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 BA7162D5C97 for ; Thu, 24 Jul 2025 14:13:19 +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=1753366401; cv=none; b=BFv7t7xJpJ7Qs65G+7r2UoORCiBB8E797bl51X1xuw9KQnPXBBZy0Cd7KvuF1osBjS4fRm5dsS+W9P7AultnQMe8HRoGEhwE6AIhq+CzypcC3fvHIpAkwLgLK50ilHZKHdV0ivO4+YGCGbVpGyPN1mcEftxTg6cKp748ckHvFaQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753366401; c=relaxed/simple; bh=9yD5qowNf+3o65b72QRPPjF5YvE3rW9R+UjlazwDXsE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Ge57KSMYFu72a16WOZf4uqtw3lmGpgWs5q4jatsFIkvU5NOg1N9AzHBcQXdn3kAyvZ3TwGIX12tMyruSsCd7tnyHRlGllEzO0B5CH+a2Pek+2jbm1zHYK9Qkpec0Dnvhaku3Y/3+2L2hDAXMKY9t7rUPUys4/wwhZyfsCzrhIa8= 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 9DA3F1A00; Thu, 24 Jul 2025 07:13:12 -0700 (PDT) Received: from [10.57.84.166] (unknown [10.57.84.166]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BDAB03F66E; Thu, 24 Jul 2025 07:13:15 -0700 (PDT) Message-ID: <48e482f2-e7a8-4d6a-bf16-ad29f9331e3b@arm.com> Date: Thu, 24 Jul 2025 15:13:14 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 17/36] arm_mpam: Add cpuhp callbacks to probe MSC hardware Content-Language: en-GB To: James Morse , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Rob Herring , Rohit Mathew , Shanker Donthineni , Zeng Heng , Lecopzer Chen , Carl Worth , shameerali.kolothum.thodi@huawei.com, D Scott Phillips OS , 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 , Rex Nie , Dave Martin , Koba Ko References: <20250711183648.30766-1-james.morse@arm.com> <20250711183648.30766-18-james.morse@arm.com> From: Ben Horgan In-Reply-To: <20250711183648.30766-18-james.morse@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi James, On 11/07/2025 19:36, James Morse wrote: > Because an MSC can only by accessed from the CPUs in its cpu-affinity > set we need to be running on one of those CPUs to probe the MSC > hardware. > > Do this work in the cpuhp callback. Probing the hardware will only > happen before MPAM is enabled, walk all the MSCs and probe those we can > reach that haven't already been probed. > > Later once MPAM is enabled, this cpuhp callback will be replaced by > one that avoids the global list. > > Enabling a static key will also take the cpuhp lock, so can't be done > from the cpuhp callback. Whenever a new MSC has been probed schedule > work to test if all the MSCs have now been probed. > > CC: Lecopzer Chen > Signed-off-by: James Morse > --- > drivers/platform/arm64/mpam/mpam_devices.c | 149 +++++++++++++++++++- > drivers/platform/arm64/mpam/mpam_internal.h | 8 +- > 2 files changed, 152 insertions(+), 5 deletions(-) > > diff --git a/drivers/platform/arm64/mpam/mpam_devices.c b/drivers/platform/arm64/mpam/mpam_devices.c > index 0d6d5180903b..89434ae3efa6 100644 > --- a/drivers/platform/arm64/mpam/mpam_devices.c > +++ b/drivers/platform/arm64/mpam/mpam_devices.c > @@ -4,6 +4,7 @@ > #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__ > > #include > +#include > #include > #include > #include > @@ -21,6 +22,7 @@ > #include > #include > #include > +#include > > #include > > @@ -39,6 +41,16 @@ struct srcu_struct mpam_srcu; > /* MPAM isn't available until all the MSC have been probed. */ > static u32 mpam_num_msc; > > +static int mpam_cpuhp_state; > +static DEFINE_MUTEX(mpam_cpuhp_state_lock); > + > +/* > + * mpam is enabled once all devices have been probed from CPU online callbacks, > + * scheduled via this work_struct. If access to an MSC depends on a CPU that > + * was not brought online at boot, this can happen surprisingly late. > + */ > +static DECLARE_WORK(mpam_enable_work, &mpam_enable); > + > /* > * An MSC is a physical container for controls and monitors, each identified by > * their RIS index. These share a base-address, interrupts and some MMIO > @@ -78,6 +90,22 @@ LIST_HEAD(mpam_classes); > /* List of all objects that can be free()d after synchronise_srcu() */ > static LLIST_HEAD(mpam_garbage); > > +static u32 __mpam_read_reg(struct mpam_msc *msc, u16 reg) > +{ > + WARN_ON_ONCE(reg > msc->mapped_hwpage_sz); > + WARN_ON_ONCE(!cpumask_test_cpu(smp_processor_id(), &msc->accessibility)); > + > + return readl_relaxed(msc->mapped_hwpage + reg); > +} > + > +static inline u32 _mpam_read_partsel_reg(struct mpam_msc *msc, u16 reg) > +{ > + lockdep_assert_held_once(&msc->part_sel_lock); > + return __mpam_read_reg(msc, reg); > +} > + > +#define mpam_read_partsel_reg(msc, reg) _mpam_read_partsel_reg(msc, MPAMF_##reg) > + > #define init_garbage(x) init_llist_node(&(x)->garbage.llist) > > static struct mpam_vmsc * > @@ -513,9 +541,84 @@ int mpam_ris_create(struct mpam_msc *msc, u8 ris_idx, > return err; > } > > -static void mpam_discovery_complete(void) > +static int mpam_msc_hw_probe(struct mpam_msc *msc) > { > - pr_err("Discovered all MSC\n"); > + u64 idr; > + int err; > + > + lockdep_assert_held(&msc->probe_lock); > + > + mutex_lock(&msc->part_sel_lock); > + idr = mpam_read_partsel_reg(msc, AIDR); > + if ((idr & MPAMF_AIDR_ARCH_MAJOR_REV) != MPAM_ARCHITECTURE_V1) { > + pr_err_once("%s does not match MPAM architecture v1.0\n", > + dev_name(&msc->pdev->dev)); The error message need only mention the major revision. You've added support for v1.1 and v1.0.> + err = -EIO; > + } else { > + msc->probed = true; > + err = 0; > + } > + mutex_unlock(&msc->part_sel_lock); > + > + return err; > +} [snip] Thanks, Ben