From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 478B2CA0FED for ; Wed, 10 Sep 2025 20:45:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=47KOM0yu8zSXt/DrfP0oUUXxO6MvTw6Ddp46fCWxAG0=; b=puMUSyZckP4ZamqnY9Kwm9y7JZ bTrLaMATs6BHCQhfh+9L0PVhK61SmeSafuIbWESm316cRVe+ntG+5VfovmI9R7RmZrYLd7xEAf/YJ NtbpMWuFwJdQM/qrSL3OvIkK5ReUZnrkOFY4pmzuCryif8wfPfwgUpXjlvcfmTeE5sEdWckaJKEc3 nAiLCQoIm3R5p4sbt6cPCtQew8QWtHo1t/MgniWzZk2y3zMx9nqEYkE62iCfob/O7GvznboovOYTx 2PzwXMLsBKyisRN4eDTs9g2v011R5PUrg1QLs90wne/n0q07J1gWI9DoY3iepBVMkDeBGwtegE43W 3qgAN3TQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uwRgp-0000000GeGX-2kv2; Wed, 10 Sep 2025 20:45:15 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uwRgg-0000000Ge65-12l6 for linux-arm-kernel@lists.infradead.org; Wed, 10 Sep 2025 20:45:11 +0000 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 592BF1C0A; Wed, 10 Sep 2025 13:44:57 -0700 (PDT) Received: from merodach.members.linode.com (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 166F13F63F; Wed, 10 Sep 2025 13:45:00 -0700 (PDT) From: James Morse To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-acpi@vger.kernel.org Cc: James Morse , 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, Jonathan Cameron , Rob Herring , Rohit Mathew , Rafael Wysocki , Len Brown , Lorenzo Pieralisi , Hanjun Guo , Sudeep Holla , Catalin Marinas , Will Deacon , Greg Kroah-Hartman , Danilo Krummrich Subject: [PATCH v2 19/29] arm_mpam: Use a static key to indicate when mpam is enabled Date: Wed, 10 Sep 2025 20:42:59 +0000 Message-Id: <20250910204309.20751-20-james.morse@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20250910204309.20751-1-james.morse@arm.com> References: <20250910204309.20751-1-james.morse@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250910_134506_458546_74BC7796 X-CRM114-Status: GOOD ( 18.13 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Once all the MSC have been probed, the system wide usable number of PARTID is known and the configuration arrays can be allocated. After this point, checking all the MSC have been probed is pointless, and the cpuhp callbacks should restore the configuration, instead of just resetting the MSC. Add a static key to enable this behaviour. This will also allow MPAM to be disabled in repsonse to an error, and the architecture code to enable/disable the context switch of the MPAM system registers. Signed-off-by: James Morse --- drivers/resctrl/mpam_devices.c | 12 ++++++++++++ drivers/resctrl/mpam_internal.h | 8 ++++++++ 2 files changed, 20 insertions(+) diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c index e7e4afc1ea95..ec1db5f8b05c 100644 --- a/drivers/resctrl/mpam_devices.c +++ b/drivers/resctrl/mpam_devices.c @@ -29,6 +29,8 @@ #include "mpam_internal.h" +DEFINE_STATIC_KEY_FALSE(mpam_enabled); /* TODO: move to arch code */ + /* * mpam_list_lock protects the SRCU lists when writing. Once the * mpam_enabled key is enabled these lists are read-only, @@ -956,6 +958,9 @@ static int mpam_discovery_cpu_online(unsigned int cpu) struct mpam_msc *msc; bool new_device_probed = false; + if (mpam_is_enabled()) + return 0; + guard(srcu)(&mpam_srcu); list_for_each_entry_srcu(msc, &mpam_all_msc, all_msc_list, srcu_read_lock_held(&mpam_srcu)) { @@ -1471,6 +1476,10 @@ static irqreturn_t __mpam_irq_handler(int irq, struct mpam_msc *msc) /* Disable this interrupt. */ mpam_disable_msc_ecr(msc); + /* Are we racing with the thread disabling MPAM? */ + if (!mpam_is_enabled()) + return IRQ_HANDLED; + /* * Schedule the teardown work. Don't use a threaded IRQ as we can't * unregister the interrupt from the threaded part of the handler. @@ -1601,6 +1610,7 @@ static void mpam_enable_once(void) return; } + static_branch_enable(&mpam_enabled); mpam_register_cpuhp_callbacks(mpam_cpu_online, mpam_cpu_offline); printk(KERN_INFO "MPAM enabled with %u PARTIDs and %u PMGs\n", @@ -1666,6 +1676,8 @@ void mpam_disable(struct work_struct *ignored) } mutex_unlock(&mpam_cpuhp_state_lock); + static_branch_disable(&mpam_enabled); + mpam_unregister_irqs(); idx = srcu_read_lock(&mpam_srcu); diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h index f04a9ef189cf..b69fa9199cb4 100644 --- a/drivers/resctrl/mpam_internal.h +++ b/drivers/resctrl/mpam_internal.h @@ -8,6 +8,7 @@ #include #include #include +#include #include #include #include @@ -17,6 +18,13 @@ #define MPAM_MSC_MAX_NUM_RIS 16 +DECLARE_STATIC_KEY_FALSE(mpam_enabled); + +static inline bool mpam_is_enabled(void) +{ + return static_branch_likely(&mpam_enabled); +} + /* * Structures protected by SRCU may not be freed for a surprising amount of * time (especially if perf is running). To ensure the MPAM error interrupt can -- 2.39.5