[Qemu-devel] [PATCH] virtio-serial: PCI device for simple host <-> guest communication

[Amit Shah]

This interface presents a char device from which bits can be
sent and read.

Sample uses for such a device can be obtaining info from the
guest like the file systems used, apps installed, etc. for
offline usage and logged-in users, clipboard copy-paste, etc.
for online usage.

Signed-off-by: Amit Shah <address@hidden>
---
 Makefile.target    |    2 +-
 hw/pc.c            |   17 +++
 hw/pci.h           |    1 +
 hw/virtio-pci.c    |   15 +++
 hw/virtio-serial.c |  320 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 hw/virtio-serial.h |   31 +++++
 hw/virtio.h        |    1 +
 qemu-options.hx    |    8 ++
 sysemu.h           |   11 ++
 vl.c               |   62 ++++++++++
 10 files changed, 467 insertions(+), 1 deletions(-)
 create mode 100644 hw/virtio-serial.c
 create mode 100644 hw/virtio-serial.h

diff --git a/Makefile.target b/Makefile.target
index 27de4b9..d8ad787 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -497,7 +497,7 @@ OBJS=vl.o osdep.o monitor.o pci.o loader.o isa_mmio.o 
machine.o \
      gdbstub.o gdbstub-xml.o
 # virtio has to be here due to weird dependency between PCI and virtio-net.
 # need to fix this properly
-OBJS+=virtio-blk.o virtio-balloon.o virtio-net.o virtio-console.o
+OBJS+=virtio-blk.o virtio-balloon.o virtio-net.o virtio-console.o 
virtio-serial.o
 ifdef CONFIG_KVM
 OBJS+=kvm.o kvm-all.o
 endif
diff --git a/hw/pc.c b/hw/pc.c
index 0934778..b4136a0 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -37,6 +37,8 @@
 #include "watchdog.h"
 #include "smbios.h"
 
+void *virtio_serial_new_port(PCIDevice *dev, int idx, char *name);
+
 /* output Bochs bios info messages */
 //#define DEBUG_BIOS
 
@@ -1164,6 +1166,21 @@ static void pc_init1(ram_addr_t ram_size,
             }
         }
     }
+
+    /* Add virtio serial devices */
+    if (pci_enabled && virtio_serial_index) {
+        void *dev;
+
+        dev = pci_create_simple(pci_bus, -1, "virtio-serial-pci");
+        if (!dev) {
+            fprintf(stderr, "qemu: could not create virtio serial pci 
device\n");
+            exit(1);
+        }
+
+        for (i = 0; i < virtio_serial_index; i++) {
+                virtio_serial_new_port(dev, i, virtio_serial_names[i]);
+        }
+    }
 }
 
 static void pc_init_pci(ram_addr_t ram_size,
diff --git a/hw/pci.h b/hw/pci.h
index 0405837..ab06008 100644
--- a/hw/pci.h
+++ b/hw/pci.h
@@ -69,6 +69,7 @@ extern target_phys_addr_t pci_mem_base;
 #define PCI_DEVICE_ID_VIRTIO_BLOCK       0x1001
 #define PCI_DEVICE_ID_VIRTIO_BALLOON     0x1002
 #define PCI_DEVICE_ID_VIRTIO_CONSOLE     0x1003
+#define PCI_DEVICE_ID_VIRTIO_SERIAL      0x1004
 
 typedef void PCIConfigWriteFunc(PCIDevice *pci_dev,
                                 uint32_t address, uint32_t data, int len);
diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
index c072423..30e56e1 100644
--- a/hw/virtio-pci.c
+++ b/hw/virtio-pci.c
@@ -334,6 +334,19 @@ static void virtio_balloon_init_pci(PCIDevice *pci_dev)
                     0x00);
 }
 
+static void virtio_serial_init_pci(PCIDevice *pci_dev)
+{
+    VirtIOPCIProxy *proxy = DO_UPCAST(VirtIOPCIProxy, pci_dev, pci_dev);
+    VirtIODevice *vdev;
+
+    vdev = virtio_serial_init(&pci_dev->qdev);
+    virtio_init_pci(proxy, vdev,
+                    PCI_VENDOR_ID_REDHAT_QUMRANET,
+                    PCI_DEVICE_ID_VIRTIO_SERIAL,
+                    PCI_CLASS_COMMUNICATION_OTHER,
+                    0x00);
+}
+
 static void virtio_pci_register_devices(void)
 {
     pci_qdev_register("virtio-blk-pci", sizeof(VirtIOPCIProxy),
@@ -344,6 +357,8 @@ static void virtio_pci_register_devices(void)
                       virtio_console_init_pci);
     pci_qdev_register("virtio-balloon-pci", sizeof(VirtIOPCIProxy),
                       virtio_balloon_init_pci);
+    pci_qdev_register("virtio-serial-pci", sizeof(VirtIOPCIProxy),
+                      virtio_serial_init_pci);
 }
 
 device_init(virtio_pci_register_devices)
diff --git a/hw/virtio-serial.c b/hw/virtio-serial.c
new file mode 100644
index 0000000..9ce06f0
--- /dev/null
+++ b/hw/virtio-serial.c
@@ -0,0 +1,320 @@
+/*
+ * Virtio serial interface
+ *
+ * This serial interface is a paravirtualised guest<->host
+ * communication channel for relaying short messages and events in
+ * either direction.
+ *
+ * There's support for multiple serial channels within one virtio PCI
+ * device to keep the guest PCI device count low.
+ *
+ * Copyright (C) 2009, Red Hat, Inc.
+ *
+ * Author(s): Amit Shah <address@hidden>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ */
+
+#include "hw.h"
+#include "pci.h"
+#include "monitor.h"
+#include "qemu-char.h"
+#include "virtio.h"
+#include "virtio-serial.h"
+#include "sysemu.h"
+
+typedef struct VirtIOSerial {
+    VirtIODevice *vdev;
+    VirtQueue *cvq;
+    struct VirtIOSerialPort *ports;
+} VirtIOSerial;
+
+typedef struct VirtIOSerialPort {
+    VirtIOSerial *virtserial;
+    VirtQueue *ivq, *ovq;
+    CharDriverState *hd;
+    char name[VIRTIO_SERIAL_NAME_MAX_LEN];
+} VirtIOSerialPort;
+
+VirtIOSerial virtio_serial;
+
+static char *get_port_name_from_idx(uint8_t idx)
+{
+    if (idx > virtio_serial_index)
+        return NULL;
+
+    return virtio_serial.ports[idx].name;
+}
+
+static VirtIOSerialPort *get_port_from_vq(VirtQueue *vq)
+{
+    int i;
+
+    for (i = 0; i < virtio_serial_index; i++) {
+        if (vq == virtio_serial.ports[i].ivq
+            || vq == virtio_serial.ports[i].ovq) {
+            return &virtio_serial.ports[i];
+        }
+    }
+    return NULL;
+}
+
+static void virtio_serial_handle_control(VirtIODevice *vdev, VirtQueue *vq)
+{
+    VirtQueueElement elem;
+
+    while (virtqueue_pop(vq, &elem)) {
+        int i;
+        char *name;
+        uint8_t idx;
+        uint32_t key;
+        ssize_t len, strlen;
+
+        len = 0;
+        for (i = 0; i < elem.out_num; i++) {
+            memcpy(&key, elem.out_sg[i].iov_base, 4);
+
+            switch(key) {
+            case VIRTIO_SERIAL_GET_PORT_NAME:
+                memcpy(&idx, elem.out_sg[i].iov_base + 4, 1);
+                name = get_port_name_from_idx(idx);
+
+                strlen = strnlen(name, VIRTIO_SERIAL_NAME_MAX_LEN);
+
+                memcpy(elem.in_sg[0].iov_base, &key, 4);
+                memcpy(elem.in_sg[0].iov_base + 4, &idx, 1);
+                memcpy(elem.in_sg[0].iov_base + 5, name, strlen);
+                len = 5 + strlen;
+                break;
+            }
+        }
+        virtqueue_push(vq, &elem, len);
+    }
+    virtio_notify(vdev, vq);
+
+    return;
+}
+
+static void virtio_serial_handle_output(VirtIODevice *vdev, VirtQueue *vq)
+{
+    VirtIOSerialPort *port = get_port_from_vq(vq);
+    VirtQueueElement elem;
+
+    while (virtqueue_pop(vq, &elem)) {
+        ssize_t len = 0;
+        int i;
+
+        if (port->hd) {
+            for (i = 0; i < elem.out_num; i++) {
+                len += qemu_chr_write(port->hd, elem.out_sg[i].iov_base,
+                                      elem.out_sg[i].iov_len);
+            }
+        }
+        virtqueue_push(vq, &elem, len);
+    }
+    virtio_notify(vdev, vq);
+}
+
+static void virtio_serial_handle_input(VirtIODevice *vdev, VirtQueue *vq)
+{
+}
+
+
+/* FIXME: we just accept a single string */
+void virtio_serial_send_input(const char *command, const char *key,
+                             const char *value)
+{
+    VirtQueueElement elem;
+    VirtIOSerialPort *s = &virtio_serial.ports[0];
+    VirtIODevice *vdev = s->virtserial->vdev;
+    VirtQueue *vq = s->ivq;
+    char buf[300];
+    ssize_t len;
+    int ret;
+    unsigned int i;
+
+    if (!virtio_queue_ready(s->ivq)) {
+        goto queue_not_ready;
+    }
+
+    len = snprintf(buf, 299, "%s %s %s\n", command, key, value);
+
+    /* FIXME! actually handle this in a for loop */
+
+    ret = virtqueue_pop(vq, &elem);
+    if (!ret) {
+        goto queue_not_ready;
+    }
+
+    i = 0;
+    /* Note: We only have PAGE_SIZE sized buffers */
+    memcpy(elem.in_sg[i].iov_base, buf, len);
+    elem.in_sg[i].iov_len = len;
+
+    virtqueue_push(vq, &elem, len);
+    virtio_notify(vdev, vq);
+    return;
+
+queue_not_ready:
+    monitor_printf(cur_mon,
+                   "vmserial: No free virtio buffer found. Message not 
sent.\n");
+    return;
+}
+
+static int cons_can_read(void *opaque)
+{
+    VirtIOSerialPort *port = (VirtIOSerialPort *) opaque;
+
+    if (!virtio_queue_ready(port->ivq)) {
+        return 0;
+    }
+
+    /* current implementations have a page sized buffer.
+     * We fall back to a one byte per read if there is not enough room.
+     */
+    if (virtqueue_avail_bytes(port->ivq, TARGET_PAGE_SIZE, 0)) {
+        return TARGET_PAGE_SIZE;
+    }
+    if (virtqueue_avail_bytes(port->ivq, 1, 0)) {
+        return 1;
+    }
+    return 0;
+}
+
+static void cons_read(void *opaque, const uint8_t *buf, int size)
+{
+    VirtIOSerialPort *port = (VirtIOSerialPort *) opaque;
+    VirtQueueElement elem;
+    int offset = 0;
+
+    /* The current kernel implementation has only one outstanding input
+     * buffer of PAGE_SIZE. Nevertheless, this function is prepared to
+     * handle multiple buffers with multiple sg element for input
+     */
+    while (offset < size) {
+        int i = 0;
+
+        if (!virtqueue_pop(port->ivq, &elem)) {
+            break;
+        }
+        while (offset < size && i < elem.in_num) {
+            int len = MIN(elem.in_sg[i].iov_len, size - offset);
+            memcpy(elem.in_sg[i].iov_base, buf + offset, len);
+            offset += len;
+            i++;
+        }
+        virtqueue_push(port->ivq, &elem, size);
+    }
+    virtio_notify(port->virtserial->vdev, port->ivq);
+}
+
+static void cons_event(void *opaque, int event)
+{
+    /* we will ignore any event for the time being */
+}
+
+static uint32_t virtio_serial_get_features(VirtIODevice *vdev)
+{
+    return 0;
+}
+
+static void virtio_serial_get_config(VirtIODevice *vdev, uint8_t *config_data)
+{
+    struct virtio_serial_config config;
+
+    /* This might have to be updated for serial port hotplug */
+    config.nr_ports = virtio_serial_index;
+    config.status = 0;
+
+    memcpy(config_data, &config, sizeof(config));
+}
+
+static void virtio_serial_set_config(VirtIODevice *vdev,
+                                     const uint8_t *config_data)
+{
+    struct virtio_serial_config config;
+
+    memcpy(&config, config_data, sizeof(config));
+
+    /* Nothing to do as of now */
+}
+
+static void virtio_serial_save(QEMUFile *f, void *opaque)
+{
+    VirtIODevice *vdev = opaque;
+
+    virtio_save(vdev, f);
+}
+
+static int virtio_serial_load(QEMUFile *f, void *opaque, int version_id)
+{
+    VirtIODevice *vdev = opaque;
+
+    if (version_id != 1)
+        return -EINVAL;
+
+    virtio_load(vdev, f);
+    return 0;
+}
+
+void *virtio_serial_new_port(PCIDevice *dev, int idx, char *name)
+{
+    VirtIOSerialPort *port;
+
+    port = &virtio_serial.ports[idx];
+
+    port->virtserial = &virtio_serial;
+
+    memcpy(port->name, name, VIRTIO_SERIAL_NAME_MAX_LEN);
+
+    port->hd = qdev_init_chardev(&dev->qdev);
+    if (port->hd) {
+        qemu_chr_add_handlers(port->hd, cons_can_read, cons_read, cons_event,
+                              port);
+    }
+
+    /* Add queue for host to guest transfers */
+    port->ivq = virtio_add_queue(port->virtserial->vdev, 2,
+                                 virtio_serial_handle_input);
+    /* Add queue for guest to host transfers */
+    port->ovq = virtio_add_queue(port->virtserial->vdev, 2,
+                                 virtio_serial_handle_output);
+
+    /* Send an update to the guest about this new port added */
+    virtio_notify_config(port->virtserial->vdev);
+    return port;
+}
+
+VirtIODevice *virtio_serial_init(DeviceState *dev)
+{
+    VirtIODevice *vdev;
+    int nr_ports = 4;
+
+    vdev = virtio_common_init("virtio-serial",
+                             VIRTIO_ID_SERIAL,
+                             sizeof(struct virtio_serial_config),
+                             sizeof(VirtIODevice));
+    if (vdev == NULL)
+        return NULL;
+
+    virtio_serial.vdev = vdev;
+    vdev->get_config = virtio_serial_get_config;
+    vdev->set_config = virtio_serial_set_config;
+    vdev->get_features = virtio_serial_get_features;
+
+    /* Add a queue for control information transfer common to all
+     * serial ports
+     */
+    virtio_serial.cvq = virtio_add_queue(vdev, 2, 
virtio_serial_handle_control);
+
+    /* Allocate space for the number of serial ports specified on the
+     * command line
+     */
+    virtio_serial.ports = qemu_mallocz(sizeof(VirtIOSerialPort) * nr_ports);
+
+    register_savevm("virtio-serial", -1, 1, virtio_serial_save,
+                    virtio_serial_load, vdev);
+
+    return vdev;
+}
diff --git a/hw/virtio-serial.h b/hw/virtio-serial.h
new file mode 100644
index 0000000..7d46c1f
--- /dev/null
+++ b/hw/virtio-serial.h
@@ -0,0 +1,31 @@
+/*
+ * Virtio Serial Support
+ *
+ * Copyright (C) 2009, Red Hat, Inc.
+ *
+ * Author(s): Amit Shah <address@hidden>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+#ifndef _QEMU_VIRTIO_SERIAL_H
+#define _QEMU_VIRTIO_SERIAL_H
+
+/* The ID for virtio serial */
+#define VIRTIO_ID_SERIAL 7
+
+struct virtio_serial_config
+{
+    uint8_t nr_ports;
+    uint16_t status;
+} __attribute__((packed));
+
+#define VIRTIO_SERIAL_GET_PORT_NAME 1
+
+
+void *virtio_serial_new_port(PCIDevice *dev, int idx, char *name);
+void virtio_serial_send_input(const char *command,
+                             const char *key, const char *value);
+
+#endif
diff --git a/hw/virtio.h b/hw/virtio.h
index 425727e..d2b50c3 100644
--- a/hw/virtio.h
+++ b/hw/virtio.h
@@ -151,5 +151,6 @@ VirtIODevice *virtio_blk_init(DeviceState *dev);
 VirtIODevice *virtio_net_init(DeviceState *dev);
 VirtIODevice *virtio_console_init(DeviceState *dev);
 VirtIODevice *virtio_balloon_init(DeviceState *dev);
+VirtIODevice *virtio_serial_init(DeviceState *dev);
 
 #endif
diff --git a/qemu-options.hx b/qemu-options.hx
index 87af798..857d8f1 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1523,6 +1523,14 @@ STEXI
 Set virtio console.
 ETEXI
 
+DEF("virtioserial", HAS_ARG, QEMU_OPTION_virtioserial, \
+    "-virtioserial c\n" \
+    "                define virtio serial device\n")
+STEXI
address@hidden -virtserial @var{c}
+Set virtio serial device.
+ETEXI
+
 DEF("show-cursor", 0, QEMU_OPTION_show_cursor, \
     "-show-cursor    show cursor\n")
 STEXI
diff --git a/sysemu.h b/sysemu.h
index 658aeec..4f2b5af 100644
--- a/sysemu.h
+++ b/sysemu.h
@@ -229,6 +229,17 @@ extern CharDriverState *parallel_hds[MAX_PARALLEL_PORTS];
 
 extern CharDriverState *virtcon_hds[MAX_VIRTIO_CONSOLES];
 
+/* virtio serial ports */
+
+#define MAX_VIRTIO_SERIAL_PORTS 4
+#define VIRTIO_SERIAL_NAME_MAX_LEN 30
+
+
+extern CharDriverState *virtio_serial_hds[MAX_VIRTIO_SERIAL_PORTS];
+extern char 
virtio_serial_names[MAX_VIRTIO_SERIAL_PORTS][VIRTIO_SERIAL_NAME_MAX_LEN];
+extern int virtio_serial_index;
+
+
 #define TFR(expr) do { if ((expr) != -1) break; } while (errno == EINTR)
 
 #ifdef NEED_CPU_H
diff --git a/vl.c b/vl.c
index fcf8532..4d31281 100644
--- a/vl.c
+++ b/vl.c
@@ -234,6 +234,9 @@ int no_quit = 0;
 CharDriverState *serial_hds[MAX_SERIAL_PORTS];
 CharDriverState *parallel_hds[MAX_PARALLEL_PORTS];
 CharDriverState *virtcon_hds[MAX_VIRTIO_CONSOLES];
+CharDriverState *virtio_serial_hds[MAX_VIRTIO_SERIAL_PORTS];
+char virtio_serial_names[MAX_VIRTIO_SERIAL_PORTS][VIRTIO_SERIAL_NAME_MAX_LEN];
+int virtio_serial_index;
 #ifdef TARGET_I386
 int win2k_install_hack = 0;
 int rtc_td_hack = 0;
@@ -4945,6 +4948,7 @@ int main(int argc, char **argv, char **envp)
     int parallel_device_index;
     const char *virtio_consoles[MAX_VIRTIO_CONSOLES];
     int virtio_console_index;
+    const char *virtio_serials[MAX_VIRTIO_SERIAL_PORTS];
     const char *loadvm = NULL;
     QEMUMachine *machine;
     const char *cpu_model;
@@ -5024,6 +5028,10 @@ int main(int argc, char **argv, char **envp)
         virtio_consoles[i] = NULL;
     virtio_console_index = 0;
 
+    for (i = 0; i < MAX_VIRTIO_SERIAL_PORTS; i++)
+        virtio_serials[i] = NULL;
+    virtio_serial_index = 0;
+
     for (i = 0; i < MAX_NODES; i++) {
         node_mem[i] = 0;
         node_cpumask[i] = 0;
@@ -5453,6 +5461,14 @@ int main(int argc, char **argv, char **envp)
                 virtio_consoles[virtio_console_index] = optarg;
                 virtio_console_index++;
                 break;
+           case QEMU_OPTION_virtioserial:
+                if (virtio_serial_index >= MAX_VIRTIO_SERIAL_PORTS) {
+                    fprintf(stderr, "qemu: too many virtio serial ports\n");
+                    exit(1);
+                }
+                virtio_serials[virtio_serial_index] = optarg;
+                virtio_serial_index++;
+                break;
             case QEMU_OPTION_parallel:
                 if (parallel_device_index >= MAX_PARALLEL_PORTS) {
                     fprintf(stderr, "qemu: too many parallel ports\n");
@@ -6038,6 +6054,43 @@ int main(int argc, char **argv, char **envp)
         }
     }
 
+    for (i = 0; i < virtio_serial_index; i++) {
+        const char *virtseropt;
+        char devname[80];
+        int j, k;
+
+        memset(devname, 0, 80);
+        j = k = 0;
+        while (isalnum(virtio_serials[i][j])) {
+            devname[k] = virtio_serials[i][j];
+            k++;
+            j++;
+        }
+
+        if (devname[0] && strncmp(devname, "none", 4)) {
+            char label[32];
+            snprintf(label, sizeof(label), "virtio-serial%d", i);
+            virtio_serial_hds[i] = qemu_chr_open(label, devname, NULL);
+            if (!virtio_serial_hds[i]) {
+                fprintf(stderr, "qemu: could not open virtio serial '%s'\n",
+                        devname);
+                exit(1);
+            }
+        }
+        virtseropt = strstr(virtio_serials[i], ",name=");
+        if (virtseropt) {
+            int j, k = 6;
+
+            for (j = 0; j < VIRTIO_SERIAL_NAME_MAX_LEN && 
isalnum(virtseropt[k]);
+                 j++, k++) {
+                virtio_serial_names[i][j] = virtseropt[k];
+            }
+            if (j < VIRTIO_SERIAL_NAME_MAX_LEN - 1) {
+                virtio_serial_names[i][j + 1] = 0;
+            }
+        }
+    }
+
     module_call_init(MODULE_INIT_DEVICE);
 
     machine->init(ram_size, boot_devices,
@@ -6172,6 +6225,15 @@ int main(int argc, char **argv, char **envp)
         }
     }
 
+    for(i = 0; i < MAX_VIRTIO_SERIAL_PORTS; i++) {
+        const char *devname = virtio_serials[i];
+        if (virtio_serial_hds[i] && devname) {
+            if (strstart(devname, "vc", 0)) {
+                qemu_chr_printf(virtio_serial_hds[i], "virtio serial%d\r\n", 
i);
+            }
+        }
+    }
+
     if (gdbstub_dev && gdbserver_start(gdbstub_dev) < 0) {
         fprintf(stderr, "qemu: could not open gdbserver on device '%s'\n",
                 gdbstub_dev);
-- 
1.6.0.6