Re: [PATCH v2 2/4] libxl: channels support

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On 09/22/2016 01:53 PM, Joao Martins wrote:
> 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. On socket case,
> we autogenerate a path if not specified in the XML. Path autogenerated
> is slightly different from qemu driver: qemu stores also on
> "channels/target" but it creates then a directory per domain with
> each channel target name. libxl doesn't appear to have a clear
> definition of private files associated with each domain, so for
> simplicity we do it slightly different. On qemu each autogenerated
> channel goes like:
>
> channels/target/<domain-name>/<target name>
>
> Whereas for libxl:
>
> channels/target/<domain-name>-<target name>
>
> Should note that if path is not specified it won't persist,
> existing only on live XML, unless user had initially specified it.
> 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>
> ---
> Since v1:
> * Autogenerated paths, and updated commit message explaning it the different
> naming. Despite per domain name being slightly different, parent
> directory is same across both drivers.
> * Remove the switch case from target type xen and rework the function structure
> a bit.
> ---
>  src/libxl/libxl_conf.c   | 120 ++++++++++++++++++++++++++++++++++++++++++++++-
>  src/libxl/libxl_conf.h   |   4 +-
>  src/libxl/libxl_domain.c |  44 ++++++++++++++++-
>  src/libxl/libxl_driver.c |   7 +++
>  4 files changed, 171 insertions(+), 4 deletions(-)
>
> diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
> index 306e441..824f2d2 100644
> --- a/src/libxl/libxl_conf.c
> +++ b/src/libxl/libxl_conf.c
> @@ -88,6 +88,7 @@ libxlDriverConfigDispose(void *obj)
>      VIR_FREE(cfg->saveDir);
>      VIR_FREE(cfg->autoDumpDir);
>      VIR_FREE(cfg->lockManagerName);
> +    VIR_FREE(cfg->channelDir);
>      virFirmwareFreeList(cfg->firmwares, cfg->nfirmwares);
>  }
>  
> @@ -1339,6 +1340,8 @@ libxlDriverConfigNew(void)
>          goto error;
>      if (VIR_STRDUP(cfg->autoDumpDir, LIBXL_DUMP_DIR) < 0)
>          goto error;
> +    if (VIR_STRDUP(cfg->channelDir, LIBXL_CHANNEL_DIR) < 0)
> +        goto error;
>  
>      if (virAsprintf(&log_file, "%s/libxl-driver.log", cfg->logDir) < 0)
>          goto error;
> @@ -1490,6 +1493,114 @@ int libxlDriverConfigLoadFile(libxlDriverConfigPtr cfg,
>  
>  }
>  
> +#ifdef LIBXL_HAVE_DEVICE_CHANNEL
> +static int
> +libxlPrepareChannel(virDomainChrDefPtr channel,
> +                    const char *channelDir,
> +                    const char *domainName)
> +{
> +    if (channel->targetType == VIR_DOMAIN_CHR_CHANNEL_TARGET_TYPE_XEN &&
> +        channel->source.type == VIR_DOMAIN_CHR_TYPE_UNIX &&
> +        !channel->source.data.nix.path) {
> +        if (virAsprintf(&channel->source.data.nix.path,
> +                        "%s/%s-%s", channelDir, domainName,
> +                        channel->target.name ? channel->target.name
> +                        : "unknown.sock") < 0)
> +            return -1;
> +
> +        channel->source.data.nix.listen = true;
> +    }
> +
> +    return 0;
> +}
> +
> +static int
> +libxlMakeChannel(virDomainChrDefPtr l_channel,
> +                 libxl_device_channel *x_channel)
> +{
> +    int ret = -1;

Similar to the other libxlMake* functions, ret could be dropped simply return -1
when encountering failure.

> +
> +    libxl_device_channel_init(x_channel);
> +
> +    if (l_channel->targetType != VIR_DOMAIN_CHR_CHANNEL_TARGET_TYPE_XEN) {
> +        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> +                       _("channel target type not supported"));
> +        return ret;
> +    }
> +
> +    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 (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;
> +    }
> +
> +    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;
> +
> +    return 0;
> +}
> +
> +static int
> +libxlMakeChannelList(libxlDriverPrivatePtr driver,
> +                     virDomainDefPtr def,
> +                     libxl_domain_config *d_config)
> +{
> +    virDomainChrDefPtr *l_channels = def->channels;
> +    size_t nchannels = def->nchannels;
> +    libxl_device_channel *x_channels;
> +    libxlDriverConfigPtr cfg;
> +    size_t i, nvchannels = 0;
> +
> +    if (VIR_ALLOC_N(x_channels, nchannels) < 0)
> +        return -1;
> +
> +    cfg = libxlDriverConfigGet(driver);
> +
> +    for (i = 0; i < nchannels; i++) {
> +        if (l_channels[i]->deviceType != VIR_DOMAIN_CHR_DEVICE_TYPE_CHANNEL)
> +            continue;
> +
> +        if (libxlPrepareChannel(l_channels[i], cfg->channelDir, def->name) < 0)
> +            goto error;
> +
> +        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;
> +    virObjectUnref(cfg);
> +
> +    return 0;
> +
> + error:
> +    for (i = 0; i < nchannels; i++)
> +        libxl_device_channel_dispose(&x_channels[i]);
> +    VIR_FREE(x_channels);
> +    virObjectUnref(cfg);
> +    return -1;
> +}
> +#endif
> +
>  #ifdef LIBXL_HAVE_PVUSB
>  int
>  libxlMakeUSBController(virDomainControllerDefPtr controller,
> @@ -1828,11 +1939,13 @@ libxlDriverNodeGetInfo(libxlDriverPrivatePtr driver, virNodeInfoPtr info)
>  }
>  
>  int
> -libxlBuildDomainConfig(virPortAllocatorPtr graphicsports,
> +libxlBuildDomainConfig(libxlDriverPrivatePtr driver,
>                         virDomainDefPtr def,
>                         libxl_ctx *ctx,
>                         libxl_domain_config *d_config)
>  {
> +    virPortAllocatorPtr graphicsports = driver->reservedGraphicsPorts;
> +

Spurious change?

>      libxl_domain_config_init(d_config);
>  
>      if (libxlMakeDomCreateInfo(ctx, def, &d_config->c_info) < 0)
> @@ -1864,6 +1977,11 @@ libxlBuildDomainConfig(virPortAllocatorPtr graphicsports,
>          return -1;
>  #endif
>  
> +#ifdef LIBXL_HAVE_DEVICE_CHANNEL
> +    if (libxlMakeChannelList(driver, 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_conf.h b/src/libxl/libxl_conf.h
> index ed5a3de..56a3d4a 100644
> --- a/src/libxl/libxl_conf.h
> +++ b/src/libxl/libxl_conf.h
> @@ -57,6 +57,7 @@
>  # define LIBXL_LIB_DIR LOCALSTATEDIR "/lib/libvirt/libxl"
>  # define LIBXL_SAVE_DIR LIBXL_LIB_DIR "/save"
>  # define LIBXL_DUMP_DIR LIBXL_LIB_DIR "/dump"
> +# define LIBXL_CHANNEL_DIR LIBXL_LIB_DIR "/channel/target"
>  # define LIBXL_BOOTLOADER_PATH "pygrub"
>  
>  
> @@ -98,6 +99,7 @@ struct _libxlDriverConfig {
>      char *libDir;
>      char *saveDir;
>      char *autoDumpDir;
> +    char *channelDir;
>  
>      virFirmwarePtr *firmwares;
>      size_t nfirmwares;
> @@ -197,7 +199,7 @@ virDomainXMLOptionPtr
>  libxlCreateXMLConf(void);
>  
>  int
> -libxlBuildDomainConfig(virPortAllocatorPtr graphicsports,
> +libxlBuildDomainConfig(libxlDriverPrivatePtr driver,
>                         virDomainDefPtr def,
>                         libxl_ctx *ctx,
>                         libxl_domain_config *d_config);

And here.

> diff --git a/src/libxl/libxl_domain.c b/src/libxl/libxl_domain.c
> index 43f4a7f..0540afb 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 */
> @@ -1181,8 +1217,7 @@ libxlDomainStart(libxlDriverPrivatePtr driver,
>      if (libxlNetworkPrepareDevices(vm->def) < 0)
>          goto cleanup_dom;
>  
> -    if (libxlBuildDomainConfig(driver->reservedGraphicsPorts, vm->def,
> -                               cfg->ctx, &d_config) < 0)
> +    if (libxlBuildDomainConfig(driver, vm->def, cfg->ctx, &d_config) < 0)

And a final one here?

Regards,
Jim

>          goto cleanup_dom;
>  
>      if (cfg->autoballoon && libxlDomainFreeMem(cfg->ctx, &d_config) < 0)
> @@ -1263,6 +1298,11 @@ 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;
>  
> diff --git a/src/libxl/libxl_driver.c b/src/libxl/libxl_driver.c
> index 42fa129..d555202 100644
> --- a/src/libxl/libxl_driver.c
> +++ b/src/libxl/libxl_driver.c
> @@ -718,6 +718,13 @@ libxlStateInitialize(bool privileged,
>                         virStrerror(errno, ebuf, sizeof(ebuf)));
>          goto error;
>      }
> +    if (virFileMakePath(cfg->channelDir) < 0) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR,
> +                       _("failed to create channel dir '%s': %s"),
> +                       cfg->channelDir,
> +                       virStrerror(errno, ebuf, sizeof(ebuf)));
> +        goto error;
> +    }
>  
>      if (!(libxl_driver->lockManager =
>            virLockManagerPluginNew(cfg->lockManagerName ?

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