[Qemu-devel] [PATCH 2/2] spice-qemu-char: register interface on post load

[Alon Levy]

The target has not seen the guest_connected event via
spice_chr_guest_open or spice_chr_write, and so spice server wrongly
assumes there is no agent active, while the client continues to send
motion events only by the agent channel, which the server ignores. The
net effect is that the mouse is static in the guest.

By registering the interface on post load spice server will pass on the
agent messages fixing the mouse behavior after migration.

Note that qemu_be_is_fe_connected is called when the vm is already
running, to avoid any possible order of vmstate loading issue, i.e.
device loading after chardev post_load being called back.

RHBZ #725965

Signed-off-by: Alon Levy <al...@redhat.com>

v3: don't store any state in vmstate, get it via
qemu_be_is_fe_connected, that way we support multiple chardevices
without having to specify a device in vmstate_register.
---
 spice-qemu-char.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/spice-qemu-char.c b/spice-qemu-char.c
index 8a9236d..c457cc3 100644
--- a/spice-qemu-char.c
+++ b/spice-qemu-char.c
@@ -2,6 +2,7 @@
 #include "trace.h"
 #include "ui/qemu-spice.h"
 #include "char/char.h"
+#include "migration/vmstate.h"
 #include <spice.h>
 #include <spice-experimental.h>
 #include <spice/protocol.h>
@@ -17,6 +18,9 @@ typedef struct SpiceCharDriver {
     uint8_t               *datapos;
     ssize_t               bufsize, datalen;
     QLIST_ENTRY(SpiceCharDriver) next;
+    struct {
+        QEMUTimer        *timer;
+    } post_load;
 } SpiceCharDriver;
 
 static QLIST_HEAD(, SpiceCharDriver) spice_chars =
@@ -173,6 +177,8 @@ static void spice_chr_close(struct CharDriverState *chr)
 #if SPICE_SERVER_VERSION >= 0x000c02
     g_free((char *)s->sin.portname);
 #endif
+    qemu_del_timer(s->post_load.timer);
+    qemu_free_timer(s->post_load.timer);
     g_free(s);
 }
 
@@ -205,6 +211,35 @@ static void print_allowed_subtypes(void)
     fprintf(stderr, "\n");
 }
 
+static void spice_chr_post_load_cb(void *opaque)
+{
+    SpiceCharDriver *s = opaque;
+
+    if (qemu_chr_be_is_fe_connected(s->chr)) {
+        spice_chr_guest_open(s->chr);
+    }
+}
+
+static int spice_chr_post_load(void *opaque, int version_id)
+{
+    SpiceCharDriver *s = opaque;
+
+    if (s && s->chr) {
+        qemu_mod_timer(s->post_load.timer, 1);
+    }
+    return 0;
+}
+
+static VMStateDescription spice_chr_vmstate = {
+    .name               = "spice-chr",
+    .version_id         = 1,
+    .minimum_version_id = 1,
+    .post_load          = spice_chr_post_load,
+    .fields = (VMStateField[]) {
+        VMSTATE_END_OF_LIST()
+    },
+};
+
 static CharDriverState *chr_open(const char *subtype)
 {
     CharDriverState *chr;
@@ -215,12 +250,16 @@ static CharDriverState *chr_open(const char *subtype)
     s->chr = chr;
     s->active = false;
     s->sin.subtype = g_strdup(subtype);
+    s->post_load.timer = qemu_new_timer_ns(vm_clock,
+                                           spice_chr_post_load_cb, s);
     chr->opaque = s;
     chr->chr_write = spice_chr_write;
     chr->chr_close = spice_chr_close;
     chr->chr_guest_open = spice_chr_guest_open;
     chr->chr_guest_close = spice_chr_guest_close;
 
+    vmstate_register(NULL, -1, &spice_chr_vmstate, s);
+
     QLIST_INSERT_HEAD(&spice_chars, s, next);
 
     return chr;
-- 
1.8.1.4