Re: [Qemu-devel] [PATCH 6/7] s390: sclp ascii console support

[Blue Swirl <blauwirbel@gmail.com>]

On Tue, Jul 24, 2012 at 7:37 AM, Christian Borntraeger
<borntraeger@de.ibm.com> wrote:
> From: Heinz Graalfs <graalfs@linux.vnet.ibm.com>
>
> This code adds console support  by implementing SCLP's ASCII Console
> Data event. This is the same console as LPARs ASCII console or z/VMs
> sysascii.
>
> The console can be specified manually with something like
> -chardev stdio,id=charconsole0 -device sclpconsole,chardev=charconsole0,id=console0
>
> Newer kernels will autodetect that console and prefer that over virtio
> console.
>
> When data is received from the character layer it creates a service
> interrupt to trigger a Read Event Data command from the guest that will
> pick up the received character byte-stream.
> When characters are echo'ed by the linux guest a Write Event Data occurs
> which is forwarded by the Event Facility to the console that supports
> a corresponding mask value.
> Console resizing is not supported.
> The character layer byte-stream is buffered using a fixed size iov
> buffer.
>
> Signed-off-by: Heinz Graalfs <graalfs@linux.vnet.ibm.com>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  hw/s390x/Makefile.objs |    2 +-
>  hw/s390x/sclpconsole.c |  323 ++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 324 insertions(+), 1 deletions(-)
>  create mode 100644 hw/s390x/sclpconsole.c
>
> diff --git a/hw/s390x/Makefile.objs b/hw/s390x/Makefile.objs
> index ed4e61a..096dfcd 100644
> --- a/hw/s390x/Makefile.objs
> +++ b/hw/s390x/Makefile.objs
> @@ -3,4 +3,4 @@ obj-y = s390-virtio-bus.o s390-virtio.o
>  obj-y := $(addprefix ../,$(obj-y))
>  obj-y += sclp.o
>  obj-y += event-facility.o
> -obj-y += sclpquiesce.o
> +obj-y += sclpquiesce.o sclpconsole.o
> diff --git a/hw/s390x/sclpconsole.c b/hw/s390x/sclpconsole.c
> new file mode 100644
> index 0000000..9a57032
> --- /dev/null
> +++ b/hw/s390x/sclpconsole.c
> @@ -0,0 +1,323 @@
> +/*
> + * SCLP event type
> + *    Ascii Console Data (VT220 Console)
> + *
> + * Copyright IBM, Corp. 2012
> + *
> + * Authors:
> + *  Heinz Graalfs <graalfs@de.ibm.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or (at your
> + * option) any later version.  See the COPYING file in the top-level directory.
> + *
> + */
> +
> +#include <hw/qdev.h>
> +#include "qemu-thread.h"
> +
> +#include "sclp.h"
> +#include "event-facility.h"
> +
> +typedef struct ASCIIConsoleData {
> +    EventBufferHeader ebh;
> +    char data[0];
> +} QEMU_PACKED ASCIIConsoleData;
> +
> +qemu_irq sclp_read_vt220;

This should go into SCLPConsole.

> +
> +/* max size for ASCII data in 4K SCCB page */
> +#define SIZE_BUFFER_VT220 4080
> +
> +typedef struct SCLPConsole {
> +    SCLPEvent event;
> +    CharDriverState *chr;
> +    /* io vector                                                       */
> +    uint8_t *iov;           /* iov buffer pointer                      */
> +    uint8_t *iov_sclp;      /* pointer to SCLP read offset             */
> +    uint8_t *iov_bs;        /* pointer byte stream read offset         */
> +    uint32_t iov_data_len;  /* length of byte stream in buffer         */
> +    uint32_t iov_sclp_rest; /* length of byte stream not read via SCLP */
> +} SCLPConsole;
> +
> +/* character layer call-back functions */
> +
> +/* Return number of bytes that fit into iov buffer */
> +static int chr_can_read(void *opaque)
> +{
> +    int can_read;
> +    SCLPConsole *scon = opaque;
> +
> +    qemu_mutex_lock(&scon->event.lock);
> +    can_read = SIZE_BUFFER_VT220 - scon->iov_data_len;
> +    qemu_mutex_unlock(&scon->event.lock);
> +
> +    return can_read;
> +}
> +
> +/* Receive n bytes from character layer, save in iov buffer,
> + * and set event pending */
> +static void receive_from_chr_layer(void *opaque, const uint8_t *buf, int size)
> +{
> +    SCLPConsole *scon = opaque;
> +
> +    assert(scon->iov);
> +
> +    qemu_mutex_lock(&scon->event.lock);
> +
> +    /* if new data do not fit into current buffer */
> +    if (scon->iov_data_len + size > SIZE_BUFFER_VT220) {
> +        /* character layer sent more than allowed */
> +        qemu_mutex_unlock(&scon->event.lock);
> +        return;
> +    }
> +    /* put byte-stream from character layer into buffer */
> +    memcpy(scon->iov_bs, buf, size);
> +    scon->iov_data_len += size;
> +    scon->iov_sclp_rest += size;
> +    scon->iov_bs += size;
> +    scon->event.event_pending = true;
> +
> +    qemu_mutex_unlock(&scon->event.lock);
> +}
> +
> +/* Send data from a char device over to the guest */
> +static void chr_read(void *opaque, const uint8_t *buf, int size)
> +{
> +    assert(opaque);
> +

I'd convert the opaque to SCLPConsole here and use that for
receive_from_chr_layer() instead of opaque.

> +    receive_from_chr_layer(opaque, buf, size);
> +    /* trigger SCLP read operation */
> +    qemu_irq_raise(sclp_read_vt220);
> +}
> +
> +static void chr_event(void *opaque, int event)
> +{
> +    SCLPConsole *scon = opaque;
> +
> +    switch (event) {
> +    case CHR_EVENT_OPENED:
> +        if (!scon->iov) {
> +            scon->iov = g_malloc0(SIZE_BUFFER_VT220);
> +            scon->iov_sclp = scon->iov;
> +            scon->iov_bs = scon->iov;
> +            scon->iov_data_len = 0;
> +            scon->iov_sclp_rest = 0;
> +        }
> +        break;
> +    case CHR_EVENT_CLOSED:
> +        if (scon->iov) {
> +            g_free(scon->iov);
> +            scon->iov = NULL;
> +        }
> +        break;
> +    }
> +}
> +
> +/* functions to be called by event facility */
> +
> +static int event_type(void)
> +{
> +    return SCLP_EVENT_ASCII_CONSOLE_DATA;
> +}
> +
> +static unsigned int send_mask(void)
> +{
> +    return SCLP_EVENT_MASK_MSG_ASCII;
> +}
> +
> +static unsigned int receive_mask(void)
> +{
> +    return SCLP_EVENT_MASK_MSG_ASCII;
> +}
> +
> +/* triggered by SCLP's read_event_data -
> + * copy console data byte-stream into provided (SCLP) buffer
> + */
> +static void get_console_data(SCLPEvent *event, uint8_t *buf, size_t *size,
> +                            int avail)
> +{
> +    SCLPConsole *cons = DO_UPCAST(SCLPConsole, event, event);
> +
> +    /* first byte is hex 0 saying an ascii string follows */
> +    *buf++ = '\0';
> +    avail--;
> +    /* if all data fit into provided SCLP buffer */
> +    if (avail >= cons->iov_sclp_rest) {
> +        /* copy character byte-stream to SCLP buffer */
> +        memcpy(buf, cons->iov_sclp, cons->iov_sclp_rest);
> +        *size = cons->iov_sclp_rest + 1;
> +        cons->iov_sclp = cons->iov;
> +        cons->iov_bs = cons->iov;
> +        cons->iov_data_len = 0;
> +        cons->iov_sclp_rest = 0;
> +        event->event_pending = false;
> +        /* data provided and no more data pending */
> +    } else {
> +        /* if provided buffer is too small, just copy part */
> +        memcpy(buf, cons->iov_sclp, avail);
> +        *size = avail + 1;
> +        cons->iov_sclp_rest -= avail;
> +        cons->iov_sclp += avail;
> +        /* more data pending */
> +    }
> +}
> +
> +static int read_event_data(SCLPEvent *event, EventBufferHeader *evt_buf_hdr,
> +                           int *slen)
> +{
> +    int avail;
> +    size_t src_len;
> +    uint8_t *to;
> +    ASCIIConsoleData *acd = (ASCIIConsoleData *) evt_buf_hdr;
> +
> +    qemu_mutex_lock(&event->lock);
> +
> +    if (!event->event_pending) {
> +        /* no data pending */
> +        qemu_mutex_unlock(&event->lock);
> +        return 0;
> +    }
> +
> +    to = (uint8_t *)&acd->data;
> +    avail = *slen - sizeof(ASCIIConsoleData);
> +    get_console_data(event, to, &src_len, avail);
> +
> +    acd->ebh.length = cpu_to_be16(sizeof(ASCIIConsoleData) + src_len);
> +    acd->ebh.type = SCLP_EVENT_ASCII_CONSOLE_DATA;
> +    acd->ebh.flags |= SCLP_EVENT_BUFFER_ACCEPTED;
> +    *slen = avail - src_len;
> +
> +    qemu_mutex_unlock(&event->lock);
> +
> +    return 1;
> +}
> +
> +/* triggered by SCLP's write_event_data
> + *  - write console data into character layer
> + *  returns < 0 if an error occured
> + */
> +static ssize_t write_console_data(SCLPEvent *event, const uint8_t *buf,
> +                                  size_t len)
> +{
> +    ssize_t ret = 0;
> +    const uint8_t *iov_offset;
> +    SCLPConsole *scon = DO_UPCAST(SCLPConsole, event, event);
> +
> +    if (!scon->chr) {
> +        /* If there's no backend, we can just say we consumed all data. */
> +        return len;
> +    }
> +
> +    iov_offset = buf;
> +    while (len > 0) {
> +        ret = qemu_chr_fe_write(scon->chr, buf, len);
> +        if (ret == 0) {
> +            /* a pty doesn't seem to be connected - no error */
> +            len = 0;
> +        } else if (ret == -EAGAIN || (ret > 0 && ret < len)) {
> +            len -= ret;
> +            iov_offset += ret;
> +        } else {
> +            len = 0;
> +        }
> +    }
> +
> +    return ret;
> +}
> +
> +static int write_event_data(SCLPEvent *event, EventBufferHeader *evt_buf_hdr)
> +{
> +    int rc;
> +    int length;
> +    ssize_t written;
> +    ASCIIConsoleData *acd = (ASCIIConsoleData *) evt_buf_hdr;
> +
> +    length = be16_to_cpu(evt_buf_hdr->length) - sizeof(EventBufferHeader);
> +    written = write_console_data(event, (uint8_t *)acd->data, length);
> +
> +    rc = SCLP_RC_NORMAL_COMPLETION;
> +    /* set event buffer accepted flag */
> +    evt_buf_hdr->flags |= SCLP_EVENT_BUFFER_ACCEPTED;
> +
> +    /* written will be zero if a pty is not connected - don't treat as error */
> +    if (written < 0) {
> +        /* event buffer not accepted due to error in character layer */
> +        evt_buf_hdr->flags &= ~(SCLP_EVENT_BUFFER_ACCEPTED);
> +        rc = SCLP_RC_CONTAINED_EQUIPMENT_CHECK;
> +    }
> +
> +    return rc;
> +}
> +
> +static void trigger_ascii_console_data(void *env, int n, int level)
> +{
> +    sclp_service_interrupt(0);
> +}
> +
> +/* qemu object creation and initialization functions */
> +
> +/* tell character layer our call-back functions */
> +static int console_init(SCLPEvent *event)
> +{
> +    static bool console_available;
> +
> +    SCLPConsole *scon = DO_UPCAST(SCLPConsole, event, event);
> +
> +    if (console_available) {
> +        error_report("Multiple VT220 operator consoles are not supported");
> +        return -1;
> +    }
> +    console_available = true;
> +    event->event_type = SCLP_EVENT_ASCII_CONSOLE_DATA;
> +    if (scon->chr) {
> +        qemu_chr_add_handlers(scon->chr, chr_can_read,
> +                              chr_read, chr_event, scon);
> +    }
> +    sclp_read_vt220 = *qemu_allocate_irqs(trigger_ascii_console_data,
> +                                          NULL, 1);
> +
> +    qemu_mutex_init(&event->lock);
> +
> +    return 0;
> +}
> +
> +static int console_exit(SCLPEvent *event)
> +{
> +    qemu_mutex_destroy(&event->lock);
> +
> +    return 0;
> +}
> +
> +static Property console_properties[] = {
> +    DEFINE_PROP_CHR("chardev", SCLPConsole, chr),
> +    DEFINE_PROP_END_OF_LIST(),
> +};
> +
> +static void console_class_init(ObjectClass *klass, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +    SCLPEventClass *ec = SCLP_EVENT_CLASS(klass);
> +
> +    dc->props = console_properties;
> +    ec->init = console_init;
> +    ec->exit = console_exit;
> +    ec->get_send_mask = send_mask;
> +    ec->get_receive_mask = receive_mask;
> +    ec->event_type = event_type;
> +    ec->read_event_data = read_event_data;
> +    ec->write_event_data = write_event_data;
> +}
> +
> +static TypeInfo sclp_console_info = {
> +    .name          = "sclpconsole",
> +    .parent        = TYPE_SCLP_EVENT,
> +    .instance_size = sizeof(SCLPConsole),
> +    .class_init    = console_class_init,
> +    .class_size    = sizeof(SCLPEventClass),
> +};
> +
> +static void register_types(void)
> +{
> +    type_register_static(&sclp_console_info);
> +}
> +type_init(register_types)
> --
> 1.7.0.1
>