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 4F882CA0FED for ; Wed, 10 Sep 2025 20:45:03 +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=ORw6AXZQgtF0XOI9/Bj1IpIj6ysZK8oQf2Ao2c+6ZAM=; b=4MJD70cVd/n/tO/5jepzqNqAzo r6WXFXp3FUL+tziyXpwWFgkgFbneARCieD7gja946FFqV9OBwwzWnvpsZO6Q6CgCLrM6VKjdp9CX7 IfUIr4GCabJqbvGNUhRkvhSRHerAa5VE2fjInNIdw0L8SsS7z/Rc0fJEXQr4KnvYVJWzKj5Txkod/ MEFls3apjNBQ6GZzVZgJGx4awO5AzyqdS4NWghZNf2pxw1ktc+kYpPQiqa7R8B2GJX1BguIyVexpg f0KwcY08dpSOUfpMRregoRVY/S5fJmcX2sjBrUYlkbCT2HzCLvYjfPjXR6QLpuaYqgkJUMT6/lMip k9JwU/jA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uwRgY-0000000GdxU-0lyh; Wed, 10 Sep 2025 20:44:58 +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 1uwRgR-0000000Gdo9-1jQI for linux-arm-kernel@lists.infradead.org; Wed, 10 Sep 2025 20:44:56 +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 80FB31C0A; Wed, 10 Sep 2025 13:44:42 -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 1A3063F63F; Wed, 10 Sep 2025 13:44:45 -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 , Ben Horgan Subject: [PATCH v2 16/29] arm_mpam: Add a helper to touch an MSC from any CPU Date: Wed, 10 Sep 2025 20:42:56 +0000 Message-Id: <20250910204309.20751-17-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_134451_609134_5D2E6AB8 X-CRM114-Status: GOOD ( 15.60 ) 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 Resetting RIS entries from the cpuhp callback is easy as the callback occurs on the correct CPU. This won't be true for any other caller that wants to reset or configure an MSC. Add a helper that schedules the provided function if necessary. Callers should take the cpuhp lock to prevent the cpuhp callbacks from changing the MSC state. Signed-off-by: James Morse Reviewed-by: Ben Horgan --- drivers/resctrl/mpam_devices.c | 37 +++++++++++++++++++++++++++++++--- 1 file changed, 34 insertions(+), 3 deletions(-) diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c index 0353313cf284..e7faf453b5d7 100644 --- a/drivers/resctrl/mpam_devices.c +++ b/drivers/resctrl/mpam_devices.c @@ -833,20 +833,51 @@ static void mpam_reset_ris_partid(struct mpam_msc_ris *ris, u16 partid) mutex_unlock(&msc->part_sel_lock); } -static void mpam_reset_ris(struct mpam_msc_ris *ris) +/* + * Called via smp_call_on_cpu() to prevent migration, while still being + * pre-emptible. + */ +static int mpam_reset_ris(void *arg) { u16 partid, partid_max; + struct mpam_msc_ris *ris = arg; mpam_assert_srcu_read_lock_held(); if (ris->in_reset_state) - return; + return 0; spin_lock(&partid_max_lock); partid_max = mpam_partid_max; spin_unlock(&partid_max_lock); for (partid = 0; partid < partid_max; partid++) mpam_reset_ris_partid(ris, partid); + + return 0; +} + +/* + * Get the preferred CPU for this MSC. If it is accessible from this CPU, + * this CPU is preferred. This can be preempted/migrated, it will only result + * in more work. + */ +static int mpam_get_msc_preferred_cpu(struct mpam_msc *msc) +{ + int cpu = raw_smp_processor_id(); + + if (cpumask_test_cpu(cpu, &msc->accessibility)) + return cpu; + + return cpumask_first_and(&msc->accessibility, cpu_online_mask); +} + +static int mpam_touch_msc(struct mpam_msc *msc, int (*fn)(void *a), void *arg) +{ + lockdep_assert_irqs_enabled(); + lockdep_assert_cpus_held(); + mpam_assert_srcu_read_lock_held(); + + return smp_call_on_cpu(mpam_get_msc_preferred_cpu(msc), fn, arg, true); } static void mpam_reset_msc(struct mpam_msc *msc, bool online) @@ -856,7 +887,7 @@ static void mpam_reset_msc(struct mpam_msc *msc, bool online) mpam_assert_srcu_read_lock_held(); list_for_each_entry_srcu(ris, &msc->ris, msc_list, srcu_read_lock_held(&mpam_srcu)) { - mpam_reset_ris(ris); + mpam_touch_msc(msc, &mpam_reset_ris, ris); /* * Set in_reset_state when coming online. The reset state -- 2.39.5