[Qemu-devel] [PATCH] 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.

RHBZ #725965

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

v2:
 call qemu_del_timer, unregister vmstate
---
 spice-qemu-char.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 54 insertions(+), 10 deletions(-)

diff --git a/spice-qemu-char.c b/spice-qemu-char.c
index aea3d24..5f81d0e 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>
@@ -26,6 +27,10 @@ typedef struct SpiceCharDriver {
     ssize_t               bufsize, datalen;
     uint32_t              debug;
     QLIST_ENTRY(SpiceCharDriver) next;
+    uint32_t              guest_open;
+    struct {
+        QEMUTimer        *timer;
+    } post_load;
 } SpiceCharDriver;
 
 static QLIST_HEAD(, SpiceCharDriver) spice_chars =
@@ -178,25 +183,19 @@ static int spice_chr_write(CharDriverState *chr, const 
uint8_t *buf, int len)
     return len;
 }
 
-static void spice_chr_close(struct CharDriverState *chr)
-{
-    SpiceCharDriver *s = chr->opaque;
-
-    printf("%s\n", __func__);
-    vmc_unregister_interface(s);
-    QLIST_REMOVE(s, next);
-    g_free(s);
-}
-
 static void spice_chr_guest_open(struct CharDriverState *chr)
 {
     SpiceCharDriver *s = chr->opaque;
+
+    s->guest_open = 1;
     vmc_register_interface(s);
 }
 
 static void spice_chr_guest_close(struct CharDriverState *chr)
 {
     SpiceCharDriver *s = chr->opaque;
+
+    s->guest_open = 0;
     vmc_unregister_interface(s);
 }
 
@@ -217,6 +216,47 @@ static void print_allowed_subtypes(void)
     fprintf(stderr, "\n");
 }
 
+static void spice_chr_post_load_cb(void *opaque)
+{
+    SpiceCharDriver *s = opaque;
+
+    spice_chr_guest_open(s->chr);
+}
+
+static int spice_chr_post_load(void *opaque, int version_id)
+{
+    SpiceCharDriver *s = opaque;
+
+    if (s && s->chr && s->guest_open) {
+        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_UINT32(guest_open, SpiceCharDriver),
+        VMSTATE_END_OF_LIST()
+    },
+};
+
+static void spice_chr_close(struct CharDriverState *chr)
+{
+    SpiceCharDriver *s = chr->opaque;
+
+    printf("%s\n", __func__);
+    vmc_unregister_interface(s);
+    QLIST_REMOVE(s, next);
+    qemu_del_timer(s->post_load.timer);
+    qemu_free_timer(s->post_load.timer);
+    vmstate_unregister(NULL, &spice_chr_vmstate, s);
+    g_free(s);
+}
+
 static CharDriverState *chr_open(QemuOpts *opts, const char *subtype)
 {
     CharDriverState *chr;
@@ -229,12 +269,16 @@ static CharDriverState *chr_open(QemuOpts *opts, const 
char *subtype)
     s->debug = debug;
     s->active = false;
     s->sin.subtype = 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