* [PATCH v3 1/2] s390/sclp: Introduce dedicated sclp-vt220 event buffer type
2026-09-24 10:47 [PATCH v3 0/2] s390/sclp: Resize for sclp-vt220 console Maximilian Immanuel Brandtner
@ 2026-09-24 10:47 ` Maximilian Immanuel Brandtner
2026-09-24 15:34 ` Hendrik Brueckner
2026-09-24 10:47 ` [PATCH v3 2/2] s390/sclp: Implement resize for sclp-vt220 console Maximilian Immanuel Brandtner
1 sibling, 1 reply; 6+ messages in thread
From: Maximilian Immanuel Brandtner @ 2026-09-24 10:47 UTC (permalink / raw)
To: oberpar, linux-s390, linux-kernel
Cc: hca, gor, agordeev, borntraeger, svens, brueckner, mjrosato,
farman, maximilian.immanuel.brandtner
Introduce sclp-vt220 event buffer type to replace the
byte-manipulation behavior in the receiver function with well defined
primitives.
Signed-off-by: Maximilian Immanuel Brandtner <maxbr@linux.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
---
drivers/s390/char/sclp_vt220.c | 24 +++++++++++++++---------
1 file changed, 15 insertions(+), 9 deletions(-)
diff --git a/drivers/s390/char/sclp_vt220.c b/drivers/s390/char/sclp_vt220.c
index 62979adcb..6de4e2e41 100644
--- a/drivers/s390/char/sclp_vt220.c
+++ b/drivers/s390/char/sclp_vt220.c
@@ -52,6 +52,12 @@ struct sclp_vt220_sccb {
struct evbuf_header evbuf;
};
+struct sclp_vt220_evbuf {
+ struct evbuf_header header;
+ char type;
+ char data[];
+} __packed;
+
#define SCLP_VT220_MAX_CHARS_PER_BUFFER (PAGE_SIZE - \
sizeof(struct sclp_vt220_request) - \
sizeof(struct sclp_vt220_sccb))
@@ -522,25 +528,25 @@ static void sclp_vt220_handle_input(const char *buffer, unsigned int count)
/*
* Called by the SCLP to report incoming event buffers.
*/
-static void
-sclp_vt220_receiver_fn(struct evbuf_header *evbuf)
+static void sclp_vt220_receiver_fn(struct evbuf_header *evbuf)
{
- char *buffer;
+ struct sclp_vt220_evbuf *buffer;
unsigned int count;
- buffer = (char *) ((addr_t) evbuf + sizeof(struct evbuf_header));
- count = evbuf->length - sizeof(struct evbuf_header);
+ if (evbuf->length < offsetof(struct sclp_vt220_evbuf, data))
+ return;
+
+ buffer = (struct sclp_vt220_evbuf *)evbuf;
+ count = evbuf->length - offsetof(struct sclp_vt220_evbuf, data);
- switch (*buffer) {
+ switch (buffer->type) {
case SCLP_VT220_SESSION_ENDED:
case SCLP_VT220_SESSION_STARTED:
sclp_vt220_reset_session();
break;
case SCLP_VT220_SESSION_DATA:
/* Send input to line discipline */
- buffer++;
- count--;
- sclp_vt220_handle_input(buffer, count);
+ sclp_vt220_handle_input(buffer->data, count);
tty_flip_buffer_push(&sclp_vt220_port);
break;
}
--
2.54.0
^ permalink raw reply [flat|nested] 6+ messages in thread* [PATCH v3 2/2] s390/sclp: Implement resize for sclp-vt220 console
2026-09-24 10:47 [PATCH v3 0/2] s390/sclp: Resize for sclp-vt220 console Maximilian Immanuel Brandtner
2026-09-24 10:47 ` [PATCH v3 1/2] s390/sclp: Introduce dedicated sclp-vt220 event buffer type Maximilian Immanuel Brandtner
@ 2026-09-24 10:47 ` Maximilian Immanuel Brandtner
2026-09-24 15:31 ` Peter Oberparleiter
2026-09-24 15:34 ` Hendrik Brueckner
1 sibling, 2 replies; 6+ messages in thread
From: Maximilian Immanuel Brandtner @ 2026-09-24 10:47 UTC (permalink / raw)
To: oberpar, linux-s390, linux-kernel
Cc: hca, gor, agordeev, borntraeger, svens, brueckner, mjrosato,
farman, maximilian.immanuel.brandtner
Add support for sclp vt220 resize events to enable host-initiated
terminal resizing when using the sclp-vt220 console.
This allows QEMU to dynamically resize the console. On older kernel
versions, these events are safely ignored as the kernel drops events
with undefined tty codes.
Signed-off-by: Maximilian Immanuel Brandtner <maxbr@linux.ibm.com>
---
drivers/s390/char/sclp_vt220.c | 63 +++++++++++++++++++++++++++++++---
1 file changed, 59 insertions(+), 4 deletions(-)
diff --git a/drivers/s390/char/sclp_vt220.c b/drivers/s390/char/sclp_vt220.c
index 6de4e2e41..b9162f36d 100644
--- a/drivers/s390/char/sclp_vt220.c
+++ b/drivers/s390/char/sclp_vt220.c
@@ -27,6 +27,7 @@
#include <linux/init.h>
#include <linux/reboot.h>
#include <linux/slab.h>
+#include <linux/workqueue.h>
#include <linux/uaccess.h>
#include "sclp.h"
@@ -58,6 +59,11 @@ struct sclp_vt220_evbuf {
char data[];
} __packed;
+struct sclp_vt220_resize_data_t {
+ u16 rows;
+ u16 cols;
+} __packed;
+
#define SCLP_VT220_MAX_CHARS_PER_BUFFER (PAGE_SIZE - \
sizeof(struct sclp_vt220_request) - \
sizeof(struct sclp_vt220_sccb))
@@ -98,6 +104,15 @@ static int __initdata sclp_vt220_init_count;
* another buffer */
static int sclp_vt220_flush_later;
+/* Work struct required for scheduling resize */
+static struct work_struct sclp_vt220_resize_work;
+
+/* Current vt220 terminal winsize */
+static struct winsize sclp_vt220_winsize = {
+ .ws_row = 24,
+ .ws_col = 80,
+};
+
static void sclp_vt220_receiver_fn(struct evbuf_header *evbuf);
static int __sclp_vt220_emit(struct sclp_vt220_request *request);
static void sclp_vt220_emit_current(void);
@@ -477,6 +492,7 @@ sclp_vt220_write(struct tty_struct *tty, const u8 *buf, size_t count)
#define SCLP_VT220_SESSION_ENDED 0x01
#define SCLP_VT220_SESSION_STARTED 0x80
#define SCLP_VT220_SESSION_DATA 0x00
+#define SCLP_VT220_SESSION_RESIZE 0x08
#ifdef CONFIG_MAGIC_SYSRQ
@@ -525,6 +541,38 @@ static void sclp_vt220_handle_input(const char *buffer, unsigned int count)
#endif
+static void sclp_vt220_resize(struct work_struct *work)
+{
+ struct tty_struct *tty;
+ struct winsize ws;
+
+ spin_lock_irq(&sclp_vt220_lock);
+ ws = sclp_vt220_winsize;
+ spin_unlock_irq(&sclp_vt220_lock);
+
+ tty = tty_port_tty_get(&sclp_vt220_port);
+ if (!tty)
+ return;
+
+ tty_do_resize(tty, &ws);
+ tty_kref_put(tty);
+}
+
+static void sclp_vt220_resize_sched(void *buffer, unsigned int count)
+{
+ struct sclp_vt220_resize_data_t *data = buffer;
+ unsigned long flags;
+
+ if (count < sizeof(*data))
+ return;
+
+ spin_lock_irqsave(&sclp_vt220_lock, flags);
+ sclp_vt220_winsize.ws_row = data->rows;
+ sclp_vt220_winsize.ws_col = data->cols;
+ schedule_work(&sclp_vt220_resize_work);
+ spin_unlock_irqrestore(&sclp_vt220_lock, flags);
+}
+
/*
* Called by the SCLP to report incoming event buffers.
*/
@@ -549,6 +597,9 @@ static void sclp_vt220_receiver_fn(struct evbuf_header *evbuf)
sclp_vt220_handle_input(buffer->data, count);
tty_flip_buffer_push(&sclp_vt220_port);
break;
+ case SCLP_VT220_SESSION_RESIZE:
+ sclp_vt220_resize_sched(buffer->data, count);
+ break;
}
}
@@ -560,10 +611,12 @@ sclp_vt220_open(struct tty_struct *tty, struct file *filp)
{
if (tty->count == 1) {
tty_port_tty_set(&sclp_vt220_port, tty);
- if (!tty->winsize.ws_row && !tty->winsize.ws_col) {
- tty->winsize.ws_row = 24;
- tty->winsize.ws_col = 80;
- }
+
+ mutex_lock(&tty->winsize_mutex);
+ spin_lock_irq(&sclp_vt220_lock);
+ tty->winsize = sclp_vt220_winsize;
+ spin_unlock_irq(&sclp_vt220_lock);
+ mutex_unlock(&tty->winsize_mutex);
}
return 0;
}
@@ -757,6 +810,8 @@ static int __init sclp_vt220_tty_init(void)
rc = tty_register_driver(driver);
if (rc)
goto out_init;
+
+ INIT_WORK(&sclp_vt220_resize_work, sclp_vt220_resize);
rc = sclp_register(&sclp_vt220_register_input);
if (rc)
goto out_reg;
--
2.54.0
^ permalink raw reply [flat|nested] 6+ messages in thread