From nobody Mon Dec 15 18:56:42 2025 Received: from canpmsgout05.his.huawei.com (canpmsgout05.his.huawei.com [113.46.200.220]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 97171253B71; Wed, 29 Oct 2025 07:57:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=113.46.200.220 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761724637; cv=none; b=WSkTH1tMeKBhWX2+3SgeP/sSO8yhAM+DUjch2tVCF9nUwCKOThP0vbPgj4+D0kxnlBOTQi3YBLuctM7Vuqi7L3ZFF3q56XTb/25iK5XyK+zp5WMyCXFsrD4CUBAWOwIXmcsRL0MHK4c6MFx9o6Mw5PqQNmwe8pV1iteSn7PjPrM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761724637; c=relaxed/simple; bh=BnieqDTxwZRLojF8KFRHEnkoQdu0ao8unONoocRfQnM=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=r1Maaia0lkcSw3FEL7ITMvQWiRkMvNDSR/+unvzNSxVPWb3Vz95JNrx1zDBcdfS9zQKGUGyImrOa1BXLX4aa6/pNcxMP11AgXkwRPp2M/CnuT1lFlR5lQTRQgi0YGQAzHXFu62pgmMjtvFkiqGOSrgxnXZKsxYoqW/pJeXNARqU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=h-partners.com; dkim=pass (1024-bit key) header.d=h-partners.com header.i=@h-partners.com header.b=G8u1pPmy; arc=none smtp.client-ip=113.46.200.220 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=h-partners.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=h-partners.com header.i=@h-partners.com header.b="G8u1pPmy" dkim-signature: v=1; a=rsa-sha256; d=h-partners.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=z1vyOpOhp4uD5m84f0sJub6GwUG0B1xwG+9pVCSYuwI=; b=G8u1pPmy1fO2CL371jWqpD3qax41pRC3q692WFthDSvTFEGBGEfdqp93EKbEsFHDco9m7lPEg VIRGQq9RsxpaYg0AhQc1dDuThF4fs/P4Kf98IMGnBf/vGWAgeyDWLMj/U1PJsKTTaHgGIZSaA18 4ZiLQs9zEfQLbAb/Y6ubeHs= Received: from mail.maildlp.com (unknown [172.19.162.254]) by canpmsgout05.his.huawei.com (SkyGuard) with ESMTPS id 4cxKM55ZVvz12LFQ; Wed, 29 Oct 2025 15:56:33 +0800 (CST) Received: from kwepemf100008.china.huawei.com (unknown [7.202.181.222]) by mail.maildlp.com (Postfix) with ESMTPS id 073C7180491; Wed, 29 Oct 2025 15:57:11 +0800 (CST) Received: from huawei.com (10.50.87.109) by kwepemf100008.china.huawei.com (7.202.181.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Wed, 29 Oct 2025 15:57:09 +0800 From: Zeng Heng To: , CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: [PATCH v2] arm64/mpam: Clean MBWU monitor overflow bit Date: Wed, 29 Oct 2025 15:56:55 +0800 Message-ID: <20251029075655.3284280-1-zengheng4@huawei.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20251017185645.26604-25-james.morse@arm.com> References: <20251017185645.26604-25-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 X-ClientProxiedBy: kwepems500002.china.huawei.com (7.221.188.17) To kwepemf100008.china.huawei.com (7.202.181.222) Content-Type: text/plain; charset="utf-8" The MSMON_MBWU register accumulates counts monotonically forward and would not automatically cleared to zero on overflow. The overflow portion is exactly what mpam_msmon_overflow_val() computes, there is no need to additionally subtract mbwu_state->prev_val. Before invoking write_msmon_ctl_flt_vals(), the overflow bit of the MSMON_MBWU register must first be read to prevent it from being inadvertently cleared by the write operation. Finally, use the overflow bit instead of relying on counter wrap-around to determine whether an overflow has occurred, that avoids the case where a wrap-around (now > prev_val) is overlooked. So with this, prev_val no longer has any use and remove it. CC: Ben Horgan Signed-off-by: Zeng Heng --- drivers/resctrl/mpam_devices.c | 22 +++++++++++++++++----- drivers/resctrl/mpam_internal.h | 3 --- 2 files changed, 17 insertions(+), 8 deletions(-) diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c index 0dd048279e02..db4cec710091 100644 --- a/drivers/resctrl/mpam_devices.c +++ b/drivers/resctrl/mpam_devices.c @@ -1039,7 +1039,6 @@ static void write_msmon_ctl_flt_vals(struct mon_read = *m, u32 ctl_val, mpam_write_monsel_reg(msc, CFG_MBWU_CTL, ctl_val | MSMON_CFG_x_CTL_EN); mbwu_state =3D &m->ris->mbwu_state[m->ctx->mon]; - mbwu_state->prev_val =3D 0; break; default: @@ -1062,6 +1061,16 @@ static u64 mpam_msmon_overflow_val(enum mpam_device_= features type) } } +static bool read_msmon_mbwu_is_overflow(struct mpam_msc *msc) +{ + u32 ctl; + + ctl =3D mpam_read_monsel_reg(msc, CFG_MBWU_CTL); + return ctl & (MSMON_CFG_x_CTL_OFLOW_STATUS | + MSMON_CFG_MBWU_CTL_OFLOW_STATUS_L) ? + true : false; +} + /* Call with MSC lock held */ static void __ris_msmon_read(void *arg) { @@ -1069,6 +1078,7 @@ static void __ris_msmon_read(void *arg) bool config_mismatch; struct mon_read *m =3D arg; u64 now, overflow_val =3D 0; + bool mbwu_overflow =3D false; struct mon_cfg *ctx =3D m->ctx; bool reset_on_next_read =3D false; struct mpam_msc_ris *ris =3D m->ris; @@ -1091,6 +1101,7 @@ static void __ris_msmon_read(void *arg) reset_on_next_read =3D mbwu_state->reset_on_next_read; mbwu_state->reset_on_next_read =3D false; } + mbwu_overflow =3D read_msmon_mbwu_is_overflow(msc); } /* @@ -1103,8 +1114,10 @@ static void __ris_msmon_read(void *arg) 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) + if (config_mismatch || reset_on_next_read) { write_msmon_ctl_flt_vals(m, ctl_val, flt_val); + mbwu_overflow =3D false; + } switch (m->type) { case mpam_feat_msmon_csu: @@ -1138,10 +1151,9 @@ static void __ris_msmon_read(void *arg) mbwu_state =3D &ris->mbwu_state[ctx->mon]; /* Add any pre-overflow value to the mbwu_state->val */ - if (mbwu_state->prev_val > now) - overflow_val =3D mpam_msmon_overflow_val(m->type) - mbwu_state->prev_va= l; + if (mbwu_overflow) + overflow_val =3D mpam_msmon_overflow_val(m->type); - mbwu_state->prev_val =3D now; mbwu_state->correction +=3D overflow_val; /* Include bandwidth consumed before the last hardware reset */ diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_interna= l.h index 4f25681b56ab..8837c0cd7b0c 100644 --- a/drivers/resctrl/mpam_internal.h +++ b/drivers/resctrl/mpam_internal.h @@ -226,9 +226,6 @@ struct msmon_mbwu_state { bool reset_on_next_read; struct mon_cfg cfg; - /* The value last read from the hardware. Used to detect overflow. */ - u64 prev_val; - /* * The value to add to the new reading to account for power management, * and shifts to trigger the overflow interrupt. -- 2.25.1