[RFC v5 09/23] vfio-user: define socket send functions

From: John Johnson <john.g.johnson@oracle.com>
To: qemu-devel@nongnu.org
Subject: [RFC v5 09/23] vfio-user: define socket send functions
Date: Thu,  5 May 2022 10:19:52 -0700	[thread overview]
Message-ID: <455feebdac7fc42700bf5a870493007f7f354cfa.1651709440.git.john.g.johnson@oracle.com> (raw)
In-Reply-To: <cover.1651709440.git.john.g.johnson@oracle.com>

Also negotiate protocol version with remote server

Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
---
 hw/vfio/pci.h           |   1 +
 hw/vfio/user-protocol.h |  41 +++++
 hw/vfio/user.h          |   2 +
 hw/vfio/pci.c           |  16 ++
 hw/vfio/user.c          | 414 +++++++++++++++++++++++++++++++++++++++++++++++-
 5 files changed, 473 insertions(+), 1 deletion(-)

diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h
index 59e636c..ec9f345 100644
--- a/hw/vfio/pci.h
+++ b/hw/vfio/pci.h
@@ -193,6 +193,7 @@ OBJECT_DECLARE_SIMPLE_TYPE(VFIOUserPCIDevice, VFIO_USER_PCI)
 struct VFIOUserPCIDevice {
     VFIOPCIDevice device;
     char *sock_name;
+    bool send_queued;   /* all sends are queued */
 };
 
 /* Use uin32_t for vendor & device so PCI_ANY_ID expands and cannot match hw */
diff --git a/hw/vfio/user-protocol.h b/hw/vfio/user-protocol.h
index d23877c..a0889f6 100644
--- a/hw/vfio/user-protocol.h
+++ b/hw/vfio/user-protocol.h
@@ -51,4 +51,45 @@ enum vfio_user_command {
 #define VFIO_USER_NO_REPLY      0x10
 #define VFIO_USER_ERROR         0x20
 
+
+/*
+ * VFIO_USER_VERSION
+ */
+typedef struct {
+    VFIOUserHdr hdr;
+    uint16_t major;
+    uint16_t minor;
+    char capabilities[];
+} VFIOUserVersion;
+
+#define VFIO_USER_MAJOR_VER     0
+#define VFIO_USER_MINOR_VER     0
+
+#define VFIO_USER_CAP           "capabilities"
+
+/* "capabilities" members */
+#define VFIO_USER_CAP_MAX_FDS   "max_msg_fds"
+#define VFIO_USER_CAP_MAX_XFER  "max_data_xfer_size"
+#define VFIO_USER_CAP_MIGR      "migration"
+
+/* "migration" member */
+#define VFIO_USER_CAP_PGSIZE    "pgsize"
+
+/*
+ * Max FDs mainly comes into play when a device supports multiple interrupts
+ * where each ones uses an eventfd to inject it into the guest.
+ * It is clamped by the the number of FDs the qio channel supports in a
+ * single message.
+ */
+#define VFIO_USER_DEF_MAX_FDS   8
+#define VFIO_USER_MAX_MAX_FDS   16
+
+/*
+ * Max transfer limits the amount of data in region and DMA messages.
+ * Region R/W will be very small (limited by how much a single instruction
+ * can process) so just use a reasonable limit here.
+ */
+#define VFIO_USER_DEF_MAX_XFER  (1024 * 1024)
+#define VFIO_USER_MAX_MAX_XFER  (64 * 1024 * 1024)
+
 #endif /* VFIO_USER_PROTOCOL_H */
diff --git a/hw/vfio/user.h b/hw/vfio/user.h
index 68a1080..00d21bf 100644
--- a/hw/vfio/user.h
+++ b/hw/vfio/user.h
@@ -76,11 +76,13 @@ typedef struct VFIOProxy {
 
 /* VFIOProxy flags */
 #define VFIO_PROXY_CLIENT        0x1
+#define VFIO_PROXY_FORCE_QUEUED  0x4
 
 VFIOProxy *vfio_user_connect_dev(SocketAddress *addr, Error **errp);
 void vfio_user_disconnect(VFIOProxy *proxy);
 void vfio_user_set_handler(VFIODevice *vbasedev,
                            void (*handler)(void *opaque, VFIOUserMsg *msg),
                            void *reqarg);
+int vfio_user_validate_version(VFIODevice *vbasedev, Error **errp);
 
 #endif /* VFIO_USER_H */
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 7ef11c0..7e5b910 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -3440,12 +3440,27 @@ static void vfio_user_pci_realize(PCIDevice *pdev, Error **errp)
     vbasedev->proxy = proxy;
     vfio_user_set_handler(vbasedev, vfio_user_pci_process_req, vdev);
 
+    if (udev->send_queued) {
+        proxy->flags |= VFIO_PROXY_FORCE_QUEUED;
+    }
+
+    vfio_user_validate_version(vbasedev, &err);
+    if (err != NULL) {
+        error_propagate(errp, err);
+        goto error;
+    }
+
     vbasedev->name = g_strdup_printf("VFIO user <%s>", udev->sock_name);
     vbasedev->dev = DEVICE(vdev);
     vbasedev->fd = -1;
     vbasedev->type = VFIO_DEVICE_TYPE_PCI;
     vbasedev->ops = &vfio_user_pci_ops;
 
+    return;
+
+error:
+    vfio_user_disconnect(proxy);
+    error_prepend(errp, VFIO_MSG_PREFIX, vdev->vbasedev.name);
 }
 
 static void vfio_user_instance_finalize(Object *obj)
@@ -3462,6 +3477,7 @@ static void vfio_user_instance_finalize(Object *obj)
 
 static Property vfio_user_pci_dev_properties[] = {
     DEFINE_PROP_STRING("socket", VFIOUserPCIDevice, sock_name),
+    DEFINE_PROP_BOOL("x-send-queued", VFIOUserPCIDevice, send_queued, false),
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/hw/vfio/user.c b/hw/vfio/user.c
index 16b37cb..dc3f1a6 100644
--- a/hw/vfio/user.c
+++ b/hw/vfio/user.c
@@ -23,12 +23,20 @@
 #include "io/channel-socket.h"
 #include "io/channel-util.h"
 #include "sysemu/iothread.h"
+#include "qapi/qmp/qdict.h"
+#include "qapi/qmp/qjson.h"
+#include "qapi/qmp/qnull.h"
+#include "qapi/qmp/qstring.h"
+#include "qapi/qmp/qnum.h"
 #include "user.h"
 
-static uint64_t max_xfer_size;
+static uint64_t max_xfer_size = VFIO_USER_DEF_MAX_XFER;
+static uint64_t max_send_fds = VFIO_USER_DEF_MAX_FDS;
+static int wait_time = 1000;   /* wait 1 sec for replies */
 static IOThread *vfio_user_iothread;
 
 static void vfio_user_shutdown(VFIOProxy *proxy);
+static int vfio_user_send_qio(VFIOProxy *proxy, VFIOUserMsg *msg);
 static VFIOUserMsg *vfio_user_getmsg(VFIOProxy *proxy, VFIOUserHdr *hdr,
                                      VFIOUserFDs *fds);
 static VFIOUserFDs *vfio_user_getfds(int numfds);
@@ -36,9 +44,16 @@ static void vfio_user_recycle(VFIOProxy *proxy, VFIOUserMsg *msg);
 
 static void vfio_user_recv(void *opaque);
 static int vfio_user_recv_one(VFIOProxy *proxy);
+static void vfio_user_send(void *opaque);
+static int vfio_user_send_one(VFIOProxy *proxy, VFIOUserMsg *msg);
 static void vfio_user_cb(void *opaque);
 
 static void vfio_user_request(void *opaque);
+static int vfio_user_send_queued(VFIOProxy *proxy, VFIOUserMsg *msg);
+static void vfio_user_send_wait(VFIOProxy *proxy, VFIOUserHdr *hdr,
+                                VFIOUserFDs *fds, int rsize, bool nobql);
+static void vfio_user_request_msg(VFIOUserHdr *hdr, uint16_t cmd,
+                                  uint32_t size, uint32_t flags);
 
 static inline void vfio_user_set_error(VFIOUserHdr *hdr, uint32_t err)
 {
@@ -56,6 +71,32 @@ static void vfio_user_shutdown(VFIOProxy *proxy)
     qio_channel_set_aio_fd_handler(proxy->ioc, proxy->ctx, NULL, NULL, NULL);
 }
 
+static int vfio_user_send_qio(VFIOProxy *proxy, VFIOUserMsg *msg)
+{
+    VFIOUserFDs *fds =  msg->fds;
+    struct iovec iov = {
+        .iov_base = msg->hdr,
+        .iov_len = msg->hdr->size,
+    };
+    size_t numfds = 0;
+    int ret, *fdp = NULL;
+    Error *local_err = NULL;
+
+    if (fds != NULL && fds->send_fds != 0) {
+        numfds = fds->send_fds;
+        fdp = fds->fds;
+    }
+
+    ret = qio_channel_writev_full(proxy->ioc, &iov, 1, fdp, numfds, &local_err);
+
+    if (ret == -1) {
+        vfio_user_set_error(msg->hdr, EIO);
+        vfio_user_shutdown(proxy);
+        error_report_err(local_err);
+    }
+    return ret;
+}
+
 static VFIOUserMsg *vfio_user_getmsg(VFIOProxy *proxy, VFIOUserHdr *hdr,
                                      VFIOUserFDs *fds)
 {
@@ -388,6 +429,53 @@ err:
     return -1;
 }
 
+/*
+ * Send messages from outgoing queue when the socket buffer has space.
+ * If we deplete 'outgoing', remove ourselves from the poll list.
+ */
+static void vfio_user_send(void *opaque)
+{
+    VFIOProxy *proxy = opaque;
+    VFIOUserMsg *msg;
+
+    QEMU_LOCK_GUARD(&proxy->lock);
+
+    if (proxy->state == VFIO_PROXY_CONNECTED) {
+        while (!QTAILQ_EMPTY(&proxy->outgoing)) {
+            msg = QTAILQ_FIRST(&proxy->outgoing);
+            if (vfio_user_send_one(proxy, msg) < 0) {
+                return;
+            }
+        }
+        qio_channel_set_aio_fd_handler(proxy->ioc, proxy->ctx,
+                                       vfio_user_recv, NULL, proxy);
+    }
+}
+
+/*
+ * Send a single message.
+ *
+ * Sent async messages are freed, others are moved to pending queue.
+ */
+static int vfio_user_send_one(VFIOProxy *proxy, VFIOUserMsg *msg)
+{
+    int ret;
+
+    ret = vfio_user_send_qio(proxy, msg);
+    if (ret < 0) {
+        return ret;
+    }
+
+    QTAILQ_REMOVE(&proxy->outgoing, msg, next);
+    if (msg->type == VFIO_MSG_ASYNC) {
+        vfio_user_recycle(proxy, msg);
+    } else {
+        QTAILQ_INSERT_TAIL(&proxy->pending, msg, next);
+    }
+
+    return 0;
+}
+
 static void vfio_user_cb(void *opaque)
 {
     VFIOProxy *proxy = opaque;
@@ -448,6 +536,130 @@ static void vfio_user_request(void *opaque)
     }
 }
 
+/*
+ * Messages are queued onto the proxy's outgoing list.
+ *
+ * It handles 3 types of messages:
+ *
+ * async messages - replies and posted writes
+ *
+ * There will be no reply from the server, so message
+ * buffers are freed after they're sent.
+ *
+ * nowait messages - map/unmap during address space transactions
+ *
+ * These are also sent async, but a reply is expected so that
+ * vfio_wait_reqs() can wait for the youngest nowait request.
+ * They transition from the outgoing list to the pending list
+ * when sent, and are freed when the reply is received.
+ *
+ * wait messages - all other requests
+ *
+ * The reply to these messages is waited for by their caller.
+ * They also transition from outgoing to pending when sent, but
+ * the message buffer is returned to the caller with the reply
+ * contents.  The caller is responsible for freeing these messages.
+ *
+ * As an optimization, if the outgoing list and the socket send
+ * buffer are empty, the message is sent inline instead of being
+ * added to the outgoing list.  The rest of the transitions are
+ * unchanged.
+ *
+ * returns 0 if the message was sent or queued
+ * returns -1 on send error
+ */
+static int vfio_user_send_queued(VFIOProxy *proxy, VFIOUserMsg *msg)
+{
+    int ret;
+
+    /*
+     * Unsent outgoing msgs - add to tail
+     */
+    if (!QTAILQ_EMPTY(&proxy->outgoing)) {
+        QTAILQ_INSERT_TAIL(&proxy->outgoing, msg, next);
+        return 0;
+    }
+
+    /*
+     * Try inline - if blocked, queue it and kick send poller
+     */
+    if (proxy->flags & VFIO_PROXY_FORCE_QUEUED) {
+        ret = QIO_CHANNEL_ERR_BLOCK;
+    } else {
+        ret = vfio_user_send_qio(proxy, msg);
+    }
+    if (ret == QIO_CHANNEL_ERR_BLOCK) {
+        QTAILQ_INSERT_HEAD(&proxy->outgoing, msg, next);
+        qio_channel_set_aio_fd_handler(proxy->ioc, proxy->ctx,
+                                       vfio_user_recv, vfio_user_send,
+                                       proxy);
+        return 0;
+    }
+    if (ret == -1) {
+        return ret;
+    }
+
+    /*
+     * Sent - free async, add others to pending
+     */
+    if (msg->type == VFIO_MSG_ASYNC) {
+        vfio_user_recycle(proxy, msg);
+    } else {
+        QTAILQ_INSERT_TAIL(&proxy->pending, msg, next);
+    }
+
+    return 0;
+}
+
+static void vfio_user_send_wait(VFIOProxy *proxy, VFIOUserHdr *hdr,
+                                VFIOUserFDs *fds, int rsize, bool nobql)
+{
+    VFIOUserMsg *msg;
+    bool iolock = false;
+    int ret;
+
+    if (hdr->flags & VFIO_USER_NO_REPLY) {
+        error_printf("vfio_user_send_wait on async message\n");
+        return;
+    }
+
+    /*
+     * We may block later, so use a per-proxy lock and drop
+     * BQL while we sleep unless 'nobql' says not to.
+     */
+    qemu_mutex_lock(&proxy->lock);
+    if (!nobql) {
+        iolock = qemu_mutex_iothread_locked();
+        if (iolock) {
+            qemu_mutex_unlock_iothread();
+        }
+    }
+
+    msg = vfio_user_getmsg(proxy, hdr, fds);
+    msg->id = hdr->id;
+    msg->rsize = rsize ? rsize : hdr->size;
+    msg->type = VFIO_MSG_WAIT;
+
+    ret = vfio_user_send_queued(proxy, msg);
+
+    if (ret == 0) {
+        while (!msg->complete) {
+            if (!qemu_cond_timedwait(&msg->cv, &proxy->lock, wait_time)) {
+                QTAILQ_REMOVE(&proxy->pending, msg, next);
+                vfio_user_set_error(hdr, ETIMEDOUT);
+                break;
+            }
+        }
+    }
+    vfio_user_recycle(proxy, msg);
+
+    /* lock order is BQL->proxy - don't hold proxy when getting BQL */
+    qemu_mutex_unlock(&proxy->lock);
+    if (iolock) {
+        qemu_mutex_lock_iothread();
+    }
+}
+
 static QLIST_HEAD(, VFIOProxy) vfio_user_sockets =
     QLIST_HEAD_INITIALIZER(vfio_user_sockets);
 
@@ -572,3 +784,203 @@ void vfio_user_disconnect(VFIOProxy *proxy)
     g_free(proxy->sockname);
     g_free(proxy);
 }
+
+static void vfio_user_request_msg(VFIOUserHdr *hdr, uint16_t cmd,
+                                  uint32_t size, uint32_t flags)
+{
+    static uint16_t next_id;
+
+    hdr->id = qatomic_fetch_inc(&next_id);
+    hdr->command = cmd;
+    hdr->size = size;
+    hdr->flags = (flags & ~VFIO_USER_TYPE) | VFIO_USER_REQUEST;
+    hdr->error_reply = 0;
+}
+
+struct cap_entry {
+    const char *name;
+    int (*check)(QObject *qobj, Error **errp);
+};
+
+static int caps_parse(QDict *qdict, struct cap_entry caps[], Error **errp)
+{
+    QObject *qobj;
+    struct cap_entry *p;
+
+    for (p = caps; p->name != NULL; p++) {
+        qobj = qdict_get(qdict, p->name);
+        if (qobj != NULL) {
+            if (p->check(qobj, errp)) {
+                return -1;
+            }
+            qdict_del(qdict, p->name);
+        }
+    }
+
+    /* warning, for now */
+    if (qdict_size(qdict) != 0) {
+        error_printf("spurious capabilities\n");
+    }
+    return 0;
+}
+
+static int check_pgsize(QObject *qobj, Error **errp)
+{
+    QNum *qn = qobject_to(QNum, qobj);
+    uint64_t pgsize;
+
+    if (qn == NULL || !qnum_get_try_uint(qn, &pgsize)) {
+        error_setg(errp, "malformed %s", VFIO_USER_CAP_PGSIZE);
+        return -1;
+    }
+    return pgsize == 4096 ? 0 : -1;
+}
+
+static struct cap_entry caps_migr[] = {
+    { VFIO_USER_CAP_PGSIZE, check_pgsize },
+    { NULL }
+};
+
+static int check_max_fds(QObject *qobj, Error **errp)
+{
+    QNum *qn = qobject_to(QNum, qobj);
+
+    if (qn == NULL || !qnum_get_try_uint(qn, &max_send_fds) ||
+        max_send_fds > VFIO_USER_MAX_MAX_FDS) {
+        error_setg(errp, "malformed %s", VFIO_USER_CAP_MAX_FDS);
+        return -1;
+    }
+    return 0;
+}
+
+static int check_max_xfer(QObject *qobj, Error **errp)
+{
+    QNum *qn = qobject_to(QNum, qobj);
+
+    if (qn == NULL || !qnum_get_try_uint(qn, &max_xfer_size) ||
+        max_xfer_size > VFIO_USER_MAX_MAX_XFER) {
+        error_setg(errp, "malformed %s", VFIO_USER_CAP_MAX_XFER);
+        return -1;
+    }
+    return 0;
+}
+
+static int check_migr(QObject *qobj, Error **errp)
+{
+    QDict *qdict = qobject_to(QDict, qobj);
+
+    if (qdict == NULL) {
+        error_setg(errp, "malformed %s", VFIO_USER_CAP_MAX_FDS);
+        return -1;
+    }
+    return caps_parse(qdict, caps_migr, errp);
+}
+
+static struct cap_entry caps_cap[] = {
+    { VFIO_USER_CAP_MAX_FDS, check_max_fds },
+    { VFIO_USER_CAP_MAX_XFER, check_max_xfer },
+    { VFIO_USER_CAP_MIGR, check_migr },
+    { NULL }
+};
+
+static int check_cap(QObject *qobj, Error **errp)
+{
+   QDict *qdict = qobject_to(QDict, qobj);
+
+    if (qdict == NULL) {
+        error_setg(errp, "malformed %s", VFIO_USER_CAP);
+        return -1;
+    }
+    return caps_parse(qdict, caps_cap, errp);
+}
+
+static struct cap_entry ver_0_0[] = {
+    { VFIO_USER_CAP, check_cap },
+    { NULL }
+};
+
+static int caps_check(int minor, const char *caps, Error **errp)
+{
+    QObject *qobj;
+    QDict *qdict;
+    int ret;
+
+    qobj = qobject_from_json(caps, NULL);
+    if (qobj == NULL) {
+        error_setg(errp, "malformed capabilities %s", caps);
+        return -1;
+    }
+    qdict = qobject_to(QDict, qobj);
+    if (qdict == NULL) {
+        error_setg(errp, "capabilities %s not an object", caps);
+        qobject_unref(qobj);
+        return -1;
+    }
+    ret = caps_parse(qdict, ver_0_0, errp);
+
+    qobject_unref(qobj);
+    return ret;
+}
+
+static GString *caps_json(void)
+{
+    QDict *dict = qdict_new();
+    QDict *capdict = qdict_new();
+    QDict *migdict = qdict_new();
+    GString *str;
+
+    qdict_put_int(migdict, VFIO_USER_CAP_PGSIZE, 4096);
+    qdict_put_obj(capdict, VFIO_USER_CAP_MIGR, QOBJECT(migdict));
+
+    qdict_put_int(capdict, VFIO_USER_CAP_MAX_FDS, VFIO_USER_MAX_MAX_FDS);
+    qdict_put_int(capdict, VFIO_USER_CAP_MAX_XFER, VFIO_USER_DEF_MAX_XFER);
+
+    qdict_put_obj(dict, VFIO_USER_CAP, QOBJECT(capdict));
+
+    str = qobject_to_json(QOBJECT(dict));
+    qobject_unref(dict);
+    return str;
+}
+
+int vfio_user_validate_version(VFIODevice *vbasedev, Error **errp)
+{
+    g_autofree VFIOUserVersion *msgp;
+    GString *caps;
+    char *reply;
+    int size, caplen;
+
+    caps = caps_json();
+    caplen = caps->len + 1;
+    size = sizeof(*msgp) + caplen;
+    msgp = g_malloc0(size);
+
+    vfio_user_request_msg(&msgp->hdr, VFIO_USER_VERSION, size, 0);
+    msgp->major = VFIO_USER_MAJOR_VER;
+    msgp->minor = VFIO_USER_MINOR_VER;
+    memcpy(&msgp->capabilities, caps->str, caplen);
+    g_string_free(caps, true);
+
+    vfio_user_send_wait(vbasedev->proxy, &msgp->hdr, NULL, 0, false);
+    if (msgp->hdr.flags & VFIO_USER_ERROR) {
+        error_setg_errno(errp, msgp->hdr.error_reply, "version reply");
+        return -1;
+    }
+
+    if (msgp->major != VFIO_USER_MAJOR_VER ||
+        msgp->minor > VFIO_USER_MINOR_VER) {
+        error_setg(errp, "incompatible server version");
+        return -1;
+    }
+
+    reply = msgp->capabilities;
+    if (reply[msgp->hdr.size - sizeof(*msgp) - 1] != '\0') {
+        error_setg(errp, "corrupt version reply");
+        return -1;
+    }
+
+    if (caps_check(msgp->minor, reply, errp) != 0) {
+        return -1;
+    }
+
+    return 0;
+}
-- 
1.8.3.1


