From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 20DC5274658; Thu, 2 Oct 2025 18:03:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759428187; cv=none; b=hl1JfKF/emoI4kOhG1OC2+Cw1P8MYvR+oRHYwTH/wfFZr0qomzKi6K8e6xsVbu+jY6CzFL1UdiobEt8nXH1w8UhmJnQl1QetfMUSoG8s5KLHValtQKT1nD8EsVbn2qjVLBEv6rl0KDYFZuJR9mD1tiHr2ecJ8n/83wEjAbah0nQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759428187; c=relaxed/simple; bh=L54zV7q/sZsrrJ9GCt0k13h+4mjw6GuQZZpN2kyTZs8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=P20R+v1Vddw/Gth8BaUFoHM0Pkb2g+omjnzZFTgrqaZXXheClH98uZ8fpTOwggQrF7ElNwwCnkDJymuteimLg5LlR673xHuXosFSHwuTiY2t8Emp9Pc3ZIDFgFli2vkZECJEJ1yAIVL1tGu/LXGV9NnIFaKyE0de4VoahMdPgro= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9671A1CE0; Thu, 2 Oct 2025 11:02:57 -0700 (PDT) Received: from [10.1.197.69] (eglon.cambridge.arm.com [10.1.197.69]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BF3863F66E; Thu, 2 Oct 2025 11:03:00 -0700 (PDT) Message-ID: <9d21e5ca-5f35-44de-a11e-194f34dd8ff2@arm.com> Date: Thu, 2 Oct 2025 19:02:59 +0100 Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 18/29] arm_mpam: Register and enable IRQs To: Jonathan Cameron Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-acpi@vger.kernel.org, D Scott Phillips OS , carl@os.amperecomputing.com, lcherian@marvell.com, bobo.shaobowang@huawei.com, tan.shaopeng@fujitsu.com, baolin.wang@linux.alibaba.com, Jamie Iles , Xin Hao , peternewman@google.com, dfustini@baylibre.com, amitsinght@marvell.com, David Hildenbrand , Dave Martin , Koba Ko , Shanker Donthineni , fenghuay@nvidia.com, baisheng.gao@unisoc.com, Rob Herring , Rohit Mathew , Rafael Wysocki , Len Brown , Lorenzo Pieralisi , Hanjun Guo , Sudeep Holla , Catalin Marinas , Will Deacon , Greg Kroah-Hartman , Danilo Krummrich References: <20250910204309.20751-1-james.morse@arm.com> <20250910204309.20751-19-james.morse@arm.com> <20250912131219.00000938@huawei.com> Content-Language: en-GB From: James Morse In-Reply-To: <20250912131219.00000938@huawei.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Jonathan, On 12/09/2025 13:12, Jonathan Cameron wrote: > On Wed, 10 Sep 2025 20:42:58 +0000 > James Morse wrote: > >> Register and enable error IRQs. All the MPAM error interrupts indicate a >> software bug, e.g. out of range partid. If the error interrupt is ever >> signalled, attempt to disable MPAM. >> >> Only the irq handler accesses the ESR register, so no locking is needed. >> The work to disable MPAM after an error needs to happen at process >> context as it takes mutex. It also unregisters the interrupts, meaning >> it can't be done from the threaded part of a threaded interrupt. >> Instead, mpam_disable() gets scheduled. >> >> Enabling the IRQs in the MSC may involve cross calling to a CPU that >> can access the MSC. >> >> Once the IRQ is requested, the mpam_disable() path can be called >> asynchronously, which will walk structures sized by max_partid. Ensure >> this size is fixed before the interrupt is requested. >> @@ -1318,11 +1405,172 @@ static void mpam_enable_merge_features(struct list_head *all_classes_list) >> } >> } >> >> +static char *mpam_errcode_names[16] = { >> + [0] = "No error", > > I think you had a bunch of defines for these in an earlier patch. Can we use > that to index here instead of [0] etc. Sure, >> + [1] = "PARTID_SEL_Range", >> + [2] = "Req_PARTID_Range", >> + [3] = "MSMONCFG_ID_RANGE", >> + [4] = "Req_PMG_Range", >> + [5] = "Monitor_Range", >> + [6] = "intPARTID_Range", >> + [7] = "Unexpected_INTERNAL", >> + [8] = "Undefined_RIS_PART_SEL", >> + [9] = "RIS_No_Control", >> + [10] = "Undefined_RIS_MON_SEL", >> + [11] = "RIS_No_Monitor", >> + [12 ... 15] = "Reserved" >> +}; > > >> +static void mpam_unregister_irqs(void) >> +{ >> + int irq, idx; >> + struct mpam_msc *msc; >> + >> + cpus_read_lock(); > > guard(cpus_read_lock)(); > guard(srcu)(&mpam_srcu); Sure, looks like I didn't realise there was a cpus_read_lock version of this when I went looking for places to add this. >> + /* take the lock as free_irq() can sleep */ The comment gets dropped as this mattered for an earlier locking scheme. (but free_irq() can still sleep) >> + idx = srcu_read_lock(&mpam_srcu); >> + list_for_each_entry_srcu(msc, &mpam_all_msc, all_msc_list, >> + srcu_read_lock_held(&mpam_srcu)) { >> + irq = platform_get_irq_byname_optional(msc->pdev, "error"); >> + if (irq <= 0) >> + continue; >> + >> + if (test_and_clear_bit(MPAM_ERROR_IRQ_HW_ENABLED, &msc->error_irq_flags)) >> + mpam_touch_msc(msc, mpam_disable_msc_ecr, msc); >> + >> + if (test_and_clear_bit(MPAM_ERROR_IRQ_REQUESTED, &msc->error_irq_flags)) { >> + if (irq_is_percpu(irq)) { >> + msc->reenable_error_ppi = 0; >> + free_percpu_irq(irq, msc->error_dev_id); >> + } else { >> + devm_free_irq(&msc->pdev->dev, irq, msc); >> + } >> + } >> + } >> + srcu_read_unlock(&mpam_srcu, idx); >> + cpus_read_unlock(); >> +} >> @@ -1332,6 +1580,27 @@ static void mpam_enable_once(void) >> partid_max_published = true; >> spin_unlock(&partid_max_lock); >> >> + /* >> + * If all the MSC have been probed, enabling the IRQs happens next. >> + * That involves cross-calling to a CPU that can reach the MSC, and >> + * the locks must be taken in this order: >> + */ >> + cpus_read_lock(); >> + mutex_lock(&mpam_list_lock); >> + mpam_enable_merge_features(&mpam_classes); >> + >> + err = mpam_register_irqs(); >> + if (err) >> + pr_warn("Failed to register irqs: %d\n", err); > > Perhaps move the print into the if (err) below? More types of error get later, and its maybe useful to know which of these failed. >> diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h >> index 6e047fbd3512..f04a9ef189cf 100644 >> --- a/drivers/resctrl/mpam_internal.h >> +++ b/drivers/resctrl/mpam_internal.h >> @@ -32,6 +32,10 @@ struct mpam_garbage { >> struct platform_device *pdev; >> }; >> >> +/* Bit positions for error_irq_flags */ >> +#define MPAM_ERROR_IRQ_REQUESTED 0 >> +#define MPAM_ERROR_IRQ_HW_ENABLED 1 > > If there aren't going to be load more of these (I've not really thought > about whether there might) then using a bitmap for these seems to add complexity > that we wouldn't see with > bool error_irq_req; > bool error_irq_hw_enabled; It's a bitmap so that mpam_unregister_irqs() can use test_and_clear_bit() on them, because with a real interrupt mpam_unregister_irqs() can run multiple times in parallel with itself. Doing this as bools would mean having a mutex to prevent that from happening. I'll do that as its a slightly simpler. Thanks, James