qemu/hw/remote/vfio-user-obj.c

/**
 * QEMU vfio-user-server server object
 *
 * Copyright © 2022 Oracle and/or its affiliates.
 *
 * This work is licensed under the terms of the GNU GPL-v2, version 2 or later.
 *
 * See the COPYING file in the top-level directory.
 *
 */

/**
 * Usage: add options:
 *     -machine x-remote,vfio-user=on,auto-shutdown=on
 *     -device <PCI-device>,id=<pci-dev-id>
 *     -object x-vfio-user-server,id=<id>,type=unix,path=<socket-path>,
 *             device=<pci-dev-id>
 *
 * Note that x-vfio-user-server object must be used with x-remote machine only.
 * This server could only support PCI devices for now.
 *
 * type - SocketAddress type - presently "unix" alone is supported. Required
 *        option
 *
 * path - named unix socket, it will be created by the server. It is
 *        a required option
 *
 * device - id of a device on the server, a required option. PCI devices
 *          alone are supported presently.
 *
 * notes - x-vfio-user-server could block IO and monitor during the
 *         initialization phase.
 */

#include "qemu/osdep.h"

#include "qom/object.h"
#include "qom/object_interfaces.h"
#include "qemu/error-report.h"
#include "trace.h"
#include "sysemu/runstate.h"
#include "hw/boards.h"
#include "hw/remote/machine.h"
#include "qapi/error.h"
#include "qapi/qapi-visit-sockets.h"
#include "qapi/qapi-events-misc.h"
#include "qemu/notify.h"
#include "qemu/thread.h"
#include "sysemu/sysemu.h"
#include "libvfio-user.h"
#include "hw/qdev-core.h"
#include "hw/pci/pci.h"
#include "qemu/timer.h"

#define TYPE_VFU_OBJECT "x-vfio-user-server"
OBJECT_DECLARE_TYPE(VfuObject, VfuObjectClass, VFU_OBJECT)

/**
 * VFU_OBJECT_ERROR - reports an error message. If auto_shutdown
 * is set, it aborts the machine on error. Otherwise, it logs an
 * error message without aborting.
 */
#define VFU_OBJECT_ERROR(o, fmt, ...)                                     \
    {                                                                     \
        if (vfu_object_auto_shutdown()) {                                 \
            error_setg(&error_abort, (fmt), ## __VA_ARGS__);              \
        } else {                                                          \
            error_report((fmt), ## __VA_ARGS__);                          \
        }                                                                 \
    }                                                                     \

struct VfuObjectClass {
    ObjectClass parent_class;

    unsigned int nr_devs;
};

struct VfuObject {
    /* private */
    Object parent;

    SocketAddress *socket;

    char *device;

    Error *err;

    Notifier machine_done;

    vfu_ctx_t *vfu_ctx;

    PCIDevice *pci_dev;

    Error *unplug_blocker;

    int vfu_poll_fd;
};

static void vfu_object_init_ctx(VfuObject *o, Error **errp);

static bool vfu_object_auto_shutdown(void)
{
    bool auto_shutdown = true;
    Error *local_err = NULL;

    if (!current_machine) {
        return auto_shutdown;
    }

    auto_shutdown = object_property_get_bool(OBJECT(current_machine),
                                             "auto-shutdown",
                                             &local_err);

    /*
     * local_err would be set if no such property exists - safe to ignore.
     * Unlikely scenario as auto-shutdown is always defined for
     * TYPE_REMOTE_MACHINE, and  TYPE_VFU_OBJECT only works with
     * TYPE_REMOTE_MACHINE
     */
    if (local_err) {
        auto_shutdown = true;
        error_free(local_err);
    }

    return auto_shutdown;
}

static void vfu_object_set_socket(Object *obj, Visitor *v, const char *name,
                                  void *opaque, Error **errp)
{
    VfuObject *o = VFU_OBJECT(obj);

    if (o->vfu_ctx) {
        error_setg(errp, "vfu: Unable to set socket property - server busy");
        return;
    }

    qapi_free_SocketAddress(o->socket);

    o->socket = NULL;

    visit_type_SocketAddress(v, name, &o->socket, errp);

    if (o->socket->type != SOCKET_ADDRESS_TYPE_UNIX) {
        error_setg(errp, "vfu: Unsupported socket type - %s",
                   SocketAddressType_str(o->socket->type));
        qapi_free_SocketAddress(o->socket);
        o->socket = NULL;
        return;
    }

    trace_vfu_prop("socket", o->socket->u.q_unix.path);

    vfu_object_init_ctx(o, errp);
}

static void vfu_object_set_device(Object *obj, const char *str, Error **errp)
{
    VfuObject *o = VFU_OBJECT(obj);

    if (o->vfu_ctx) {
        error_setg(errp, "vfu: Unable to set device property - server busy");
        return;
    }

    g_free(o->device);

    o->device = g_strdup(str);

    trace_vfu_prop("device", str);

    vfu_object_init_ctx(o, errp);
}

static void vfu_object_ctx_run(void *opaque)
{
    VfuObject *o = opaque;
    const char *vfu_id;
    char *vfu_path, *pci_dev_path;
    int ret = -1;

    while (ret != 0) {
        ret = vfu_run_ctx(o->vfu_ctx);
        if (ret < 0) {
            if (errno == EINTR) {
                continue;
            } else if (errno == ENOTCONN) {
                vfu_id = object_get_canonical_path_component(OBJECT(o));
                vfu_path = object_get_canonical_path(OBJECT(o));
                g_assert(o->pci_dev);
                pci_dev_path = object_get_canonical_path(OBJECT(o->pci_dev));
                 /* o->device is a required property and is non-NULL here */
                g_assert(o->device);
                qapi_event_send_vfu_client_hangup(vfu_id, vfu_path,
                                                  o->device, pci_dev_path);
                qemu_set_fd_handler(o->vfu_poll_fd, NULL, NULL, NULL);
                o->vfu_poll_fd = -1;
                object_unparent(OBJECT(o));
                g_free(vfu_path);
                g_free(pci_dev_path);
                break;
            } else {
                VFU_OBJECT_ERROR(o, "vfu: Failed to run device %s - %s",
                                 o->device, strerror(errno));
                break;
            }
        }
    }
}

static void vfu_object_attach_ctx(void *opaque)
{
    VfuObject *o = opaque;
    GPollFD pfds[1];
    int ret;

    qemu_set_fd_handler(o->vfu_poll_fd, NULL, NULL, NULL);

    pfds[0].fd = o->vfu_poll_fd;
    pfds[0].events = G_IO_IN | G_IO_HUP | G_IO_ERR;

retry_attach:
    ret = vfu_attach_ctx(o->vfu_ctx);
    if (ret < 0 && (errno == EAGAIN || errno == EWOULDBLOCK)) {
        /**
         * vfu_object_attach_ctx can block QEMU's main loop
         * during attach - the monitor and other IO
         * could be unresponsive during this time.
         */
        (void)qemu_poll_ns(pfds, 1, 500 * (int64_t)SCALE_MS);
        goto retry_attach;
    } else if (ret < 0) {
        VFU_OBJECT_ERROR(o, "vfu: Failed to attach device %s to context - %s",
                         o->device, strerror(errno));
        return;
    }

    o->vfu_poll_fd = vfu_get_poll_fd(o->vfu_ctx);
    if (o->vfu_poll_fd < 0) {
        VFU_OBJECT_ERROR(o, "vfu: Failed to get poll fd %s", o->device);
        return;
    }

    qemu_set_fd_handler(o->vfu_poll_fd, vfu_object_ctx_run, NULL, o);
}

/*
 * TYPE_VFU_OBJECT depends on the availability of the 'socket' and 'device'
 * properties. It also depends on devices instantiated in QEMU. These
 * dependencies are not available during the instance_init phase of this
 * object's life-cycle. As such, the server is initialized after the
 * machine is setup. machine_init_done_notifier notifies TYPE_VFU_OBJECT
 * when the machine is setup, and the dependencies are available.
 */
static void vfu_object_machine_done(Notifier *notifier, void *data)
{
    VfuObject *o = container_of(notifier, VfuObject, machine_done);
    Error *err = NULL;

    vfu_object_init_ctx(o, &err);

    if (err) {
        error_propagate(&error_abort, err);
    }
}

/**
 * vfu_object_init_ctx: Create and initialize libvfio-user context. Add
 *     an unplug blocker for the associated PCI device. Setup a FD handler
 *     to process incoming messages in the context's socket.
 *
 *     The socket and device properties are mandatory, and this function
 *     will not create the context without them - the setters for these
 *     properties should call this function when the property is set. The
 *     machine should also be ready when this function is invoked - it is
 *     because QEMU objects are initialized before devices, and the
 *     associated PCI device wouldn't be available at the object
 *     initialization time. Until these conditions are satisfied, this
 *     function would return early without performing any task.
 */
static void vfu_object_init_ctx(VfuObject *o, Error **errp)
{
    ERRP_GUARD();
    DeviceState *dev = NULL;
    vfu_pci_type_t pci_type = VFU_PCI_TYPE_CONVENTIONAL;
    int ret;

    if (o->vfu_ctx || !o->socket || !o->device ||
            !phase_check(PHASE_MACHINE_READY)) {
        return;
    }

    if (o->err) {
        error_propagate(errp, o->err);
        o->err = NULL;
        return;
    }

    o->vfu_ctx = vfu_create_ctx(VFU_TRANS_SOCK, o->socket->u.q_unix.path,
                                LIBVFIO_USER_FLAG_ATTACH_NB,
                                o, VFU_DEV_TYPE_PCI);
    if (o->vfu_ctx == NULL) {
        error_setg(errp, "vfu: Failed to create context - %s", strerror(errno));
        return;
    }

    dev = qdev_find_recursive(sysbus_get_default(), o->device);
    if (dev == NULL) {
        error_setg(errp, "vfu: Device %s not found", o->device);
        goto fail;
    }

    if (!object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
        error_setg(errp, "vfu: %s not a PCI device", o->device);
        goto fail;
    }

    o->pci_dev = PCI_DEVICE(dev);

    object_ref(OBJECT(o->pci_dev));

    if (pci_is_express(o->pci_dev)) {
        pci_type = VFU_PCI_TYPE_EXPRESS;
    }

    ret = vfu_pci_init(o->vfu_ctx, pci_type, PCI_HEADER_TYPE_NORMAL, 0);
    if (ret < 0) {
        error_setg(errp,
                   "vfu: Failed to attach PCI device %s to context - %s",
                   o->device, strerror(errno));
        goto fail;
    }

    error_setg(&o->unplug_blocker,
               "vfu: %s for %s must be deleted before unplugging",
               TYPE_VFU_OBJECT, o->device);
    qdev_add_unplug_blocker(DEVICE(o->pci_dev), o->unplug_blocker);

    ret = vfu_realize_ctx(o->vfu_ctx);
    if (ret < 0) {
        error_setg(errp, "vfu: Failed to realize device %s- %s",
                   o->device, strerror(errno));
        goto fail;
    }

    o->vfu_poll_fd = vfu_get_poll_fd(o->vfu_ctx);
    if (o->vfu_poll_fd < 0) {
        error_setg(errp, "vfu: Failed to get poll fd %s", o->device);
        goto fail;
    }

    qemu_set_fd_handler(o->vfu_poll_fd, vfu_object_attach_ctx, NULL, o);

    return;

fail:
    vfu_destroy_ctx(o->vfu_ctx);
    if (o->unplug_blocker && o->pci_dev) {
        qdev_del_unplug_blocker(DEVICE(o->pci_dev), o->unplug_blocker);
        error_free(o->unplug_blocker);
        o->unplug_blocker = NULL;
    }
    if (o->pci_dev) {
        object_unref(OBJECT(o->pci_dev));
        o->pci_dev = NULL;
    }
    o->vfu_ctx = NULL;
}

static void vfu_object_init(Object *obj)
{
    VfuObjectClass *k = VFU_OBJECT_GET_CLASS(obj);
    VfuObject *o = VFU_OBJECT(obj);

    k->nr_devs++;

    if (!object_dynamic_cast(OBJECT(current_machine), TYPE_REMOTE_MACHINE)) {
        error_setg(&o->err, "vfu: %s only compatible with %s machine",
                   TYPE_VFU_OBJECT, TYPE_REMOTE_MACHINE);
        return;
    }

    if (!phase_check(PHASE_MACHINE_READY)) {
        o->machine_done.notify = vfu_object_machine_done;
        qemu_add_machine_init_done_notifier(&o->machine_done);
    }

    o->vfu_poll_fd = -1;
}

static void vfu_object_finalize(Object *obj)
{
    VfuObjectClass *k = VFU_OBJECT_GET_CLASS(obj);
    VfuObject *o = VFU_OBJECT(obj);

    k->nr_devs--;

    qapi_free_SocketAddress(o->socket);

    o->socket = NULL;

    if (o->vfu_poll_fd != -1) {
        qemu_set_fd_handler(o->vfu_poll_fd, NULL, NULL, NULL);
        o->vfu_poll_fd = -1;
    }

    if (o->vfu_ctx) {
        vfu_destroy_ctx(o->vfu_ctx);
        o->vfu_ctx = NULL;
    }

    g_free(o->device);

    o->device = NULL;

    if (o->unplug_blocker && o->pci_dev) {
        qdev_del_unplug_blocker(DEVICE(o->pci_dev), o->unplug_blocker);
        error_free(o->unplug_blocker);
        o->unplug_blocker = NULL;
    }

    if (o->pci_dev) {
        object_unref(OBJECT(o->pci_dev));
        o->pci_dev = NULL;
    }

    if (!k->nr_devs && vfu_object_auto_shutdown()) {
        qemu_system_shutdown_request(SHUTDOWN_CAUSE_GUEST_SHUTDOWN);
    }

    if (o->machine_done.notify) {
        qemu_remove_machine_init_done_notifier(&o->machine_done);
        o->machine_done.notify = NULL;
    }
}

static void vfu_object_class_init(ObjectClass *klass, void *data)
{
    VfuObjectClass *k = VFU_OBJECT_CLASS(klass);

    k->nr_devs = 0;

    object_class_property_add(klass, "socket", "SocketAddress", NULL,
                              vfu_object_set_socket, NULL, NULL);
    object_class_property_set_description(klass, "socket",
                                          "SocketAddress "
                                          "(ex: type=unix,path=/tmp/sock). "
                                          "Only UNIX is presently supported");
    object_class_property_add_str(klass, "device", NULL,
                                  vfu_object_set_device);
    object_class_property_set_description(klass, "device",
                                          "device ID - only PCI devices "
                                          "are presently supported");
}

static const TypeInfo vfu_object_info = {
    .name = TYPE_VFU_OBJECT,
    .parent = TYPE_OBJECT,
    .instance_size = sizeof(VfuObject),
    .instance_init = vfu_object_init,
    .instance_finalize = vfu_object_finalize,
    .class_size = sizeof(VfuObjectClass),
    .class_init = vfu_object_class_init,
    .interfaces = (InterfaceInfo[]) {
        { TYPE_USER_CREATABLE },
        { }
    }
};

static void vfu_register_types(void)
{
    type_register_static(&vfu_object_info);
}

type_init(vfu_register_types);