From 20fdd01e51a2799f8185bc0ae0e3e000fb2ced7d Mon Sep 17 00:00:00 2001 From: Philippe Mathieu-Daudé Date: Tue, 13 Aug 2024 21:23:16 +0100 Subject: buildsys: Fix building without plugins on Darwin MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Since commit 0082475e26 the plugin symbol list is unconditionally added to the linker flags, leading to a build failure: Undefined symbols for architecture arm64: "_qemu_plugin_entry_code", referenced from: ... ld: symbol(s) not found for architecture arm64 clang: error: linker command failed with exit code 1 (use -v to see invocation) ninja: build stopped: subcommand failed. Fix by restricting the whole meson file to the --enable-plugins configure argument. Fixes: 0082475e26 ("meson: merge plugin_ldflags into emulator_link_args") Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2476 Signed-off-by: Philippe Mathieu-Daudé Acked-by: Richard Henderson Message-Id: <20240813112457.92560-1-philmd@linaro.org> Signed-off-by: Alex Bennée Message-Id: <20240813202329.1237572-9-alex.bennee@linaro.org> --- plugins/meson.build | 50 ++++++++++++++++++++++++++------------------------ 1 file changed, 26 insertions(+), 24 deletions(-) (limited to 'plugins') diff --git a/plugins/meson.build b/plugins/meson.build index 18a0303bff..1cc039d29b 100644 --- a/plugins/meson.build +++ b/plugins/meson.build @@ -1,3 +1,7 @@ +if not get_option('plugins') + subdir_done() +endif + # Modules need more symbols than just those in plugins/qemu-plugins.symbols if not enable_modules if host_os == 'darwin' @@ -12,29 +16,27 @@ if not enable_modules endif endif -if get_option('plugins') - if host_os == 'windows' - dlltool = find_program('dlltool', required: true) +if host_os == 'windows' + dlltool = find_program('dlltool', required: true) - # Generate a .lib file for plugins to link against. - # First, create a .def file listing all the symbols a plugin should expect to have - # available in qemu - win32_plugin_def = configure_file( - input: files('qemu-plugins.symbols'), - output: 'qemu_plugin_api.def', - capture: true, - command: ['sed', '-e', '0,/^/s//EXPORTS/; s/[{};]//g', '@INPUT@']) - # then use dlltool to assemble a delaylib. - win32_qemu_plugin_api_lib = configure_file( - input: win32_plugin_def, - output: 'libqemu_plugin_api.a', - command: [dlltool, '--input-def', '@INPUT@', - '--output-delaylib', '@OUTPUT@', '--dllname', 'qemu.exe'] - ) - endif - specific_ss.add(files( - 'loader.c', - 'core.c', - 'api.c', - )) + # Generate a .lib file for plugins to link against. + # First, create a .def file listing all the symbols a plugin should expect to have + # available in qemu + win32_plugin_def = configure_file( + input: files('qemu-plugins.symbols'), + output: 'qemu_plugin_api.def', + capture: true, + command: ['sed', '-e', '0,/^/s//EXPORTS/; s/[{};]//g', '@INPUT@']) + # then use dlltool to assemble a delaylib. + win32_qemu_plugin_api_lib = configure_file( + input: win32_plugin_def, + output: 'libqemu_plugin_api.a', + command: [dlltool, '--input-def', '@INPUT@', + '--output-delaylib', '@OUTPUT@', '--dllname', 'qemu.exe'] + ) endif +specific_ss.add(files( + 'loader.c', + 'core.c', + 'api.c', +)) -- cgit 1.4.1 From 278035fc81510bd88501afb78bd5ab652beffa76 Mon Sep 17 00:00:00 2001 From: Pierrick Bouvier Date: Tue, 13 Aug 2024 21:23:29 +0100 Subject: plugins: fix race condition with scoreboards MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit A deadlock can be created if a new vcpu (a) triggers a scoreboard reallocation, and another vcpu (b) wants to create a new scoreboard at the same time. In this case, (a) holds the plugin lock, and starts an exclusive section, waiting for (b). But at the same time, (b) is waiting for plugin lock. The solution is to drop the lock before entering the exclusive section. This bug can be easily reproduced by creating a callback for any tb exec, that allocates a new scoreboard. In this case, as soon as we reach more than 16 vcpus, the deadlock occurs. Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2344 Signed-off-by: Pierrick Bouvier Message-Id: <20240812220748.95167-2-pierrick.bouvier@linaro.org> [AJB: tweak var position to meet coding style] Signed-off-by: Alex Bennée Reviewed-by: Richard Henderson Message-Id: <20240813202329.1237572-22-alex.bennee@linaro.org> --- plugins/core.c | 43 +++++++++++++++++++++++++++++++------------ 1 file changed, 31 insertions(+), 12 deletions(-) (limited to 'plugins') diff --git a/plugins/core.c b/plugins/core.c index 12c67b4b4e..2897453cac 100644 --- a/plugins/core.c +++ b/plugins/core.c @@ -214,30 +214,49 @@ CPUPluginState *qemu_plugin_create_vcpu_state(void) static void plugin_grow_scoreboards__locked(CPUState *cpu) { - if (cpu->cpu_index < plugin.scoreboard_alloc_size) { + size_t scoreboard_size = plugin.scoreboard_alloc_size; + bool need_realloc = false; + + if (cpu->cpu_index < scoreboard_size) { return; } - bool need_realloc = FALSE; - while (cpu->cpu_index >= plugin.scoreboard_alloc_size) { - plugin.scoreboard_alloc_size *= 2; - need_realloc = TRUE; + while (cpu->cpu_index >= scoreboard_size) { + scoreboard_size *= 2; + need_realloc = true; } + if (!need_realloc) { + return; + } - if (!need_realloc || QLIST_EMPTY(&plugin.scoreboards)) { - /* nothing to do, we just updated sizes for future scoreboards */ + if (QLIST_EMPTY(&plugin.scoreboards)) { + /* just update size for future scoreboards */ + plugin.scoreboard_alloc_size = scoreboard_size; return; } + /* + * A scoreboard creation/deletion might be in progress. If a new vcpu is + * initialized at the same time, we are safe, as the new + * plugin.scoreboard_alloc_size was not yet written. + */ + qemu_rec_mutex_unlock(&plugin.lock); + /* cpus must be stopped, as tb might still use an existing scoreboard. */ start_exclusive(); - struct qemu_plugin_scoreboard *score; - QLIST_FOREACH(score, &plugin.scoreboards, entry) { - g_array_set_size(score->data, plugin.scoreboard_alloc_size); + /* re-acquire lock */ + qemu_rec_mutex_lock(&plugin.lock); + /* in case another vcpu is created between unlock and exclusive section. */ + if (scoreboard_size > plugin.scoreboard_alloc_size) { + struct qemu_plugin_scoreboard *score; + QLIST_FOREACH(score, &plugin.scoreboards, entry) { + g_array_set_size(score->data, scoreboard_size); + } + plugin.scoreboard_alloc_size = scoreboard_size; + /* force all tb to be flushed, as scoreboard pointers were changed. */ + tb_flush(cpu); } - /* force all tb to be flushed, as scoreboard pointers were changed. */ - tb_flush(cpu); end_exclusive(); } -- cgit 1.4.1