From nobody Sun Feb 8 17:43:07 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 571AF33B976; Fri, 17 Oct 2025 18:59:31 +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=1760727572; cv=none; b=N0+M5TH7pbte2r3iiYt5d08KN5efPalzPSFCKMEZqE1KkxR8VFYxULeA2T0Lc/ZJ8mWdCvwDIqDN7WwdiepGHYxygfiDX795GxxwgRwrH4rpmWMXlt0T2LJgcKJap5vfUSbIAogkbwfpq8qc+VL2LeItRrCHI+Gwj+GKPnEeJBs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760727572; c=relaxed/simple; bh=Dpt6i/tnWpfQ6LIvDiDIXTCIS2tD9fqDKWNVjDUPWlc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=YJt4LBPMRL9y76FBwrwvFeTl8p3rlDbEmoPbl/Dz/mePVC6b2gpqwEJ2WeOKuNWCfP+G9pqEPbFB2SqkOFPcYYnwCf+VXgTTsdNlJQKa2fIDWZDWkzp7YwZ93N7GYf3zgv8jHF1qZT3Sbqm1AFyhSmLA/Vx7z+zpVkUXcpdHdMc= 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 B690E1C2B; Fri, 17 Oct 2025 11:59:22 -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 8D2AC3F66E; Fri, 17 Oct 2025 11:59:25 -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 , Jeremy Linton , Gavin Shan , Fenghua Yu Subject: [PATCH v3 27/29] arm_mpam: Add helper to reset saved mbwu state Date: Fri, 17 Oct 2025 18:56:43 +0000 Message-Id: <20251017185645.26604-28-james.morse@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20251017185645.26604-1-james.morse@arm.com> References: <20251017185645.26604-1-james.morse@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" resctrl expects to reset the bandwidth counters when the filesystem is mounted. To allow this, add a helper that clears the saved mbwu state. Instead of cross calling to each CPU that can access the component MSC to write to the counter, set a flag that causes it to be zero'd on the the next read. This is easily done by forcing a configuration update. Signed-off-by: James Morse Reviewed-by: Fenghua Yu Tested-by: Fenghua Yu Reviewed-by: Jonathan Cameron --- Changes since v2: * Switched to guard and fixed non _srcu list walker. * Made a comment about what is proteted by which lock a list. --- drivers/resctrl/mpam_devices.c | 46 ++++++++++++++++++++++++++++++++- drivers/resctrl/mpam_internal.h | 7 ++++- 2 files changed, 51 insertions(+), 2 deletions(-) diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c index c207a6d2832c..89d4f42168ed 100644 --- a/drivers/resctrl/mpam_devices.c +++ b/drivers/resctrl/mpam_devices.c @@ -1066,9 +1066,11 @@ static u64 mpam_msmon_overflow_val(enum mpam_device_= features type) static void __ris_msmon_read(void *arg) { bool nrdy =3D false; + bool config_mismatch; struct mon_read *m =3D arg; u64 now, overflow_val =3D 0; struct mon_cfg *ctx =3D m->ctx; + bool reset_on_next_read =3D false; struct mpam_msc_ris *ris =3D m->ris; struct msmon_mbwu_state *mbwu_state; struct mpam_props *rprops =3D &ris->props; @@ -1083,6 +1085,14 @@ static void __ris_msmon_read(void *arg) FIELD_PREP(MSMON_CFG_MON_SEL_RIS, ris->ris_idx); mpam_write_monsel_reg(msc, CFG_MON_SEL, mon_sel); =20 + if (m->type =3D=3D mpam_feat_msmon_mbwu) { + mbwu_state =3D &ris->mbwu_state[ctx->mon]; + if (mbwu_state) { + reset_on_next_read =3D mbwu_state->reset_on_next_read; + mbwu_state->reset_on_next_read =3D false; + } + } + /* * Read the existing configuration to avoid re-writing the same values. * This saves waiting for 'nrdy' on subsequent reads. @@ -1090,7 +1100,10 @@ static void __ris_msmon_read(void *arg) read_msmon_ctl_flt_vals(m, &cur_ctl, &cur_flt); clean_msmon_ctl_val(&cur_ctl); gen_msmon_ctl_flt_vals(m, &ctl_val, &flt_val); - if (cur_flt !=3D flt_val || cur_ctl !=3D (ctl_val | MSMON_CFG_x_CTL_EN)) + config_mismatch =3D cur_flt !=3D flt_val || + cur_ctl !=3D (ctl_val | MSMON_CFG_x_CTL_EN); + + if (config_mismatch || reset_on_next_read) write_msmon_ctl_flt_vals(m, ctl_val, flt_val); =20 switch (m->type) { @@ -1242,6 +1255,37 @@ int mpam_msmon_read(struct mpam_component *comp, str= uct mon_cfg *ctx, return err; } =20 +void mpam_msmon_reset_mbwu(struct mpam_component *comp, struct mon_cfg *ct= x) +{ + struct mpam_msc *msc; + struct mpam_vmsc *vmsc; + struct mpam_msc_ris *ris; + + if (!mpam_is_enabled()) + return; + + guard(srcu)(&mpam_srcu); + list_for_each_entry_srcu(vmsc, &comp->vmsc, comp_list, + srcu_read_lock_held(&mpam_srcu)) { + if (!mpam_has_feature(mpam_feat_msmon_mbwu, &vmsc->props)) + continue; + + msc =3D vmsc->msc; + list_for_each_entry_srcu(ris, &vmsc->ris, vmsc_list, + srcu_read_lock_held(&mpam_srcu)) { + if (!mpam_has_feature(mpam_feat_msmon_mbwu, &ris->props)) + continue; + + if (WARN_ON_ONCE(!mpam_mon_sel_lock(msc))) + continue; + + ris->mbwu_state[ctx->mon].correction =3D 0; + ris->mbwu_state[ctx->mon].reset_on_next_read =3D true; + mpam_mon_sel_unlock(msc); + } + } +} + static void mpam_reset_msc_bitmap(struct mpam_msc *msc, u16 reg, u16 wd) { u32 num_words, msb; diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_interna= l.h index ff38b4bbfc2b..6632699ae814 100644 --- a/drivers/resctrl/mpam_internal.h +++ b/drivers/resctrl/mpam_internal.h @@ -204,10 +204,14 @@ struct mon_cfg { =20 /* * Changes to enabled and cfg are protected by the msc->lock. - * Changes to prev_val and correction are protected by the msc's mon_sel_l= ock. + * The msc's mon_sel_lock protects: + * - reset_on_next_read + * - prev_val + * - correction */ struct msmon_mbwu_state { bool enabled; + bool reset_on_next_read; struct mon_cfg cfg; =20 /* The value last read from the hardware. Used to detect overflow. */ @@ -369,6 +373,7 @@ int mpam_apply_config(struct mpam_component *comp, u16 = partid, =20 int mpam_msmon_read(struct mpam_component *comp, struct mon_cfg *ctx, enum mpam_device_features, u64 *val); +void mpam_msmon_reset_mbwu(struct mpam_component *comp, struct mon_cfg *ct= x); =20 int mpam_get_cpumask_from_cache_id(unsigned long cache_id, u32 cache_level, cpumask_t *affinity); --=20 2.39.5