From patchwork Thu May 21 16:39:00 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Robert Foley X-Patchwork-Id: 11563433 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 29E1F739 for ; Thu, 21 May 2020 16:45:48 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D2C652072C for ; Thu, 21 May 2020 16:45:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="q3/we0bW" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D2C652072C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:34322 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jboKI-0007Kr-S3 for patchwork-qemu-devel@patchwork.kernel.org; Thu, 21 May 2020 12:45:46 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:49652) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jboHx-0001cv-Gb for qemu-devel@nongnu.org; Thu, 21 May 2020 12:43:21 -0400 Received: from mail-qt1-x844.google.com ([2607:f8b0:4864:20::844]:41268) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jboHv-0006TF-6E for qemu-devel@nongnu.org; Thu, 21 May 2020 12:43:21 -0400 Received: by mail-qt1-x844.google.com with SMTP id m44so5980524qtm.8 for ; Thu, 21 May 2020 09:43:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=XkuJ6MkZisGtrqNcI/WmjmrJib8LTmp/yxFiG3GQPeA=; b=q3/we0bWpMx2wZYtvNo7PDfKbGGLd1MU7T2yd8K3VQCepk6ILUxIUVlKeYd2TKHYva DbwPOgaKDfpYeqFy87uJ8NBd4ZgWHpIdY/rxr86qceO5fF/VDPKhTwiNOkQja8pToIJR LKRaH+xnVRWTbkKVo0auD2RtPpg6ieznb3DND5XPHt3B5VVyG7orv749L3IbxCqMeN70 LyddUZe5/Kdlwx6zjb06cj0xynwcGt2M4rIzRbk21X6zTM5bd1AvROjJU/9TC0C1HAhm YK75CqBOoyNlZ7/T9SK6StIPnjh+st4UVAoQVseT7REkwtVe2V7s/whfWdHqIJP0CgDI u2XA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=XkuJ6MkZisGtrqNcI/WmjmrJib8LTmp/yxFiG3GQPeA=; b=TFAgyS112mauIQPte9gKJCT+FtYnmALU290UWrg2EzXtdRlJVI+J4cHhSQQKPLNiUq mWeVKijaOWK1t98HcNvQnU5Yqu7rwkka5modmxARGSb85XVtKKO5oEt16YDqkFEf/keG oX80YcXYQFH/Zc2vuBSpghI0M0Jy6pCKhFzzVFHqUgfRgSkroEsOCmNmhWZPbhy0Oh0x xSBIJff1Q/h4syiWcb9vW9ZKztsrSLRVaZkveS6bVUQT1RVvcObhqm5vvQN+hoEmV4QS wpWcwDOxdwiLDbdJhBMIGcDRMtnenH/DCe/Opr07lzj5YbkWd1R02jP1FpE5WFoVuk1F LN4w== X-Gm-Message-State: AOAM5314x4TDST4nTLTkYQ4bFK4l9bdXSWWRB79TWTHYc+RYI0c1Y/uq 4U+BmmVSYkhaTzLnsD9FqZCFYgG+f28HBA== X-Google-Smtp-Source: ABdhPJzVzUwKTxuOR8q6Lhlfvb+TG02ayREFkvuJz6uDhW3g1IOY0w5Zc+M3uyDgyOvXFljDSG1zYg== X-Received: by 2002:ac8:4f4e:: with SMTP id i14mr11835684qtw.167.1590079397651; Thu, 21 May 2020 09:43:17 -0700 (PDT) Received: from Rfoley-MA01.hsd1.ma.comcast.net ([2601:199:4480:60c0:1944:c530:655c:5583]) by smtp.gmail.com with ESMTPSA id x24sm5923829qth.57.2020.05.21.09.43.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 May 2020 09:43:17 -0700 (PDT) From: Robert Foley To: qemu-devel@nongnu.org Subject: [PATCH v9 03/74] cpu: introduce cpu_mutex_lock/unlock Date: Thu, 21 May 2020 12:39:00 -0400 Message-Id: <20200521164011.638-4-robert.foley@linaro.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200521164011.638-1-robert.foley@linaro.org> References: <20200521164011.638-1-robert.foley@linaro.org> Received-SPF: pass client-ip=2607:f8b0:4864:20::844; envelope-from=robert.foley@linaro.org; helo=mail-qt1-x844.google.com X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: richard.henderson@linaro.org, cota@braap.org, alex.bennee@linaro.org, robert.foley@linaro.org, peter.puhov@linaro.org Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" From: "Emilio G. Cota" The few direct users of &cpu->lock will be converted soon. The per-thread bitmap introduced here might seem unnecessary, since a bool could just do. However, once we complete the conversion to per-vCPU locks, we will need to cover the use case where all vCPUs are locked by the same thread, which explains why the bitmap is introduced here. Reviewed-by: Richard Henderson Signed-off-by: Emilio G. Cota [RF: Add assert in smp_parse. Make cpu_mutex_lock stub empty] Signed-off-by: Robert Foley --- cpus.c | 45 +++++++++++++++++++++++++++++++++++++++++-- hw/core/machine.c | 1 + include/hw/core/cpu.h | 36 ++++++++++++++++++++++++++++++++++ stubs/Makefile.objs | 1 + stubs/cpu-lock.c | 20 +++++++++++++++++++ 5 files changed, 101 insertions(+), 2 deletions(-) create mode 100644 stubs/cpu-lock.c diff --git a/cpus.c b/cpus.c index 77a2d7b7cf..c2da430221 100644 --- a/cpus.c +++ b/cpus.c @@ -92,6 +92,44 @@ static unsigned int throttle_percentage; #define CPU_THROTTLE_PCT_MAX 99 #define CPU_THROTTLE_TIMESLICE_NS 10000000 +/* + * Note: we index the bitmap with cpu->cpu_index + 1 so that the logic + * also works during early CPU initialization, when cpu->cpu_index is set to + * UNASSIGNED_CPU_INDEX == -1. + */ +static __thread DECLARE_BITMAP(cpu_lock_bitmap, CPU_LOCK_BITMAP_SIZE); + +bool no_cpu_mutex_locked(void) +{ + return bitmap_empty(cpu_lock_bitmap, CPU_LOCK_BITMAP_SIZE); +} + +void cpu_mutex_lock_impl(CPUState *cpu, const char *file, int line) +{ +/* coverity gets confused by the indirect function call */ +#ifdef __COVERITY__ + qemu_mutex_lock_impl(&cpu->lock, file, line); +#else + QemuMutexLockFunc f = atomic_read(&qemu_mutex_lock_func); + + g_assert(!cpu_mutex_locked(cpu)); + set_bit(cpu->cpu_index + 1, cpu_lock_bitmap); + f(&cpu->lock, file, line); +#endif +} + +void cpu_mutex_unlock_impl(CPUState *cpu, const char *file, int line) +{ + g_assert(cpu_mutex_locked(cpu)); + qemu_mutex_unlock_impl(&cpu->lock, file, line); + clear_bit(cpu->cpu_index + 1, cpu_lock_bitmap); +} + +bool cpu_mutex_locked(const CPUState *cpu) +{ + return test_bit(cpu->cpu_index + 1, cpu_lock_bitmap); +} + bool cpu_is_stopped(CPUState *cpu) { return cpu->stopped || !runstate_is_running(); @@ -101,9 +139,9 @@ static inline bool cpu_work_list_empty(CPUState *cpu) { bool ret; - qemu_mutex_lock(&cpu->lock); + cpu_mutex_lock(cpu); ret = QSIMPLEQ_EMPTY(&cpu->work_list); - qemu_mutex_unlock(&cpu->lock); + cpu_mutex_unlock(cpu); return ret; } @@ -1845,6 +1883,9 @@ void qemu_mutex_lock_iothread_impl(const char *file, int line) { QemuMutexLockFunc bql_lock = atomic_read(&qemu_bql_mutex_lock_func); + /* enforce locking order */ + g_assert(no_cpu_mutex_locked()); + g_assert(!qemu_mutex_iothread_locked()); bql_lock(&qemu_global_mutex, file, line); iothread_locked = true; diff --git a/hw/core/machine.c b/hw/core/machine.c index bb3a7b18b1..03a9081f55 100644 --- a/hw/core/machine.c +++ b/hw/core/machine.c @@ -763,6 +763,7 @@ static void smp_parse(MachineState *ms, QemuOpts *opts) ms->smp.threads = threads; ms->smp.sockets = sockets; } + assert(ms->smp.max_cpus <= CPU_LOCK_BITMAP_SIZE); if (ms->smp.cpus > 1) { Error *blocker = NULL; diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h index 873bf23a39..2912d9a7c1 100644 --- a/include/hw/core/cpu.h +++ b/include/hw/core/cpu.h @@ -457,6 +457,39 @@ extern CPUTailQ cpus; extern __thread CPUState *current_cpu; +/** + * cpu_mutex_lock - lock a CPU's mutex + * @cpu: the CPU whose mutex is to be locked + * + * To avoid deadlock, a CPU's mutex must be acquired after the BQL. + */ +#define cpu_mutex_lock(cpu) \ + cpu_mutex_lock_impl(cpu, __FILE__, __LINE__) +void cpu_mutex_lock_impl(CPUState *cpu, const char *file, int line); + +/** + * cpu_mutex_unlock - unlock a CPU's mutex + * @cpu: the CPU whose mutex is to be unlocked + */ +#define cpu_mutex_unlock(cpu) \ + cpu_mutex_unlock_impl(cpu, __FILE__, __LINE__) +void cpu_mutex_unlock_impl(CPUState *cpu, const char *file, int line); + +/** + * cpu_mutex_locked - check whether a CPU's mutex is locked + * @cpu: the CPU of interest + * + * Returns true if the calling thread is currently holding the CPU's mutex. + */ +bool cpu_mutex_locked(const CPUState *cpu); + +/** + * no_cpu_mutex_locked - check whether any CPU mutex is held + * + * Returns true if the calling thread is not holding any CPU mutex. + */ +bool no_cpu_mutex_locked(void); + static inline void cpu_tb_jmp_cache_clear(CPUState *cpu) { unsigned int i; @@ -1179,4 +1212,7 @@ extern const VMStateDescription vmstate_cpu_common; #define UNASSIGNED_CPU_INDEX -1 #define UNASSIGNED_CLUSTER_INDEX -1 +/* XXX: is this really the max number of CPUs? */ +#define CPU_LOCK_BITMAP_SIZE 2048 + #endif diff --git a/stubs/Makefile.objs b/stubs/Makefile.objs index 45be5dc0ed..d2dd6c94cc 100644 --- a/stubs/Makefile.objs +++ b/stubs/Makefile.objs @@ -5,6 +5,7 @@ stub-obj-y += blockdev-close-all-bdrv-states.o stub-obj-y += clock-warp.o stub-obj-y += cpu-get-clock.o stub-obj-y += cpu-get-icount.o +stub-obj-y += cpu-lock.o stub-obj-y += dump.o stub-obj-y += error-printf.o stub-obj-y += fdset.o diff --git a/stubs/cpu-lock.c b/stubs/cpu-lock.c new file mode 100644 index 0000000000..1981a00fb3 --- /dev/null +++ b/stubs/cpu-lock.c @@ -0,0 +1,20 @@ +#include "qemu/osdep.h" +#include "hw/core/cpu.h" + +void cpu_mutex_lock_impl(CPUState *cpu, const char *file, int line) +{ +} + +void cpu_mutex_unlock_impl(CPUState *cpu, const char *file, int line) +{ +} + +bool cpu_mutex_locked(const CPUState *cpu) +{ + return true; +} + +bool no_cpu_mutex_locked(void) +{ + return true; +}