X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;ds=sidebyside;f=cpus-common.c;h=3ca58c64e8068aa048de67696af5dd064cfd2d00;hb=HEAD;hp=023cfebfa3214f34146d10e66753da93b0162364;hpb=e65472c7bc413d79faa61eb1d05c540b03945894;p=mirror_qemu.git diff --git a/cpus-common.c b/cpus-common.c deleted file mode 100644 index 023cfebfa3..0000000000 --- a/cpus-common.c +++ /dev/null @@ -1,345 +0,0 @@ -/* - * CPU thread main loop - common bits for user and system mode emulation - * - * Copyright (c) 2003-2005 Fabrice Bellard - * - * This library is free software; you can redistribute it and/or - * modify it under the terms of the GNU Lesser General Public - * License as published by the Free Software Foundation; either - * version 2 of the License, or (at your option) any later version. - * - * This library is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - * Lesser General Public License for more details. - * - * You should have received a copy of the GNU Lesser General Public - * License along with this library; if not, see . - */ - -#include "qemu/osdep.h" -#include "qemu/main-loop.h" -#include "exec/cpu-common.h" -#include "qom/cpu.h" -#include "sysemu/cpus.h" - -static QemuMutex qemu_cpu_list_lock; -static QemuCond exclusive_cond; -static QemuCond exclusive_resume; -static QemuCond qemu_work_cond; - -/* >= 1 if a thread is inside start_exclusive/end_exclusive. Written - * under qemu_cpu_list_lock, read with atomic operations. - */ -static int pending_cpus; - -void qemu_init_cpu_list(void) -{ - /* This is needed because qemu_init_cpu_list is also called by the - * child process in a fork. */ - pending_cpus = 0; - - qemu_mutex_init(&qemu_cpu_list_lock); - qemu_cond_init(&exclusive_cond); - qemu_cond_init(&exclusive_resume); - qemu_cond_init(&qemu_work_cond); -} - -void cpu_list_lock(void) -{ - qemu_mutex_lock(&qemu_cpu_list_lock); -} - -void cpu_list_unlock(void) -{ - qemu_mutex_unlock(&qemu_cpu_list_lock); -} - -static bool cpu_index_auto_assigned; - -static int cpu_get_free_index(void) -{ - CPUState *some_cpu; - int cpu_index = 0; - - cpu_index_auto_assigned = true; - CPU_FOREACH(some_cpu) { - cpu_index++; - } - return cpu_index; -} - -void cpu_list_add(CPUState *cpu) -{ - qemu_mutex_lock(&qemu_cpu_list_lock); - if (cpu->cpu_index == UNASSIGNED_CPU_INDEX) { - cpu->cpu_index = cpu_get_free_index(); - assert(cpu->cpu_index != UNASSIGNED_CPU_INDEX); - } else { - assert(!cpu_index_auto_assigned); - } - QTAILQ_INSERT_TAIL_RCU(&cpus, cpu, node); - qemu_mutex_unlock(&qemu_cpu_list_lock); -} - -void cpu_list_remove(CPUState *cpu) -{ - qemu_mutex_lock(&qemu_cpu_list_lock); - if (!QTAILQ_IN_USE(cpu, node)) { - /* there is nothing to undo since cpu_exec_init() hasn't been called */ - qemu_mutex_unlock(&qemu_cpu_list_lock); - return; - } - - assert(!(cpu_index_auto_assigned && cpu != QTAILQ_LAST(&cpus))); - - QTAILQ_REMOVE_RCU(&cpus, cpu, node); - cpu->cpu_index = UNASSIGNED_CPU_INDEX; - qemu_mutex_unlock(&qemu_cpu_list_lock); -} - -struct qemu_work_item { - struct qemu_work_item *next; - run_on_cpu_func func; - run_on_cpu_data data; - bool free, exclusive, done; -}; - -static void queue_work_on_cpu(CPUState *cpu, struct qemu_work_item *wi) -{ - qemu_mutex_lock(&cpu->work_mutex); - if (cpu->queued_work_first == NULL) { - cpu->queued_work_first = wi; - } else { - cpu->queued_work_last->next = wi; - } - cpu->queued_work_last = wi; - wi->next = NULL; - wi->done = false; - qemu_mutex_unlock(&cpu->work_mutex); - - qemu_cpu_kick(cpu); -} - -void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data, - QemuMutex *mutex) -{ - struct qemu_work_item wi; - - if (qemu_cpu_is_self(cpu)) { - func(cpu, data); - return; - } - - wi.func = func; - wi.data = data; - wi.done = false; - wi.free = false; - wi.exclusive = false; - - queue_work_on_cpu(cpu, &wi); - while (!atomic_mb_read(&wi.done)) { - CPUState *self_cpu = current_cpu; - - qemu_cond_wait(&qemu_work_cond, mutex); - current_cpu = self_cpu; - } -} - -void async_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data) -{ - struct qemu_work_item *wi; - - wi = g_malloc0(sizeof(struct qemu_work_item)); - wi->func = func; - wi->data = data; - wi->free = true; - - queue_work_on_cpu(cpu, wi); -} - -/* Wait for pending exclusive operations to complete. The CPU list lock - must be held. */ -static inline void exclusive_idle(void) -{ - while (pending_cpus) { - qemu_cond_wait(&exclusive_resume, &qemu_cpu_list_lock); - } -} - -/* Start an exclusive operation. - Must only be called from outside cpu_exec. */ -void start_exclusive(void) -{ - CPUState *other_cpu; - int running_cpus; - - qemu_mutex_lock(&qemu_cpu_list_lock); - exclusive_idle(); - - /* Make all other cpus stop executing. */ - atomic_set(&pending_cpus, 1); - - /* Write pending_cpus before reading other_cpu->running. */ - smp_mb(); - running_cpus = 0; - CPU_FOREACH(other_cpu) { - if (atomic_read(&other_cpu->running)) { - other_cpu->has_waiter = true; - running_cpus++; - qemu_cpu_kick(other_cpu); - } - } - - atomic_set(&pending_cpus, running_cpus + 1); - while (pending_cpus > 1) { - qemu_cond_wait(&exclusive_cond, &qemu_cpu_list_lock); - } - - /* Can release mutex, no one will enter another exclusive - * section until end_exclusive resets pending_cpus to 0. - */ - qemu_mutex_unlock(&qemu_cpu_list_lock); -} - -/* Finish an exclusive operation. */ -void end_exclusive(void) -{ - qemu_mutex_lock(&qemu_cpu_list_lock); - atomic_set(&pending_cpus, 0); - qemu_cond_broadcast(&exclusive_resume); - qemu_mutex_unlock(&qemu_cpu_list_lock); -} - -/* Wait for exclusive ops to finish, and begin cpu execution. */ -void cpu_exec_start(CPUState *cpu) -{ - atomic_set(&cpu->running, true); - - /* Write cpu->running before reading pending_cpus. */ - smp_mb(); - - /* 1. start_exclusive saw cpu->running == true and pending_cpus >= 1. - * After taking the lock we'll see cpu->has_waiter == true and run---not - * for long because start_exclusive kicked us. cpu_exec_end will - * decrement pending_cpus and signal the waiter. - * - * 2. start_exclusive saw cpu->running == false but pending_cpus >= 1. - * This includes the case when an exclusive item is running now. - * Then we'll see cpu->has_waiter == false and wait for the item to - * complete. - * - * 3. pending_cpus == 0. Then start_exclusive is definitely going to - * see cpu->running == true, and it will kick the CPU. - */ - if (unlikely(atomic_read(&pending_cpus))) { - qemu_mutex_lock(&qemu_cpu_list_lock); - if (!cpu->has_waiter) { - /* Not counted in pending_cpus, let the exclusive item - * run. Since we have the lock, just set cpu->running to true - * while holding it; no need to check pending_cpus again. - */ - atomic_set(&cpu->running, false); - exclusive_idle(); - /* Now pending_cpus is zero. */ - atomic_set(&cpu->running, true); - } else { - /* Counted in pending_cpus, go ahead and release the - * waiter at cpu_exec_end. - */ - } - qemu_mutex_unlock(&qemu_cpu_list_lock); - } -} - -/* Mark cpu as not executing, and release pending exclusive ops. */ -void cpu_exec_end(CPUState *cpu) -{ - atomic_set(&cpu->running, false); - - /* Write cpu->running before reading pending_cpus. */ - smp_mb(); - - /* 1. start_exclusive saw cpu->running == true. Then it will increment - * pending_cpus and wait for exclusive_cond. After taking the lock - * we'll see cpu->has_waiter == true. - * - * 2. start_exclusive saw cpu->running == false but here pending_cpus >= 1. - * This includes the case when an exclusive item started after setting - * cpu->running to false and before we read pending_cpus. Then we'll see - * cpu->has_waiter == false and not touch pending_cpus. The next call to - * cpu_exec_start will run exclusive_idle if still necessary, thus waiting - * for the item to complete. - * - * 3. pending_cpus == 0. Then start_exclusive is definitely going to - * see cpu->running == false, and it can ignore this CPU until the - * next cpu_exec_start. - */ - if (unlikely(atomic_read(&pending_cpus))) { - qemu_mutex_lock(&qemu_cpu_list_lock); - if (cpu->has_waiter) { - cpu->has_waiter = false; - atomic_set(&pending_cpus, pending_cpus - 1); - if (pending_cpus == 1) { - qemu_cond_signal(&exclusive_cond); - } - } - qemu_mutex_unlock(&qemu_cpu_list_lock); - } -} - -void async_safe_run_on_cpu(CPUState *cpu, run_on_cpu_func func, - run_on_cpu_data data) -{ - struct qemu_work_item *wi; - - wi = g_malloc0(sizeof(struct qemu_work_item)); - wi->func = func; - wi->data = data; - wi->free = true; - wi->exclusive = true; - - queue_work_on_cpu(cpu, wi); -} - -void process_queued_cpu_work(CPUState *cpu) -{ - struct qemu_work_item *wi; - - if (cpu->queued_work_first == NULL) { - return; - } - - qemu_mutex_lock(&cpu->work_mutex); - while (cpu->queued_work_first != NULL) { - wi = cpu->queued_work_first; - cpu->queued_work_first = wi->next; - if (!cpu->queued_work_first) { - cpu->queued_work_last = NULL; - } - qemu_mutex_unlock(&cpu->work_mutex); - if (wi->exclusive) { - /* Running work items outside the BQL avoids the following deadlock: - * 1) start_exclusive() is called with the BQL taken while another - * CPU is running; 2) cpu_exec in the other CPU tries to takes the - * BQL, so it goes to sleep; start_exclusive() is sleeping too, so - * neither CPU can proceed. - */ - qemu_mutex_unlock_iothread(); - start_exclusive(); - wi->func(cpu, wi->data); - end_exclusive(); - qemu_mutex_lock_iothread(); - } else { - wi->func(cpu, wi->data); - } - qemu_mutex_lock(&cpu->work_mutex); - if (wi->free) { - g_free(wi); - } else { - atomic_mb_set(&wi->done, true); - } - } - qemu_mutex_unlock(&cpu->work_mutex); - qemu_cond_broadcast(&qemu_work_cond); -}