Julian Ganz <neither@nut.email> writes:
> We recently introduced new plugin API for registration of discontinuity
> related callbacks. This change introduces a minimal plugin showcasing
> the new API. It simply counts the occurances of interrupts, exceptions
> and host calls per CPU and reports the counts when exitting.
> ---
> contrib/plugins/meson.build | 3 +-
> contrib/plugins/traps.c | 96 +++++++++++++++++++++++++++++++++++++
> 2 files changed, 98 insertions(+), 1 deletion(-)
> create mode 100644 contrib/plugins/traps.c
>
> diff --git a/contrib/plugins/meson.build b/contrib/plugins/meson.build
> index 63a32c2b4f..9a3015e1c1 100644
> --- a/contrib/plugins/meson.build
> +++ b/contrib/plugins/meson.build
> @@ -1,5 +1,6 @@
> contrib_plugins = ['bbv', 'cache', 'cflow', 'drcov', 'execlog', 'hotblocks',
> - 'hotpages', 'howvec', 'hwprofile', 'ips', 'stoptrigger']
> + 'hotpages', 'howvec', 'hwprofile', 'ips', 'stoptrigger',
> + 'traps']
I wonder if this is better in tests/tcg/plugins? We need to do something
to ensure it gets covered by CI although we might want to be smarter
about running it together with a test binary that will actually pick up
something.
> if host_os != 'windows'
> # lockstep uses socket.h
> contrib_plugins += 'lockstep'
<snip>
> +QEMU_PLUGIN_EXPORT
> +int qemu_plugin_install(qemu_plugin_id_t id, const qemu_info_t *info,
> + int argc, char **argv)
> +{
> + if (!info->system_emulation) {
> + fputs("trap plugin can only be used in system emulation mode.\n",
> + stderr);
> + return -1;
> + }
> +
> + max_vcpus = info->system.max_vcpus;
> + traps = qemu_plugin_scoreboard_new(sizeof(TrapCounters));
> + qemu_plugin_register_vcpu_init_cb(id, vcpu_init);
> + qemu_plugin_vcpu_for_each(id, vcpu_init);
Hmm at first glances this seems redundant - however I guess this is
covering the use case you load the plugin after the system is up and
running.
I wonder if you have unearthed a foot-gun in the API that is easy to
fall into? Maybe we should expand qemu_plugin_register_vcpu_init_cb to
call the call back immediately for existing vcpus?
> +
> + qemu_plugin_register_vcpu_discon_cb(id, QEMU_PLUGIN_DISCON_TRAPS,
> + vcpu_discon);
> +
> + qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);
> +
> + return 0;
> +}
--
Alex Bennée
Virtualisation Tech Lead @ Linaro
