[RFC,v4,13/49] multi-process: introduce proxy object

diff --git a/hw/Makefile.objs b/hw/Makefile.objs
index 4e28053..e016100 100644
--- a/hw/Makefile.objs
+++ b/hw/Makefile.objs
@@ -44,6 +44,8 @@  endif
 common-obj-y += $(devices-dirs-y)
 obj-y += $(devices-dirs-y)
 
+common-obj-$(CONFIG_MPQEMU) += proxy/
+
 remote-pci-obj-$(CONFIG_MPQEMU) += core/
 remote-pci-obj-$(CONFIG_MPQEMU) += block/
 remote-pci-obj-$(CONFIG_MPQEMU) += pci/
diff --git a/hw/proxy/Makefile.objs b/hw/proxy/Makefile.objs
new file mode 100644
index 0000000..eb81624
--- /dev/null
+++ b/hw/proxy/Makefile.objs
@@ -0,0 +1 @@ 
+common-obj-$(CONFIG_MPQEMU) += qemu-proxy.o
diff --git a/hw/proxy/qemu-proxy.c b/hw/proxy/qemu-proxy.c
new file mode 100644
index 0000000..baba4da
--- /dev/null
+++ b/hw/proxy/qemu-proxy.c
@@ -0,0 +1,247 @@ 
+/*
+ * Copyright 2019, Oracle and/or its affiliates.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <unistd.h>
+#include <assert.h>
+#include <string.h>
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "io/mpqemu-link.h"
+#include "exec/memory.h"
+#include "exec/cpu-common.h"
+#include "exec/address-spaces.h"
+#include "qemu/int128.h"
+#include "qemu/range.h"
+#include "hw/pci/pci.h"
+#include "qemu/option.h"
+#include "qemu/config-file.h"
+#include "qapi/qmp/qjson.h"
+#include "qapi/qmp/qstring.h"
+#include "sysemu/sysemu.h"
+#include "hw/proxy/qemu-proxy.h"
+
+static void pci_proxy_dev_realize(PCIDevice *dev, Error **errp);
+
+int remote_spawn(PCIProxyDev *pdev, const char *command, Error **errp)
+{
+    char *args[3];
+    pid_t rpid;
+    int fd[2] = {-1, -1};
+    Error *local_error = NULL;
+
+    if (pdev->managed) {
+        /* Child is forked by external program (such as libvirt). */
+        return -1;
+    }
+
+    if (socketpair(AF_UNIX, SOCK_STREAM, 0, fd)) {
+        error_setg(errp, "Unable to create unix socket.");
+        return -1;
+    }
+    /* TODO: Restrict the forked process' permissions and capabilities. */
+    rpid = qemu_fork(&local_error);
+
+    if (rpid == -1) {
+        error_setg(errp, "Unable to spawn emulation program.");
+        close(fd[0]);
+        close(fd[1]);
+        return -1;
+    }
+
+    if (rpid == 0) {
+        close(fd[0]);
+
+        args[0] = g_strdup(command);
+        args[1] = g_strdup_printf("%d", fd[1]);
+        args[2] = NULL;
+        execvp(args[0], (char *const *)args);
+        exit(1);
+    }
+    pdev->remote_pid = rpid;
+    pdev->rsocket = fd[0];
+
+    close(fd[1]);
+
+    return 0;
+}
+
+static int get_proxy_sock(PCIDevice *dev)
+{
+    PCIProxyDev *pdev;
+
+    pdev = PCI_PROXY_DEV(dev);
+
+    return pdev->rsocket;
+}
+
+static void set_proxy_sock(PCIDevice *dev, int socket)
+{
+    PCIProxyDev *pdev;
+
+    pdev = PCI_PROXY_DEV(dev);
+
+    pdev->rsocket = socket;
+    pdev->managed = true;
+
+}
+
+static int config_op_send(PCIProxyDev *dev, uint32_t addr, uint32_t *val, int l,
+                          unsigned int op)
+{
+    MPQemuMsg msg;
+    struct conf_data_msg conf_data;
+    int wait;
+
+    memset(&msg, 0, sizeof(MPQemuMsg));
+    conf_data.addr = addr;
+    conf_data.val = (op == CONF_WRITE) ? *val : 0;
+    conf_data.l = l;
+
+    msg.data2 = (uint8_t *)malloc(sizeof(conf_data));
+    if (!msg.data2) {
+        return -ENOMEM;
+    }
+
+    memcpy(msg.data2, (const uint8_t *)&conf_data, sizeof(conf_data));
+    msg.size = sizeof(conf_data);
+    msg.cmd = op;
+    msg.bytestream = 1;
+
+    if (op == CONF_WRITE) {
+        msg.num_fds = 0;
+    } else {
+        wait = GET_REMOTE_WAIT;
+        msg.num_fds = 1;
+        msg.fds[0] = wait;
+    }
+
+    mpqemu_msg_send(dev->mpqemu_link, &msg, dev->mpqemu_link->com);
+
+    if (op == CONF_READ) {
+        *val = (uint32_t)wait_for_remote(wait);
+        PUT_REMOTE_WAIT(wait);
+    }
+
+    free(msg.data2);
+
+    return 0;
+}
+
+static uint32_t pci_proxy_read_config(PCIDevice *d, uint32_t addr, int len)
+{
+    uint32_t val;
+
+    (void)pci_default_read_config(d, addr, len);
+
+    config_op_send(PCI_PROXY_DEV(d), addr, &val, len, CONF_READ);
+
+    return val;
+}
+
+static void pci_proxy_write_config(PCIDevice *d, uint32_t addr, uint32_t val,
+                                   int l)
+{
+    pci_default_write_config(d, addr, val, l);
+
+    config_op_send(PCI_PROXY_DEV(d), addr, &val, l, CONF_WRITE);
+}
+
+static void pci_proxy_dev_class_init(ObjectClass *klass, void *data)
+{
+    PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
+
+    k->realize = pci_proxy_dev_realize;
+    k->config_read = pci_proxy_read_config;
+    k->config_write = pci_proxy_write_config;
+}
+
+static const TypeInfo pci_proxy_dev_type_info = {
+    .name          = TYPE_PCI_PROXY_DEV,
+    .parent        = TYPE_PCI_DEVICE,
+    .instance_size = sizeof(PCIProxyDev),
+    .abstract      = true,
+    .class_size    = sizeof(PCIProxyDevClass),
+    .class_init    = pci_proxy_dev_class_init,
+    .interfaces = (InterfaceInfo[]) {
+        { INTERFACE_CONVENTIONAL_PCI_DEVICE },
+        { },
+    },
+};
+
+static void pci_proxy_dev_register_types(void)
+{
+    type_register_static(&pci_proxy_dev_type_info);
+}
+
+type_init(pci_proxy_dev_register_types)
+
+static void init_proxy(PCIDevice *dev, char *command, Error **errp)
+{
+    PCIProxyDev *pdev = PCI_PROXY_DEV(dev);
+    Error *local_error = NULL;
+
+    if (!pdev->managed) {
+        if (command) {
+            remote_spawn(pdev, command, &local_error);
+        } else {
+            return;
+        }
+    } else {
+        pdev->remote_pid = atoi(pdev->rid);
+        if (pdev->remote_pid == -1) {
+            error_setg(errp, "Remote PID is -1");
+            return;
+        }
+    }
+
+    pdev->mpqemu_link = mpqemu_link_create();
+
+    if (!pdev->mpqemu_link) {
+        error_setg(errp, "Failed to create proxy link");
+        return;
+    }
+
+    mpqemu_init_channel(pdev->mpqemu_link, &pdev->mpqemu_link->com,
+                        pdev->socket);
+}
+
+static void pci_proxy_dev_realize(PCIDevice *device, Error **errp)
+{
+    PCIProxyDev *dev = PCI_PROXY_DEV(device);
+    PCIProxyDevClass *k = PCI_PROXY_DEV_GET_CLASS(dev);
+    Error *local_err = NULL;
+
+    if (k->realize) {
+        k->realize(dev, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+        }
+    }
+
+    dev->set_proxy_sock = set_proxy_sock;
+    dev->get_proxy_sock = get_proxy_sock;
+    dev->init_proxy = init_proxy;
+}
diff --git a/include/hw/proxy/qemu-proxy.h b/include/hw/proxy/qemu-proxy.h
new file mode 100644
index 0000000..3648a77
--- /dev/null
+++ b/include/hw/proxy/qemu-proxy.h
@@ -0,0 +1,81 @@ 
+/*
+ * Copyright 2019, Oracle and/or its affiliates.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef QEMU_PROXY_H
+#define QEMU_PROXY_H
+
+#include "io/mpqemu-link.h"
+
+#define TYPE_PCI_PROXY_DEV "pci-proxy-dev"
+
+#define PCI_PROXY_DEV(obj) \
+            OBJECT_CHECK(PCIProxyDev, (obj), TYPE_PCI_PROXY_DEV)
+
+#define PCI_PROXY_DEV_CLASS(klass) \
+            OBJECT_CLASS_CHECK(PCIProxyDevClass, (klass), TYPE_PCI_PROXY_DEV)
+
+#define PCI_PROXY_DEV_GET_CLASS(obj) \
+            OBJECT_GET_CLASS(PCIProxyDevClass, (obj), TYPE_PCI_PROXY_DEV)
+
+typedef struct PCIProxyDev {
+    PCIDevice parent_dev;
+
+    int n_mr_sections;
+    MemoryRegionSection *mr_sections;
+
+    MPQemuLinkState *mpqemu_link;
+
+    EventNotifier intr;
+    EventNotifier resample;
+
+    pid_t remote_pid;
+    int rsocket;
+    int socket;
+
+    char *rid;
+
+    bool managed;
+    char *dev_id;
+
+    QLIST_ENTRY(PCIProxyDev) next;
+
+    void (*set_proxy_sock) (PCIDevice *dev, int socket);
+    int (*get_proxy_sock) (PCIDevice *dev);
+
+    void (*set_remote_opts) (PCIDevice *dev, QDict *qdict, unsigned int cmd);
+    void (*proxy_ready) (PCIDevice *dev);
+    void (*init_proxy) (PCIDevice *pdev, char *command, Error **errp);
+
+} PCIProxyDev;
+
+typedef struct PCIProxyDevClass {
+    PCIDeviceClass parent_class;
+
+    void (*realize)(PCIProxyDev *dev, Error **errp);
+
+    char *command;
+} PCIProxyDevClass;
+
+int remote_spawn(PCIProxyDev *pdev, const char *command, Error **errp);
+
+
+#endif /* QEMU_PROXY_H */
diff --git a/remote/remote-main.c b/remote/remote-main.c
index 7689b57..6c2eb91 100644
--- a/remote/remote-main.c
+++ b/remote/remote-main.c
@@ -50,6 +50,32 @@ 
 static MPQemuLinkState *mpqemu_link;
 PCIDevice *remote_pci_dev;
 
+static void process_config_write(MPQemuMsg *msg)
+{
+    struct conf_data_msg *conf = (struct conf_data_msg *)msg->data2;
+
+    qemu_mutex_lock_iothread();
+    pci_default_write_config(remote_pci_dev, conf->addr, conf->val, conf->l);
+    qemu_mutex_unlock_iothread();
+}
+
+static void process_config_read(MPQemuMsg *msg)
+{
+    struct conf_data_msg *conf = (struct conf_data_msg *)msg->data2;
+    uint32_t val;
+    int wait;
+
+    wait = msg->fds[0];
+
+    qemu_mutex_lock_iothread();
+    val = pci_default_read_config(remote_pci_dev, conf->addr, conf->l);
+    qemu_mutex_unlock_iothread();
+
+    notify_proxy(wait, val);
+
+    PUT_REMOTE_WAIT(wait);
+}
+
 static void process_msg(GIOCondition cond, MPQemuChannel *chan)
 {
     MPQemuMsg *msg = NULL;
@@ -71,8 +97,10 @@  static void process_msg(GIOCondition cond, MPQemuChannel *chan)
     case INIT:
         break;
     case CONF_WRITE:
+        process_config_write(msg);
         break;
     case CONF_READ:
+        process_config_read(msg);
         break;
     default:
         error_setg(&err, "Unknown command");