Re: [Qemu-devel] [multiprocess RFC PATCH 21/37] multi-process: QMP/HMP commands to add a device to the remote process

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* elena.ufimtseva@oracle.com (elena.ufimtseva@oracle.com) wrote:
> From: Jagannathan Raman <jag.raman@oracle.com>
> 
> Adds rdevice_add QMP & HMP commands to hotplug device to a remote device.
> 
> Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
> Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
> Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
> ---
>  hmp-commands.hx         | 14 ++++++++
>  hmp.h                   |  1 +
>  hw/proxy/monitor.c      | 92 +++++++++++++++++++++++++++++++++++++++++++++++++
>  include/io/proxy-link.h |  2 ++
>  include/monitor/qdev.h  |  4 +++
>  monitor.c               |  5 +++
>  qapi/misc.json          | 22 ++++++++++++
>  remote/remote-main.c    | 48 ++++++++++++++++++++++++++
>  8 files changed, 188 insertions(+)
> 
> diff --git a/hmp-commands.hx b/hmp-commands.hx
> index fb3c8ba..7e8e8ab 100644
> --- a/hmp-commands.hx
> +++ b/hmp-commands.hx
> @@ -727,6 +727,20 @@ ETEXI
>  
>  #if defined(CONFIG_MPQEMU)
>      {
> +        .name       = "rdevice_add",
> +        .args_type  = "rdev_id:s,driver:s,id:s,drive:s,bus:s",
> +        .params     = "rdev_id driver id drive bus",
> +        .help       = "add device to remote proc, like -rdevice on the command line",
> +        .cmd        = hmp_rdevice_add,
> +    },
> +
> +STEXI
> +@item rdevice_add @var{config}
> +@findex rdevice_add
> +Add device to remote proc.
> +ETEXI
> +
> +    {
>          .name       = "remote_proc_list",
>          .args_type  = "",
>          .params     = "",
> diff --git a/hmp.h b/hmp.h
> index 0940634..355a27e 100644
> --- a/hmp.h
> +++ b/hmp.h
> @@ -150,5 +150,6 @@ void hmp_info_vm_generation_id(Monitor *mon, const QDict *qdict);
>  void hmp_info_memory_size_summary(Monitor *mon, const QDict *qdict);
>  void hmp_info_sev(Monitor *mon, const QDict *qdict);
>  void hmp_remote_proc_list(Monitor *mon, const QDict *qdict);
> +void hmp_rdevice_add(Monitor *mon, const QDict *qdict);
>  
>  #endif
> diff --git a/hw/proxy/monitor.c b/hw/proxy/monitor.c
> index 3005eec..2e2cda0 100644
> --- a/hw/proxy/monitor.c
> +++ b/hw/proxy/monitor.c
> @@ -23,6 +23,7 @@
>   */
>  
>  #include <sys/types.h>
> +#include <string.h>
>  
>  #include "qemu/osdep.h"
>  #include "qapi/qapi-types-block-core.h"
> @@ -33,6 +34,13 @@
>  #include "hw/boards.h"
>  #include "hw/i386/pc.h"
>  #include "hw/proxy/qemu-proxy.h"
> +#include "qapi/qapi-commands-misc.h"
> +#include "monitor/qdev.h"
> +#include "qapi/qmp/qdict.h"
> +#include "qapi/qmp/qjson.h"
> +#include "qapi/qmp/qstring.h"
> +#include "qapi/error.h"
> +#include "io/proxy-link.h"
>  
>  /*
>   * TODO: Is there a callback where the allocated memory for QMP could be free'd
> @@ -87,3 +95,87 @@ void hmp_remote_proc_list(Monitor *mon, const QDict *qdict)
>                         pdev->remote_pid, pdev->rid, id, k->command);
>      }
>  }
> +
> +static PCIProxyDev *get_proxy_device(QDict *qdict, Error **errp)
> +{
> +    PCMachineState *pcms = PC_MACHINE(current_machine);
> +    PCIProxyDev *pdev = NULL;
> +    const char *rdev_id;
> +
> +    if (!qdict_haskey(qdict, "rdev_id")) {
> +        error_setg(errp, "Please specify a value for rdev_id");
> +        return NULL;
> +    }
> +
> +    rdev_id = qdict_get_str(qdict, "rdev_id");
> +
> +    pdev = (PCIProxyDev *)g_hash_table_lookup(pcms->remote_devs, rdev_id);
> +    if (!pdev) {
> +        error_setg(errp,
> +                   "No remote device by ID %s. Use query-remote command to get remote devices",
> +                   rdev_id);
> +    }
> +
> +    return pdev;
> +}
> +
> +static void rdevice_add_del(QDict *qdict, proc_cmd_t cmd, Error **errp)
> +{
> +    PCMachineState *pcms = PC_MACHINE(current_machine);
> +    ProcMsg msg = {0};
> +    PCIProxyDev *pdev = NULL;
> +    const char *id;
> +    QString *json;
> +    int wait;
> +
> +    pdev = get_proxy_device(qdict, errp);
> +    if (*errp) {
> +        return;
> +    }
> +
> +    qdict_del(qdict, "rdev_id");
> +
> +    id = qdict_get_str(qdict, "id");
> +
> +    json = qobject_to_json(QOBJECT(qdict));
> +
> +    wait = GET_REMOTE_WAIT;
> +
> +    msg.cmd = cmd;
> +    msg.bytestream = 1;
> +    msg.size = strlen(qstring_get_str(json));
> +    msg.data2 = (uint8_t *)qstring_get_str(json);
> +    msg.num_fds = 1;
> +    msg.fds[0] = wait;
> +
> +    proxy_proc_send(pdev->proxy_link, &msg);
> +    (void)wait_for_remote(wait);
> +    PUT_REMOTE_WAIT(wait);

Can this not fail? For example what happens if the external
process dies just about here?

> +    qstring_destroy_obj(QOBJECT(json));

All of this:
    build some JSON
    send it to the remote
    wait for the response

all looks like something more generic than a device add/del - separate
function?

> +    /* TODO: Only on success */
> +    if (cmd == DEVICE_ADD) {
> +        (void)g_hash_table_insert(pcms->remote_devs, (gpointer)g_strdup(id),
> +                                  (gpointer)pdev);
> +    }
> +}
> +
> +void qmp_rdevice_add(QDict *qdict, QObject **ret_data, Error **errp)
> +{
> +    rdevice_add_del(qdict, DEVICE_ADD, errp);
> +}
> +
> +void hmp_rdevice_add(Monitor *mon, const QDict *qdict)
> +{
> +    Error *err = NULL;
> +
> +    /* TODO: Is it OK to modify the QDict argument from HMP? */
> +    rdevice_add_del((QDict *)qdict, DEVICE_ADD, &err);
> +
> +    if (err) {
> +        monitor_printf(mon, "rdevice_add error: %s\n",
> +                       error_get_pretty(err));
> +        error_free(err);
> +    }
> +}
> diff --git a/include/io/proxy-link.h b/include/io/proxy-link.h
> index 175e2f1..8781508 100644
> --- a/include/io/proxy-link.h
> +++ b/include/io/proxy-link.h
> @@ -60,6 +60,7 @@ typedef struct ProxyLinkState ProxyLinkState;
>   * BAR_READ         Reads from PCI BAR region
>   * SET_IRQFD        Sets the IRQFD to be used to raise interrupts directly
>   *                  from remote device
> + * DEVICE_ADD       QMP/HMP command to hotplug device
>   *
>   */
>  typedef enum {
> @@ -70,6 +71,7 @@ typedef enum {
>      BAR_WRITE,
>      BAR_READ,
>      SET_IRQFD,
> +    DEVICE_ADD,
>      MAX,
>  } proc_cmd_t;
>  
> diff --git a/include/monitor/qdev.h b/include/monitor/qdev.h
> index 0ff3331..065701c 100644
> --- a/include/monitor/qdev.h
> +++ b/include/monitor/qdev.h
> @@ -10,6 +10,10 @@ void hmp_info_qdm(Monitor *mon, const QDict *qdict);
>  void hmp_info_qom_tree(Monitor *mon, const QDict *dict);
>  void qmp_device_add(QDict *qdict, QObject **ret_data, Error **errp);
>  
> +#ifdef CONFIG_MPQEMU
> +void qmp_rdevice_add(QDict *qdict, QObject **ret_data, Error **errp);
> +#endif
> +

I don't think you need to bother ifdef'ing the headers

>  int qdev_device_help(QemuOpts *opts);
>  DeviceState *qdev_device_add(QemuOpts *opts, Error **errp);
>  void qdev_set_id(DeviceState *dev, const char *id);
> diff --git a/monitor.c b/monitor.c
> index defa129..0ad52e5 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -1155,6 +1155,11 @@ static void monitor_init_qmp_commands(void)
>      qmp_register_command(&qmp_commands, "netdev_add", qmp_netdev_add,
>                           QCO_NO_OPTIONS);
>  
> +#ifdef CONFIG_MPQEMU
> +    qmp_register_command(&qmp_commands, "rdevice_add", qmp_rdevice_add,
> +                         QCO_NO_OPTIONS);
> +#endif
> +
>      QTAILQ_INIT(&qmp_cap_negotiation_commands);
>      qmp_register_command(&qmp_cap_negotiation_commands, "qmp_capabilities",
>                           qmp_marshal_qmp_capabilities, QCO_ALLOW_PRECONFIG);
> diff --git a/qapi/misc.json b/qapi/misc.json
> index 8b3ca4f..28d49ea 100644
> --- a/qapi/misc.json
> +++ b/qapi/misc.json
> @@ -1663,6 +1663,28 @@
>    'gen': false } # so we can get the additional arguments
>  
>  ##
> +# @rdevice_add:
> +#
> +# @rdev_id: ID of the remote device root
> +#
> +# @driver: the name of the new device's driver
> +#
> +# @bus: the device's parent bus (device tree path)
> +#
> +# @id: the device's ID, must be unique
> +#
> +# Additional arguments depend on the type.
> +#
> +# Add a device.
> +#
> +# Since: 3.0
> +##
> +{ 'command': 'rdevice_add',
> +  'data': {'rdev_id': 'str', 'driver': 'str', '*bus': 'str', '*id': 'str'},
> +  'if': 'defined(CONFIG_MPQEMU)',
> +  'gen': false } # so we can get the additional arguments
> +
> +##
>  # @device_del:
>  #
>  # Remove a device from a guest
> diff --git a/remote/remote-main.c b/remote/remote-main.c
> index 4683e7d..03c14de 100644
> --- a/remote/remote-main.c
> +++ b/remote/remote-main.c
> @@ -48,6 +48,11 @@
>  #include "exec/memattrs.h"
>  #include "exec/address-spaces.h"
>  #include "remote/iohub.h"
> +#include "qapi/qmp/qjson.h"
> +#include "qapi/qmp/qobject.h"
> +#include "qemu/option.h"
> +#include "qemu/config-file.h"
> +#include "monitor/qdev.h"
>  
>  static ProxyLinkState *proxy_link;
>  PCIDevice *remote_pci_dev;
> @@ -138,6 +143,44 @@ fail:
>      PUT_REMOTE_WAIT(wait);
>  }
>  
> +static void process_device_add_msg(ProcMsg *msg)
> +{
> +    Error *local_err = NULL;
> +    const char *json = (const char *)msg->data2;
> +    int wait = msg->fds[0];
> +    QObject *qobj = NULL;
> +    QDict *qdict = NULL;
> +    QemuOpts *opts = NULL;
> +
> +    qobj = qobject_from_json(json, &local_err);
> +    if (local_err) {
> +        goto fail;
> +    }
> +
> +    qdict = qobject_to(QDict, qobj);
> +    assert(qdict);
> +
> +    opts = qemu_opts_from_qdict(qemu_find_opts("device"), qdict, &local_err);
> +    if (local_err) {
> +        goto fail;
> +    }
> +
> +    (void)qdev_device_add(opts, &local_err);
> +    if (local_err) {
> +        goto fail;
> +    }
> +
> +fail:
> +    if (local_err) {
> +        error_report_err(local_err);
> +        /* TODO: communicate the exact error message to proxy */
> +    }
> +
> +    notify_proxy(wait, 1);
> +
> +    PUT_REMOTE_WAIT(wait);
> +}
> +
>  static void process_msg(GIOCondition cond)
>  {
>      ProcMsg *msg = NULL;
> @@ -189,6 +232,9 @@ static void process_msg(GIOCondition cond)
>      case SET_IRQFD:
>          process_set_irqfd_msg(remote_pci_dev, msg);
>          break;
> +    case DEVICE_ADD:
> +        process_device_add_msg(msg);
> +        break;

wrong patch?

>      default:
>          error_setg(&err, "Unknown command");
>          goto finalize_loop;
> @@ -225,6 +271,8 @@ int main(int argc, char *argv[])
>  
>      bdrv_init_with_whitelist();
>  
> +    qemu_add_opts(&qemu_device_opts);
> +

wrong patch?
>      if (qemu_init_main_loop(&err)) {
>          error_report_err(err);
>          return -EBUSY;
> -- 
> 1.8.3.1
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK