spice: add chardev (v5)

Adding a chardev backend for spice, where spice determines what
to do with it based on the name attribute given during chardev creation.
For usage by spice vdagent in conjunction with a properly named
virtio-serial device, and future smartcard channel usage.

Example usage:
 qemu -device virtio-serial -chardev spicevmc,name=vdagent,id=vdagent \
 -device virtserialport,chardev=vdagent,name=com.redhat.spice.0

v4->v5:
 * add tracing events
 * fix missing comma
 * fix help string to show debug is optional

v3->v4:
 * updated commit message

v1->v3 changes: (v2 had a wrong commit message)
 * removed spice-qemu-char.h, folded into ui/qemu-spice.h
 * removed dead IOCTL code
 * removed comment
 * removed ifdef CONFIG_SPICE from qemu-config.c and qemu-options.hx help.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

1 files changed, 190 insertions, 0 deletions

diff --git a/spice-qemu-char.c b/spice-qemu-char.c
new file mode 100644
index 0000000000..517f337c43
--- /dev/null
+++ b/spice-qemu-char.c
@@ -0,0 +1,190 @@
+#include "config-host.h"
+#include "trace.h"
+#include "ui/qemu-spice.h"
+#include <spice.h>
+#include <spice-experimental.h>
+
+#include "osdep.h"
+
+#define dprintf(_scd, _level, _fmt, ...)                                \
+    do {                                                                \
+        static unsigned __dprintf_counter = 0;                          \
+        if (_scd->debug >= _level) {                                    \
+            fprintf(stderr, "scd: %3d: " _fmt, ++__dprintf_counter, ## __VA_ARGS__);\
+        }                                                               \
+    } while (0)
+
+#define VMC_MAX_HOST_WRITE    2048
+
+typedef struct SpiceCharDriver {
+    CharDriverState*      chr;
+    SpiceCharDeviceInstance     sin;
+    char                  *subtype;
+    bool                  active;
+    uint8_t               *buffer;
+    uint8_t               *datapos;
+    ssize_t               bufsize, datalen;
+    uint32_t              debug;
+} SpiceCharDriver;
+
+static int vmc_write(SpiceCharDeviceInstance *sin, const uint8_t *buf, int len)
+{
+    SpiceCharDriver *scd = container_of(sin, SpiceCharDriver, sin);
+    ssize_t out = 0;
+    ssize_t last_out;
+    uint8_t* p = (uint8_t*)buf;
+
+    while (len > 0) {
+        last_out = MIN(len, VMC_MAX_HOST_WRITE);
+        qemu_chr_read(scd->chr, p, last_out);
+        if (last_out > 0) {
+            out += last_out;
+            len -= last_out;
+            p += last_out;
+        } else {
+            break;
+        }
+    }
+
+    dprintf(scd, 3, "%s: %lu/%zd\n", __func__, out, len + out);
+    trace_spice_vmc_write(out, len + out);
+    return out;
+}
+
+static int vmc_read(SpiceCharDeviceInstance *sin, uint8_t *buf, int len)
+{
+    SpiceCharDriver *scd = container_of(sin, SpiceCharDriver, sin);
+    int bytes = MIN(len, scd->datalen);
+
+    dprintf(scd, 2, "%s: %p %d/%d/%zd\n", __func__, scd->datapos, len, bytes, scd->datalen);
+    if (bytes > 0) {
+        memcpy(buf, scd->datapos, bytes);
+        scd->datapos += bytes;
+        scd->datalen -= bytes;
+        assert(scd->datalen >= 0);
+        if (scd->datalen == 0) {
+            scd->datapos = 0;
+        }
+    }
+    trace_spice_vmc_read(bytes, len);
+    return bytes;
+}
+
+static SpiceCharDeviceInterface vmc_interface = {
+    .base.type          = SPICE_INTERFACE_CHAR_DEVICE,
+    .base.description   = "spice virtual channel char device",
+    .base.major_version = SPICE_INTERFACE_CHAR_DEVICE_MAJOR,
+    .base.minor_version = SPICE_INTERFACE_CHAR_DEVICE_MINOR,
+    .write              = vmc_write,
+    .read               = vmc_read,
+};
+
+
+static void vmc_register_interface(SpiceCharDriver *scd)
+{
+    if (scd->active) {
+        return;
+    }
+    dprintf(scd, 1, "%s\n", __func__);
+    scd->sin.base.sif = &vmc_interface.base;
+    qemu_spice_add_interface(&scd->sin.base);
+    scd->active = true;
+    trace_spice_vmc_register_interface(scd);
+}
+
+static void vmc_unregister_interface(SpiceCharDriver *scd)
+{
+    if (!scd->active) {
+        return;
+    }
+    dprintf(scd, 1, "%s\n", __func__);
+    spice_server_remove_interface(&scd->sin.base);
+    scd->active = false;
+    trace_spice_vmc_unregister_interface(scd);
+}
+
+
+static int spice_chr_write(CharDriverState *chr, const uint8_t *buf, int len)
+{
+    SpiceCharDriver *s = chr->opaque;
+
+    dprintf(s, 2, "%s: %d\n", __func__, len);
+    vmc_register_interface(s);
+    assert(s->datalen == 0);
+    if (s->bufsize < len) {
+        s->bufsize = len;
+        s->buffer = qemu_realloc(s->buffer, s->bufsize);
+    }
+    memcpy(s->buffer, buf, len);
+    s->datapos = s->buffer;
+    s->datalen = len;
+    spice_server_char_device_wakeup(&s->sin);
+    return len;
+}
+
+static void spice_chr_close(struct CharDriverState *chr)
+{
+    SpiceCharDriver *s = chr->opaque;
+
+    printf("%s\n", __func__);
+    vmc_unregister_interface(s);
+    qemu_free(s);
+}
+
+static void print_allowed_subtypes(void)
+{
+    const char** psubtype;
+    int i;
+
+    fprintf(stderr, "allowed names: ");
+    for(i=0, psubtype = spice_server_char_device_recognized_subtypes();
+        *psubtype != NULL; ++psubtype, ++i) {
+        if (i == 0) {
+            fprintf(stderr, "%s", *psubtype);
+        } else {
+            fprintf(stderr, ", %s", *psubtype);
+        }
+    }
+    fprintf(stderr, "\n");
+}
+
+CharDriverState *qemu_chr_open_spice(QemuOpts *opts)
+{
+    CharDriverState *chr;
+    SpiceCharDriver *s;
+    const char* name = qemu_opt_get(opts, "name");
+    uint32_t debug = qemu_opt_get_number(opts, "debug", 0);
+    const char** psubtype = spice_server_char_device_recognized_subtypes();
+    const char *subtype = NULL;
+
+    if (name == NULL) {
+        fprintf(stderr, "spice-qemu-char: missing name parameter\n");
+        print_allowed_subtypes();
+        return NULL;
+    }
+    for(;*psubtype != NULL; ++psubtype) {
+        if (strcmp(name, *psubtype) == 0) {
+            subtype = *psubtype;
+            break;
+        }
+    }
+    if (subtype == NULL) {
+        fprintf(stderr, "spice-qemu-char: unsupported name\n");
+        print_allowed_subtypes();
+        return NULL;
+    }
+
+    chr = qemu_mallocz(sizeof(CharDriverState));
+    s = qemu_mallocz(sizeof(SpiceCharDriver));
+    s->chr = chr;
+    s->debug = debug;
+    s->active = false;
+    s->sin.subtype = subtype;
+    chr->opaque = s;
+    chr->chr_write = spice_chr_write;
+    chr->chr_close = spice_chr_close;
+
+    qemu_chr_generic_open(chr);
+
+    return chr;
+}