Commit f24bb728 authored by Marc-André Lureau's avatar Marc-André Lureau Committed by Gerd Hoffmann
Browse files

Add vhost-user-backend 



Create a vhost-user-backend object that holds a connection to a
vhost-user backend (or "slave" process) and can be referenced from
virtio devices that support it. See later patches for input & gpu
usage.

Note: a previous iteration of this object made it user-creatable, and
allowed managed sub-process spawning, but that has been dropped for
now.

Signed-off-by: default avatarMarc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20190503130034.24916-4-marcandre.lureau@redhat.com
Signed-off-by: default avatarGerd Hoffmann <kraxel@redhat.com>
parent 78067fde

MAINTAINERS

+2 −0
Original line number Diff line number Diff line
@@ -1478,6 +1478,8 @@ F: hw/*/*vhost* 
F: docs/interop/vhost-user.json

F: docs/interop/vhost-user.txt

F: contrib/vhost-user-*/

F: backends/vhost-user.c

F: include/sysemu/vhost-user-backend.h



virtio

M: Michael S. Tsirkin <mst@redhat.com>

backends/Makefile.objs

+2 −0
Original line number Diff line number Diff line
@@ -14,4 +14,6 @@ common-obj-y += cryptodev-vhost.o 
common-obj-$(CONFIG_VHOST_CRYPTO) += cryptodev-vhost-user.o

endif



common-obj-$(call land,$(CONFIG_VHOST_USER),$(CONFIG_VIRTIO)) += vhost-user.o



common-obj-$(CONFIG_LINUX) += hostmem-memfd.o

backends/vhost-user.c

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/*

 * QEMU vhost-user backend

 *

 * Copyright (C) 2018 Red Hat Inc

 *

 * Authors:

 *  Marc-André Lureau <marcandre.lureau@redhat.com>

 *

 * This work is licensed under the terms of the GNU GPL, version 2 or later.

 * See the COPYING file in the top-level directory.

 */





#include "qemu/osdep.h"

#include "hw/qdev.h"

#include "qapi/error.h"

#include "qapi/qmp/qerror.h"

#include "qemu/error-report.h"

#include "qom/object_interfaces.h"

#include "sysemu/vhost-user-backend.h"

#include "sysemu/kvm.h"

#include "io/channel-command.h"

#include "hw/virtio/virtio-bus.h"



static bool

ioeventfd_enabled(void)

{

    return kvm_enabled() && kvm_eventfds_enabled();

}



int

vhost_user_backend_dev_init(VhostUserBackend *b, VirtIODevice *vdev,

                            unsigned nvqs, Error **errp)

{

    int ret;



    assert(!b->vdev && vdev);



    if (!ioeventfd_enabled()) {

        error_setg(errp, "vhost initialization failed: requires kvm");

        return -1;

    }



    if (!vhost_user_init(&b->vhost_user, &b->chr, errp)) {

        return -1;

    }



    b->vdev = vdev;

    b->dev.nvqs = nvqs;

    b->dev.vqs = g_new(struct vhost_virtqueue, nvqs);



    ret = vhost_dev_init(&b->dev, &b->vhost_user, VHOST_BACKEND_TYPE_USER, 0);

    if (ret < 0) {

        error_setg_errno(errp, -ret, "vhost initialization failed");

        return -1;

    }



    return 0;

}



void

vhost_user_backend_start(VhostUserBackend *b)

{

    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(b->vdev)));

    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);

    int ret, i ;



    if (b->started) {

        return;

    }



    if (!k->set_guest_notifiers) {

        error_report("binding does not support guest notifiers");

        return;

    }



    ret = vhost_dev_enable_notifiers(&b->dev, b->vdev);

    if (ret < 0) {

        return;

    }



    ret = k->set_guest_notifiers(qbus->parent, b->dev.nvqs, true);

    if (ret < 0) {

        error_report("Error binding guest notifier");

        goto err_host_notifiers;

    }



    b->dev.acked_features = b->vdev->guest_features;

    ret = vhost_dev_start(&b->dev, b->vdev);

    if (ret < 0) {

        error_report("Error start vhost dev");

        goto err_guest_notifiers;

    }



    /* guest_notifier_mask/pending not used yet, so just unmask

     * everything here.  virtio-pci will do the right thing by

     * enabling/disabling irqfd.

     */

    for (i = 0; i < b->dev.nvqs; i++) {

        vhost_virtqueue_mask(&b->dev, b->vdev,

                             b->dev.vq_index + i, false);

    }



    b->started = true;

    return;



err_guest_notifiers:

    k->set_guest_notifiers(qbus->parent, b->dev.nvqs, false);

err_host_notifiers:

    vhost_dev_disable_notifiers(&b->dev, b->vdev);

}



void

vhost_user_backend_stop(VhostUserBackend *b)

{

    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(b->vdev)));

    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);

    int ret = 0;



    if (!b->started) {

        return;

    }



    vhost_dev_stop(&b->dev, b->vdev);



    if (k->set_guest_notifiers) {

        ret = k->set_guest_notifiers(qbus->parent,

                                     b->dev.nvqs, false);

        if (ret < 0) {

            error_report("vhost guest notifier cleanup failed: %d", ret);

        }

    }

    assert(ret >= 0);



    vhost_dev_disable_notifiers(&b->dev, b->vdev);

    b->started = false;

}



static void set_chardev(Object *obj, const char *value, Error **errp)

{

    VhostUserBackend *b = VHOST_USER_BACKEND(obj);

    Chardev *chr;



    if (b->completed) {

        error_setg(errp, QERR_PERMISSION_DENIED);

        return;

    }



    g_free(b->chr_name);

    b->chr_name = g_strdup(value);



    chr = qemu_chr_find(b->chr_name);

    if (chr == NULL) {

        error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,

                  "Chardev '%s' not found", b->chr_name);

        return;

    }



    if (!qemu_chr_fe_init(&b->chr, chr, errp)) {

        return;

    }



    b->completed = true;

    /* could call vhost_dev_init() so early message can be exchanged */

}



static char *get_chardev(Object *obj, Error **errp)

{

    VhostUserBackend *b = VHOST_USER_BACKEND(obj);

    Chardev *chr = qemu_chr_fe_get_driver(&b->chr);



    if (chr && chr->label) {

        return g_strdup(chr->label);

    }



    return NULL;

}



static void vhost_user_backend_init(Object *obj)

{

    object_property_add_str(obj, "chardev", get_chardev, set_chardev, NULL);

}



static void vhost_user_backend_finalize(Object *obj)

{

    VhostUserBackend *b = VHOST_USER_BACKEND(obj);



    g_free(b->dev.vqs);

    g_free(b->chr_name);



    vhost_user_cleanup(&b->vhost_user);

    qemu_chr_fe_deinit(&b->chr, true);

}



static const TypeInfo vhost_user_backend_info = {

    .name = TYPE_VHOST_USER_BACKEND,

    .parent = TYPE_OBJECT,

    .instance_size = sizeof(VhostUserBackend),

    .instance_init = vhost_user_backend_init,

    .instance_finalize = vhost_user_backend_finalize,

    .class_size = sizeof(VhostUserBackendClass),

};



static void register_types(void)

{

    type_register_static(&vhost_user_backend_info);

}



type_init(register_types);

include/sysemu/vhost-user-backend.h

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Original line number Diff line number Diff line 
/*

 * QEMU vhost-user backend

 *

 * Copyright (C) 2018 Red Hat Inc

 *

 * Authors:

 *  Marc-André Lureau <marcandre.lureau@redhat.com>

 *

 * This work is licensed under the terms of the GNU GPL, version 2 or later.

 * See the COPYING file in the top-level directory.

 */

#ifndef QEMU_VHOST_USER_BACKEND_H

#define QEMU_VHOST_USER_BACKEND_H



#include "qom/object.h"

#include "exec/memory.h"

#include "qemu/option.h"

#include "qemu/bitmap.h"

#include "hw/virtio/vhost.h"

#include "hw/virtio/vhost-user.h"

#include "chardev/char-fe.h"

#include "io/channel.h"



#define TYPE_VHOST_USER_BACKEND "vhost-user-backend"

#define VHOST_USER_BACKEND(obj) \

    OBJECT_CHECK(VhostUserBackend, (obj), TYPE_VHOST_USER_BACKEND)

#define VHOST_USER_BACKEND_GET_CLASS(obj) \

    OBJECT_GET_CLASS(VhostUserBackendClass, (obj), TYPE_VHOST_USER_BACKEND)

#define VHOST_USER_BACKEND_CLASS(klass) \

    OBJECT_CLASS_CHECK(VhostUserBackendClass, (klass), TYPE_VHOST_USER_BACKEND)



typedef struct VhostUserBackend VhostUserBackend;

typedef struct VhostUserBackendClass VhostUserBackendClass;



struct VhostUserBackendClass {

    ObjectClass parent_class;

};



struct VhostUserBackend {

    /* private */

    Object parent;



    char *chr_name;

    CharBackend chr;

    VhostUserState vhost_user;

    struct vhost_dev dev;

    VirtIODevice *vdev;

    bool started;

    bool completed;

};



int vhost_user_backend_dev_init(VhostUserBackend *b, VirtIODevice *vdev,

                                unsigned nvqs, Error **errp);

void vhost_user_backend_start(VhostUserBackend *b);

void vhost_user_backend_stop(VhostUserBackend *b);



#endif