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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: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20190503130034.24916-4-marcandre.lureau@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
tags/v4.1.0-rc0
Marc-André Lureau 4 months ago
parent
commit
f24bb7287d
4 changed files with 270 additions and 0 deletions
  1. 2
    0
      MAINTAINERS
  2. 2
    0
      backends/Makefile.objs
  3. 209
    0
      backends/vhost-user.c
  4. 57
    0
      include/sysemu/vhost-user-backend.h

+ 2
- 0
MAINTAINERS View File

@@ -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>

+ 2
- 0
backends/Makefile.objs View File

@@ -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

+ 209
- 0
backends/vhost-user.c View File

@@ -0,0 +1,209 @@
/*
* 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);

+ 57
- 0
include/sysemu/vhost-user-backend.h View File

@@ -0,0 +1,57 @@
/*
* 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

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