guest will be destroyed when create guest with parameter "-usbdevice tablet".

[chao zhou]

Environment:
------------
Host OS (ia32/ia32e/IA64):ia32e
Guest OS (ia32/ia32e/IA64):ia32e
Guest OS Type (Linux/Windows):windows
kvm.git Commit:2c4aa55a6af070262cca425745e8e54310e96b8d
qemu.git Commit:ab0302ee764fd702465aef6d88612cdff4302809
Host Kernel Version:3.18.0-rc3
Hardware: Ivytown_EP,Haswell_EP

Bug detailed description:
--------------------------
when create guest with parameter "-usbdevice tablet", then guest will be destroyed.

note:
this shoule be a qemu bug:
kvm + qemu = result
2c4aa55a + ab0302ee = bad
2c4aa55a + 54600752 = good

Reproduce steps:
----------------
1. create guest
qemu-system-x86_64 --enable-kvm -m 4G smp 2 -net none win8.1.qcow -usbdevice tablet

Current result:
----------------
the guest will be destroyed when create guest with "-usbdevice tablet"

Expected result:
----------------
the guest works fine when create guest with "-usbdevice tablet"

Basic root-causing log:
----------------------
[root@vt-hsw2 ~]# qemu-system-x86_64 -enable-kvm -m 4G -smp 2 -net none /root/cathy/win8.1.qcow -usbdevice tablet
qemu-system-x86_64: util/qemu-option.c:387: qemu_opt_get_bool_helper: Assertion `opt->desc && opt->desc->type == QEMU_OPT_BOOL' failed.
Aborted (core dumped)

[Tiejun Chen (tiejun-chen)]

Could you test this?

Signed-off-by: Tiejun Chen <email address hidden>
---
 util/qemu-option.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/util/qemu-option.c b/util/qemu-option.c
index a708241..7cb3601 100644
--- a/util/qemu-option.c
+++ b/util/qemu-option.c
@@ -377,7 +377,7 @@ static bool qemu_opt_get_bool_helper(QemuOpts *opts, const char *name,
     }

     opt = qemu_opt_find(opts, name);
- if (opt == NULL) {
+ if ((opt == NULL) || !opt->desc) {
         const QemuOptDesc *desc = find_desc_by_name(opts->list->desc, name);
         if (desc && desc->def_value_str) {
             parse_option_bool(name, desc->def_value_str, &ret, &error_abort);
--

[chao zhou (chao-zhou)]

test the patch with qemu.git commit ab0302ee764fd702465aef6d88612cdff4302809
 create guest with parameter "-usbdevice tablet" , the guest works fine.

[chao zhou (chao-zhou)]

kvm.git+ qemu.git:bab5bb39_64ea8038
kernel:3.19.0-rc3
create guest with parameter "-usbdevice tablet" , the guest works fine.