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

[Alexander Graf]

On 29.10.2012, at 13:13, Jens Freimann wrote:

> From: Heinz Graalfs <address@hidden>
> 
> 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 <address@hidden>
> Signed-off-by: Christian Borntraeger <address@hidden>
> Signed-off-by: Jens Freimann <address@hidden>
> ---
> hw/s390x/Makefile.objs |   2 +-
> hw/s390x/sclpconsole.c | 306 +++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 307 insertions(+), 1 deletion(-)
> 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..0ec5623
> --- /dev/null
> +++ b/hw/s390x/sclpconsole.c
> @@ -0,0 +1,306 @@
> +/*
> + * SCLP event type
> + *    Ascii Console Data (VT220 Console)
> + *
> + * Copyright IBM, Corp. 2012
> + *
> + * Authors:
> + *  Heinz Graalfs <address@hidden>
> + *
> + * 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;
> +
> +/* 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 */
> +    qemu_irq irq_read_vt220;
> +} 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;
> +
> +    can_read = SIZE_BUFFER_VT220 - scon->iov_data_len;
> +
> +    return can_read;
> +}
> +
> +/* Receive n bytes from character layer, save in iov buffer,
> + * and set event pending */
> +static void receive_from_chr_layer(SCLPConsole *scon, const uint8_t *buf,
> +                                   int size)
> +{
> +    assert(scon->iov);
> +
> +    /* read data must fit into current buffer */
> +    assert(size <= SIZE_BUFFER_VT220 - scon->iov_data_len);
> +
> +    /* 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;
> +}
> +
> +/* Send data from a char device over to the guest */
> +static void chr_read(void *opaque, const uint8_t *buf, int size)
> +{
> +    SCLPConsole *scon = opaque;
> +
> +    assert(scon);
> +
> +    receive_from_chr_layer(scon, buf, size);
> +    /* trigger SCLP read operation */
> +    qemu_irq_raise(scon->irq_read_vt220);

I don't think you need to model this through a qemu_irq here. Just directly 
call your interrupt injection function. Maybe we want to later add real 
payloaded s390 style qemu_s390_irq support. By that time we can reconsider that 
decision.

Either way, the code as is is functional, so I'll apply it nevertheless :)


Alex