a/net/vhost-user.c b/net/vhost-user.c
index 17532daaf3..e30cbe74bd 100644
--- a/net/vhost-user.c
+++ b/net/vhost-user.c
@@ -297,6 +297,7 @@ static void net_vhost_user_event(void *opaque, QEMUChrEvent event)
     case CHR_EVENT_BREAK:
     case CHR_EVENT_MUX_IN:
     case CHR_EVENT_MUX_OUT:
+    case CHR_EVENT_RESIZE:
         /* Ignore */
         break;
     }
-- 
2.27.0

[PATCH v3 3/9] chardev: add qemu_chr_resize()

[Szymon Lukasz]

This function should be called whenever we learn about a new size of
the terminal connected to a chardev.

Signed-off-by: Szymon Lukasz <noh4hss@gmail.com>
---
 chardev/char.c         | 11 +++++++++++
 include/chardev/char.h |  2 ++
 2 files changed, 13 insertions(+)

diff --git a/chardev/char.c b/chardev/char.c
index 904f8bf6e3..1dc22aca95 100644
--- a/chardev/char.c
+++ b/chardev/char.c
@@ -354,6 +354,17 @@ int qemu_chr_wait_connected(Chardev *chr, Error **errp)
     return 0;
 }
 
+void qemu_chr_resize(Chardev *chr, uint16_t cols, uint16_t rows)
+{
+    if (cols != chr->cols || rows != chr->rows) {
+        chr->cols = cols;
+        chr->rows = rows;
+        if (chr->be_open) {
+            qemu_chr_be_event(chr, CHR_EVENT_RESIZE);
+        }
+    }
+}
+
 QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename,
                                 bool permit_mux_mon)
 {
diff --git a/include/chardev/char.h b/include/chardev/char.h
index 42203e9fa4..01099121f1 100644
--- a/include/chardev/char.h
+++ b/include/chardev/char.h
@@ -230,6 +230,8 @@ int qemu_chr_write(Chardev *s, const uint8_t *buf, int len, bool write_all);
 #define qemu_chr_write_all(s, buf, len) qemu_chr_write(s, buf, len, true)
 int qemu_chr_wait_connected(Chardev *chr, Error **errp);
 
+void qemu_chr_resize(Chardev *chr, uint16_t cols, uint16_t rows);
+
 #define TYPE_CHARDEV "chardev"
 #define CHARDEV(obj) OBJECT_CHECK(Chardev, (obj), TYPE_CHARDEV)
 #define CHARDEV_CLASS(klass) \
-- 
2.27.0

[PATCH v3 4/9] char-mux: add support for the terminal size

[Szymon Lukasz]

The terminal size of a mux chardev should be the same as the real
chardev, so listen for CHR_EVENT_RESIZE to be up to date.

We forward CHR_EVENT_RESIZE only to the focused frontend. This means
frontends should probably update their view of the terminal size on
receiving CHR_EVENT_MUX_IN.

Signed-off-by: Szymon Lukasz <noh4hss@gmail.com>
---
 chardev/char-mux.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/chardev/char-mux.c b/chardev/char-mux.c
index 46c44af67c..fa81f8341e 100644
--- a/chardev/char-mux.c
+++ b/chardev/char-mux.c
@@ -247,9 +247,24 @@ void mux_chr_send_all_event(Chardev *chr, QEMUChrEvent event)
     }
 }
 
+static void mux_update_winsize(Chardev *chr)
+{
+    MuxChardev *d = MUX_CHARDEV(chr);
+    uint16_t cols, rows;
+
+    qemu_chr_fe_get_winsize(&d->chr, &cols, &rows);
+    qemu_chr_resize(chr, cols, rows);
+}
+
 static void mux_chr_event(void *opaque, QEMUChrEvent event)
 {
-    mux_chr_send_all_event(CHARDEV(opaque), event);
+    Chardev *chr = CHARDEV(opaque);
+
+    if (event == CHR_EVENT_RESIZE) {
+        mux_update_winsize(chr);
+    } else {
+        mux_chr_send_all_event(chr, event);
+    }
 }
 
 static GSource *mux_chr_add_watch(Chardev *s, GIOCondition cond)
@@ -330,6 +345,7 @@ static void qemu_chr_open_mux(Chardev *chr,
      */
     *be_opened = machine_init_done;
     qemu_chr_fe_init(&d->chr, drv, errp);
+    mux_update_winsize(chr);
 }
 
 static void qemu_chr_parse_mux(QemuOpts *opts, ChardevBackend *backend,
-- 
2.27.0

[PATCH v3 5/9] main-loop: change the handling of SIGWINCH

[Szymon Lukasz]

Block SIGWINCH, so it is delivered only via signalfd.
Install a handler that uses NotifierList to tell
interested parties about SIGWINCH delivery.

Signed-off-by: Szymon Lukasz <noh4hss@gmail.com>
---
 include/qemu/main-loop.h |  4 ++++
 ui/curses.c              | 11 ++++++-----
 util/main-loop.c         | 21 +++++++++++++++++++++
 3 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/include/qemu/main-loop.h b/include/qemu/main-loop.h
index a6d20b0719..f27dba1fd8 100644
--- a/include/qemu/main-loop.h
+++ b/include/qemu/main-loop.h
@@ -325,4 +325,8 @@ typedef struct MainLoopPoll {
 void main_loop_poll_add_notifier(Notifier *notify);
 void main_loop_poll_remove_notifier(Notifier *notify);
 
+#ifndef _WIN32
+void sigwinch_add_notifier(Notifier *n);
+#endif
+
 #endif
diff --git a/ui/curses.c b/ui/curses.c
index a59b23a9cf..e5895d506f 100644
--- a/ui/curses.c
+++ b/ui/curses.c
@@ -34,6 +34,7 @@
 #include <iconv.h>
 
 #include "qapi/error.h"
+#include "qemu/main-loop.h"
 #include "qemu/module.h"
 #include "ui/console.h"
 #include "ui/input.h"
@@ -146,7 +147,7 @@ static void curses_resize(DisplayChangeListener *dcl,
 }
 
 #if !defined(_WIN32) && defined(SIGWINCH) && defined(KEY_RESIZE)
-static volatile sig_atomic_t got_sigwinch;
+static bool got_sigwinch;
 static void curses_winch_check(void)
 {
     struct winsize {
@@ -169,17 +170,17 @@ static void curses_winch_check(void)
     invalidate = 1;
 }
 
-static void curses_winch_handler(int signum)
+static void curses_winch_handler(Notifier *n, void *data)
 {
     got_sigwinch = true;
 }
 
 static void curses_winch_init(void)
 {
-    struct sigaction old, winch = {
-        .sa_handler  = curses_winch_handler,
+    static Notifier n = {
+        .notify = curses_winch_handler
     };
-    sigaction(SIGWINCH, &winch, &old);
+    sigwinch_add_notifier(&n);
 }
 #else
 static void curses_winch_check(void) {}
diff --git a/util/main-loop.c b/util/main-loop.c
index eda63fe4e0..0f5c8f3af1 100644
--- a/util/main-loop.c
+++ b/util/main-loop.c
@@ -90,6 +90,7 @@ static int qemu_signal_init(Error **errp)
     sigaddset(&set, SIGIO);
     sigaddset(&set, SIGALRM);
     sigaddset(&set, SIGBUS);
+    sigaddset(&set, SIGWINCH);
     /* SIGINT cannot be handled via signalfd, so that ^C can be used
      * to interrupt QEMU when it is being run under gdb.  SIGHUP and
      * SIGTERM are also handled asynchronously, even though it is not
@@ -111,6 +112,26 @@ static int qemu_signal_init(Error **errp)
     return 0;
 }
 
+static NotifierList sigwinch_notifiers =
+    NOTIFIER_LIST_INITIALIZER(sigwinch_notifiers);
+
+static void sigwinch_handler(int signum)
+{
+    notifier_list_notify(&sigwinch_notifiers, NULL);
+}
+
+void sigwinch_add_notifier(Notifier *n)
+{
+    if (notifier_list_empty(&sigwinch_notifiers)) {
+        struct sigaction action = {
+            .sa_handler = sigwinch_handler,
+        };
+        sigaction(SIGWINCH, &action, NULL);
+    }
+
+    notifier_list_add(&sigwinch_notifiers, n);
+}
+
 #else /* _WIN32 */
 
 static int qemu_signal_init(Error **errp)
-- 
2.27.0

[PATCH v3 6/9] char-stdio: add support for the terminal size

[Szymon Lukasz]

Update the terminal size upon SIGWINCH delivery.

Signed-off-by: Szymon Lukasz <noh4hss@gmail.com>
---
 chardev/char-stdio.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/chardev/char-stdio.c b/chardev/char-stdio.c
index 82eaebc1db..4c3c8a80b6 100644
--- a/chardev/char-stdio.c
+++ b/chardev/char-stdio.c
@@ -34,7 +34,9 @@
 #include "chardev/char-win-stdio.h"
 #else
 #include <termios.h>
+#include <sys/ioctl.h>
 #include "chardev/char-fd.h"
+#include "qemu/main-loop.h"
 #endif
 
 #ifndef _WIN32
@@ -45,6 +47,13 @@ static bool stdio_in_use;
 static bool stdio_allow_signal;
 static bool stdio_echo_state;
 
+typedef struct {
+    FDChardev parent;
+    Notifier resize_notifier;
+} StdioChardev;
+
+#define STDIO_CHARDEV(obj) OBJECT_CHECK(StdioChardev, (obj), TYPE_CHARDEV_STDIO)
+
 static void term_exit(void)
 {
     if (stdio_in_use) {
@@ -82,11 +91,26 @@ static void term_stdio_handler(int sig)
     qemu_chr_set_echo_stdio(NULL, stdio_echo_state);
 }
 
+static void qemu_chr_resize_stdio(Chardev *chr)
+{
+    struct winsize ws;
+    if (ioctl(1, TIOCGWINSZ, &ws) != -1) {
+        qemu_chr_resize(chr, ws.ws_col, ws.ws_row);
+    }
+}
+
+static void term_resize_notify(Notifier *n, void *data)
+{
+    StdioChardev *s = container_of(n, StdioChardev, resize_notifier);
+    qemu_chr_resize_stdio(CHARDEV(s));
+}
+
 static void qemu_chr_open_stdio(Chardev *chr,
                                 ChardevBackend *backend,
                                 bool *be_opened,
                                 Error **errp)
 {
+    StdioChardev *s = STDIO_CHARDEV(chr);
     ChardevStdio *opts = backend->u.stdio.data;
     struct sigaction act;
 
@@ -116,6 +140,10 @@ static void qemu_chr_open_stdio(Chardev *chr,
         stdio_allow_signal = opts->signal;
     }
     qemu_chr_set_echo_stdio(chr, false);
+
+    qemu_chr_resize_stdio(chr);
+    s->resize_notifier.notify = term_resize_notify;
+    sigwinch_add_notifier(&s->resize_notifier);
 }
 #endif
 
@@ -155,6 +183,7 @@ static const TypeInfo char_stdio_type_info = {
     .parent = TYPE_CHARDEV_WIN_STDIO,
 #else
     .parent = TYPE_CHARDEV_FD,
+    .instance_size = sizeof(StdioChardev),
 #endif
     .instance_finalize = char_stdio_finalize,
     .class_init = char_stdio_class_init,
-- 
2.27.0

[PATCH v3 7/9] qmp: add chardev-resize command

[Szymon Lukasz]

The managment software can use this command to notify QEMU about the
size of the terminal connected to a chardev, QEMU can then forward this
information to the guest if the chardev is connected to a virtio console
device.

Signed-off-by: Szymon Lukasz <noh4hss@gmail.com>
Suggested-by: Daniel P. Berrangé <berrange@redhat.com>
---
 chardev/char.c | 14 ++++++++++++++
 qapi/char.json | 25 +++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/chardev/char.c b/chardev/char.c
index 1dc22aca95..c1bdfc8b5f 100644
--- a/chardev/char.c
+++ b/chardev/char.c
@@ -1182,6 +1182,20 @@ void qmp_chardev_send_break(const char *id, Error **errp)
     qemu_chr_be_event(chr, CHR_EVENT_BREAK);
 }
 
+void qmp_chardev_resize(const char *id, uint16_t cols, uint16_t rows,
+                        Error **errp)
+{
+    Chardev *chr;
+
+    chr = qemu_chr_find(id);
+    if (chr == NULL) {
+        error_setg(errp, "Chardev '%s' not found", id);
+        return;
+    }
+
+    qemu_chr_resize(chr, cols, rows);
+}
+
 /*
  * Add a timeout callback for the chardev (in milliseconds), return
  * the GSource object created. Please use this to add timeout hook for
diff --git a/qapi/char.json b/qapi/char.json
index daceb20f84..dc2d6cab22 100644
--- a/qapi/char.json
+++ b/qapi/char.json
@@ -573,3 +573,28 @@
 { 'event': 'VSERPORT_CHANGE',
   'data': { 'id': 'str',
             'open': 'bool' } }
+
+##
+# @chardev-resize:
+#
+# Notifies a chardev about the current size of the terminal connected
+# to this chardev.
+#
+# @id: the chardev's ID, must exist
+# @cols: the number of columns
+# @rows: the number of rows
+#
+# Returns: Nothing on success
+#
+# Since: 5.1
+#
+# Example:
+#
+# -> { "execute": "chardev-resize", "arguments": { "id": "foo", "cols": 80, "rows": 24 } }
+# <- { "return": {} }
+#
+##
+{ 'command': 'chardev-resize',
+  'data': { 'id': 'str',
+            'cols': 'uint16',
+            'rows': 'uint16' } }
-- 
2.27.0

[PATCH v3 8/9] virtio-serial-bus: add terminal resize messages

[Szymon Lukasz]

Implement the part of the virtio spec that allows to notify the virtio
driver about terminal resizes. The virtio spec contains two methods to
achieve that:

For legacy drivers, we have only one port and we put the terminal size
in the config space and inject the config changed interrupt.

For multiport devices, we use the control virtqueue to send a packet
containing the terminal size. Note that the Linux kernel expects
the fields indicating the number of rows and columns in a packet to be
in a different order than the one specified in the current version of
the virtio spec. We follow the Linux implementation, so hopefully there
is no implementation of this functionality conforming to the spec.

Signed-off-by: Szymon Lukasz <noh4hss@gmail.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/char/trace-events              |  1 +
 hw/char/virtio-serial-bus.c       | 42 +++++++++++++++++++++++++++++--
 hw/core/machine.c                 |  1 +
 include/hw/virtio/virtio-serial.h |  5 ++++
 4 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/hw/char/trace-events b/hw/char/trace-events
index d20eafd56f..be40df47ea 100644
--- a/hw/char/trace-events
+++ b/hw/char/trace-events
@@ -10,6 +10,7 @@ serial_ioport_write(uint16_t addr, uint8_t value) "write addr 0x%02x val 0x%02x"
 
 # virtio-serial-bus.c
 virtio_serial_send_control_event(unsigned int port, uint16_t event, uint16_t value) "port %u, event %u, value %u"
+virtio_serial_send_console_resize(unsigned int port, uint16_t cols, uint16_t rows) "port %u, cols %u, rows %u"
 virtio_serial_throttle_port(unsigned int port, bool throttle) "port %u, throttle %d"
 virtio_serial_handle_control_message(uint16_t event, uint16_t value) "event %u, value %u"
 virtio_serial_handle_control_message_port(unsigned int port) "port %u"
diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c
index 262089c0c9..6d9e94a64e 100644
--- a/hw/char/virtio-serial-bus.c
+++ b/hw/char/virtio-serial-bus.c
@@ -261,6 +261,42 @@ static size_t send_control_event(VirtIOSerial *vser, uint32_t port_id,
     return send_control_msg(vser, &cpkt, sizeof(cpkt));
 }
 
+/*
+ * This struct should be added to the Linux kernel uapi headers
+ * and later imported to standard-headers/linux/virtio_console.h
+ */
+struct virtio_console_resize {
+    __virtio16 rows;
+    __virtio16 cols;
+};
+
+void virtio_serial_send_console_resize(VirtIOSerialPort *port,
+                                       uint16_t cols, uint16_t rows)
+{
+    VirtIOSerial *vser = port->vser;
+    VirtIODevice *vdev = VIRTIO_DEVICE(vser);
+
+    if (virtio_vdev_has_feature(vdev, VIRTIO_CONSOLE_F_MULTIPORT)) {
+        struct {
+            struct virtio_console_control control;
+            struct virtio_console_resize resize;
+        } buffer;
+
+        virtio_stl_p(vdev, &buffer.control.id, port->id);
+        virtio_stw_p(vdev, &buffer.control.event, VIRTIO_CONSOLE_RESIZE);
+        virtio_stw_p(vdev, &buffer.resize.cols, cols);
+        virtio_stw_p(vdev, &buffer.resize.rows, rows);
+
+        trace_virtio_serial_send_console_resize(port->id, cols, rows);
+        send_control_msg(vser, &buffer, sizeof(buffer));
+
+    } else if (virtio_vdev_has_feature(vdev, VIRTIO_CONSOLE_F_SIZE)) {
+        vser->port0_cols = cols;
+        vser->port0_rows = rows;
+        virtio_notify_config(vdev);
+    }
+}
+
 /* Functions for use inside qemu to open and read from/write to ports */
 int virtio_serial_open(VirtIOSerialPort *port)
 {
@@ -572,8 +608,8 @@ static void get_config(VirtIODevice *vdev, uint8_t *config_data)
     struct virtio_console_config *config =
         (struct virtio_console_config *)config_data;
 
-    config->cols = 0;
-    config->rows = 0;
+    config->cols = virtio_tswap16(vdev, vser->port0_cols);
+    config->rows = virtio_tswap16(vdev, vser->port0_rows);
     config->max_nr_ports = virtio_tswap32(vdev,
                                           vser->serial.max_virtserial_ports);
 }
@@ -1168,6 +1204,8 @@ static Property virtio_serial_properties[] = {
                                                   31),
     DEFINE_PROP_BIT64("emergency-write", VirtIOSerial, host_features,
                       VIRTIO_CONSOLE_F_EMERG_WRITE, true),
+    DEFINE_PROP_BIT64("console-size", VirtIOSerial, host_features,
+                      VIRTIO_CONSOLE_F_SIZE, true),
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/hw/core/machine.c b/hw/core/machine.c
index 1d80ab0e1d..c370c220f0 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -30,6 +30,7 @@
 
 GlobalProperty hw_compat_5_0[] = {
     { "virtio-balloon-device", "page-poison", "false" },
+    { "virtio-serial-device", "console-size", "off" },
 };
 const size_t hw_compat_5_0_len = G_N_ELEMENTS(hw_compat_5_0);
 
diff --git a/include/hw/virtio/virtio-serial.h b/include/hw/virtio/virtio-serial.h
index ed3e916b68..1d6436c0b1 100644
--- a/include/hw/virtio/virtio-serial.h
+++ b/include/hw/virtio/virtio-serial.h
@@ -188,6 +188,8 @@ struct VirtIOSerial {
     virtio_serial_conf serial;
 
     uint64_t host_features;
+
+    uint16_t port0_cols, port0_rows;
 };
 
 /* Interface to the virtio-serial bus */
@@ -222,6 +224,9 @@ size_t virtio_serial_guest_ready(VirtIOSerialPort *port);
  */
 void virtio_serial_throttle_port(VirtIOSerialPort *port, bool throttle);
 
+void virtio_serial_send_console_resize(VirtIOSerialPort *port,
+                                       uint16_t cols, uint16_t rows);
+
 #define TYPE_VIRTIO_SERIAL "virtio-serial-device"
 #define VIRTIO_SERIAL(obj) \
         OBJECT_CHECK(VirtIOSerial, (obj), TYPE_VIRTIO_SERIAL)
-- 
2.27.0

[PATCH v3 9/9] virtio-console: notify the guest about terminal resizes

[Szymon Lukasz]

If a virtio serial port is a console port forward terminal resize
messages from the chardev backend to the guest.

Signed-off-by: Szymon Lukasz <noh4hss@gmail.com>
---
 hw/char/virtio-console.c | 62 +++++++++++++++++++++++++++++++++++++---
 1 file changed, 58 insertions(+), 4 deletions(-)

diff --git a/hw/char/virtio-console.c b/hw/char/virtio-console.c
index 97b9240ef5..c4c2c7a844 100644
--- a/hw/char/virtio-console.c
+++ b/hw/char/virtio-console.c
@@ -29,6 +29,7 @@ typedef struct VirtConsole {
 
     CharBackend chr;
     guint watch;
+    uint16_t cols, rows;
 } VirtConsole;
 
 /*
@@ -104,6 +105,33 @@ static ssize_t flush_buf(VirtIOSerialPort *port,
     return ret;
 }
 
+static void virtconsole_send_resize(VirtIOSerialPort *port)
+{
+    uint16_t cols, rows;
+    VirtConsole *vcon = VIRTIO_CONSOLE(port);
+
+    /*
+     * We probably shouldn't send these messages before
+     * we told the guest it is a console port (which we do
+     * by sending VIRTIO_CONSOLE_CONSOLE_PORT message).
+     * Instead of adding a new field to the device state
+     * lets just use the guest_connected field for that purpose
+     * since the guest should not care about the terminal size
+     * before opening the port.
+     */
+    if (!port->guest_connected) {
+        return;
+    }
+
+    qemu_chr_fe_get_winsize(&vcon->chr, &cols, &rows);
+
+    if (cols != vcon->cols || rows != vcon->rows) {
+        vcon->cols = cols;
+        vcon->rows = rows;
+        virtio_serial_send_console_resize(port, cols, rows);
+    }
+}
+
 /* Callback function that's called when the guest opens/closes the port */
 static void set_guest_connected(VirtIOSerialPort *port, int guest_connected)
 {
@@ -111,7 +139,9 @@ static void set_guest_connected(VirtIOSerialPort *port, int guest_connected)
     DeviceState *dev = DEVICE(port);
     VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port);
 
-    if (!k->is_console) {
+    if (k->is_console) {
+        virtconsole_send_resize(port);
+    } else {
         qemu_chr_fe_set_open(&vcon->chr, guest_connected);
     }
 
@@ -171,6 +201,23 @@ static void chr_event(void *opaque, QEMUChrEvent event)
     }
 }
 
+static void chr_event_console(void *opaque, QEMUChrEvent event)
+{
+    VirtConsole *vcon = opaque;
+    VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(vcon);
+
+    trace_virtio_console_chr_event(port->id, event);
+    switch (event) {
+    case CHR_EVENT_OPENED:
+    case CHR_EVENT_MUX_IN:
+    case CHR_EVENT_RESIZE:
+        virtconsole_send_resize(port);
+        break;
+    default:
+        break;
+    }
+}
+
 static int chr_be_change(void *opaque)
 {
     VirtConsole *vcon = opaque;
@@ -179,7 +226,9 @@ static int chr_be_change(void *opaque)
 
     if (k->is_console) {
         qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read,
-                                 NULL, chr_be_change, vcon, NULL, true);
+                                 chr_event_console, chr_be_change,
+                                 vcon, NULL, true);
+        virtconsole_send_resize(port);
     } else {
         qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read,
                                  chr_event, chr_be_change, vcon, NULL, false);
@@ -207,7 +256,7 @@ static void virtconsole_enable_backend(VirtIOSerialPort *port, bool enable)
         VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port);
 
         qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read,
-                                 k->is_console ? NULL : chr_event,
+                                 k->is_console ? chr_event_console : chr_event,
                                  chr_be_change, vcon, NULL, false);
     } else {
         qemu_chr_fe_set_handlers(&vcon->chr, NULL, NULL, NULL,
@@ -227,6 +276,11 @@ static void virtconsole_realize(DeviceState *dev, Error **errp)
         return;
     }
 
+    if (k->is_console) {
+        vcon->cols = (uint16_t) -1;
+        vcon->rows = (uint16_t) -1;
+    }
+
     if (qemu_chr_fe_backend_connected(&vcon->chr)) {
         /*
          * For consoles we don't block guest data transfer just
@@ -239,7 +293,7 @@ static void virtconsole_realize(DeviceState *dev, Error **errp)
          */
         if (k->is_console) {
             qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read,
-                                     NULL, chr_be_change,
+                                     chr_event_console, chr_be_change,
                                      vcon, NULL, true);
             virtio_serial_open(port);
         } else {
-- 
2.27.0

Re: [PATCH v3 0/9] virtio-console: notify about the terminal size

[Filip Hejsek]

I have found this 3 year old patch adding virtio console resize
support, which seems to have been forgotten at that time. I would like
to see this feature merged.

Szymon, you have originally submitted this patch, would you be willing
to update it for the latest development tree and resubmit it?

If it turns out that Szymon doesn't want to work on this anymore for
any reason (or doesn't respond), could I resubmit the patch myself?
The contributing guidelines don't say anything about this. I'm
especially unsure how to deal with Signed-off-by, as in such case I
would be (re)submitting sombody else's work, but potentially with my
modifications. I'm willing to update and test the patch, and if
necessary, address any review feedback.

 - Filip Hejsek


> The goal of this series is to have a resizable terminal into a guest
> without having to set up networking and using, e.g. ssh.
> 
> The virtio spec allows a virtio-console device to notify the guest
> about
> terminal resizes in the host. Linux Kernel implements the driver part
> of
> the spec. This series implement the device part in QEMU.
> 
> This series adds support for a resizable terminal if a virtio console
> device is connected to the stdio backend. 
> 
> This series also introduces resize messages that can be sent over QMP
> to
> notify QEMU about the size of the terminal connented to some chardev.
> In the libvirt setting, it will allow to implement a resizable
> terminal 
> for virsh console and other libvirt clients.
> 
> 
> v3:
> add resize messages over QMP, as suggested by Daniel
> 
> v2:
> fix adding a new virtio feature bit to the virtio console device
> 
> Szymon Lukasz (9):
>   chardev: add cols, rows fields
>   chardev: add CHR_EVENT_RESIZE
>   chardev: add qemu_chr_resize()
>   char-mux: add support for the terminal size
>   main-loop: change the handling of SIGWINCH
>   char-stdio: add support for the terminal size
>   qmp: add chardev-resize command
>   virtio-serial-bus: add terminal resize messages
>   virtio-console: notify the guest about terminal resizes
> 
>  backends/cryptodev-vhost-user.c   |  1 +
>  chardev/char-fe.c                 | 13 +++++++
>  chardev/char-mux.c                | 18 ++++++++-
>  chardev/char-stdio.c              | 29 ++++++++++++++
>  chardev/char.c                    | 26 +++++++++++++
>  hw/block/vhost-user-blk.c         |  1 +
>  hw/char/terminal3270.c            |  1 +
>  hw/char/trace-events              |  1 +
>  hw/char/virtio-console.c          | 63
> +++++++++++++++++++++++++++++--
>  hw/char/virtio-serial-bus.c       | 42 ++++++++++++++++++++-
>  hw/core/machine.c                 |  1 +
>  hw/ipmi/ipmi_bmc_extern.c         |  1 +
>  hw/usb/ccid-card-passthru.c       |  1 +
>  hw/usb/dev-serial.c               |  1 +
>  hw/usb/redirect.c                 |  1 +
>  include/chardev/char-fe.h         | 10 +++++
>  include/chardev/char.h            |  7 ++++
>  include/hw/virtio/virtio-serial.h |  5 +++
>  include/qemu/main-loop.h          |  4 ++
>  monitor/hmp.c                     |  1 +
>  monitor/qmp.c                     |  1 +
>  net/vhost-user.c                  |  1 +
>  qapi/char.json                    | 25 ++++++++++++
>  ui/curses.c                       | 11 +++---
>  util/main-loop.c                  | 21 +++++++++++
>  25 files changed, 274 insertions(+), 12 deletions(-)
> 

Re: [PATCH v3 0/9] virtio-console: notify about the terminal size

[Amit Shah]

On Mon, 2023-10-23 at 05:12 +0200, Filip Hejsek wrote:
> I have found this 3 year old patch adding virtio console resize
> support, which seems to have been forgotten at that time. I would like
> to see this feature merged.
> 
> Szymon, you have originally submitted this patch, would you be willing
> to update it for the latest development tree and resubmit it?
> 
> If it turns out that Szymon doesn't want to work on this anymore for
> any reason (or doesn't respond), could I resubmit the patch myself?
> The contributing guidelines don't say anything about this. I'm
> especially unsure how to deal with Signed-off-by, as in such case I
> would be (re)submitting sombody else's work, but potentially with my
> modifications. I'm willing to update and test the patch, and if
> necessary, address any review feedback.

You should keep Szymon's SOB, mention your changes in the commit
message below that SOB and put in your own after.

	Amit

Re: [PATCH v3 0/9] virtio-console: notify about the terminal size

[Dominique Martinet]

Filip Hejsek wrote on Mon, Oct 23, 2023 at 05:12:14AM +0200:
> I have found this 3 year old patch adding virtio console resize
> support, which seems to have been forgotten at that time. I would like
> to see this feature merged.

It's been a couple more years... :)

Have you had a look at this, or did you find another way of handling
terminal resizes cleanly enough?


Thanks,
-- 
Dominique Martinet

Re: [PATCH v3 0/9] virtio-console: notify about the terminal size

[Michael S. Tsirkin]

On Tue, Sep 09, 2025 at 10:48:31PM +0900, Dominique Martinet wrote:
> Filip Hejsek wrote on Mon, Oct 23, 2023 at 05:12:14AM +0200:
> > I have found this 3 year old patch adding virtio console resize
> > support, which seems to have been forgotten at that time. I would like
> > to see this feature merged.
> 
> It's been a couple more years... :)
> 
> Have you had a look at this, or did you find another way of handling
> terminal resizes cleanly enough?
> 
> 
> Thanks,
> -- 
> Dominique Martinet

just resubmit the way Amit suggested at the time.

Re: [PATCH v3 0/9] virtio-console: notify about the terminal size

[Filip Hejsek]

On Tue, 2025-09-09 at 22:48 +0900, Dominique Martinet wrote:
> Filip Hejsek wrote on Mon, Oct 23, 2023 at 05:12:14AM +0200:
> > I have found this 3 year old patch adding virtio console resize
> > support, which seems to have been forgotten at that time. I would like
> > to see this feature merged.
> 
> It's been a couple more years... :)
> 
> Have you had a look at this, or did you find another way of handling
> terminal resizes cleanly enough?

I had indeed looked into this back in 2023 and even did some work on
it, but unfortunately I had abandoned it before getting to the finish
line.

From what I remember, I found that the patches didn't merge cleanly, so
I attempted to reconcile them with the changes made in QEMU master
since the original patches were submitted. As part of that work, I felt
that I needed to take responsibility for the patches, the same way I
would for a patch I wrote on my own.

Due to my yak shaving tendencies, I got distracted by several things. I
ended up investigating a test failure caused by a bug in unrelated code
(which I reported as issue #1969). I wrote terminal size detection code
for Windows. And I remember there being something in the patches that I
wasn't really happy about and intended to rewrite, but I never got
around to doing that. After a while, I lost my enthusiasm, and because
I had other things to worry about, this work ended up just sitting
there on my SSD for almost two years.

So anyway, for now I have now uploaded my version of the patches here:
https://gitlab.com/filip-hejsek/qemu/-/commits/console-resize-old

I will try to merge it with the current master again, which should be
ready in a short time. I can't promise much more than that, though. :)

Best regards,
Filip Hejsek

Re: [PATCH v3 0/9] virtio-console: notify about the terminal size

[Filip Hejsek]

> I will try to merge it with the current master again, which should be
> ready in a short time.

Done. You can find an updated version of the patches at
<https://gitlab.com/filip-hejsek/qemu/-/commits/console-resize>.
I haven't tested the updated version though. I will maybe do some
testing and then submit it to the mailing list for review, although if
anyone else would like to take over then feel free to do so.

Re: [PATCH v3 0/9] virtio-console: notify about the terminal size

[Filip Hejsek]

On Thu, 2025-09-11 at 18:43 +0200, Filip Hejsek wrote:
> > I will try to merge it with the current master again, which should be
> > ready in a short time.
> 
> Done. You can find an updated version of the patches at
> <https://gitlab.com/filip-hejsek/qemu/-/commits/console-resize>.
> I haven't tested the updated version though. I will maybe do some
> testing and then submit it to the mailing list for review, although if
> anyone else would like to take over then feel free to do so.

I have done some tests and it seems that lines and columns are swapped.
Maybe the implementation in the linux kernel was changed to conform to
the spec?

Re: [PATCH v3 0/9] virtio-console: notify about the terminal size

[Dominique Martinet]

Filip Hejsek wrote on Thu, Sep 11, 2025 at 11:19:15PM +0200:
> > Done. You can find an updated version of the patches at
> > <https://gitlab.com/filip-hejsek/qemu/-/commits/console-resize>.
> > I haven't tested the updated version though. I will maybe do some
> > testing and then submit it to the mailing list for review, although if
> > anyone else would like to take over then feel free to do so.
> 
> I have done some tests and it seems that lines and columns are swapped.
> Maybe the implementation in the linux kernel was changed to conform to
> the spec?

Yes, they have:
https://git.kernel.org/linus/5326ab737a47278dbd16ed3ee7380b26c7056ddd

I had also rebased the patches but wasn't sure how it was supposed to
work, but perhaps that was why it appeared not to work instead...
(I assumed running qemu with something like that would "just resize",
but also tried the qmp command to no avail:
-serial none -device virtio-serial-pci -chardev stdio,id=foo -device virtconsole,chardev=foo
)

I'll retry with your branch, thank you !
-- 
Dominique Martinet | Asmadeus