Re: [PATCH v1 2/4] libxl: channels support

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On 09/19/2016 11:57 PM, Jim Fehlig wrote:
> On 09/16/2016 05:43 PM, Joao Martins wrote:
>> And allow libxl to handle channel element which creates a Xen
>> console visible to the guest as a low-bandwitdh communication
>> channel. If type is PTY we also fetch the tty after boot using
>> libxl_channel_getinfo to fetch the tty path.  Since support for
>> libxl channels only came on Xen >= 4.5 we therefore need to
>> conditionally compile it with LIBXL_HAVE_DEVICE_CHANNEL.
>>
>> After this patch and having a qemu guest agent:
>>  $ cat domain.xml | grep -a1 channel | head -n 5 | tail -n 4
>>  <channel type='unix'>
>>    <source mode='bind' path='/tmp/channel'/>
>>    <target type='xen' name='org.qemu.guest_agent.0'/>
>>  </channel>
>>
>>  $ virsh create domain.xml
>>  $ echo '{"execute":"guest-network-get-interfaces"}' | socat
>>  stdio,ignoreeof  unix-connect:/tmp/channel
>>
>>  {"execute":"guest-network-get-interfaces"}
>>  {"return": [{"name": "lo", "ip-addresses": [{"ip-address-type": "ipv4",
>>  "ip-address": "127.0.0.1", "prefix": 8}, {"ip-address-type": "ipv6",
>>  "ip-address": "::1", "prefix": 128}], "hardware-address":
>>  "00:00:00:00:00:00"}, {"name": "eth0", "ip-addresses":
>>  [{"ip-address-type": "ipv4", "ip-address": "10.100.0.6", "prefix": 24},
>>  {"ip-address-type": "ipv6", "ip-address": "fe80::216:3eff:fe40:88eb",
>>  "prefix": 64}], "hardware-address": "00:16:3e:40:88:eb"}, {"name":
>>  "sit0"}]}
>>
>> Signed-off-by: Joao Martins <joao.m.martins@xxxxxxxxxx>
>> ---
>>
>> NB: Should path be autogenerated if not included?
>> ---
>>  src/libxl/libxl_conf.c   | 90 ++++++++++++++++++++++++++++++++++++++++++++++++
>>  src/libxl/libxl_domain.c | 41 ++++++++++++++++++++++
>>  2 files changed, 131 insertions(+)
>>
>> diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
>> index 306e441..6fe0fa0 100644
>> --- a/src/libxl/libxl_conf.c
>> +++ b/src/libxl/libxl_conf.c
>> @@ -1490,6 +1490,91 @@ int libxlDriverConfigLoadFile(libxlDriverConfigPtr cfg,
>>  
>>  }
>>  
>> +#ifdef LIBXL_HAVE_DEVICE_CHANNEL
>> +static int
>> +libxlMakeChannel(virDomainChrDefPtr l_channel,
>> +                 libxl_device_channel *x_channel)
>> +{
>> +    int ret = -1;
>> +
>> +    libxl_device_channel_init(x_channel);
>> +
>> +    switch (l_channel->source.type) {
>> +    case VIR_DOMAIN_CHR_TYPE_PTY:
>> +        x_channel->connection = LIBXL_CHANNEL_CONNECTION_PTY;
>> +        break;
>> +    case VIR_DOMAIN_CHR_TYPE_UNIX:
>> +        x_channel->connection = LIBXL_CHANNEL_CONNECTION_SOCKET;
>> +        if (!l_channel->source.data.nix.path) {
>> +            virReportError(VIR_ERR_OPERATION_INVALID, "%s",
>> +                           _("channel path missing for unix type"));
>> +            return ret;
>> +        }
> 
> Will need to change if, as we think, a missing source path should be auto generated.
Yeap, will change this.

> 
>> +        if (VIR_STRDUP(x_channel->u.socket.path,
>> +                       l_channel->source.data.nix.path) < 0)
>> +            return ret;
>> +        break;
>> +    default:
>> +        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
>> +                       _("channel source type not supported"));
>> +        break;
>> +    }
>> +
>> +    switch (l_channel->targetType) {
>> +    case VIR_DOMAIN_CHR_CHANNEL_TARGET_TYPE_XEN:
>> +        if (!l_channel->target.name) {
>> +            virReportError(VIR_ERR_OPERATION_INVALID, "%s",
>> +                           _("channel target name missing"));
>> +            return ret;
>> +        }
>> +        if (VIR_STRDUP(x_channel->name, l_channel->target.name) < 0)
>> +            return ret;
>> +        ret = 0;
>> +        break;
>> +    default:
>> +        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
>> +                       _("channel target type not supported"));
>> +        break;
>> +    }
> 
> IMO we can check for targetType ==  VIR_DOMAIN_CHR_CHANNEL_TARGET_TYPE_XEN on
> entry to this function and do away with the switch statement.
Indeed, it's definitely clearer.

> 
>> +
>> +    return ret;
>> +}
>> +
>> +static int
>> +libxlMakeChannelList(virDomainDefPtr def, libxl_domain_config *d_config)
>> +{
>> +    virDomainChrDefPtr *l_channels = def->channels;
>> +    size_t nchannels = def->nchannels;
>> +    libxl_device_channel *x_channels;
>> +    size_t i, nvchannels = 0;
>> +
>> +    if (VIR_ALLOC_N(x_channels, nchannels) < 0)
>> +        return -1;
>> +
>> +    for (i = 0; i < nchannels; i++) {
>> +        if (l_channels[i]->deviceType != VIR_DOMAIN_CHR_DEVICE_TYPE_CHANNEL)
>> +            continue;
>> +
>> +        if (libxlMakeChannel(l_channels[i], &x_channels[nvchannels]) < 0)
>> +            goto error;
>> +
>> +        nvchannels++;
>> +    }
>> +
>> +    VIR_SHRINK_N(x_channels, nchannels, nchannels - nvchannels);
>> +    d_config->channels = x_channels;
>> +    d_config->num_channels = nvchannels;
>> +
>> +    return 0;
>> +
>> + error:
>> +    for (i = 0; i < nchannels; i++)
>> +        libxl_device_channel_dispose(&x_channels[i]);
>> +    VIR_FREE(x_channels);
>> +    return -1;
>> +}
>> +#endif
>> +
>>  #ifdef LIBXL_HAVE_PVUSB
>>  int
>>  libxlMakeUSBController(virDomainControllerDefPtr controller,
>> @@ -1864,6 +1949,11 @@ libxlBuildDomainConfig(virPortAllocatorPtr graphicsports,
>>          return -1;
>>  #endif
>>  
>> +#ifdef LIBXL_HAVE_DEVICE_CHANNEL
>> +    if (libxlMakeChannelList(def, d_config) < 0)
>> +        return -1;
>> +#endif
>> +
>>      /*
>>       * Now that any potential VFBs are defined, update the build info with
>>       * the data of the primary display. Some day libxl might implicitely do
>> diff --git a/src/libxl/libxl_domain.c b/src/libxl/libxl_domain.c
>> index 43f4a7f..86c7d8e 100644
>> --- a/src/libxl/libxl_domain.c
>> +++ b/src/libxl/libxl_domain.c
>> @@ -1059,6 +1059,42 @@ libxlDomainCreateIfaceNames(virDomainDefPtr def, libxl_domain_config *d_config)
>>      }
>>  }
>>  
>> +#ifdef LIBXL_HAVE_DEVICE_CHANNEL
>> +static void
>> +libxlDomainCreateChannelPTY(virDomainDefPtr def, libxl_ctx *ctx)
>> +{
>> +    libxl_device_channel *x_channels;
>> +    virDomainChrDefPtr chr;
>> +    size_t i;
>> +    int nchannels;
>> +
>> +    x_channels = libxl_device_channel_list(ctx, def->id, &nchannels);
>> +    if (!x_channels)
>> +        return;
>> +
>> +    for (i = 0; i < def->nchannels; i++) {
>> +        libxl_channelinfo channelinfo;
>> +        int ret;
>> +
>> +        chr = def->channels[i];
>> +        if (chr->source.type != VIR_DOMAIN_CHR_TYPE_PTY)
>> +            continue;
>> +
>> +        ret = libxl_device_channel_getinfo(ctx, def->id, &x_channels[i],
>> +                                           &channelinfo);
>> +
>> +        if (!ret && channelinfo.u.pty.path &&
>> +            channelinfo.u.pty.path != '\0') {
>> +                VIR_FREE(chr->source.data.file.path);
>> +                ignore_value(VIR_STRDUP(chr->source.data.file.path,
>> +                                        channelinfo.u.pty.path));
>> +            }
>> +    }
>> +
>> +    for (i = 0; i < nchannels; i++)
>> +        libxl_device_channel_dispose(&x_channels[i]);
>> +}
>> +#endif
>>  
>>  #ifdef LIBXL_HAVE_SRM_V2
>>  # define LIBXL_DOMSTART_RESTORE_VER_ATTR /* empty */
>> @@ -1263,6 +1299,11 @@ libxlDomainStart(libxlDriverPrivatePtr driver,
>>  
>>      libxlDomainCreateIfaceNames(vm->def, &d_config);
>>  
>> +#ifdef LIBXL_HAVE_DEVICE_CHANNEL
>> +    if (vm->def->nchannels > 0)
>> +        libxlDomainCreateChannelPTY(vm->def, cfg->ctx);
>> +#endif
>> +
>>      if ((dom_xml = virDomainDefFormat(vm->def, cfg->caps, 0)) == NULL)
>>          goto destroy_dom;
>>  
> 
> Otherwise, looks good.
Cool!

Joao
> 
> Regards,
> Jim
> 

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