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

[Lei Li]

On 10/27/2012 01:17 AM, Luiz Capitulino wrote:
> 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".
ok

> > +
> > +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?

Sure, I will drop this.

> > +    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.

Now the option format is optional, if it's not set then default by 'utf8'.
I think it's a reasonable behaver. :)

> > +#
> > +# @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.
ok

> > +#
> > +# 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.

Sure.

> > +#
> > +# 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.

Hmm, I guess it's because the chr->filename could be NULL. but we can still
get it since CharDriverState keeps the inited type of backend. I am not sure
that check chr->init against the cirmem init funciton could work, I'll have
a try.

> > +
> > +    /* 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.

ok.

> > +    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?

I have considered your suggestion on this in v4. The reason why I did not
add the assert is that I think we have already check with this when cirmem
init, so there is no need to check it again. Correct me if I am wrong. :)

> > +
> > +    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?

Yes, sorry I forgot to drop here.. :(

> > +        .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,


--
Lei