From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id EAFC73DA7CA; Fri, 24 Jul 2026 11:19:22 +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=1784891966; cv=none; b=LMSAP2W0ioNTNOLuPDS9Zks61qv1yib2W/mJPQq4zycDVe1MnXT3bY2g2cYLSz2DZ9igVL0gXeC0ZQfc+DSbpbmcx+QFMXOtVR8+uRQQDA8lNSRhljNFIYWamEjmm4ZlFV19dEgI8Bu0fS23d/HgQQTAD9026ZsFetskMHPd/Kg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784891966; c=relaxed/simple; bh=6DmPCA8NJHL/ZnEaVWd3asm4aMXes0MHBhltqBYPzUM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=SzPmsMGuW7gx/zGQ9/U/aDYK4W2NvlKQUrfiZzZGD45Zl0jAepWn8ZNPz615PE5xI7wdDYQnb48nBZS2Cjs9/h3GguNKV0qXnBSdTDs8nUty3RqTgUAFUBjbEX687NJu1rFnxRFj6aRJdlMb57REMYeXNOMYZwpOSW5gQ9BKF8o= 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; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=rt8qOQDU; 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 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="rt8qOQDU" 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 04AF31477; Fri, 24 Jul 2026 04:19:17 -0700 (PDT) Received: from [192.168.178.24] (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DD6543F59E; Fri, 24 Jul 2026 04:19:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1784891961; bh=6DmPCA8NJHL/ZnEaVWd3asm4aMXes0MHBhltqBYPzUM=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=rt8qOQDUCbtSI1jimM0mrdL+fE4d2WYXQ0SO9UgDHn+T4tx7DW6bqmzbBBifj/dxV 4RxZlqG4EdGj9kRiYhgQUeu+0CAH0+se3xveU5a34dmf0LOZBG/mRD9qu9shMX0sRb mPsuEhchgGPJesQC0IwJ7alze55pAHkDENU8Ce4c= Message-ID: Date: Fri, 24 Jul 2026 13:19:14 +0200 Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 06/10] arm_mpam: propagate MSC access errors for state saving function To: Sudeep Holla Cc: Lorenzo Pieralisi , Hanjun Guo , Catalin Marinas , Will Deacon , "Rafael J . Wysocki" , Len Brown , James Morse , Ben Horgan , Reinette Chatre , Fenghua Yu , Jonathan Cameron , Srivathsa L Rao , Ganapatrao Kulkarni , Trilok Soni , Srinivas Ramana , Niyas Sait , Lee Trager , linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20260723155454.1760823-1-andre.przywara@arm.com> <20260723155454.1760823-7-andre.przywara@arm.com> <20260724-important-curassow-of-support-ce4777@sudeepholla> Content-Language: en-GB From: Andre Przywara In-Reply-To: <20260724-important-curassow-of-support-ce4777@sudeepholla> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi, On 7/24/26 12:07, Sudeep Holla wrote: > On Thu, Jul 23, 2026 at 05:54:50PM +0200, Andre Przywara wrote: >> Allow the mpam_save_mbwu_state() function to return an error, and >> propagate read and write errors from the lower level up. >> >> Signed-off-by: Andre Przywara >> --- >> drivers/resctrl/mpam_devices.c | 29 ++++++++++++++++++++++------- >> 1 file changed, 22 insertions(+), 7 deletions(-) >> >> diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c >> index bcff53477133..6329443c451f 100644 >> --- a/drivers/resctrl/mpam_devices.c >> +++ b/drivers/resctrl/mpam_devices.c >> @@ -1833,22 +1833,37 @@ static int mpam_save_mbwu_state(void *arg) >> >> mon_sel = FIELD_PREP(MSMON_CFG_MON_SEL_MON_SEL, i) | >> FIELD_PREP(MSMON_CFG_MON_SEL_RIS, ris->ris_idx); >> - mpam_write_monsel_reg(msc, CFG_MON_SEL, mon_sel); >> - mpam_read_monsel_reg(msc, CFG_MBWU_FLT, &cur_flt); >> - mpam_read_monsel_reg(msc, CFG_MBWU_CTL, &cur_ctl); >> - mpam_write_monsel_reg(msc, CFG_MBWU_CTL, 0); >> + ret = mpam_write_monsel_reg(msc, CFG_MON_SEL, mon_sel); >> + if (ret) >> + return ret; >> + ret = mpam_read_monsel_reg(msc, CFG_MBWU_FLT, &cur_flt); >> + if (ret) >> + return ret; >> + ret = mpam_read_monsel_reg(msc, CFG_MBWU_CTL, &cur_ctl); >> + if (ret) >> + return ret; > > How does it work in general with PCC. Now that you can fail at any point, > what happens to the write that occurs before a failed read like above one. > Who will take care of erasing those new writes or it doesn't matter ? > Just checking as I don't have much knowledge on MPAM intrinsics. TBH I don't know, but I think we consider MPAM botched at this point, and just stop the driver, similar to an error IRQ? But I am not sure this is properly implemented at this point. The focus of these first six patches was merely to lay the dirty groundwork for *being able* to handle errors, and do this now rather than in the future. Cheers, Andre