Add vhost-user as a vhost backend.

The initialization takes a chardev backed by a unix domain socket.
It should implement qemu_fe_set_msgfds in order to be able to pass
file descriptors to the remote process.

Each ioctl request of vhost-kernel has a vhost-user message equivalent,
which is sent over the control socket.

The general approach is to copy the data from the supplied argument
pointer to a designated field in the message. If a file descriptor is
to be passed it will be placed in the fds array for inclusion in
the sendmsg control header.

VHOST_SET_MEM_TABLE ignores the supplied vhost_memory structure and scans
the global ram_list for ram blocks with a valid fd field set. This would
be set when the '-object memory-file' option with share=on property is used.

Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
Signed-off-by: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/virtio/Makefile.objs

@@ -5,4 +5,4 @@ common-obj-y += virtio-mmio.o
 common-obj-$(CONFIG_VIRTIO_BLK_DATA_PLANE) += dataplane/
 
 obj-y += virtio.o virtio-balloon.o 
-obj-$(CONFIG_LINUX) += vhost.o vhost-backend.o
+obj-$(CONFIG_LINUX) += vhost.o vhost-backend.o vhost-user.o

hw/virtio/vhost-backend.c

@@ -14,6 +14,8 @@
 
 #include <sys/ioctl.h>
 
+extern const VhostOps user_ops;
+
 static int vhost_kernel_call(struct vhost_dev *dev, unsigned long int request,
                              void *arg)
 {
@@ -57,6 +59,9 @@ int vhost_set_backend_type(struct vhost_dev *dev, VhostBackendType backend_type)
     case VHOST_BACKEND_TYPE_KERNEL:
         dev->vhost_ops = &kernel_ops;
         break;
+    case VHOST_BACKEND_TYPE_USER:
+        dev->vhost_ops = &user_ops;
+        break;
     default:
         error_report("Unknown vhost backend type\n");
         r = -1;

hw/virtio/vhost-user.c

@@ -0,0 +1,342 @@
+/*
+ * vhost-user
+ *
+ * Copyright (c) 2013 Virtual Open Systems Sarl.
+ *
+ * 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 "hw/virtio/vhost.h"
+#include "hw/virtio/vhost-backend.h"
+#include "sysemu/char.h"
+#include "sysemu/kvm.h"
+#include "qemu/error-report.h"
+#include "qemu/sockets.h"
+
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <linux/vhost.h>
+
+#define VHOST_MEMORY_MAX_NREGIONS    8
+
+typedef enum VhostUserRequest {
+    VHOST_USER_NONE = 0,
+    VHOST_USER_GET_FEATURES = 1,
+    VHOST_USER_SET_FEATURES = 2,
+    VHOST_USER_SET_OWNER = 3,
+    VHOST_USER_RESET_OWNER = 4,
+    VHOST_USER_SET_MEM_TABLE = 5,
+    VHOST_USER_SET_LOG_BASE = 6,
+    VHOST_USER_SET_LOG_FD = 7,
+    VHOST_USER_SET_VRING_NUM = 8,
+    VHOST_USER_SET_VRING_ADDR = 9,
+    VHOST_USER_SET_VRING_BASE = 10,
+    VHOST_USER_GET_VRING_BASE = 11,
+    VHOST_USER_SET_VRING_KICK = 12,
+    VHOST_USER_SET_VRING_CALL = 13,
+    VHOST_USER_SET_VRING_ERR = 14,
+    VHOST_USER_MAX
+} VhostUserRequest;
+
+typedef struct VhostUserMemoryRegion {
+    uint64_t guest_phys_addr;
+    uint64_t memory_size;
+    uint64_t userspace_addr;
+} VhostUserMemoryRegion;
+
+typedef struct VhostUserMemory {
+    uint32_t nregions;
+    uint32_t padding;
+    VhostUserMemoryRegion regions[VHOST_MEMORY_MAX_NREGIONS];
+} VhostUserMemory;
+
+typedef struct VhostUserMsg {
+    VhostUserRequest request;
+
+#define VHOST_USER_VERSION_MASK     (0x3)
+#define VHOST_USER_REPLY_MASK       (0x1<<2)
+    uint32_t flags;
+    uint32_t size; /* the following payload size */
+    union {
+#define VHOST_USER_VRING_IDX_MASK   (0xff)
+#define VHOST_USER_VRING_NOFD_MASK  (0x1<<8)
+        uint64_t u64;
+        struct vhost_vring_state state;
+        struct vhost_vring_addr addr;
+        VhostUserMemory memory;
+    };
+} QEMU_PACKED VhostUserMsg;
+
+static VhostUserMsg m __attribute__ ((unused));
+#define VHOST_USER_HDR_SIZE (sizeof(m.request) \
+                            + sizeof(m.flags) \
+                            + sizeof(m.size))
+
+#define VHOST_USER_PAYLOAD_SIZE (sizeof(m) - VHOST_USER_HDR_SIZE)
+
+/* The version of the protocol we support */
+#define VHOST_USER_VERSION    (0x1)
+
+static bool ioeventfd_enabled(void)
+{
+    return kvm_enabled() && kvm_eventfds_enabled();
+}
+
+static unsigned long int ioctl_to_vhost_user_request[VHOST_USER_MAX] = {
+    -1,                     /* VHOST_USER_NONE */
+    VHOST_GET_FEATURES,     /* VHOST_USER_GET_FEATURES */
+    VHOST_SET_FEATURES,     /* VHOST_USER_SET_FEATURES */
+    VHOST_SET_OWNER,        /* VHOST_USER_SET_OWNER */
+    VHOST_RESET_OWNER,      /* VHOST_USER_RESET_OWNER */
+    VHOST_SET_MEM_TABLE,    /* VHOST_USER_SET_MEM_TABLE */
+    VHOST_SET_LOG_BASE,     /* VHOST_USER_SET_LOG_BASE */
+    VHOST_SET_LOG_FD,       /* VHOST_USER_SET_LOG_FD */
+    VHOST_SET_VRING_NUM,    /* VHOST_USER_SET_VRING_NUM */
+    VHOST_SET_VRING_ADDR,   /* VHOST_USER_SET_VRING_ADDR */
+    VHOST_SET_VRING_BASE,   /* VHOST_USER_SET_VRING_BASE */
+    VHOST_GET_VRING_BASE,   /* VHOST_USER_GET_VRING_BASE */
+    VHOST_SET_VRING_KICK,   /* VHOST_USER_SET_VRING_KICK */
+    VHOST_SET_VRING_CALL,   /* VHOST_USER_SET_VRING_CALL */
+    VHOST_SET_VRING_ERR     /* VHOST_USER_SET_VRING_ERR */
+};
+
+static VhostUserRequest vhost_user_request_translate(unsigned long int request)
+{
+    VhostUserRequest idx;
+
+    for (idx = 0; idx < VHOST_USER_MAX; idx++) {
+        if (ioctl_to_vhost_user_request[idx] == request) {
+            break;
+        }
+    }
+
+    return (idx == VHOST_USER_MAX) ? VHOST_USER_NONE : idx;
+}
+
+static int vhost_user_read(struct vhost_dev *dev, VhostUserMsg *msg)
+{
+    CharDriverState *chr = dev->opaque;
+    uint8_t *p = (uint8_t *) msg;
+    int r, size = VHOST_USER_HDR_SIZE;
+
+    r = qemu_chr_fe_read_all(chr, p, size);
+    if (r != size) {
+        error_report("Failed to read msg header. Read %d instead of %d.\n", r,
+                size);
+        goto fail;
+    }
+
+    /* validate received flags */
+    if (msg->flags != (VHOST_USER_REPLY_MASK | VHOST_USER_VERSION)) {
+        error_report("Failed to read msg header."
+                " Flags 0x%x instead of 0x%x.\n", msg->flags,
+                VHOST_USER_REPLY_MASK | VHOST_USER_VERSION);
+        goto fail;
+    }
+
+    /* validate message size is sane */
+    if (msg->size > VHOST_USER_PAYLOAD_SIZE) {
+        error_report("Failed to read msg header."
+                " Size %d exceeds the maximum %zu.\n", msg->size,
+                VHOST_USER_PAYLOAD_SIZE);
+        goto fail;
+    }
+
+    if (msg->size) {
+        p += VHOST_USER_HDR_SIZE;
+        size = msg->size;
+        r = qemu_chr_fe_read_all(chr, p, size);
+        if (r != size) {
+            error_report("Failed to read msg payload."
+                         " Read %d instead of %d.\n", r, msg->size);
+            goto fail;
+        }
+    }
+
+    return 0;
+
+fail:
+    return -1;
+}
+
+static int vhost_user_write(struct vhost_dev *dev, VhostUserMsg *msg,
+                            int *fds, int fd_num)
+{
+    CharDriverState *chr = dev->opaque;
+    int size = VHOST_USER_HDR_SIZE + msg->size;
+
+    if (fd_num) {
+        qemu_chr_fe_set_msgfds(chr, fds, fd_num);
+    }
+
+    return qemu_chr_fe_write_all(chr, (const uint8_t *) msg, size) == size ?
+            0 : -1;
+}
+
+static int vhost_user_call(struct vhost_dev *dev, unsigned long int request,
+        void *arg)
+{
+    VhostUserMsg msg;
+    VhostUserRequest msg_request;
+    RAMBlock *block = 0;
+    struct vhost_vring_file *file = 0;
+    int need_reply = 0;
+    int fds[VHOST_MEMORY_MAX_NREGIONS];
+    size_t fd_num = 0;
+
+    assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
+
+    msg_request = vhost_user_request_translate(request);
+    msg.request = msg_request;
+    msg.flags = VHOST_USER_VERSION;
+    msg.size = 0;
+
+    switch (request) {
+    case VHOST_GET_FEATURES:
+        need_reply = 1;
+        break;
+
+    case VHOST_SET_FEATURES:
+    case VHOST_SET_LOG_BASE:
+        msg.u64 = *((__u64 *) arg);
+        msg.size = sizeof(m.u64);
+        break;
+
+    case VHOST_SET_OWNER:
+    case VHOST_RESET_OWNER:
+        break;
+
+    case VHOST_SET_MEM_TABLE:
+        QTAILQ_FOREACH(block, &ram_list.blocks, next)
+        {
+            if (block->fd > 0) {
+                msg.memory.regions[fd_num].userspace_addr =
+                    (uintptr_t) block->host;
+                msg.memory.regions[fd_num].memory_size = block->length;
+                msg.memory.regions[fd_num].guest_phys_addr = block->offset;
+                fds[fd_num++] = block->fd;
+            }
+        }
+
+        msg.memory.nregions = fd_num;
+
+        if (!fd_num) {
+            error_report("Failed initializing vhost-user memory map\n"
+                    "consider using -object memory-backend-file share=on\n");
+            return -1;
+        }
+
+        msg.size = sizeof(m.memory.nregions);
+        msg.size += sizeof(m.memory.padding);
+        msg.size += fd_num * sizeof(VhostUserMemoryRegion);
+
+        break;
+
+    case VHOST_SET_LOG_FD:
+        fds[fd_num++] = *((int *) arg);
+        break;
+
+    case VHOST_SET_VRING_NUM:
+    case VHOST_SET_VRING_BASE:
+        memcpy(&msg.state, arg, sizeof(struct vhost_vring_state));
+        msg.size = sizeof(m.state);
+        break;
+
+    case VHOST_GET_VRING_BASE:
+        memcpy(&msg.state, arg, sizeof(struct vhost_vring_state));
+        msg.size = sizeof(m.state);
+        need_reply = 1;
+        break;
+
+    case VHOST_SET_VRING_ADDR:
+        memcpy(&msg.addr, arg, sizeof(struct vhost_vring_addr));
+        msg.size = sizeof(m.addr);
+        break;
+
+    case VHOST_SET_VRING_KICK:
+    case VHOST_SET_VRING_CALL:
+    case VHOST_SET_VRING_ERR:
+        file = arg;
+        msg.u64 = file->index & VHOST_USER_VRING_IDX_MASK;
+        msg.size = sizeof(m.u64);
+        if (ioeventfd_enabled() && file->fd > 0) {
+            fds[fd_num++] = file->fd;
+        } else {
+            msg.u64 |= VHOST_USER_VRING_NOFD_MASK;
+        }
+        break;
+    default:
+        error_report("vhost-user trying to send unhandled ioctl\n");
+        return -1;
+        break;
+    }
+
+    if (vhost_user_write(dev, &msg, fds, fd_num) < 0) {
+        return 0;
+    }
+
+    if (need_reply) {
+        if (vhost_user_read(dev, &msg) < 0) {
+            return 0;
+        }
+
+        if (msg_request != msg.request) {
+            error_report("Received unexpected msg type."
+                    " Expected %d received %d\n", msg_request, msg.request);
+            return -1;
+        }
+
+        switch (msg_request) {
+        case VHOST_USER_GET_FEATURES:
+            if (msg.size != sizeof(m.u64)) {
+                error_report("Received bad msg size.\n");
+                return -1;
+            }
+            *((__u64 *) arg) = msg.u64;
+            break;
+        case VHOST_USER_GET_VRING_BASE:
+            if (msg.size != sizeof(m.state)) {
+                error_report("Received bad msg size.\n");
+                return -1;
+            }
+            memcpy(arg, &msg.state, sizeof(struct vhost_vring_state));
+            break;
+        default:
+            error_report("Received unexpected msg type.\n");
+            return -1;
+            break;
+        }
+    }
+
+    return 0;
+}
+
+static int vhost_user_init(struct vhost_dev *dev, void *opaque)
+{
+    assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
+
+    dev->opaque = opaque;
+
+    return 0;
+}
+
+static int vhost_user_cleanup(struct vhost_dev *dev)
+{
+    assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
+
+    dev->opaque = 0;
+
+    return 0;
+}
+
+const VhostOps user_ops = {
+        .backend_type = VHOST_BACKEND_TYPE_USER,
+        .vhost_call = vhost_user_call,
+        .vhost_backend_init = vhost_user_init,
+        .vhost_backend_cleanup = vhost_user_cleanup
+        };