From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 683FCC44501 for ; Thu, 9 Jul 2026 07:35:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=j8+zcmKjsYTD7t/6LKmYib1wjgZiKLxo4tUgtQMTmbE=; b=kx8MV86JXvu2Wk3mKXFkmZkCPJ NkQ2wQ7NzFpqHuOXiFJ8eBTDF2f1sqCPabHPVMXEn/kps3E9gB1+LZWsNst+7D9JQNTEf+L186J1V OUtr8SPy6LkGNQy5s0hCtpNOXPFyHTe4j8C+SZcnqcKovvXMO6UFM4C1HNDKOmfdlr/0inOdbO3I3 Ghf5NhLRhHGJJLHS1Kd4WSOPGeUnoQmwI4Kvixh/drtg5SkFVbsUCYs0sZx3KprPMABr0X7JWHGVf qDICEi6PceNrdTqsMpU0M811krYThZdK6r9+XxV2WJ0Xrgcx1OfL9FD7P43GaR4bX55azXsw6XEPS X24glQ5g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1whjIQ-00000001JRc-3loF; Thu, 09 Jul 2026 07:35:46 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1whjIP-00000001JRE-1Tyr for linux-arm-kernel@lists.infradead.org; Thu, 09 Jul 2026 07:35:46 +0000 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 8AC7E15A1; Thu, 9 Jul 2026 00:35:39 -0700 (PDT) Received: from [10.41.150.148] (e142021.arm.com [10.41.150.148]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 98A4F3F66F; Thu, 9 Jul 2026 00:35:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1783582543; bh=vbqbyvnuH57S9mignVB1GcRt0BG6A+IPR4PiiZgLl1I=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=eTbrozMbjn/07jRWaVHEaVVGOFY7UnCtcWBon3bSgmbrPNm54rB2AEmKGeNN0CkRO t3d1lamvVNDo4vXf9PJXZ7u67nukR+KVXeUoCHd+cXZeDS6fdjfFq2OjIDc2xYbyWm jBdT5neNOIZYsfXu1k9U35WIDVPXfsDP3EHExMuA= Message-ID: <1e5149fe-ef5f-48f1-9ee8-a7de2d6bc2af@arm.com> Date: Thu, 9 Jul 2026 09:35:37 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 03/15] arm_mpam: propagate MSC read errors for hw_probe functions To: Ben Horgan , Lorenzo Pieralisi , Hanjun Guo , Sudeep Holla , Catalin Marinas , Will Deacon , "Rafael J . Wysocki" , Len Brown , James Morse , Reinette Chatre , Fenghua Yu Cc: Jonathan Cameron , Srivathsa L Rao , Ganapatrao Kulkarni , Trilok Soni , Srinivas Ramana , Niyas Sait , linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20260702162229.4008659-1-andre.przywara@arm.com> <20260702162229.4008659-4-andre.przywara@arm.com> Content-Language: en-GB From: Andre Przywara In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260709_003545_485348_A9E76208 X-CRM114-Status: GOOD ( 21.44 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Ben, thanks for having a thorough look! On 7/1/26 22:00, Ben Horgan wrote: > Hi Andre, > > On 7/2/26 17:22, Andre Przywara wrote: >> Allow the functions probing for MSC hardware and features to return an >> error, and propagate read errors from the lower level up. >> >> Signed-off-by: Andre Przywara >> --- >> drivers/resctrl/mpam_devices.c | 62 ++++++++++++++++++++++++---------- >> 1 file changed, 44 insertions(+), 18 deletions(-) >> >> diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c >> index ce8738adb6ff..011d1e3544d7 100644 >> --- a/drivers/resctrl/mpam_devices.c >> +++ b/drivers/resctrl/mpam_devices.c >> @@ -800,20 +800,22 @@ static bool mpam_ris_hw_probe_csu_nrdy(struct mpam_msc_ris *ris) >> mpam_write_monsel_reg(msc, CFG_CSU_CTL, ctl_val); >> >> _mpam_write_monsel_reg(msc, MSMON_CSU, MSMON___NRDY); >> - _mpam_read_monsel_reg(msc, MSMON_CSU, &now); >> + if (_mpam_read_monsel_reg(msc, MSMON_CSU, &now)) >> + return false; > > This early return leaves the mon_sel lock held. Ouch, well spotted. I think this "if (WARN_ON_ONCE(...))" wrapper distracted me from the lock... Changed it to use "goto out_unlock;" > >> can_set = now & MSMON___NRDY; > > As you're adding early returns to this function does it make sense to > return early if can_set is false? Well, this could have been done before as well, but it executes the remaining accesses nevertheless. I don't feel like judging whether this has a side effect, so just mimicked the current behaviour. I feel like this should be a separate patch, if we need it. Thanks, Andre >> >> _mpam_write_monsel_reg(msc, MSMON_CSU, 0); >> /* Configuration change to try and coax hardware into setting nrdy */ >> mpam_write_monsel_reg(msc, CFG_CSU_FLT, 0x1); >> - _mpam_read_monsel_reg(msc, MSMON_CSU, &now); >> + if (_mpam_read_monsel_reg(msc, MSMON_CSU, &now)) >> + return false; >> can_clear = !(now & MSMON___NRDY); >> mpam_mon_sel_unlock(msc); >> >> return (!can_set || !can_clear); >> } >> >> -static void mpam_ris_hw_probe(struct mpam_msc_ris *ris) >> +static int mpam_ris_hw_probe(struct mpam_msc_ris *ris) >> { >> int err; >> struct mpam_msc *msc = ris->vmsc->msc; >> @@ -828,7 +830,9 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris) >> if (FIELD_GET(MPAMF_IDR_HAS_CCAP_PART, ris->idr)) { >> u32 ccap_features; >> >> - mpam_read_partsel_reg(msc, CCAP_IDR, &ccap_features); >> + err = mpam_read_partsel_reg(msc, CCAP_IDR, &ccap_features); >> + if (err) >> + return err; >> >> props->cmax_wd = FIELD_GET(MPAMF_CCAP_IDR_CMAX_WD, ccap_features); >> if (props->cmax_wd && >> @@ -853,7 +857,9 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris) >> if (FIELD_GET(MPAMF_IDR_HAS_CPOR_PART, ris->idr)) { >> u32 cpor_features; >> >> - mpam_read_partsel_reg(msc, CPOR_IDR, &cpor_features); >> + err = mpam_read_partsel_reg(msc, CPOR_IDR, &cpor_features); >> + if (err) >> + return err; >> >> props->cpbm_wd = FIELD_GET(MPAMF_CPOR_IDR_CPBM_WD, cpor_features); >> if (props->cpbm_wd) >> @@ -863,8 +869,9 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris) >> /* Memory bandwidth partitioning */ >> if (FIELD_GET(MPAMF_IDR_HAS_MBW_PART, ris->idr)) { >> u32 mbw_features; >> - >> - mpam_read_partsel_reg(msc, MBW_IDR, &mbw_features); >> + err = mpam_read_partsel_reg(msc, MBW_IDR, &mbw_features); >> + if (err) >> + return err; >> >> /* portion bitmap resolution */ >> props->mbw_pbm_bits = FIELD_GET(MPAMF_MBW_IDR_BWPBM_WD, mbw_features); >> @@ -893,8 +900,9 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris) >> /* Priority partitioning */ >> if (FIELD_GET(MPAMF_IDR_HAS_PRI_PART, ris->idr)) { >> u32 pri_features; >> - >> - mpam_read_partsel_reg(msc, PRI_IDR, &pri_features); >> + err = mpam_read_partsel_reg(msc, PRI_IDR, &pri_features); >> + if (err) >> + return err; >> >> props->intpri_wd = FIELD_GET(MPAMF_PRI_IDR_INTPRI_WD, pri_features); >> if (props->intpri_wd && FIELD_GET(MPAMF_PRI_IDR_HAS_INTPRI, pri_features)) { >> @@ -915,7 +923,9 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris) >> if (FIELD_GET(MPAMF_IDR_HAS_MSMON, ris->idr)) { >> u32 msmon_features; >> >> - mpam_read_partsel_reg(msc, MSMON_IDR, &msmon_features); >> + err = mpam_read_partsel_reg(msc, MSMON_IDR, &msmon_features); >> + if (err) >> + return err; >> >> /* >> * If the firmware max-nrdy-us property is missing, the >> @@ -928,7 +938,9 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris) >> if (FIELD_GET(MPAMF_MSMON_IDR_MSMON_CSU, msmon_features)) { >> u32 csumonidr; >> >> - mpam_read_partsel_reg(msc, CSUMON_IDR, &csumonidr); >> + err = mpam_read_partsel_reg(msc, CSUMON_IDR, &csumonidr); >> + if (err) >> + return err; >> >> props->num_csu_mon = FIELD_GET(MPAMF_CSUMON_IDR_NUM_MON, csumonidr); >> if (props->num_csu_mon) { >> @@ -954,7 +966,9 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris) >> bool has_long; >> u32 mbwumon_idr; >> >> - mpam_read_partsel_reg(msc, MBWUMON_IDR, &mbwumon_idr); >> + err = mpam_read_partsel_reg(msc, MBWUMON_IDR, &mbwumon_idr); >> + if (err) >> + return err; >> >> props->num_mbwu_mon = FIELD_GET(MPAMF_MBWUMON_IDR_NUM_MON, mbwumon_idr); >> if (props->num_mbwu_mon) { >> @@ -987,16 +1001,22 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris) >> u16 partid_max; >> u32 nrwidr; >> >> - mpam_read_partsel_reg(msc, PARTID_NRW_IDR, &nrwidr); >> + err = mpam_read_partsel_reg(msc, PARTID_NRW_IDR, &nrwidr); >> + if (err) >> + return err; >> + >> partid_max = FIELD_GET(MPAMF_PARTID_NRW_IDR_INTPARTID_MAX, nrwidr); >> >> mpam_set_feature(mpam_feat_partid_nrw, props); >> msc->partid_max = min(msc->partid_max, partid_max); >> } >> + >> + return 0; >> } >> >> static int mpam_msc_hw_probe(struct mpam_msc *msc) >> { >> + int ret; >> u64 idr; >> u16 partid_max; >> u8 ris_idx, pmg_max; >> @@ -1012,10 +1032,12 @@ static int mpam_msc_hw_probe(struct mpam_msc *msc) >> >> /* Grab an IDR value to find out how many RIS there are */ >> mutex_lock(&msc->part_sel_lock); >> - mpam_msc_read_idr(msc, &idr); >> - mpam_read_partsel_reg(msc, IIDR, &msc->iidr); >> - >> + ret = mpam_msc_read_idr(msc, &idr); >> + if (!ret) >> + ret = mpam_read_partsel_reg(msc, IIDR, &msc->iidr); >> mutex_unlock(&msc->part_sel_lock); >> + if (ret) >> + return ret; >> >> mpam_enable_quirks(msc); >> >> @@ -1028,8 +1050,10 @@ static int mpam_msc_hw_probe(struct mpam_msc *msc) >> for (ris_idx = 0; ris_idx <= msc->ris_max; ris_idx++) { >> mutex_lock(&msc->part_sel_lock); >> __mpam_part_sel(ris_idx, 0, msc); >> - mpam_msc_read_idr(msc, &idr); >> + ret = mpam_msc_read_idr(msc, &idr); >> mutex_unlock(&msc->part_sel_lock); >> + if (ret) >> + return ret; >> >> partid_max = FIELD_GET(MPAMF_IDR_PARTID_MAX, idr); >> pmg_max = FIELD_GET(MPAMF_IDR_PMG_MAX, idr); >> @@ -1046,8 +1070,10 @@ static int mpam_msc_hw_probe(struct mpam_msc *msc) >> >> mutex_lock(&msc->part_sel_lock); >> __mpam_part_sel(ris_idx, 0, msc); >> - mpam_ris_hw_probe(ris); >> + ret = mpam_ris_hw_probe(ris); >> mutex_unlock(&msc->part_sel_lock); >> + if (ret) >> + return ret; >> } >> >> /* Clear any stale errors */ >