From nobody Mon Feb 9 17:22:54 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 292BA376479; Tue, 3 Feb 2026 21:45:28 +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=1770155129; cv=none; b=AuPS4906Zud23viYUcqrbIcMBpRvxoHEm4I57vQDOcvjJpuz8f8A1k2IdrnG7tFZ4M4sfd909QYBZWc0Gg3c0YXUNY7OJUVQanIy4GslUg+eBkOhjlpW+ZaAUUWoK3Y+HunuJbQIFCdHIN1Us3EAdY5PNdC/IMG5ZD3SqRonx2o= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770155129; c=relaxed/simple; bh=3IWYplKHxq8qRQvUK/1nsgOwnp95r549K3W0HMxvO3Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=JT0tcEirRjStB8MAovnKCusQg6MqFX2y50h44Vl7iE5Q02dWi+YSK5w65EICxlnXqkgqVDCexnkf41W2SII2Iv04pQl1IRwwkTck3lPPtKOqkUpMtUuI3BLH1aj02GHeC7KNcxdPR4QR4uKm2AX8oZ3vziPIRQcdLOBKLZBJ5uw= 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 5FAB9339; Tue, 3 Feb 2026 13:45:21 -0800 (PST) Received: from e134344.cambridge.arm.com (e134344.arm.com [10.1.196.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 362653F778; Tue, 3 Feb 2026 13:45:22 -0800 (PST) From: Ben Horgan To: ben.horgan@arm.com Cc: amitsinght@marvell.com, baisheng.gao@unisoc.com, baolin.wang@linux.alibaba.com, carl@os.amperecomputing.com, dave.martin@arm.com, david@kernel.org, dfustini@baylibre.com, fenghuay@nvidia.com, gshan@redhat.com, james.morse@arm.com, jonathan.cameron@huawei.com, kobak@nvidia.com, lcherian@marvell.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, peternewman@google.com, punit.agrawal@oss.qualcomm.com, quic_jiles@quicinc.com, reinette.chatre@intel.com, rohit.mathew@arm.com, scott@os.amperecomputing.com, sdonthineni@nvidia.com, tan.shaopeng@fujitsu.com, xhao@linux.alibaba.com, catalin.marinas@arm.com, will@kernel.org, corbet@lwn.net, maz@kernel.org, oupton@kernel.org, joey.gouly@arm.com, suzuki.poulose@arm.com, kvmarm@lists.linux.dev, zengheng4@huawei.com, linux-doc@vger.kernel.org, Shaopeng Tan Subject: [PATCH v4 15/41] arm_mpam: resctrl: Pick the caches we will use as resctrl resources Date: Tue, 3 Feb 2026 21:43:16 +0000 Message-ID: <20260203214342.584712-16-ben.horgan@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260203214342.584712-1-ben.horgan@arm.com> References: <20260203214342.584712-1-ben.horgan@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: James Morse Systems with MPAM support may have a variety of control types at any point of their system layout. We can only expose certain types of control, and only if they exist at particular locations. Start with the well-known caches. These have to be depth 2 or 3 and support MPAM's cache portion bitmap controls, with a number of portions fewer than resctrl's limit. Tested-by: Gavin Shan Tested-by: Shaopeng Tan Tested-by: Peter Newman Reviewed-by: Jonathan Cameron Signed-off-by: James Morse Signed-off-by: Ben Horgan --- Changes since rfc: Jonathan: Remove brackets Compress debug message Use temp var, r Changes since v2: Return -EINVAL in mpam_resctrl_control_init() for unknown rid --- drivers/resctrl/mpam_resctrl.c | 90 +++++++++++++++++++++++++++++++++- 1 file changed, 88 insertions(+), 2 deletions(-) diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c index 90cdb5fdd3d6..a59d1659fe12 100644 --- a/drivers/resctrl/mpam_resctrl.c +++ b/drivers/resctrl/mpam_resctrl.c @@ -65,9 +65,94 @@ struct rdt_resource *resctrl_arch_get_resource(enum resc= trl_res_level l) return &mpam_resctrl_controls[l].resctrl_res; } =20 +static bool cache_has_usable_cpor(struct mpam_class *class) +{ + struct mpam_props *cprops =3D &class->props; + + if (!mpam_has_feature(mpam_feat_cpor_part, cprops)) + return false; + + /* resctrl uses u32 for all bitmap configurations */ + return class->props.cpbm_wd <=3D 32; +} + +/* Test whether we can export MPAM_CLASS_CACHE:{2,3}? */ +static void mpam_resctrl_pick_caches(void) +{ + struct mpam_class *class; + struct mpam_resctrl_res *res; + + lockdep_assert_cpus_held(); + + guard(srcu)(&mpam_srcu); + list_for_each_entry_srcu(class, &mpam_classes, classes_list, + srcu_read_lock_held(&mpam_srcu)) { + if (class->type !=3D MPAM_CLASS_CACHE) { + pr_debug("class %u is not a cache\n", class->level); + continue; + } + + if (class->level !=3D 2 && class->level !=3D 3) { + pr_debug("class %u is not L2 or L3\n", class->level); + continue; + } + + if (!cache_has_usable_cpor(class)) { + pr_debug("class %u cache misses CPOR\n", class->level); + continue; + } + + if (!cpumask_equal(&class->affinity, cpu_possible_mask)) { + pr_debug("class %u has missing CPUs, mask %*pb !=3D %*pb\n", class->lev= el, + cpumask_pr_args(&class->affinity), + cpumask_pr_args(cpu_possible_mask)); + continue; + } + + if (class->level =3D=3D 2) + res =3D &mpam_resctrl_controls[RDT_RESOURCE_L2]; + else + res =3D &mpam_resctrl_controls[RDT_RESOURCE_L3]; + res->class =3D class; + exposed_alloc_capable =3D true; + } +} + static int mpam_resctrl_control_init(struct mpam_resctrl_res *res) { - /* TODO: initialise the resctrl resources */ + struct mpam_class *class =3D res->class; + struct rdt_resource *r =3D &res->resctrl_res; + + switch (r->rid) { + case RDT_RESOURCE_L2: + case RDT_RESOURCE_L3: + r->alloc_capable =3D true; + r->schema_fmt =3D RESCTRL_SCHEMA_BITMAP; + r->cache.arch_has_sparse_bitmasks =3D true; + + r->cache.cbm_len =3D class->props.cpbm_wd; + /* mpam_devices will reject empty bitmaps */ + r->cache.min_cbm_bits =3D 1; + + if (r->rid =3D=3D RDT_RESOURCE_L2) { + r->name =3D "L2"; + r->ctrl_scope =3D RESCTRL_L2_CACHE; + } else { + r->name =3D "L3"; + r->ctrl_scope =3D RESCTRL_L3_CACHE; + } + + /* + * Which bits are shared with other ...things... + * Unknown devices use partid-0 which uses all the bitmap + * fields. Until we configured the SMMU and GIC not to do this + * 'all the bits' is the correct answer here. + */ + r->cache.shareable_bits =3D resctrl_get_default_ctrl(r); + break; + default: + return -EINVAL; + } =20 return 0; } @@ -324,7 +409,8 @@ int mpam_resctrl_setup(void) res->resctrl_res.rid =3D rid; } =20 - /* TODO: pick MPAM classes to map to resctrl resources */ + /* Find some classes to use for controls */ + mpam_resctrl_pick_caches(); =20 /* Initialise the resctrl structures from the classes */ for_each_mpam_resctrl_control(res, rid) { --=20 2.43.0