riscv/qemu - qemu - Gitea: Git with a cup of tea

Author	SHA1	Message	Date
Stefan Hajnoczi	c1fe694357	coroutine-win32: use QEMU_DEFINE_STATIC_CO_TLS() Thread-Local Storage variables cannot be used directly from coroutine code because the compiler may optimize TLS variable accesses across qemu_coroutine_yield() calls. When the coroutine is re-entered from another thread the TLS variables from the old thread must no longer be used. Use QEMU_DEFINE_STATIC_CO_TLS() for the current and leader variables. I think coroutine-win32.c could get away with __thread because the variables are only used in situations where either the stale value is correct (current) or outside coroutine context (loading leader when current is NULL). Due to the difficulty of being sure that this is really safe in all scenarios it seems worth converting it anyway. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Message-Id: <20220307153853.602859-4-stefanha@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Signed-off-by: Kevin Wolf <kwolf@redhat.com>	4 years ago
Marc-André Lureau	0f9668e0c1	Remove qemu-common.h include from most units Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> Message-Id: <20220323155743.1585078-33-marcandre.lureau@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>	4 years ago
Peter Lieven	8adcd6fb6d	coroutine: add a macro for the coroutine stack size Signed-off-by: Peter Lieven <pl@kamp.de> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Richard Henderson <rth@twiddle.net> Signed-off-by: Kevin Wolf <kwolf@redhat.com>	10 years ago
Peter Maydell	aafd758410	util: Clean up includes Clean up includes so that osdep.h is included first and headers which it implies are not included manually. This commit was created with scripts/clean-includes. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Message-id: 1454089805-5470-6-git-send-email-peter.maydell@linaro.org	10 years ago
Daniel P. Berrange	10817bf09d	coroutine: move into libqemuutil.a library The coroutine files are currently referenced by the block-obj-y variable. The coroutine functionality though is already used by more than just the block code. eg migration code uses coroutine yield. In the future the I/O channel code will also use the coroutine yield functionality. Since the coroutine code is nicely self-contained it can be easily built as part of the libqemuutil.a library, making it widely available. The headers are also moved into include/qemu, instead of the include/block directory, since they are now part of the util codebase, and the impl was never in the block/ directory either. Signed-off-by: Daniel P. Berrange <berrange@redhat.com>	11 years ago
Peter Maydell	ff4873cb8c	coroutine-win32.c: Add noinline attribute to work around gcc bug A gcc codegen bug in x86_64-w64-mingw32-gcc (GCC) 4.6.3 means that non-debug builds of QEMU for Windows tend to assert when using coroutines. Work around this by marking qemu_coroutine_switch as noinline. If we allow gcc to inline qemu_coroutine_switch into coroutine_trampoline, then it hoists the code to get the address of the TLS variable "current" out of the while() loop. This is an invalid transformation because the SwitchToFiber() call may be called when running thread A but return in thread B, and so we might be in a different thread context each time round the loop. This can happen quite often. Typically. a coroutine is started when a VCPU thread does bdrv_aio_readv: VCPU thread main VCPU thread coroutine I/O coroutine bdrv_aio_readv -----> start I/O operation thread_pool_submit_co <------------ yields back to emulation Then I/O finishes and the thread-pool.c event notifier triggers in the I/O thread. event_notifier_ready calls thread_pool_co_cb, and the I/O coroutine now restarts in another thread: iothread main iothread coroutine I/O coroutine (formerly in VCPU thread) event_notifier_ready thread_pool_co_cb -----> current = I/O coroutine; call AIO callback But on Win32, because of the bug, the "current" being set here the current coroutine of the VCPU thread, not the iothread. noinline is a good-enough workaround, and quite unlikely to break in the future. (Thanks to Paolo Bonzini for assistance in diagnosing the problem and providing the detailed example/ascii art quoted above.) Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Message-id: 1403535303-14939-1-git-send-email-peter.maydell@linaro.org Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Richard Henderson <rth@twiddle.net>	12 years ago
Paolo Bonzini	737e150e89	block: move include files to include/block/ Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>	13 years ago
Anthony Liguori	7267c0947d	Use glib memory allocation and free functions qemu_malloc/qemu_free no longer exist after this commit. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>	15 years ago
Kevin Wolf	00dccaf1f8	coroutine: introduce coroutines Asynchronous code is becoming very complex. At the same time synchronous code is growing because it is convenient to write. Sometimes duplicate code paths are even added, one synchronous and the other asynchronous. This patch introduces coroutines which allow code that looks synchronous but is asynchronous under the covers. A coroutine has its own stack and is therefore able to preserve state across blocking operations, which traditionally require callback functions and manual marshalling of parameters. Creating and starting a coroutine is easy: coroutine = qemu_coroutine_create(my_coroutine); qemu_coroutine_enter(coroutine, my_data); The coroutine then executes until it returns or yields: void coroutine_fn my_coroutine(void opaque) { MyData my_data = opaque; /* do some work / qemu_coroutine_yield(); / do some more work */ } Yielding switches control back to the caller of qemu_coroutine_enter(). This is typically used to switch back to the main thread's event loop after issuing an asynchronous I/O request. The request callback will then invoke qemu_coroutine_enter() once more to switch back to the coroutine. Note that if coroutines are used only from threads which hold the global mutex they will never execute concurrently. This makes programming with coroutines easier than with threads. Race conditions cannot occur since only one coroutine may be active at any time. Other coroutines can only run across yield. This coroutines implementation is based on the gtk-vnc implementation written by Anthony Liguori <anthony@codemonkey.ws> but it has been significantly rewritten by Kevin Wolf <kwolf@redhat.com> to use setjmp()/longjmp() instead of the more expensive swapcontext() and by Paolo Bonzini <pbonzini@redhat.com> for Windows Fibers support. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>	15 years ago