Re: [Qemu-devel] [PATCH 2/4] QAPI: Introduce memchar-write QMP command

[Luiz Capitulino]

On Fri, 26 Oct 2012 19:21:50 +0800
Lei Li <address@hidden> wrote:

> Signed-off-by: Lei Li <address@hidden>
> ---
>  hmp-commands.hx  |   17 +++++++++++++++++
>  hmp.c            |   15 +++++++++++++++
>  hmp.h            |    1 +
>  qapi-schema.json |   47 +++++++++++++++++++++++++++++++++++++++++++++++
>  qemu-char.c      |   44 ++++++++++++++++++++++++++++++++++++++++++++
>  qmp-commands.hx  |   34 ++++++++++++++++++++++++++++++++++
>  6 files changed, 158 insertions(+), 0 deletions(-)
> 
> diff --git a/hmp-commands.hx b/hmp-commands.hx
> index e0b537d..a37b8e9 100644
> --- a/hmp-commands.hx
> +++ b/hmp-commands.hx
> @@ -825,6 +825,23 @@ Inject an NMI on the given CPU (x86 only).
>  ETEXI
>  
>      {
> +        .name       = "memchar_write",
> +        .args_type  = "chardev:s,data:s",
> +        .params     = "chardev data",
> +        .mhandler.cmd = hmp_memchar_write,
> +    },
> +
> +STEXI
> address@hidden memchar_write @var{chardev} @var{data}
> address@hidden memchar_write
> +Provide writing interface for CirMemCharDriver. Write @var{data}
> +to cirmemchr char device. Note that we  will add 'control' options
> +for read and write command that specifies behavior when the queue
> +is full/empty, for now just assume a drop behaver in these two commands.

You can drop everything after "Note".

> +
> +ETEXI
> +
> +    {
>          .name       = "migrate",
>          .args_type  = "detach:-d,blk:-b,inc:-i,uri:s",
>          .params     = "[-d] [-b] [-i] uri",
> diff --git a/hmp.c b/hmp.c
> index 2b97982..082985b 100644
> --- a/hmp.c
> +++ b/hmp.c
> @@ -683,6 +683,21 @@ void hmp_pmemsave(Monitor *mon, const QDict *qdict)
>      hmp_handle_error(mon, &errp);
>  }
>  
> +void hmp_memchar_write(Monitor *mon, const QDict *qdict)
> +{
> +    uint32_t size;
> +    const char *chardev = qdict_get_str(qdict, "chardev");
> +    const char *data = qdict_get_str(qdict, "data");
> +    enum DataFormat format;

Why do you need this variable?

> +    Error *errp = NULL;
> +
> +    size = strlen(data);
> +    format = DATA_FORMAT_UTF8;
> +    qmp_memchar_write(chardev, size, data, true, format, &errp);
> +
> +    hmp_handle_error(mon, &errp);
> +}
> +
>  static void hmp_cont_cb(void *opaque, int err)
>  {
>      if (!err) {
> diff --git a/hmp.h b/hmp.h
> index 71ea384..406ebb1 100644
> --- a/hmp.h
> +++ b/hmp.h
> @@ -43,6 +43,7 @@ void hmp_system_powerdown(Monitor *mon, const QDict *qdict);
>  void hmp_cpu(Monitor *mon, const QDict *qdict);
>  void hmp_memsave(Monitor *mon, const QDict *qdict);
>  void hmp_pmemsave(Monitor *mon, const QDict *qdict);
> +void hmp_memchar_write(Monitor *mon, const QDict *qdict);
>  void hmp_cont(Monitor *mon, const QDict *qdict);
>  void hmp_system_wakeup(Monitor *mon, const QDict *qdict);
>  void hmp_inject_nmi(Monitor *mon, const QDict *qdict);
> diff --git a/qapi-schema.json b/qapi-schema.json
> index c615ee2..43ef6bc 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -325,6 +325,53 @@
>  { 'command': 'query-chardev', 'returns': ['ChardevInfo'] }
>  
>  ##
> +# @DataFormat:
> +#
> +# An enumeration of data format. The default value would
> +# be utf8.

Please, remove the "default value" part. This is decided by the command
using this type.

> +#
> +# @utf8: The data format is 'utf8'.
> +#
> +# @base64: The data format is 'base64'.
> +#
> +# Note: The data format start with 'utf8' and 'base64',
> +#       will support other data format as well.

Please, drop this note. It's not needed.

> +#
> +# Since: 1.3
> +##
> +{ 'enum': 'DataFormat'
> +  'data': [ 'utf8', 'base64' ] }
> +
> +##
> +# @memchar-write:
> +#
> +# Provide writing interface for memchardev. Write data to memchar
> +# char device.
> +#
> +# @chardev: the name of the memchar char device.
> +#
> +# @size: the size to write in bytes. Should be power of 2.
> +#
> +# @data: the source data write to memchar.
> +#
> +# @format: #optional the format of the data write to memchardev, by
> +#          default is 'utf8'.
> +#
> +# Returns: Nothing on success
> +#          If @chardev is not a valid memchr device, DeviceNotFound
> +#
> +# Notes: The option 'block' is not supported now due to the miss
> +#        feature in qmp. Will add it later when we gain the necessary
> +#        infrastructure enhancement. For now just assume 'drop' behaver
> +#        for this command.

Please, replace this note with an explanation of the current behavior. No
need to talk about the future.

> +#
> +# Since: 1.3
> +##
> +{ 'command': 'memchar-write',
> +  'data': {'chardev': 'str', 'size': 'int', 'data': 'str',
> +           '*format': 'DataFormat'} }
> +
> +##
>  # @CommandInfo:
>  #
>  # Information about a QMP command
> diff --git a/qemu-char.c b/qemu-char.c
> index c3ec43d..6114e29 100644
> --- a/qemu-char.c
> +++ b/qemu-char.c
> @@ -2717,6 +2717,50 @@ fail:
>      return NULL;
>  }
>  
> +void qmp_memchar_write(const char *chardev, int64_t size,
> +                       const char *data, bool has_format,
> +                       enum DataFormat format,
> +                       Error **errp)
> +{
> +    CharDriverState *chr;
> +    guchar *write_data;
> +    int ret;
> +    gsize write_count;
> +
> +    chr = qemu_chr_find(chardev);
> +    if (!chr) {
> +        error_set(errp, QERR_DEVICE_NOT_FOUND, chardev);
> +        return;
> +    }
> +
> +    if (strcmp(chr->filename, "memchr") != 0) {
> +        error_setg(errp,"%s is not memory char device\n", chardev);
> +        return;
> +    }

This is wrong, as it's unreliable. A hackish (but hopefully correct) way
of doing this would be to check chr->init against the circmem init function.
But please, put this behind a function because it's ugly.

> +
> +    /* XXX: For the sync command as 'block', waiting for the qmp
> +     * to support necessary feature. Now just act as 'drop' */

Please, replace this note with an explanation of the current behavior.

> +    if (cirmem_chr_is_full(chr)) {
> +        error_setg(errp, "Failed to write to memchr %s", chardev);
> +        return;
> +    }
> +
> +    write_count = (gsize)size;
> +
> +    if (has_format && (format == DATA_FORMAT_BASE64)) {
> +        write_data = g_base64_decode(data, &write_count);
> +    } else {
> +        write_data = (uint8_t *)data;
> +    }
> +
> +    ret = cirmem_chr_write(chr, write_data, write_count);

IIRC circmem_chr_write() doesn't check if write_count if a power of two,
what happens if it isn't?

> +
> +    if (ret < 0) {
> +        error_setg(errp, "Failed to write to memchr %s", chardev);
> +        return;
> +    }
> +}
> +
>  QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename)
>  {
>      char host[65], port[33], width[8], height[8];
> diff --git a/qmp-commands.hx b/qmp-commands.hx
> index 5ba8c48..7548b9b 100644
> --- a/qmp-commands.hx
> +++ b/qmp-commands.hx
> @@ -466,6 +466,40 @@ Note: inject-nmi fails when the guest doesn't support 
> injecting.
>  EQMP
>  
>      {
> +        .name       = "memchar-write",
> +        .args_type  = "chardev:s,size:i,data:s,format:s?,control:s?",

You've dropped 'control', haven't you?

> +        .help       = "write size of data to memchar chardev",
> +        .mhandler.cmd_new = qmp_marshal_input_memchar_write,
> +    },
> +
> +SQMP
> +memchar-write
> +-------------
> +
> +Provide writing interface for memchardev. Write data to memchar
> +char device.
> +
> +Arguments:
> +
> +- "chardev": the name of the char device, must be unique (json-string)
> +- "size": the memory size, in bytes, should be power of 2 (json-int)
> +- "data": the source data writed to memchar (json-string)
> +- "format": the data format write to memchardev, default is
> +            utf8. (json-string, optional)
> +          - Possible values: "utf8", "base64"
> +
> +Example:
> +
> +-> { "execute": "memchar-write",
> +                "arguments": { "chardev": foo,
> +                               "size": 8,
> +                               "data": "abcdefgh",
> +                               "format": "utf8" } }
> +<- { "return": {} }
> +
> +EQMP
> +
> +    {
>          .name       = "xen-save-devices-state",
>          .args_type  = "filename:F",
>      .mhandler.cmd_new = qmp_marshal_input_xen_save_devices_state,