diff options
author | Claudio Fontana <cfontana@suse.de> | 2020-07-06 19:39:45 +0200 |
---|---|---|
committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-10-05 16:41:22 +0200 |
commit | a77dabc33bcc36ec348854f23e89e0de22ca045b (patch) | |
tree | 0f5ef16d52f342cc0e389d3f952da7475dc06aef /accel/tcg | |
parent | 430065dab060f04a74f915ea1260dcc79701ca75 (diff) | |
download | qemu-a77dabc33bcc36ec348854f23e89e0de22ca045b.zip qemu-a77dabc33bcc36ec348854f23e89e0de22ca045b.tar.gz qemu-a77dabc33bcc36ec348854f23e89e0de22ca045b.tar.bz2 |
cpus: extract out TCG-specific code to accel/tcg
TCG is the first accelerator to register a "CpusAccel" interface
on initialization, providing functions for starting a vcpu,
kicking a vcpu, sychronizing state and getting virtual clock
and ticks.
Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
[added const]
Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'accel/tcg')
-rw-r--r-- | accel/tcg/meson.build | 2 | ||||
-rw-r--r-- | accel/tcg/tcg-all.c | 11 | ||||
-rw-r--r-- | accel/tcg/tcg-cpus.c | 551 | ||||
-rw-r--r-- | accel/tcg/tcg-cpus.h | 17 |
4 files changed, 575 insertions, 6 deletions
diff --git a/accel/tcg/meson.build b/accel/tcg/meson.build index 96a76ed..19b9343 100644 --- a/accel/tcg/meson.build +++ b/accel/tcg/meson.build @@ -12,4 +12,4 @@ tcg_ss.add(when: 'CONFIG_SOFTMMU', if_false: files('user-exec-stub.c')) tcg_ss.add(when: 'CONFIG_PLUGIN', if_true: [files('plugin-gen.c'), libdl]) specific_ss.add_all(when: 'CONFIG_TCG', if_true: tcg_ss) -specific_ss.add(when: ['CONFIG_SOFTMMU', 'CONFIG_TCG'], if_true: files('tcg-all.c', 'cputlb.c')) +specific_ss.add(when: ['CONFIG_SOFTMMU', 'CONFIG_TCG'], if_true: files('tcg-all.c', 'cputlb.c', 'tcg-cpus.c')) diff --git a/accel/tcg/tcg-all.c b/accel/tcg/tcg-all.c index 2d13df3..000fe4d 100644 --- a/accel/tcg/tcg-all.c +++ b/accel/tcg/tcg-all.c @@ -24,18 +24,15 @@ */ #include "qemu/osdep.h" -#include "sysemu/accel.h" +#include "qemu-common.h" #include "sysemu/tcg.h" -#include "qom/object.h" -#include "cpu.h" -#include "sysemu/cpus.h" #include "sysemu/cpu-timers.h" -#include "qemu/main-loop.h" #include "tcg/tcg.h" #include "qapi/error.h" #include "qemu/error-report.h" #include "hw/boards.h" #include "qapi/qapi-builtin-visit.h" +#include "tcg-cpus.h" struct TCGState { AccelState parent_obj; @@ -124,6 +121,8 @@ static void tcg_accel_instance_init(Object *obj) s->mttcg_enabled = default_mttcg_enabled(); } +bool mttcg_enabled; + static int tcg_init(MachineState *ms) { TCGState *s = TCG_STATE(current_accel()); @@ -131,6 +130,8 @@ static int tcg_init(MachineState *ms) tcg_exec_init(s->tb_size * 1024 * 1024); cpu_interrupt_handler = tcg_handle_interrupt; mttcg_enabled = s->mttcg_enabled; + cpus_register_accel(&tcg_cpus); + return 0; } diff --git a/accel/tcg/tcg-cpus.c b/accel/tcg/tcg-cpus.c new file mode 100644 index 0000000..4f15c7f --- /dev/null +++ b/accel/tcg/tcg-cpus.c @@ -0,0 +1,551 @@ +/* + * QEMU System Emulator + * + * Copyright (c) 2003-2008 Fabrice Bellard + * Copyright (c) 2014 Red Hat Inc. + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +#include "qemu/osdep.h" +#include "qemu-common.h" +#include "sysemu/tcg.h" +#include "sysemu/replay.h" +#include "qemu/main-loop.h" +#include "qemu/guest-random.h" +#include "exec/exec-all.h" +#include "hw/boards.h" + +#include "tcg-cpus.h" + +/* Kick all RR vCPUs */ +static void qemu_cpu_kick_rr_cpus(void) +{ + CPUState *cpu; + + CPU_FOREACH(cpu) { + cpu_exit(cpu); + }; +} + +static void tcg_kick_vcpu_thread(CPUState *cpu) +{ + if (qemu_tcg_mttcg_enabled()) { + cpu_exit(cpu); + } else { + qemu_cpu_kick_rr_cpus(); + } +} + +/* + * TCG vCPU kick timer + * + * The kick timer is responsible for moving single threaded vCPU + * emulation on to the next vCPU. If more than one vCPU is running a + * timer event with force a cpu->exit so the next vCPU can get + * scheduled. + * + * The timer is removed if all vCPUs are idle and restarted again once + * idleness is complete. + */ + +static QEMUTimer *tcg_kick_vcpu_timer; +static CPUState *tcg_current_rr_cpu; + +#define TCG_KICK_PERIOD (NANOSECONDS_PER_SECOND / 10) + +static inline int64_t qemu_tcg_next_kick(void) +{ + return qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + TCG_KICK_PERIOD; +} + +/* Kick the currently round-robin scheduled vCPU to next */ +static void qemu_cpu_kick_rr_next_cpu(void) +{ + CPUState *cpu; + do { + cpu = qatomic_mb_read(&tcg_current_rr_cpu); + if (cpu) { + cpu_exit(cpu); + } + } while (cpu != qatomic_mb_read(&tcg_current_rr_cpu)); +} + +static void kick_tcg_thread(void *opaque) +{ + timer_mod(tcg_kick_vcpu_timer, qemu_tcg_next_kick()); + qemu_cpu_kick_rr_next_cpu(); +} + +static void start_tcg_kick_timer(void) +{ + assert(!mttcg_enabled); + if (!tcg_kick_vcpu_timer && CPU_NEXT(first_cpu)) { + tcg_kick_vcpu_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, + kick_tcg_thread, NULL); + } + if (tcg_kick_vcpu_timer && !timer_pending(tcg_kick_vcpu_timer)) { + timer_mod(tcg_kick_vcpu_timer, qemu_tcg_next_kick()); + } +} + +static void stop_tcg_kick_timer(void) +{ + assert(!mttcg_enabled); + if (tcg_kick_vcpu_timer && timer_pending(tcg_kick_vcpu_timer)) { + timer_del(tcg_kick_vcpu_timer); + } +} + +static void qemu_tcg_destroy_vcpu(CPUState *cpu) +{ +} + +static void qemu_tcg_rr_wait_io_event(void) +{ + CPUState *cpu; + + while (all_cpu_threads_idle()) { + stop_tcg_kick_timer(); + qemu_cond_wait_iothread(first_cpu->halt_cond); + } + + start_tcg_kick_timer(); + + CPU_FOREACH(cpu) { + qemu_wait_io_event_common(cpu); + } +} + +static int64_t tcg_get_icount_limit(void) +{ + int64_t deadline; + + if (replay_mode != REPLAY_MODE_PLAY) { + /* + * Include all the timers, because they may need an attention. + * Too long CPU execution may create unnecessary delay in UI. + */ + deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL, + QEMU_TIMER_ATTR_ALL); + /* Check realtime timers, because they help with input processing */ + deadline = qemu_soonest_timeout(deadline, + qemu_clock_deadline_ns_all(QEMU_CLOCK_REALTIME, + QEMU_TIMER_ATTR_ALL)); + + /* + * Maintain prior (possibly buggy) behaviour where if no deadline + * was set (as there is no QEMU_CLOCK_VIRTUAL timer) or it is more than + * INT32_MAX nanoseconds ahead, we still use INT32_MAX + * nanoseconds. + */ + if ((deadline < 0) || (deadline > INT32_MAX)) { + deadline = INT32_MAX; + } + + return icount_round(deadline); + } else { + return replay_get_instructions(); + } +} + +static void notify_aio_contexts(void) +{ + /* Wake up other AioContexts. */ + qemu_clock_notify(QEMU_CLOCK_VIRTUAL); + qemu_clock_run_timers(QEMU_CLOCK_VIRTUAL); +} + +static void handle_icount_deadline(void) +{ + assert(qemu_in_vcpu_thread()); + if (icount_enabled()) { + int64_t deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL, + QEMU_TIMER_ATTR_ALL); + + if (deadline == 0) { + notify_aio_contexts(); + } + } +} + +static void prepare_icount_for_run(CPUState *cpu) +{ + if (icount_enabled()) { + int insns_left; + + /* + * These should always be cleared by process_icount_data after + * each vCPU execution. However u16.high can be raised + * asynchronously by cpu_exit/cpu_interrupt/tcg_handle_interrupt + */ + g_assert(cpu_neg(cpu)->icount_decr.u16.low == 0); + g_assert(cpu->icount_extra == 0); + + cpu->icount_budget = tcg_get_icount_limit(); + insns_left = MIN(0xffff, cpu->icount_budget); + cpu_neg(cpu)->icount_decr.u16.low = insns_left; + cpu->icount_extra = cpu->icount_budget - insns_left; + + replay_mutex_lock(); + + if (cpu->icount_budget == 0 && replay_has_checkpoint()) { + notify_aio_contexts(); + } + } +} + +static void process_icount_data(CPUState *cpu) +{ + if (icount_enabled()) { + /* Account for executed instructions */ + icount_update(cpu); + + /* Reset the counters */ + cpu_neg(cpu)->icount_decr.u16.low = 0; + cpu->icount_extra = 0; + cpu->icount_budget = 0; + + replay_account_executed_instructions(); + + replay_mutex_unlock(); + } +} + +static int tcg_cpu_exec(CPUState *cpu) +{ + int ret; +#ifdef CONFIG_PROFILER + int64_t ti; +#endif + + assert(tcg_enabled()); +#ifdef CONFIG_PROFILER + ti = profile_getclock(); +#endif + cpu_exec_start(cpu); + ret = cpu_exec(cpu); + cpu_exec_end(cpu); +#ifdef CONFIG_PROFILER + qatomic_set(&tcg_ctx->prof.cpu_exec_time, + tcg_ctx->prof.cpu_exec_time + profile_getclock() - ti); +#endif + return ret; +} + +/* + * Destroy any remaining vCPUs which have been unplugged and have + * finished running + */ +static void deal_with_unplugged_cpus(void) +{ + CPUState *cpu; + + CPU_FOREACH(cpu) { + if (cpu->unplug && !cpu_can_run(cpu)) { + qemu_tcg_destroy_vcpu(cpu); + cpu_thread_signal_destroyed(cpu); + break; + } + } +} + +/* + * Single-threaded TCG + * + * In the single-threaded case each vCPU is simulated in turn. If + * there is more than a single vCPU we create a simple timer to kick + * the vCPU and ensure we don't get stuck in a tight loop in one vCPU. + * This is done explicitly rather than relying on side-effects + * elsewhere. + */ + +static void *tcg_rr_cpu_thread_fn(void *arg) +{ + CPUState *cpu = arg; + + assert(tcg_enabled()); + rcu_register_thread(); + tcg_register_thread(); + + qemu_mutex_lock_iothread(); + qemu_thread_get_self(cpu->thread); + + cpu->thread_id = qemu_get_thread_id(); + cpu->can_do_io = 1; + cpu_thread_signal_created(cpu); + qemu_guest_random_seed_thread_part2(cpu->random_seed); + + /* wait for initial kick-off after machine start */ + while (first_cpu->stopped) { + qemu_cond_wait_iothread(first_cpu->halt_cond); + + /* process any pending work */ + CPU_FOREACH(cpu) { + current_cpu = cpu; + qemu_wait_io_event_common(cpu); + } + } + + start_tcg_kick_timer(); + + cpu = first_cpu; + + /* process any pending work */ + cpu->exit_request = 1; + + while (1) { + qemu_mutex_unlock_iothread(); + replay_mutex_lock(); + qemu_mutex_lock_iothread(); + /* Account partial waits to QEMU_CLOCK_VIRTUAL. */ + icount_account_warp_timer(); + + /* + * Run the timers here. This is much more efficient than + * waking up the I/O thread and waiting for completion. + */ + handle_icount_deadline(); + + replay_mutex_unlock(); + + if (!cpu) { + cpu = first_cpu; + } + + while (cpu && cpu_work_list_empty(cpu) && !cpu->exit_request) { + + qatomic_mb_set(&tcg_current_rr_cpu, cpu); + current_cpu = cpu; + + qemu_clock_enable(QEMU_CLOCK_VIRTUAL, + (cpu->singlestep_enabled & SSTEP_NOTIMER) == 0); + + if (cpu_can_run(cpu)) { + int r; + + qemu_mutex_unlock_iothread(); + prepare_icount_for_run(cpu); + + r = tcg_cpu_exec(cpu); + + process_icount_data(cpu); + qemu_mutex_lock_iothread(); + + if (r == EXCP_DEBUG) { + cpu_handle_guest_debug(cpu); + break; + } else if (r == EXCP_ATOMIC) { + qemu_mutex_unlock_iothread(); + cpu_exec_step_atomic(cpu); + qemu_mutex_lock_iothread(); + break; + } + } else if (cpu->stop) { + if (cpu->unplug) { + cpu = CPU_NEXT(cpu); + } + break; + } + + cpu = CPU_NEXT(cpu); + } /* while (cpu && !cpu->exit_request).. */ + + /* Does not need qatomic_mb_set because a spurious wakeup is okay. */ + qatomic_set(&tcg_current_rr_cpu, NULL); + + if (cpu && cpu->exit_request) { + qatomic_mb_set(&cpu->exit_request, 0); + } + + if (icount_enabled() && all_cpu_threads_idle()) { + /* + * When all cpus are sleeping (e.g in WFI), to avoid a deadlock + * in the main_loop, wake it up in order to start the warp timer. + */ + qemu_notify_event(); + } + + qemu_tcg_rr_wait_io_event(); + deal_with_unplugged_cpus(); + } + + rcu_unregister_thread(); + return NULL; +} + +/* + * Multi-threaded TCG + * + * In the multi-threaded case each vCPU has its own thread. The TLS + * variable current_cpu can be used deep in the code to find the + * current CPUState for a given thread. + */ + +static void *tcg_cpu_thread_fn(void *arg) +{ + CPUState *cpu = arg; + + assert(tcg_enabled()); + g_assert(!icount_enabled()); + + rcu_register_thread(); + tcg_register_thread(); + + qemu_mutex_lock_iothread(); + qemu_thread_get_self(cpu->thread); + + cpu->thread_id = qemu_get_thread_id(); + cpu->can_do_io = 1; + current_cpu = cpu; + cpu_thread_signal_created(cpu); + qemu_guest_random_seed_thread_part2(cpu->random_seed); + + /* process any pending work */ + cpu->exit_request = 1; + + do { + if (cpu_can_run(cpu)) { + int r; + qemu_mutex_unlock_iothread(); + r = tcg_cpu_exec(cpu); + qemu_mutex_lock_iothread(); + switch (r) { + case EXCP_DEBUG: + cpu_handle_guest_debug(cpu); + break; + case EXCP_HALTED: + /* + * during start-up the vCPU is reset and the thread is + * kicked several times. If we don't ensure we go back + * to sleep in the halted state we won't cleanly + * start-up when the vCPU is enabled. + * + * cpu->halted should ensure we sleep in wait_io_event + */ + g_assert(cpu->halted); + break; + case EXCP_ATOMIC: + qemu_mutex_unlock_iothread(); + cpu_exec_step_atomic(cpu); + qemu_mutex_lock_iothread(); + default: + /* Ignore everything else? */ + break; + } + } + + qatomic_mb_set(&cpu->exit_request, 0); + qemu_wait_io_event(cpu); + } while (!cpu->unplug || cpu_can_run(cpu)); + + qemu_tcg_destroy_vcpu(cpu); + cpu_thread_signal_destroyed(cpu); + qemu_mutex_unlock_iothread(); + rcu_unregister_thread(); + return NULL; +} + +static void tcg_start_vcpu_thread(CPUState *cpu) +{ + char thread_name[VCPU_THREAD_NAME_SIZE]; + static QemuCond *single_tcg_halt_cond; + static QemuThread *single_tcg_cpu_thread; + static int tcg_region_inited; + + assert(tcg_enabled()); + /* + * Initialize TCG regions--once. Now is a good time, because: + * (1) TCG's init context, prologue and target globals have been set up. + * (2) qemu_tcg_mttcg_enabled() works now (TCG init code runs before the + * -accel flag is processed, so the check doesn't work then). + */ + if (!tcg_region_inited) { + tcg_region_inited = 1; + tcg_region_init(); + /* + * If MTTCG, and we will create multiple cpus, + * then we will have cpus running in parallel. + */ + if (qemu_tcg_mttcg_enabled()) { + MachineState *ms = MACHINE(qdev_get_machine()); + if (ms->smp.max_cpus > 1) { + parallel_cpus = true; + } + } + } + + if (qemu_tcg_mttcg_enabled() || !single_tcg_cpu_thread) { + cpu->thread = g_malloc0(sizeof(QemuThread)); + cpu->halt_cond = g_malloc0(sizeof(QemuCond)); + qemu_cond_init(cpu->halt_cond); + + if (qemu_tcg_mttcg_enabled()) { + /* create a thread per vCPU with TCG (MTTCG) */ + snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "CPU %d/TCG", + cpu->cpu_index); + + qemu_thread_create(cpu->thread, thread_name, tcg_cpu_thread_fn, + cpu, QEMU_THREAD_JOINABLE); + + } else { + /* share a single thread for all cpus with TCG */ + snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "ALL CPUs/TCG"); + qemu_thread_create(cpu->thread, thread_name, + tcg_rr_cpu_thread_fn, + cpu, QEMU_THREAD_JOINABLE); + + single_tcg_halt_cond = cpu->halt_cond; + single_tcg_cpu_thread = cpu->thread; + } +#ifdef _WIN32 + cpu->hThread = qemu_thread_get_handle(cpu->thread); +#endif + } else { + /* For non-MTTCG cases we share the thread */ + cpu->thread = single_tcg_cpu_thread; + cpu->halt_cond = single_tcg_halt_cond; + cpu->thread_id = first_cpu->thread_id; + cpu->can_do_io = 1; + cpu->created = true; + } +} + +static int64_t tcg_get_virtual_clock(void) +{ + if (icount_enabled()) { + return icount_get(); + } + return cpu_get_clock(); +} + +static int64_t tcg_get_elapsed_ticks(void) +{ + if (icount_enabled()) { + return icount_get(); + } + return cpu_get_ticks(); +} + +const CpusAccel tcg_cpus = { + .create_vcpu_thread = tcg_start_vcpu_thread, + .kick_vcpu_thread = tcg_kick_vcpu_thread, + .get_virtual_clock = tcg_get_virtual_clock, + .get_elapsed_ticks = tcg_get_elapsed_ticks, +}; diff --git a/accel/tcg/tcg-cpus.h b/accel/tcg/tcg-cpus.h new file mode 100644 index 0000000..8b1d9d2 --- /dev/null +++ b/accel/tcg/tcg-cpus.h @@ -0,0 +1,17 @@ +/* + * Accelerator CPUS Interface + * + * Copyright 2020 SUSE LLC + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + */ + +#ifndef TCG_CPUS_H +#define TCG_CPUS_H + +#include "sysemu/cpus.h" + +extern const CpusAccel tcg_cpus; + +#endif /* TCG_CPUS_H */ |