From nobody Tue Dec 2 02:32:16 2025 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 061203587D5; Wed, 19 Nov 2025 12:26:03 +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=1763555164; cv=none; b=uKFP85e6pOk6js/uNSBaq9POOs1JqaJf3ggXtb3KmP7khNSuRLFp1ZBXpV5mx3a1yP0SfT3tNNTrN6UDyWhTD98wsFIYkzh7r4bFRr/5Hq0rbAAcQ9FViMzNY/Rv6ER3huD9IypRpcJE8fnKP1NWtTH2L+A78OSpQKcMQqjyFQ0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763555164; c=relaxed/simple; bh=cINLaMy+HXxzVe5B4bXSCNhwOhsF9gTh10VEYWjwkYk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=YiJ2gjHOMkYgoUJfBjeZptUPPh37S3gxYQSUGI1uXZcyL9a0Z3bmIMMwQfM4kE+z2RIeNtcgpUYE/ubkL+4cadSXx79m0xs+R49LnEe7HGzyQ7wbibSMeDbTnnLPXINHzqT0/nj3Z1vszbtGDUf0qWyvz6GYSsNzYfpuciNBCn0= 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 0799E1BCA; Wed, 19 Nov 2025 04:25:55 -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 66EEA3F740; Wed, 19 Nov 2025 04:25:57 -0800 (PST) From: Ben Horgan To: james.morse@arm.com Cc: amitsinght@marvell.com, baisheng.gao@unisoc.com, baolin.wang@linux.alibaba.com, bobo.shaobowang@huawei.com, carl@os.amperecomputing.com, catalin.marinas@arm.com, dakr@kernel.org, dave.martin@arm.com, david@redhat.com, dfustini@baylibre.com, fenghuay@nvidia.com, gregkh@linuxfoundation.org, gshan@redhat.com, guohanjun@huawei.com, jeremy.linton@arm.com, jonathan.cameron@huawei.com, kobak@nvidia.com, lcherian@marvell.com, lenb@kernel.org, linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, lpieralisi@kernel.org, peternewman@google.com, quic_jiles@quicinc.com, rafael@kernel.org, robh@kernel.org, rohit.mathew@arm.com, scott@os.amperecomputing.com, sdonthineni@nvidia.com, sudeep.holla@arm.com, tan.shaopeng@fujitsu.com, will@kernel.org, xhao@linux.alibaba.com, reinette.chatre@intel.com, Ben Horgan , Zeng Heng , Shaopeng Tan Subject: [PATCH v6 28/34] arm_mpam: Consider overflow in bandwidth counter state Date: Wed, 19 Nov 2025 12:22:58 +0000 Message-ID: <20251119122305.302149-29-ben.horgan@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251119122305.302149-1-ben.horgan@arm.com> References: <20251119122305.302149-1-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" Use the overflow status bit to track overflow on each bandwidth counter read and add the counter size to the correction when overflow is detected. This assumes that only a single overflow has occurred since the last read of the counter. Overflow interrupts, on hardware that supports them could be used to remove this limitation. Cc: Zeng Heng Reviewed-by: Gavin Shan Reviewed-by: Zeng Heng Reviewed-by: Jonathan Cameron Reviewed-by: Shaopeng Tan Reviewed-by: Fenghua Yu Tested-by: Carl Worth Tested-by: Gavin Shan Tested-by: Zeng Heng Tested-by: Shaopeng Tan Tested-by: Hanjun Guo Signed-off-by: Ben Horgan --- drivers/resctrl/mpam_devices.c | 24 ++++++++++++++++++++++-- drivers/resctrl/mpam_internal.h | 3 ++- 2 files changed, 24 insertions(+), 3 deletions(-) diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c index c8ea37558f69..ecb5ecad50f8 100644 --- a/drivers/resctrl/mpam_devices.c +++ b/drivers/resctrl/mpam_devices.c @@ -985,11 +985,18 @@ static void write_msmon_ctl_flt_vals(struct mon_read = *m, u32 ctl_val, } } =20 +static u64 mpam_msmon_overflow_val(enum mpam_device_features type) +{ + /* TODO: scaling, and long counters */ + return BIT_ULL(hweight_long(MSMON___VALUE)); +} + static void __ris_msmon_read(void *arg) { u64 now; bool nrdy =3D false; bool config_mismatch; + bool overflow; struct mon_read *m =3D arg; struct mon_cfg *ctx =3D m->ctx; struct mpam_msc_ris *ris =3D m->ris; @@ -1011,13 +1018,20 @@ static void __ris_msmon_read(void *arg) * This saves waiting for 'nrdy' on subsequent reads. */ read_msmon_ctl_flt_vals(m, &cur_ctl, &cur_flt); + overflow =3D cur_ctl & MSMON_CFG_x_CTL_OFLOW_STATUS; + clean_msmon_ctl_val(&cur_ctl); gen_msmon_ctl_flt_vals(m, &ctl_val, &flt_val); config_mismatch =3D cur_flt !=3D flt_val || cur_ctl !=3D (ctl_val | MSMON_CFG_x_CTL_EN); =20 - if (config_mismatch) + if (config_mismatch) { write_msmon_ctl_flt_vals(m, ctl_val, flt_val); + overflow =3D false; + } else if (overflow) { + mpam_write_monsel_reg(msc, CFG_MBWU_CTL, + cur_ctl & ~MSMON_CFG_x_CTL_OFLOW_STATUS); + } =20 switch (m->type) { case mpam_feat_msmon_csu: @@ -1037,7 +1051,13 @@ static void __ris_msmon_read(void *arg) =20 mbwu_state =3D &ris->mbwu_state[ctx->mon]; =20 - /* Include bandwidth consumed before the last hardware reset */ + if (overflow) + mbwu_state->correction +=3D mpam_msmon_overflow_val(m->type); + + /* + * Include bandwidth consumed before the last hardware reset and + * a counter size increment for each overflow. + */ now +=3D mbwu_state->correction; break; default: diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_interna= l.h index 12ce80bc7ff7..218e2f48c7bf 100644 --- a/drivers/resctrl/mpam_internal.h +++ b/drivers/resctrl/mpam_internal.h @@ -211,7 +211,8 @@ struct msmon_mbwu_state { struct mon_cfg cfg; =20 /* - * The value to add to the new reading to account for power management. + * The value to add to the new reading to account for power management, + * and overflow. */ u64 correction; =20 --=20 2.43.0