From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) (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 A72DF290083; Tue, 22 Apr 2025 15:52:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.176.79.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745337124; cv=none; b=kVQkEvi7vOxCXWzImqKdDWGUacpQE2q5W9SpgakQc7tQXfrj35u4toQafTrOUyxkIZ5Y1xYe5TnaXn3w+/E/TNjkCZGWFkH+rwrPDrTrvoRnugUYAc1KtuAxThs4OZqwqwxuPoi/kq2CCqHtlffVJSr6dyMFOIkP/80hSq8mrNc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745337124; c=relaxed/simple; bh=AH+Q8UtE92o5RJ5wRhCdSovwJClD9/7ON4gllAZdkcc=; h=Date:From:To:CC:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=tdjgwkRGxKaDi7T+R3JHDain/AwcmsHem0huq5tTl8K9J5+L0ij4Ye4oqVEtRKxYa2tl0AjTwm3XChzdEZ1DY4GxcfRzc5TzKDHOZs3hBNOu34dyqibpmAm3N4V3ooQC9h9WVMdFCw1QkJvDihOY5lyjnHcHcTf8v+nhK/4q3fE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=185.176.79.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.18.186.31]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4ZhmsQ2dpLz6L5Gs; Tue, 22 Apr 2025 23:50:18 +0800 (CST) Received: from frapeml500008.china.huawei.com (unknown [7.182.85.71]) by mail.maildlp.com (Postfix) with ESMTPS id ECFA01401F4; Tue, 22 Apr 2025 23:51:58 +0800 (CST) Received: from localhost (10.203.177.66) by frapeml500008.china.huawei.com (7.182.85.71) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Tue, 22 Apr 2025 17:51:58 +0200 Date: Tue, 22 Apr 2025 16:51:57 +0100 From: Jonathan Cameron To: Alejandro Lucero Palau CC: , , , , , , , , , Subject: Re: [PATCH v13 11/22] cxl: define a driver interface for HPA free space enumeration Message-ID: <20250422165157.00006953@huawei.com> In-Reply-To: References: <20250414151336.3852990-1-alejandro.lucero-palau@amd.com> <20250414151336.3852990-12-alejandro.lucero-palau@amd.com> <20250415145016.00003725@huawei.com> <20250417173650.00003ee0@huawei.com> X-Mailer: Claws Mail 4.3.0 (GTK 3.24.42; x86_64-w64-mingw32) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: lhrpeml500011.china.huawei.com (7.191.174.215) To frapeml500008.china.huawei.com (7.182.85.71) On Thu, 17 Apr 2025 22:22:19 +0100 Alejandro Lucero Palau wrote: > On 4/17/25 17:36, Jonathan Cameron wrote: > > On Thu, 17 Apr 2025 13:11:00 +0100 > > Alejandro Lucero Palau wrote: > > > >> On 4/15/25 14:50, Jonathan Cameron wrote: > >>> On Mon, 14 Apr 2025 16:13:25 +0100 > >>> alejandro.lucero-palau@amd.com wrote: > >>> > >>>> From: Alejandro Lucero > >>>> > >>>> CXL region creation involves allocating capacity from device DPA > >>>> (device-physical-address space) and assigning it to decode a given HPA > >>>> (host-physical-address space). Before determining how much DPA to > >>>> allocate the amount of available HPA must be determined. Also, not all > >>>> HPA is created equal, some specifically targets RAM, some target PMEM, > >>>> some is prepared for device-memory flows like HDM-D and HDM-DB, and some > >>>> is host-only (HDM-H). > >>>> > >>>> Wrap all of those concerns into an API that retrieves a root decoder > >>>> (platform CXL window) that fits the specified constraints and the > >>>> capacity available for a new region. > >>>> > >>>> Add a complementary function for releasing the reference to such root > >>>> decoder. > >>>> > >>>> Based on https://lore.kernel.org/linux-cxl/168592159290.1948938.13522227102445462976.stgit@dwillia2-xfh.jf.intel.com/ > >>>> > >>>> Signed-off-by: Alejandro Lucero > >>> One trivial comment inline. > >>> > >>> Reviewed-by: Jonathan Cameron > >>> > >>>> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c > >>>> index 80caaf14d08a..0a9eab4f8e2e 100644 > >>>> --- a/drivers/cxl/core/region.c > >>>> +++ b/drivers/cxl/core/region.c > >>>> +static int find_max_hpa(struct device *dev, void *data) > >>>> +{ > >>>> + struct cxlrd_max_context *ctx = data; > >>>> + struct cxl_switch_decoder *cxlsd; > >>>> + struct cxl_root_decoder *cxlrd; > >>>> + struct resource *res, *prev; > >>>> + struct cxl_decoder *cxld; > >>>> + resource_size_t max; > >>>> + int found = 0; > >>>> + > >>>> + if (!is_root_decoder(dev)) > >>>> + return 0; > >>>> + > >>>> + cxlrd = to_cxl_root_decoder(dev); > >>>> + cxlsd = &cxlrd->cxlsd; > >>>> + cxld = &cxlsd->cxld; > >>>> + > >>>> + /* > >>>> + * None flags are declared as bitmaps but for the sake of better code > >>> None? > >> > >> Not sure you refer to syntax or semantics here. Assuming is the former: > > Just the wording of the comment. I'm not sure what it means. > > > Ok. I just want to make clear those flags fields used in the > bitmap_subset are not declared as bitmaps, just in case someone points > this out. > > I do not think this is problematic, and a good idea you gave me, but > better to comment on it before someone complains about it. > Ah.. Ok. So something like: Fields are not declared as bitmaps, but bitmap_subset may still be used. > > > > >> > >> No flags fields? > > Not following that either. > >> > >>> > >>>> + * used here as such, restricting the bitmap size to those bits used by > >>>> + * any Type2 device driver requester. > >>>> + */ > >>>