From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54892) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1anSyE-0006vv-77 for qemu-devel@nongnu.org; Tue, 05 Apr 2016 11:32:48 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1anSyC-0007GI-4G for qemu-devel@nongnu.org; Tue, 05 Apr 2016 11:32:46 -0400 Received: from mail-wm0-x233.google.com ([2a00:1450:400c:c09::233]:38205) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1anSyB-0007Fi-Ht for qemu-devel@nongnu.org; Tue, 05 Apr 2016 11:32:44 -0400 Received: by mail-wm0-x233.google.com with SMTP id u206so9439404wme.1 for ; Tue, 05 Apr 2016 08:32:42 -0700 (PDT) From: =?UTF-8?q?Alex=20Benn=C3=A9e?= Date: Tue, 5 Apr 2016 16:32:23 +0100 Message-Id: <1459870344-16773-11-git-send-email-alex.bennee@linaro.org> In-Reply-To: <1459870344-16773-1-git-send-email-alex.bennee@linaro.org> References: <1459870344-16773-1-git-send-email-alex.bennee@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: [Qemu-devel] [RFC v2 10/11] tcg: drop global lock during TCG code execution List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: mttcg@listserver.greensocs.com, fred.konrad@greensocs.com, a.rigo@virtualopensystems.com, serge.fdrv@gmail.com, cota@braap.org Cc: peter.maydell@linaro.org, claudio.fontana@huawei.com, Peter Crosthwaite , jan.kiszka@siemens.com, "Michael S. Tsirkin" , mark.burton@greensocs.com, qemu-devel@nongnu.org, Eduardo Habkost , pbonzini@redhat.com, =?UTF-8?q?Alex=20Benn=C3=A9e?= , rth@twiddle.net From: Jan Kiszka This finally allows TCG to benefit from the iothread introduction: Drop the global mutex while running pure TCG CPU code. Reacquire the lock when entering MMIO or PIO emulation, or when leaving the TCG loop. We have to revert a few optimization for the current TCG threading model, namely kicking the TCG thread in qemu_mutex_lock_iothread and not kicking it in qemu_cpu_kick. We also need to disable RAM block reordering until we have a more efficient locking mechanism at hand. Still, a Linux x86 UP guest and my Musicpal ARM model boot fine here. These numbers demonstrate where we gain something: 20338 jan 20 0 331m 75m 6904 R 99 0.9 0:50.95 qemu-system-arm 20337 jan 20 0 331m 75m 6904 S 20 0.9 0:26.50 qemu-system-arm The guest CPU was fully loaded, but the iothread could still run mostly independent on a second core. Without the patch we don't get beyond 32206 jan 20 0 330m 73m 7036 R 82 0.9 1:06.00 qemu-system-arm 32204 jan 20 0 330m 73m 7036 S 21 0.9 0:17.03 qemu-system-arm We don't benefit significantly, though, when the guest is not fully loading a host CPU. Signed-off-by: Jan Kiszka Message-Id: <1439220437-23957-10-git-send-email-fred.konrad@greensocs.com> [FK: Rebase, fix qemu_devices_reset deadlock, rm address_space_* mutex] Signed-off-by: KONRAD Frederic [EGC: fixed iothread lock for cpu-exec IRQ handling] Signed-off-by: Emilio G. Cota [AJB: -smp single-threaded fix, rm old info from commit msg] Signed-off-by: Alex BennĂ©e --- v1 (ajb): - SMP failure now fixed by previous commit Changes from Fred Konrad (mttcg-v7 via paolo): * Rebase on the current HEAD. * Fixes a deadlock in qemu_devices_reset(). * Remove the mutex in address_space_* v2 (ajb): - merge with tcg: grab iothread lock in cpu-exec interrupt handling - use existing fns for tracking lock state - lock iothread for mem_region - add assert on mem region modification - ensure smm_helper holds iothread - Add JK s-o-b - Fix-up FK s-o-b annotation --- cpu-exec.c | 12 ++++++++++++ cpus.c | 26 +++----------------------- cputlb.c | 1 + exec.c | 12 ++++++++++++ hw/i386/kvmvapic.c | 3 +++ memory.c | 2 ++ softmmu_template.h | 17 +++++++++++++++++ target-i386/smm_helper.c | 7 +++++++ translate-all.c | 11 +++++++++-- 9 files changed, 66 insertions(+), 25 deletions(-) diff --git a/cpu-exec.c b/cpu-exec.c index bd50fef..f558508 100644 --- a/cpu-exec.c +++ b/cpu-exec.c @@ -28,6 +28,7 @@ #include "qemu/rcu.h" #include "exec/tb-hash.h" #include "exec/log.h" +#include "qemu/main-loop.h" #if defined(TARGET_I386) && !defined(CONFIG_USER_ONLY) #include "hw/i386/apic.h" #endif @@ -452,6 +453,8 @@ int cpu_exec(CPUState *cpu) for(;;) { interrupt_request = cpu->interrupt_request; if (unlikely(interrupt_request)) { + qemu_mutex_lock_iothread(); + if (unlikely(cpu->singlestep_enabled & SSTEP_NOIRQ)) { /* Mask out external interrupts for this step. */ interrupt_request &= ~CPU_INTERRUPT_SSTEP_MASK; @@ -504,6 +507,11 @@ int cpu_exec(CPUState *cpu) the program flow was changed */ next_tb = 0; } + + if (qemu_mutex_iothread_locked()) { + qemu_mutex_unlock_iothread(); + } + } if (unlikely(cpu->exit_request || replay_has_interrupt())) { @@ -609,8 +617,12 @@ int cpu_exec(CPUState *cpu) g_assert(env == &x86_cpu->env); #endif #endif /* buggy compiler */ + cpu->can_do_io = 1; tb_lock_reset(); + if (qemu_mutex_iothread_locked()) { + qemu_mutex_unlock_iothread(); + } } } /* for(;;) */ diff --git a/cpus.c b/cpus.c index e22bb77..02fae13 100644 --- a/cpus.c +++ b/cpus.c @@ -920,8 +920,6 @@ static void qemu_kvm_init_cpu_signals(CPUState *cpu) #endif /* _WIN32 */ static QemuMutex qemu_global_mutex; -static QemuCond qemu_io_proceeded_cond; -static unsigned iothread_requesting_mutex; static QemuThread io_thread; @@ -937,7 +935,6 @@ void qemu_init_cpu_loop(void) qemu_cond_init(&qemu_cpu_cond); qemu_cond_init(&qemu_pause_cond); qemu_cond_init(&qemu_work_cond); - qemu_cond_init(&qemu_io_proceeded_cond); qemu_mutex_init(&qemu_global_mutex); qemu_thread_get_self(&io_thread); @@ -1049,10 +1046,6 @@ static void qemu_tcg_wait_io_event(CPUState *cpu) qemu_cond_wait(cpu->halt_cond, &qemu_global_mutex); } - while (iothread_requesting_mutex) { - qemu_cond_wait(&qemu_io_proceeded_cond, &qemu_global_mutex); - } - CPU_FOREACH(cpu) { qemu_wait_io_event_common(cpu); } @@ -1319,22 +1312,7 @@ bool qemu_mutex_iothread_locked(void) void qemu_mutex_lock_iothread(void) { - atomic_inc(&iothread_requesting_mutex); - /* In the simple case there is no need to bump the VCPU thread out of - * TCG code execution. - */ - if (!tcg_enabled() || qemu_in_vcpu_thread() || - !first_cpu || !first_cpu->created) { - qemu_mutex_lock(&qemu_global_mutex); - atomic_dec(&iothread_requesting_mutex); - } else { - if (qemu_mutex_trylock(&qemu_global_mutex)) { - qemu_cpu_kick_no_halt(); - qemu_mutex_lock(&qemu_global_mutex); - } - atomic_dec(&iothread_requesting_mutex); - qemu_cond_broadcast(&qemu_io_proceeded_cond); - } + qemu_mutex_lock(&qemu_global_mutex); iothread_locked = true; } @@ -1580,7 +1558,9 @@ static int tcg_cpu_exec(CPUState *cpu) cpu->icount_decr.u16.low = decr; cpu->icount_extra = count; } + qemu_mutex_unlock_iothread(); ret = cpu_exec(cpu); + qemu_mutex_lock_iothread(); #ifdef CONFIG_PROFILER tcg_time += profile_getclock() - ti; #endif diff --git a/cputlb.c b/cputlb.c index 466663b..1412049 100644 --- a/cputlb.c +++ b/cputlb.c @@ -18,6 +18,7 @@ */ #include "qemu/osdep.h" +#include "qemu/main-loop.h" #include "cpu.h" #include "exec/exec-all.h" #include "exec/memory.h" diff --git a/exec.c b/exec.c index c46c123..9e83673 100644 --- a/exec.c +++ b/exec.c @@ -2112,6 +2112,12 @@ static void check_watchpoint(int offset, int len, MemTxAttrs attrs, int flags) } cpu->watchpoint_hit = wp; + /* + * Unlock iothread mutex before calling cpu_loop_exit + * or cpu_resume_from_signal. + */ + qemu_mutex_unlock_iothread(); + /* Unlocked by cpu_loop_exit or cpu_resume_from_signal. */ tb_lock(); tb_check_watchpoint(cpu); @@ -2347,8 +2353,14 @@ static void io_mem_init(void) memory_region_init_io(&io_mem_rom, NULL, &unassigned_mem_ops, NULL, NULL, UINT64_MAX); memory_region_init_io(&io_mem_unassigned, NULL, &unassigned_mem_ops, NULL, NULL, UINT64_MAX); + + /* io_mem_notdirty calls tb_invalidate_phys_page_fast, + * which must be called without the iothread mutex. + */ memory_region_init_io(&io_mem_notdirty, NULL, ¬dirty_mem_ops, NULL, NULL, UINT64_MAX); + memory_region_clear_global_locking(&io_mem_notdirty); + memory_region_init_io(&io_mem_watch, NULL, &watch_mem_ops, NULL, NULL, UINT64_MAX); } diff --git a/hw/i386/kvmvapic.c b/hw/i386/kvmvapic.c index 7c0d542..a0439a8 100644 --- a/hw/i386/kvmvapic.c +++ b/hw/i386/kvmvapic.c @@ -447,6 +447,9 @@ static void patch_instruction(VAPICROMState *s, X86CPU *cpu, target_ulong ip) resume_all_vcpus(); if (!kvm_enabled()) { + /* Unlock iothread mutex before calling cpu_resume_from_signal. */ + qemu_mutex_unlock_iothread(); + /* Unlocked by cpu_resume_from_signal. */ tb_lock(); cs->current_tb = NULL; diff --git a/memory.c b/memory.c index f76f85d..2eae609 100644 --- a/memory.c +++ b/memory.c @@ -916,6 +916,8 @@ void memory_region_transaction_commit(void) AddressSpace *as; assert(memory_region_transaction_depth); + assert(qemu_mutex_iothread_locked()); + --memory_region_transaction_depth; if (!memory_region_transaction_depth) { if (memory_region_update_pending) { diff --git a/softmmu_template.h b/softmmu_template.h index 208f808..0b6c609 100644 --- a/softmmu_template.h +++ b/softmmu_template.h @@ -151,6 +151,7 @@ static inline DATA_TYPE glue(io_read, SUFFIX)(CPUArchState *env, CPUState *cpu = ENV_GET_CPU(env); hwaddr physaddr = iotlbentry->addr; MemoryRegion *mr = iotlb_to_region(cpu, physaddr, iotlbentry->attrs); + bool locked = false; physaddr = (physaddr & TARGET_PAGE_MASK) + addr; cpu->mem_io_pc = retaddr; @@ -159,8 +160,15 @@ static inline DATA_TYPE glue(io_read, SUFFIX)(CPUArchState *env, } cpu->mem_io_vaddr = addr; + if (mr->global_locking) { + qemu_mutex_lock_iothread(); + locked = true; + } memory_region_dispatch_read(mr, physaddr, &val, 1 << SHIFT, iotlbentry->attrs); + if (locked) { + qemu_mutex_unlock_iothread(); + } return val; } #endif @@ -358,6 +366,7 @@ static inline void glue(io_write, SUFFIX)(CPUArchState *env, CPUState *cpu = ENV_GET_CPU(env); hwaddr physaddr = iotlbentry->addr; MemoryRegion *mr = iotlb_to_region(cpu, physaddr, iotlbentry->attrs); + bool locked = false; physaddr = (physaddr & TARGET_PAGE_MASK) + addr; if (mr != &io_mem_rom && mr != &io_mem_notdirty && !cpu->can_do_io) { @@ -366,8 +375,16 @@ static inline void glue(io_write, SUFFIX)(CPUArchState *env, cpu->mem_io_vaddr = addr; cpu->mem_io_pc = retaddr; + + if (mr->global_locking) { + qemu_mutex_lock_iothread(); + locked = true; + } memory_region_dispatch_write(mr, physaddr, val, 1 << SHIFT, iotlbentry->attrs); + if (locked) { + qemu_mutex_unlock_iothread(); + } } void helper_le_st_name(CPUArchState *env, target_ulong addr, DATA_TYPE val, diff --git a/target-i386/smm_helper.c b/target-i386/smm_helper.c index 4dd6a2c..6a5489b 100644 --- a/target-i386/smm_helper.c +++ b/target-i386/smm_helper.c @@ -18,6 +18,7 @@ */ #include "qemu/osdep.h" +#include "qemu/main-loop.h" #include "cpu.h" #include "exec/helper-proto.h" #include "exec/log.h" @@ -42,11 +43,14 @@ void helper_rsm(CPUX86State *env) #define SMM_REVISION_ID 0x00020000 #endif +/* Called we iothread lock taken */ void cpu_smm_update(X86CPU *cpu) { CPUX86State *env = &cpu->env; bool smm_enabled = (env->hflags & HF_SMM_MASK); + g_assert(qemu_mutex_iothread_locked()); + if (cpu->smram) { memory_region_set_enabled(cpu->smram, smm_enabled); } @@ -333,7 +337,10 @@ void helper_rsm(CPUX86State *env) } env->hflags2 &= ~HF2_SMM_INSIDE_NMI_MASK; env->hflags &= ~HF_SMM_MASK; + + qemu_mutex_lock_iothread(); cpu_smm_update(cpu); + qemu_mutex_unlock_iothread(); qemu_log_mask(CPU_LOG_INT, "SMM: after RSM\n"); log_cpu_state_mask(CPU_LOG_INT, CPU(cpu), CPU_DUMP_CCOP); diff --git a/translate-all.c b/translate-all.c index 935d24c..0c377bb 100644 --- a/translate-all.c +++ b/translate-all.c @@ -1318,6 +1318,7 @@ void tb_invalidate_phys_range(tb_page_addr_t start, tb_page_addr_t end) * this TB. * * Called with mmap_lock held for user-mode emulation + * If called from generated code, iothread mutex must not be held. */ void tb_invalidate_phys_page_range(tb_page_addr_t start, tb_page_addr_t end, int is_cpu_write_access) @@ -1430,7 +1431,9 @@ void tb_invalidate_phys_page_range(tb_page_addr_t start, tb_page_addr_t end, } #ifdef CONFIG_SOFTMMU -/* len must be <= 8 and start must be a multiple of len */ +/* len must be <= 8 and start must be a multiple of len. + * Called via softmmu_template.h, with iothread mutex not held. + */ void tb_invalidate_phys_page_fast(tb_page_addr_t start, int len) { PageDesc *p; @@ -1579,6 +1582,7 @@ static TranslationBlock *tb_find_pc(uintptr_t tc_ptr) } #if !defined(CONFIG_USER_ONLY) +/* If called from generated code, iothread mutex must not be held. */ void tb_invalidate_phys_addr(AddressSpace *as, hwaddr addr) { ram_addr_t ram_addr; @@ -1625,7 +1629,10 @@ void tb_check_watchpoint(CPUState *cpu) #ifndef CONFIG_USER_ONLY /* in deterministic execution mode, instructions doing device I/Os - must be at the end of the TB */ + * must be at the end of the TB. + * + * Called by softmmu_template.h, with iothread mutex not held. + */ void cpu_io_recompile(CPUState *cpu, uintptr_t retaddr) { #if defined(TARGET_MIPS) || defined(TARGET_SH4) -- 2.7.4