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 1B28BC43458 for ; Thu, 9 Jul 2026 08:42:29 +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=ckK2RwEssTySA3oHIaQkKqHQVEUyMNHj+aPdXRefLNo=; b=ZbWHhRadDFBOps4YC09e2bCjnA d7FQrYAK484IuMhYVrUqRQ6V3vW1R6aWsI1KcmCugfBnGVAYBm57ZRKAp11m94VcrLID3yXE+OjU/ 83EbW6Fi86u+116CF5mrsz/j4G2NdTJ8g8GbjCC3R7pAmio/5zpJCbLzcDbpX1kw82Dqh3vQwXs3p /vf9+nBCLqWHZTnaBtHYTjTNXQQS9H0dPA5k8bV+P4u6wxKBXfimPNLphcjFDLL5Dsv4UoxLjYfjH kTMVD6bMYizgkwFv/a/wv52CSG9maDFo7vgCDFNKEZoj5+neZK7iM9gLNQTrI9Sl/sryyR4GR5PVa GtjprgkA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1whkKs-00000001TDn-2LNf; Thu, 09 Jul 2026 08:42:22 +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 1whkKp-00000001T7z-0xl3 for linux-arm-kernel@lists.infradead.org; Thu, 09 Jul 2026 08:42:21 +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 BF2423569; Thu, 9 Jul 2026 01:42:10 -0700 (PDT) Received: from [10.2.212.8] (e134344.arm.com [10.2.212.8]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 70BCE3F7B4; Thu, 9 Jul 2026 01:42:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1783586535; bh=zjBAqrENqI9UKJncydX8E7PPCy7T9YRwl+p8i+rrRGE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=lDYx2BNSQhrqnFBtotVihF8a6KkjV8XFA9g50zpOYqFBge/0wS8+VXnZ9UQifg1BU KxPo6RSJELf9baYOB5YAhmzcCxEKRsX4d+przm1pRCURJfAvjSTUfVV7NmBdPBXz65 kA+98SQAD3ZBY0Iy46odNBK13598yzEOTberXIAY= Message-ID: Date: Thu, 9 Jul 2026 09:42:10 +0100 MIME-Version: 1.0 User-Agent: Thunderbird Daily Subject: Re: [PATCH v2 04/15] arm_mpam: propagate MSC read errors for mpam_msc_read_mbwu_l() To: Andre Przywara , 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> <20260702162229.4008659-5-andre.przywara@arm.com> <717a2f77-7caa-4cf5-acd5-c2f86686e34e@arm.com> Content-Language: en-US From: Ben Horgan In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260709_014219_428495_219CD3C5 X-CRM114-Status: GOOD ( 16.66 ) 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 Andre, On 7/9/26 08:36, Andre Przywara wrote: > Hi Ben, > > On 7/1/26 22:06, Ben Horgan wrote: >> Hi Andre, >> >> On 7/2/26 17:22, Andre Przywara wrote: >>> Allow the mpam_msc_read_mbwu_l() function to return an error, and >>> propagate read errors from the lower level up. >>> >>> Signed-off-by: Andre Przywara >>> --- >>>   drivers/resctrl/mpam_devices.c | 13 ++++++++++--- >>>   1 file changed, 10 insertions(+), 3 deletions(-) >>> >>> diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/ >>> mpam_devices.c >>> index 011d1e3544d7..1d06902fb970 100644 >>> --- a/drivers/resctrl/mpam_devices.c >>> +++ b/drivers/resctrl/mpam_devices.c >>> @@ -1106,6 +1106,7 @@ static bool >>> mpam_ris_has_mbwu_long_counter(struct mpam_msc_ris *ris) >>>     static u64 mpam_msc_read_mbwu_l(struct mpam_msc *msc) >> >> Now that your changing the other helpers to return an error and pass a >> pointer to hold the register value it would seem more consistent for >> this call to follow the same pattern. > > Ah, I wasn't entirely sure whether this MSMON___L_NRDY is just some > error flag (abuse), since NRDY is some kind of architecture feature. Yeah, as only 32 bit reads are supported it's abused to report the case where we can't get a stable reading of the upper bits. Architecturally, NRDY is (optionally) used to say we haven't yet got a stable value after a configuration. Thanks, Ben > If that's indeed here the case, I will be changing the prototype and > adjust the function. > > Cheers, > Andre > >> Thanks, >> >> Ben >> >>>   { >>> +    int ret; >>>       int retry = 3; >>>       u32 mbwu_l_low; >>>       u32 mbwu_l_high1, mbwu_l_high2; >>> @@ -1115,11 +1116,17 @@ static u64 mpam_msc_read_mbwu_l(struct >>> mpam_msc *msc) >>>       WARN_ON_ONCE((MSMON_MBWU_L + sizeof(u64)) > msc- >>> >mapped_hwpage_sz); >>>       WARN_ON_ONCE(!cpumask_test_cpu(smp_processor_id(), &msc- >>> >accessibility)); >>>   -    __mpam_read_reg(msc, MSMON_MBWU_L + 4, &mbwu_l_high2); >>> +    ret = __mpam_read_reg(msc, MSMON_MBWU_L + 4, &mbwu_l_high2); >>> +    if (ret) >>> +        return MSMON___L_NRDY; >>> + >>>       do { >>>           mbwu_l_high1 = mbwu_l_high2; >>> -        __mpam_read_reg(msc, MSMON_MBWU_L, &mbwu_l_low); >>> -        __mpam_read_reg(msc, MSMON_MBWU_L + 4, &mbwu_l_high2); >>> +        ret = __mpam_read_reg(msc, MSMON_MBWU_L, &mbwu_l_low); >>> +        if (!ret) >>> +            ret = __mpam_read_reg(msc, MSMON_MBWU_L + 4, >>> &mbwu_l_high2); >>> +        if (ret) >>> +            return MSMON___L_NRDY; >>>             retry--; >>>       } while (mbwu_l_high1 != mbwu_l_high2 && retry > 0); >> >