diff mbox series

[v1,07/24] vfio-user: connect vfio proxy to remote server

Message ID 4160c1d364dc64f9e70445a905b2cc5ba3ba9c5b.1667542066.git.john.g.johnson@oracle.com (mailing list archive)
State New, archived
Headers show
Series vfio-user client | expand

Commit Message

John Johnson Nov. 8, 2022, 11:13 p.m. UTC 
add user.c & user.h files for vfio-user code
add proxy struct to handle comms with remote server

Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
---
 MAINTAINERS                   |   4 +
 hw/vfio/meson.build           |   1 +
 hw/vfio/pci.c                 |  19 +++++
 hw/vfio/user.c                | 170 ++++++++++++++++++++++++++++++++++++++++++
 hw/vfio/user.h                |  78 +++++++++++++++++++
 include/hw/vfio/vfio-common.h |   2 +
 6 files changed, 274 insertions(+)
 create mode 100644 hw/vfio/user.c
 create mode 100644 hw/vfio/user.h

Comments

John Levon Dec. 9, 2022, 3:23 p.m. UTC | #1 
On Tue, Nov 08, 2022 at 03:13:29PM -0800, John Johnson wrote:

> add user.c & user.h files for vfio-user code
> add proxy struct to handle comms with remote server

LGTM

Reviewed-by: John Levon <john.levon@nutanix.com>

regards
john
Cédric Le Goater Dec. 12, 2022, 4:24 p.m. UTC | #2 
On 11/9/22 00:13, John Johnson wrote:
> add user.c & user.h files for vfio-user code
> add proxy struct to handle comms with remote server
> 
> Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
> Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
> Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
> ---
>   MAINTAINERS                   |   4 +
>   hw/vfio/meson.build           |   1 +
>   hw/vfio/pci.c                 |  19 +++++
>   hw/vfio/user.c                | 170 ++++++++++++++++++++++++++++++++++++++++++
>   hw/vfio/user.h                |  78 +++++++++++++++++++
>   include/hw/vfio/vfio-common.h |   2 +
>   6 files changed, 274 insertions(+)
>   create mode 100644 hw/vfio/user.c
>   create mode 100644 hw/vfio/user.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 999340d..5d64d02 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1987,8 +1987,12 @@ L: qemu-s390x@nongnu.org
>   vfio-user
>   M: John G Johnson <john.g.johnson@oracle.com>
>   M: Thanos Makatos <thanos.makatos@nutanix.com>
> +M: Elena Ufimtseva <elena.ufimtseva@oracle.com>
> +M: Jagannathan Raman <jag.raman@oracle.com>
>   S: Supported
>   F: docs/devel/vfio-user.rst
> +F: hw/vfio/user.c
> +F: hw/vfio/user.h
>   
>   vhost
>   M: Michael S. Tsirkin <mst@redhat.com>
> diff --git a/hw/vfio/meson.build b/hw/vfio/meson.build
> index da9af29..2f86f72 100644
> --- a/hw/vfio/meson.build
> +++ b/hw/vfio/meson.build
> @@ -9,6 +9,7 @@ vfio_ss.add(when: 'CONFIG_VFIO_PCI', if_true: files(
>     'pci-quirks.c',
>     'pci.c',
>   ))
> +vfio_ss.add(when: 'CONFIG_VFIO_USER', if_true: files('user.c'))
>   vfio_ss.add(when: 'CONFIG_VFIO_CCW', if_true: files('ccw.c'))
>   vfio_ss.add(when: 'CONFIG_VFIO_PLATFORM', if_true: files('platform.c'))
>   vfio_ss.add(when: 'CONFIG_VFIO_XGMAC', if_true: files('calxeda-xgmac.c'))
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index dc19869..e5f2413 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -43,6 +43,7 @@
>   #include "qapi/error.h"
>   #include "migration/blocker.h"
>   #include "migration/qemu-file.h"
> +#include "hw/vfio/user.h"
>   
>   /* convenience macros for PCI config space */
>   #define VDEV_CONFIG_READ(vbasedev, off, size, data) \
> @@ -3452,6 +3453,9 @@ static void vfio_user_pci_realize(PCIDevice *pdev, Error **errp)
>       VFIOUserPCIDevice *udev = VFIO_USER_PCI(pdev);
>       VFIOPCIDevice *vdev = VFIO_PCI_BASE(pdev);
>       VFIODevice *vbasedev = &vdev->vbasedev;
> +    SocketAddress addr;
> +    VFIOProxy *proxy;
> +    Error *err = NULL;
>   
>       /*
>        * TODO: make option parser understand SocketAddress
> @@ -3464,6 +3468,16 @@ static void vfio_user_pci_realize(PCIDevice *pdev, Error **errp)
>           return;
>       }
>   
> +    memset(&addr, 0, sizeof(addr));
> +    addr.type = SOCKET_ADDRESS_TYPE_UNIX;
> +    addr.u.q_unix.path = udev->sock_name;
> +    proxy = vfio_user_connect_dev(&addr, &err);
> +    if (!proxy) {

The underlying error of vfio_user_connect_dev() should be propagated.

> +        error_setg(errp, "Remote proxy not found");
> +        return;
> +    }
> +    vbasedev->proxy = proxy;
> +
>       vbasedev->name = g_strdup_printf("VFIO user <%s>", udev->sock_name);
>       vbasedev->ops = &vfio_user_pci_ops;
>       vbasedev->type = VFIO_DEVICE_TYPE_PCI;
> @@ -3474,8 +3488,13 @@ static void vfio_user_pci_realize(PCIDevice *pdev, Error **errp)
>   static void vfio_user_instance_finalize(Object *obj)
>   {
>       VFIOPCIDevice *vdev = VFIO_PCI_BASE(obj);
> +    VFIODevice *vbasedev = &vdev->vbasedev;
>   
>       vfio_put_device(vdev);
> +
> +    if (vbasedev->proxy != NULL) {

could be an assert ?

> +        vfio_user_disconnect(vbasedev->proxy);
> +    }
>   }
>   
>   static Property vfio_user_pci_dev_properties[] = {
> diff --git a/hw/vfio/user.c b/hw/vfio/user.c
> new file mode 100644
> index 0000000..4f09060
> --- /dev/null
> +++ b/hw/vfio/user.c
> @@ -0,0 +1,170 @@
> +/*
> + * vfio protocol over a UNIX socket.
> + *
> + * Copyright © 2018, 2021 Oracle and/or its affiliates.
> + *
> + * 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 <linux/vfio.h>
> +#include <sys/ioctl.h>
> +
> +#include "qemu/error-report.h"
> +#include "qapi/error.h"
> +#include "qemu/main-loop.h"
> +#include "hw/hw.h"
> +#include "hw/vfio/vfio-common.h"
> +#include "hw/vfio/vfio.h"
> +#include "qemu/sockets.h"
> +#include "io/channel.h"
> +#include "io/channel-socket.h"
> +#include "io/channel-util.h"
> +#include "sysemu/iothread.h"
> +#include "user.h"
> +
> +static IOThread *vfio_user_iothread;
> +
> +static void vfio_user_shutdown(VFIOProxy *proxy);
> +
> +
> +/*
> + * Functions called by main, CPU, or iothread threads
> + */
> +
> +static void vfio_user_shutdown(VFIOProxy *proxy)
> +{
> +    qio_channel_shutdown(proxy->ioc, QIO_CHANNEL_SHUTDOWN_READ, NULL);
> +    qio_channel_set_aio_fd_handler(proxy->ioc, proxy->ctx, NULL, NULL, NULL);
> +}
> +
> +/*
> + * Functions only called by iothread
> + */
> +
> +static void vfio_user_cb(void *opaque)
> +{
> +    VFIOProxy *proxy = opaque;
> +
> +    QEMU_LOCK_GUARD(&proxy->lock);
> +
> +    proxy->state = VFIO_PROXY_CLOSED;
> +    qemu_cond_signal(&proxy->close_cv);
> +}
> +
> +
> +/*
> + * Functions called by main or CPU threads
> + */
> +
> +static QLIST_HEAD(, VFIOProxy) vfio_user_sockets =
> +    QLIST_HEAD_INITIALIZER(vfio_user_sockets);
> +
> +VFIOProxy *vfio_user_connect_dev(SocketAddress *addr, Error **errp)
> +{
> +    VFIOProxy *proxy;
> +    QIOChannelSocket *sioc;
> +    QIOChannel *ioc;
> +    char *sockname;
> +
> +    if (addr->type != SOCKET_ADDRESS_TYPE_UNIX) {
> +        error_setg(errp, "vfio_user_connect - bad address family");
> +        return NULL;
> +    }
> +    sockname = addr->u.q_unix.path;
> +
> +    sioc = qio_channel_socket_new();
> +    ioc = QIO_CHANNEL(sioc);
> +    if (qio_channel_socket_connect_sync(sioc, addr, errp)) {
> +        object_unref(OBJECT(ioc));
> +        return NULL;
> +    }
> +    qio_channel_set_blocking(ioc, false, NULL);
> +
> +    proxy = g_malloc0(sizeof(VFIOProxy));
> +    proxy->sockname = g_strdup_printf("unix:%s", sockname);
> +    proxy->ioc = ioc;
> +    proxy->flags = VFIO_PROXY_CLIENT;
> +    proxy->state = VFIO_PROXY_CONNECTED;
> +
> +    qemu_mutex_init(&proxy->lock);
> +    qemu_cond_init(&proxy->close_cv);
> +
> +    if (vfio_user_iothread == NULL) {
> +        vfio_user_iothread = iothread_create("VFIO user", errp);
> +    }
> +
> +    proxy->ctx = iothread_get_aio_context(vfio_user_iothread);
> +
> +    QTAILQ_INIT(&proxy->outgoing);
> +    QTAILQ_INIT(&proxy->incoming);
> +    QTAILQ_INIT(&proxy->free);
> +    QTAILQ_INIT(&proxy->pending);
> +    QLIST_INSERT_HEAD(&vfio_user_sockets, proxy, next);
> +
> +    return proxy;
> +}
> +
> +void vfio_user_disconnect(VFIOProxy *proxy)
> +{
> +    VFIOUserMsg *r1, *r2;
> +
> +    qemu_mutex_lock(&proxy->lock);
> +
> +    /* our side is quitting */
> +    if (proxy->state == VFIO_PROXY_CONNECTED) {
> +        vfio_user_shutdown(proxy);
> +        if (!QTAILQ_EMPTY(&proxy->pending)) {
> +            error_printf("vfio_user_disconnect: outstanding requests\n");
> +        }
> +    }
> +    object_unref(OBJECT(proxy->ioc));
> +    proxy->ioc = NULL;
> +
> +    proxy->state = VFIO_PROXY_CLOSING;
> +    QTAILQ_FOREACH_SAFE(r1, &proxy->outgoing, next, r2) {
> +        qemu_cond_destroy(&r1->cv);
> +        QTAILQ_REMOVE(&proxy->pending, r1, next);
> +        g_free(r1);
> +    }
> +    QTAILQ_FOREACH_SAFE(r1, &proxy->incoming, next, r2) {
> +        qemu_cond_destroy(&r1->cv);
> +        QTAILQ_REMOVE(&proxy->incoming, r1, next);
> +        g_free(r1);
> +    }
> +    QTAILQ_FOREACH_SAFE(r1, &proxy->pending, next, r2) {
> +        qemu_cond_destroy(&r1->cv);
> +        QTAILQ_REMOVE(&proxy->pending, r1, next);
> +        g_free(r1);
> +    }
> +    QTAILQ_FOREACH_SAFE(r1, &proxy->free, next, r2) {
> +        qemu_cond_destroy(&r1->cv);
> +        QTAILQ_REMOVE(&proxy->free, r1, next);
> +        g_free(r1);
> +    }
> +
> +    /*
> +     * Make sure the iothread isn't blocking anywhere
> +     * with a ref to this proxy by waiting for a BH
> +     * handler to run after the proxy fd handlers were
> +     * deleted above.
> +     */
> +    aio_bh_schedule_oneshot(proxy->ctx, vfio_user_cb, proxy);
> +    qemu_cond_wait(&proxy->close_cv, &proxy->lock);
> +
> +    /* we now hold the only ref to proxy */
> +    qemu_mutex_unlock(&proxy->lock);
> +    qemu_cond_destroy(&proxy->close_cv);
> +    qemu_mutex_destroy(&proxy->lock);
> +
> +    QLIST_REMOVE(proxy, next);
> +    if (QLIST_EMPTY(&vfio_user_sockets)) {
> +        iothread_destroy(vfio_user_iothread);
> +        vfio_user_iothread = NULL;
> +    }
> +
> +    g_free(proxy->sockname);
> +    g_free(proxy);
> +}
> diff --git a/hw/vfio/user.h b/hw/vfio/user.h
> new file mode 100644
> index 0000000..da92862
> --- /dev/null
> +++ b/hw/vfio/user.h
> @@ -0,0 +1,78 @@
> +#ifndef VFIO_USER_H
> +#define VFIO_USER_H
> +
> +/*
> + * vfio protocol over a UNIX socket.
> + *
> + * Copyright © 2018, 2021 Oracle and/or its affiliates.
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2.  See
> + * the COPYING file in the top-level directory.
> + *
> + */
> +
> +typedef struct {
> +    int send_fds;
> +    int recv_fds;
> +    int *fds;
> +} VFIOUserFDs;
> +
> +enum msg_type {
> +    VFIO_MSG_NONE,
> +    VFIO_MSG_ASYNC,
> +    VFIO_MSG_WAIT,
> +    VFIO_MSG_NOWAIT,
> +    VFIO_MSG_REQ,
> +};
> +
> +typedef struct VFIOUserMsg {
> +    QTAILQ_ENTRY(VFIOUserMsg) next;
> +    VFIOUserFDs *fds;
> +    uint32_t rsize;
> +    uint32_t id;
> +    QemuCond cv;
> +    bool complete;
> +    enum msg_type type;
> +} VFIOUserMsg;
> +
> +
> +enum proxy_state {
> +    VFIO_PROXY_CONNECTED = 1,
> +    VFIO_PROXY_ERROR = 2,
> +    VFIO_PROXY_CLOSING = 3,
> +    VFIO_PROXY_CLOSED = 4,
> +};
> +
> +typedef QTAILQ_HEAD(VFIOUserMsgQ, VFIOUserMsg) VFIOUserMsgQ;
> +
> +typedef struct VFIOProxy {

VFIOUserProxy ? to be consistent with the namespace.

Thanks,

C.

> +    QLIST_ENTRY(VFIOProxy) next;
> +    char *sockname;
> +    struct QIOChannel *ioc;
> +    void (*request)(void *opaque, VFIOUserMsg *msg);
> +    void *req_arg;
> +    int flags;
> +    QemuCond close_cv;
> +    AioContext *ctx;
> +    QEMUBH *req_bh;
> +
> +    /*
> +     * above only changed when BQL is held
> +     * below are protected by per-proxy lock
> +     */
> +    QemuMutex lock;
> +    VFIOUserMsgQ free;
> +    VFIOUserMsgQ pending;
> +    VFIOUserMsgQ incoming;
> +    VFIOUserMsgQ outgoing;
> +    VFIOUserMsg *last_nowait;
> +    enum proxy_state state;
> +} VFIOProxy;
> +
> +/* VFIOProxy flags */
> +#define VFIO_PROXY_CLIENT        0x1
> +
> +VFIOProxy *vfio_user_connect_dev(SocketAddress *addr, Error **errp);
> +void vfio_user_disconnect(VFIOProxy *proxy);
> +
> +#endif /* VFIO_USER_H */
> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> index 7713d98..fb7d865 100644
> --- a/include/hw/vfio/vfio-common.h
> +++ b/include/hw/vfio/vfio-common.h
> @@ -76,6 +76,7 @@ typedef struct VFIOAddressSpace {
>   
>   struct VFIOGroup;
>   typedef struct VFIOContIO VFIOContIO;
> +typedef struct VFIOProxy VFIOProxy;
>   
>   typedef struct VFIOContainer {
>       VFIOAddressSpace *space;
> @@ -147,6 +148,7 @@ typedef struct VFIODevice {
>       VFIOMigration *migration;
>       Error *migration_blocker;
>       OnOffAuto pre_copy_dirty_page_tracking;
> +    VFIOProxy *proxy;
>       struct vfio_region_info **regions;
>   } VFIODevice;
>
diff mbox series

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index 999340d..5d64d02 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1987,8 +1987,12 @@  L: qemu-s390x@nongnu.org
 vfio-user
 M: John G Johnson <john.g.johnson@oracle.com>
 M: Thanos Makatos <thanos.makatos@nutanix.com>
+M: Elena Ufimtseva <elena.ufimtseva@oracle.com>
+M: Jagannathan Raman <jag.raman@oracle.com>
 S: Supported
 F: docs/devel/vfio-user.rst
+F: hw/vfio/user.c
+F: hw/vfio/user.h
 
 vhost
 M: Michael S. Tsirkin <mst@redhat.com>
diff --git a/hw/vfio/meson.build b/hw/vfio/meson.build
index da9af29..2f86f72 100644
--- a/hw/vfio/meson.build
+++ b/hw/vfio/meson.build
@@ -9,6 +9,7 @@  vfio_ss.add(when: 'CONFIG_VFIO_PCI', if_true: files(
   'pci-quirks.c',
   'pci.c',
 ))
+vfio_ss.add(when: 'CONFIG_VFIO_USER', if_true: files('user.c'))
 vfio_ss.add(when: 'CONFIG_VFIO_CCW', if_true: files('ccw.c'))
 vfio_ss.add(when: 'CONFIG_VFIO_PLATFORM', if_true: files('platform.c'))
 vfio_ss.add(when: 'CONFIG_VFIO_XGMAC', if_true: files('calxeda-xgmac.c'))
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index dc19869..e5f2413 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -43,6 +43,7 @@ 
 #include "qapi/error.h"
 #include "migration/blocker.h"
 #include "migration/qemu-file.h"
+#include "hw/vfio/user.h"
 
 /* convenience macros for PCI config space */
 #define VDEV_CONFIG_READ(vbasedev, off, size, data) \
@@ -3452,6 +3453,9 @@  static void vfio_user_pci_realize(PCIDevice *pdev, Error **errp)
     VFIOUserPCIDevice *udev = VFIO_USER_PCI(pdev);
     VFIOPCIDevice *vdev = VFIO_PCI_BASE(pdev);
     VFIODevice *vbasedev = &vdev->vbasedev;
+    SocketAddress addr;
+    VFIOProxy *proxy;
+    Error *err = NULL;
 
     /*
      * TODO: make option parser understand SocketAddress
@@ -3464,6 +3468,16 @@  static void vfio_user_pci_realize(PCIDevice *pdev, Error **errp)
         return;
     }
 
+    memset(&addr, 0, sizeof(addr));
+    addr.type = SOCKET_ADDRESS_TYPE_UNIX;
+    addr.u.q_unix.path = udev->sock_name;
+    proxy = vfio_user_connect_dev(&addr, &err);
+    if (!proxy) {
+        error_setg(errp, "Remote proxy not found");
+        return;
+    }
+    vbasedev->proxy = proxy;
+
     vbasedev->name = g_strdup_printf("VFIO user <%s>", udev->sock_name);
     vbasedev->ops = &vfio_user_pci_ops;
     vbasedev->type = VFIO_DEVICE_TYPE_PCI;
@@ -3474,8 +3488,13 @@  static void vfio_user_pci_realize(PCIDevice *pdev, Error **errp)
 static void vfio_user_instance_finalize(Object *obj)
 {
     VFIOPCIDevice *vdev = VFIO_PCI_BASE(obj);
+    VFIODevice *vbasedev = &vdev->vbasedev;
 
     vfio_put_device(vdev);
+
+    if (vbasedev->proxy != NULL) {
+        vfio_user_disconnect(vbasedev->proxy);
+    }
 }
 
 static Property vfio_user_pci_dev_properties[] = {
diff --git a/hw/vfio/user.c b/hw/vfio/user.c
new file mode 100644
index 0000000..4f09060
--- /dev/null
+++ b/hw/vfio/user.c
@@ -0,0 +1,170 @@ 
+/*
+ * vfio protocol over a UNIX socket.
+ *
+ * Copyright © 2018, 2021 Oracle and/or its affiliates.
+ *
+ * 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 <linux/vfio.h>
+#include <sys/ioctl.h>
+
+#include "qemu/error-report.h"
+#include "qapi/error.h"
+#include "qemu/main-loop.h"
+#include "hw/hw.h"
+#include "hw/vfio/vfio-common.h"
+#include "hw/vfio/vfio.h"
+#include "qemu/sockets.h"
+#include "io/channel.h"
+#include "io/channel-socket.h"
+#include "io/channel-util.h"
+#include "sysemu/iothread.h"
+#include "user.h"
+
+static IOThread *vfio_user_iothread;
+
+static void vfio_user_shutdown(VFIOProxy *proxy);
+
+
+/*
+ * Functions called by main, CPU, or iothread threads
+ */
+
+static void vfio_user_shutdown(VFIOProxy *proxy)
+{
+    qio_channel_shutdown(proxy->ioc, QIO_CHANNEL_SHUTDOWN_READ, NULL);
+    qio_channel_set_aio_fd_handler(proxy->ioc, proxy->ctx, NULL, NULL, NULL);
+}
+
+/*
+ * Functions only called by iothread
+ */
+
+static void vfio_user_cb(void *opaque)
+{
+    VFIOProxy *proxy = opaque;
+
+    QEMU_LOCK_GUARD(&proxy->lock);
+
+    proxy->state = VFIO_PROXY_CLOSED;
+    qemu_cond_signal(&proxy->close_cv);
+}
+
+
+/*
+ * Functions called by main or CPU threads
+ */
+
+static QLIST_HEAD(, VFIOProxy) vfio_user_sockets =
+    QLIST_HEAD_INITIALIZER(vfio_user_sockets);
+
+VFIOProxy *vfio_user_connect_dev(SocketAddress *addr, Error **errp)
+{
+    VFIOProxy *proxy;
+    QIOChannelSocket *sioc;
+    QIOChannel *ioc;
+    char *sockname;
+
+    if (addr->type != SOCKET_ADDRESS_TYPE_UNIX) {
+        error_setg(errp, "vfio_user_connect - bad address family");
+        return NULL;
+    }
+    sockname = addr->u.q_unix.path;
+
+    sioc = qio_channel_socket_new();
+    ioc = QIO_CHANNEL(sioc);
+    if (qio_channel_socket_connect_sync(sioc, addr, errp)) {
+        object_unref(OBJECT(ioc));
+        return NULL;
+    }
+    qio_channel_set_blocking(ioc, false, NULL);
+
+    proxy = g_malloc0(sizeof(VFIOProxy));
+    proxy->sockname = g_strdup_printf("unix:%s", sockname);
+    proxy->ioc = ioc;
+    proxy->flags = VFIO_PROXY_CLIENT;
+    proxy->state = VFIO_PROXY_CONNECTED;
+
+    qemu_mutex_init(&proxy->lock);
+    qemu_cond_init(&proxy->close_cv);
+
+    if (vfio_user_iothread == NULL) {
+        vfio_user_iothread = iothread_create("VFIO user", errp);
+    }
+
+    proxy->ctx = iothread_get_aio_context(vfio_user_iothread);
+
+    QTAILQ_INIT(&proxy->outgoing);
+    QTAILQ_INIT(&proxy->incoming);
+    QTAILQ_INIT(&proxy->free);
+    QTAILQ_INIT(&proxy->pending);
+    QLIST_INSERT_HEAD(&vfio_user_sockets, proxy, next);
+
+    return proxy;
+}
+
+void vfio_user_disconnect(VFIOProxy *proxy)
+{
+    VFIOUserMsg *r1, *r2;
+
+    qemu_mutex_lock(&proxy->lock);
+
+    /* our side is quitting */
+    if (proxy->state == VFIO_PROXY_CONNECTED) {
+        vfio_user_shutdown(proxy);
+        if (!QTAILQ_EMPTY(&proxy->pending)) {
+            error_printf("vfio_user_disconnect: outstanding requests\n");
+        }
+    }
+    object_unref(OBJECT(proxy->ioc));
+    proxy->ioc = NULL;
+
+    proxy->state = VFIO_PROXY_CLOSING;
+    QTAILQ_FOREACH_SAFE(r1, &proxy->outgoing, next, r2) {
+        qemu_cond_destroy(&r1->cv);
+        QTAILQ_REMOVE(&proxy->pending, r1, next);
+        g_free(r1);
+    }
+    QTAILQ_FOREACH_SAFE(r1, &proxy->incoming, next, r2) {
+        qemu_cond_destroy(&r1->cv);
+        QTAILQ_REMOVE(&proxy->incoming, r1, next);
+        g_free(r1);
+    }
+    QTAILQ_FOREACH_SAFE(r1, &proxy->pending, next, r2) {
+        qemu_cond_destroy(&r1->cv);
+        QTAILQ_REMOVE(&proxy->pending, r1, next);
+        g_free(r1);
+    }
+    QTAILQ_FOREACH_SAFE(r1, &proxy->free, next, r2) {
+        qemu_cond_destroy(&r1->cv);
+        QTAILQ_REMOVE(&proxy->free, r1, next);
+        g_free(r1);
+    }
+
+    /*
+     * Make sure the iothread isn't blocking anywhere
+     * with a ref to this proxy by waiting for a BH
+     * handler to run after the proxy fd handlers were
+     * deleted above.
+     */
+    aio_bh_schedule_oneshot(proxy->ctx, vfio_user_cb, proxy);
+    qemu_cond_wait(&proxy->close_cv, &proxy->lock);
+
+    /* we now hold the only ref to proxy */
+    qemu_mutex_unlock(&proxy->lock);
+    qemu_cond_destroy(&proxy->close_cv);
+    qemu_mutex_destroy(&proxy->lock);
+
+    QLIST_REMOVE(proxy, next);
+    if (QLIST_EMPTY(&vfio_user_sockets)) {
+        iothread_destroy(vfio_user_iothread);
+        vfio_user_iothread = NULL;
+    }
+
+    g_free(proxy->sockname);
+    g_free(proxy);
+}
diff --git a/hw/vfio/user.h b/hw/vfio/user.h
new file mode 100644
index 0000000..da92862
--- /dev/null
+++ b/hw/vfio/user.h
@@ -0,0 +1,78 @@ 
+#ifndef VFIO_USER_H
+#define VFIO_USER_H
+
+/*
+ * vfio protocol over a UNIX socket.
+ *
+ * Copyright © 2018, 2021 Oracle and/or its affiliates.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+typedef struct {
+    int send_fds;
+    int recv_fds;
+    int *fds;
+} VFIOUserFDs;
+
+enum msg_type {
+    VFIO_MSG_NONE,
+    VFIO_MSG_ASYNC,
+    VFIO_MSG_WAIT,
+    VFIO_MSG_NOWAIT,
+    VFIO_MSG_REQ,
+};
+
+typedef struct VFIOUserMsg {
+    QTAILQ_ENTRY(VFIOUserMsg) next;
+    VFIOUserFDs *fds;
+    uint32_t rsize;
+    uint32_t id;
+    QemuCond cv;
+    bool complete;
+    enum msg_type type;
+} VFIOUserMsg;
+
+
+enum proxy_state {
+    VFIO_PROXY_CONNECTED = 1,
+    VFIO_PROXY_ERROR = 2,
+    VFIO_PROXY_CLOSING = 3,
+    VFIO_PROXY_CLOSED = 4,
+};
+
+typedef QTAILQ_HEAD(VFIOUserMsgQ, VFIOUserMsg) VFIOUserMsgQ;
+
+typedef struct VFIOProxy {
+    QLIST_ENTRY(VFIOProxy) next;
+    char *sockname;
+    struct QIOChannel *ioc;
+    void (*request)(void *opaque, VFIOUserMsg *msg);
+    void *req_arg;
+    int flags;
+    QemuCond close_cv;
+    AioContext *ctx;
+    QEMUBH *req_bh;
+
+    /*
+     * above only changed when BQL is held
+     * below are protected by per-proxy lock
+     */
+    QemuMutex lock;
+    VFIOUserMsgQ free;
+    VFIOUserMsgQ pending;
+    VFIOUserMsgQ incoming;
+    VFIOUserMsgQ outgoing;
+    VFIOUserMsg *last_nowait;
+    enum proxy_state state;
+} VFIOProxy;
+
+/* VFIOProxy flags */
+#define VFIO_PROXY_CLIENT        0x1
+
+VFIOProxy *vfio_user_connect_dev(SocketAddress *addr, Error **errp);
+void vfio_user_disconnect(VFIOProxy *proxy);
+
+#endif /* VFIO_USER_H */
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 7713d98..fb7d865 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -76,6 +76,7 @@  typedef struct VFIOAddressSpace {
 
 struct VFIOGroup;
 typedef struct VFIOContIO VFIOContIO;
+typedef struct VFIOProxy VFIOProxy;
 
 typedef struct VFIOContainer {
     VFIOAddressSpace *space;
@@ -147,6 +148,7 @@  typedef struct VFIODevice {
     VFIOMigration *migration;
     Error *migration_blocker;
     OnOffAuto pre_copy_dirty_page_tracking;
+    VFIOProxy *proxy;
     struct vfio_region_info **regions;
 } VFIODevice;