From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3A83C131E54; Tue, 23 Jan 2024 00:18:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705969116; cv=none; b=LLDaP7dBaH+PQ20kxBcQA0Xhg4tzqQlIRMjgLRtvcakP0wOHmH5Vx+9mQOyEVpy68jVXp523Ass1D0XR6fadi7pyPhBUCSK+BDxTBD81B25UkJjV05JFAfee4g9r5LMvka6UGcHsMkZLPrJ4wEad35IA0y9q8g7TgSVqUqQ0cvU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705969116; c=relaxed/simple; bh=RV0+e90dhErUGu5zwjQjY1yyiILpw+YI7UcjYm0Mx9E=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=eQwBYjdCnJWI17x4w3YqJh6KVDaUp2lDqiF1o7QbZLukqmN2MOgplQtNJBsf0XJztEucQdqu18dQVST9eH1OMlHxVUAlLuLl7IwH32AUdUOJJpHyekIqg9SaaiufpLPW5Pjqcm7CSooT5rAjk+FyyKo8kPAcJxYxeKwYX1JeMiY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=pl2n7QN0; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="pl2n7QN0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 96354C433C7; Tue, 23 Jan 2024 00:18:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1705969115; bh=RV0+e90dhErUGu5zwjQjY1yyiILpw+YI7UcjYm0Mx9E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pl2n7QN0cTCOhdqcp6RjX8gPpSnCPp59/QpA57fe4/uaUmFI26gVC76FU2UWfW+09 UuudZ/Utlj+ZZt7dKwkOaTixOJ8hkjwPEwlvwTZmzeq/g2Dzoh6DFcLTiTxkGKTqbr 8C5dwNQEFaO0UNAgXvPEtT2B8kaCocr1OOV/YE6Y= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Peter Zijlstra (Intel)" , Frederic Weisbecker , "Rafael J. Wysocki" , Sasha Levin Subject: [PATCH 6.7 006/641] x86: Fix CPUIDLE_FLAG_IRQ_ENABLE leaking timer reprogram Date: Mon, 22 Jan 2024 15:48:30 -0800 Message-ID: <20240122235818.302868255@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240122235818.091081209@linuxfoundation.org> References: <20240122235818.091081209@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.7-stable review patch. If anyone has any objections, please let me know. ------------------ From: Peter Zijlstra [ Upstream commit edc8fc01f608108b0b7580cb2c29dfb5135e5f0e ] intel_idle_irq() re-enables IRQs very early. As a result, an interrupt may fire before mwait() is eventually called. If such an interrupt queues a timer, it may go unnoticed until mwait returns and the idle loop handles the tick re-evaluation. And monitoring TIF_NEED_RESCHED doesn't help because a local timer enqueue doesn't set that flag. The issue is mitigated by the fact that this idle handler is only invoked for shallow C-states when, presumably, the next tick is supposed to be close enough. There may still be rare cases though when the next tick is far away and the selected C-state is shallow, resulting in a timer getting ignored for a while. Fix this with using sti_mwait() whose IRQ-reenablement only triggers upon calling mwait(), dealing with the race while keeping the interrupt latency within acceptable bounds. Fixes: c227233ad64c (intel_idle: enable interrupts before C1 on Xeons) Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Frederic Weisbecker Signed-off-by: Peter Zijlstra (Intel) Acked-by: Rafael J. Wysocki Link: https://lkml.kernel.org/r/20231115151325.6262-3-frederic@kernel.org Signed-off-by: Sasha Levin --- arch/x86/include/asm/mwait.h | 11 +++++++++-- drivers/idle/intel_idle.c | 19 +++++++------------ 2 files changed, 16 insertions(+), 14 deletions(-) diff --git a/arch/x86/include/asm/mwait.h b/arch/x86/include/asm/mwait.h index 778df05f8539..bae83810505b 100644 --- a/arch/x86/include/asm/mwait.h +++ b/arch/x86/include/asm/mwait.h @@ -115,8 +115,15 @@ static __always_inline void mwait_idle_with_hints(unsigned long eax, unsigned lo } __monitor((void *)¤t_thread_info()->flags, 0, 0); - if (!need_resched()) - __mwait(eax, ecx); + + if (!need_resched()) { + if (ecx & 1) { + __mwait(eax, ecx); + } else { + __sti_mwait(eax, ecx); + raw_local_irq_disable(); + } + } } current_clr_polling(); } diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c index dcda0afecfc5..3e01a6b23e75 100644 --- a/drivers/idle/intel_idle.c +++ b/drivers/idle/intel_idle.c @@ -131,11 +131,12 @@ static unsigned int mwait_substates __initdata; #define MWAIT2flg(eax) ((eax & 0xFF) << 24) static __always_inline int __intel_idle(struct cpuidle_device *dev, - struct cpuidle_driver *drv, int index) + struct cpuidle_driver *drv, + int index, bool irqoff) { struct cpuidle_state *state = &drv->states[index]; unsigned long eax = flg2MWAIT(state->flags); - unsigned long ecx = 1; /* break on interrupt flag */ + unsigned long ecx = 1*irqoff; /* break on interrupt flag */ mwait_idle_with_hints(eax, ecx); @@ -159,19 +160,13 @@ static __always_inline int __intel_idle(struct cpuidle_device *dev, static __cpuidle int intel_idle(struct cpuidle_device *dev, struct cpuidle_driver *drv, int index) { - return __intel_idle(dev, drv, index); + return __intel_idle(dev, drv, index, true); } static __cpuidle int intel_idle_irq(struct cpuidle_device *dev, struct cpuidle_driver *drv, int index) { - int ret; - - raw_local_irq_enable(); - ret = __intel_idle(dev, drv, index); - raw_local_irq_disable(); - - return ret; + return __intel_idle(dev, drv, index, false); } static __cpuidle int intel_idle_ibrs(struct cpuidle_device *dev, @@ -184,7 +179,7 @@ static __cpuidle int intel_idle_ibrs(struct cpuidle_device *dev, if (smt_active) __update_spec_ctrl(0); - ret = __intel_idle(dev, drv, index); + ret = __intel_idle(dev, drv, index, true); if (smt_active) __update_spec_ctrl(spec_ctrl); @@ -196,7 +191,7 @@ static __cpuidle int intel_idle_xstate(struct cpuidle_device *dev, struct cpuidle_driver *drv, int index) { fpu_idle_fpregs(); - return __intel_idle(dev, drv, index); + return __intel_idle(dev, drv, index, true); } /** -- 2.43.0