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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 71CCEC4167B for ; Thu, 7 Dec 2023 04:36:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229871AbjLGEgR (ORCPT ); Wed, 6 Dec 2023 23:36:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37494 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229552AbjLGEgN (ORCPT ); Wed, 6 Dec 2023 23:36:13 -0500 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.9]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CE091126; Wed, 6 Dec 2023 20:36:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1701923779; x=1733459779; h=from:date:subject:mime-version:content-transfer-encoding: message-id:references:in-reply-to:to:cc; bh=GLP9N2ferQtSs1kZ5RuoBDkk5vqBcdypuQXPjkQVI40=; b=X8ibD31HmjD6dEsDuWjAgiWKn+hA7mbiNP6hjPU98obC9wFJihP0jgww sDbBe/GUyaVDqnYe9p+2dSbG8eaPjQj1E+M2511LGHJujH4OcIxh+8AhU dsnMEsSH4+rWoCIP2H1H+ELP3riFep82wBlkgLsXxldbQGUi2wVubz+VE DzmZ8le5Q6p6YOqabb/hIJYVH8/r1+xBF/CSlCm4NY1FYHWXmnX3Tclju QD1D6AeH5iqYrXP6M4Pfv4MPIaWY5yAYpEx7VZfz2bmsrFc9plT0KpWOr f68Z8RAKes8s0lz/jukPPCuo+/6VpQc4omZ+1TUfpwnqGt53Y0jnne9xY w==; X-IronPort-AV: E=McAfee;i="6600,9927,10916"; a="1053229" X-IronPort-AV: E=Sophos;i="6.04,256,1695711600"; d="scan'208";a="1053229" Received: from orviesa001.jf.intel.com ([10.64.159.141]) by fmvoesa103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Dec 2023 20:36:18 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.04,256,1695711600"; d="scan'208";a="19570383" Received: from apbrezen-mobl.amr.corp.intel.com (HELO [192.168.1.200]) ([10.213.160.175]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Dec 2023 20:36:18 -0800 From: Vishal Verma Date: Wed, 06 Dec 2023 21:36:15 -0700 Subject: [PATCH v2 2/2] dax: add a sysfs knob to control memmap_on_memory behavior MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20231206-vv-dax_abi-v2-2-f4f4f2336d08@intel.com> References: <20231206-vv-dax_abi-v2-0-f4f4f2336d08@intel.com> In-Reply-To: <20231206-vv-dax_abi-v2-0-f4f4f2336d08@intel.com> To: Dave Jiang Cc: Dan Williams , linux-kernel@vger.kernel.org, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, Vishal Verma , David Hildenbrand , Dave Hansen , Huang Ying , Jonathan Cameron X-Mailer: b4 0.13-dev-26615 X-Developer-Signature: v=1; a=openpgp-sha256; l=3572; i=vishal.l.verma@intel.com; h=from:subject:message-id; bh=GLP9N2ferQtSs1kZ5RuoBDkk5vqBcdypuQXPjkQVI40=; b=owGbwMvMwCXGf25diOft7jLG02pJDKmF3gcKzPfKbereozs7go1h30Gr2z0vtixXrP9WH6aV0 WHGt+ZHRykLgxgXg6yYIsvfPR8Zj8ltz+cJTHCEmcPKBDKEgYtTACZyspDhN8uE/G1d5ypauhc5 5IRuu+B2hOnShtvJ7DXprIF6ZywyzRn+8DjbsxYyqgbaKfAVlauEsdSHtL+9VmC32TWz50b1pt/ 8AA== X-Developer-Key: i=vishal.l.verma@intel.com; a=openpgp; fpr=F8682BE134C67A12332A2ED07AFA61BEA3B84DFF Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add a sysfs knob for dax devices to control the memmap_on_memory setting if the dax device were to be hotplugged as system memory. The default memmap_on_memory setting for dax devices originating via pmem or hmem is set to 'false' - i.e. no memmap_on_memory semantics, to preserve legacy behavior. For dax devices via CXL, the default is on. The sysfs control allows the administrator to override the above defaults if needed. Cc: David Hildenbrand Cc: Dan Williams Cc: Dave Jiang Cc: Dave Hansen Cc: Huang Ying Reviewed-by: Jonathan Cameron Reviewed-by: David Hildenbrand Signed-off-by: Vishal Verma --- drivers/dax/bus.c | 40 +++++++++++++++++++++++++++++++++ Documentation/ABI/testing/sysfs-bus-dax | 13 +++++++++++ 2 files changed, 53 insertions(+) diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c index 1ff1ab5fa105..11abb57cc031 100644 --- a/drivers/dax/bus.c +++ b/drivers/dax/bus.c @@ -1270,6 +1270,45 @@ static ssize_t numa_node_show(struct device *dev, } static DEVICE_ATTR_RO(numa_node); +static ssize_t memmap_on_memory_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct dev_dax *dev_dax = to_dev_dax(dev); + + return sprintf(buf, "%d\n", dev_dax->memmap_on_memory); +} + +static ssize_t memmap_on_memory_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t len) +{ + struct dev_dax *dev_dax = to_dev_dax(dev); + struct dax_region *dax_region = dev_dax->region; + ssize_t rc; + bool val; + + rc = kstrtobool(buf, &val); + if (rc) + return rc; + + if (dev_dax->memmap_on_memory == val) + return len; + + device_lock(dax_region->dev); + if (!dax_region->dev->driver) { + device_unlock(dax_region->dev); + return -ENXIO; + } + + device_lock(dev); + dev_dax->memmap_on_memory = val; + device_unlock(dev); + + device_unlock(dax_region->dev); + return rc == 0 ? len : rc; +} +static DEVICE_ATTR_RW(memmap_on_memory); + static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n) { struct device *dev = container_of(kobj, struct device, kobj); @@ -1296,6 +1335,7 @@ static struct attribute *dev_dax_attributes[] = { &dev_attr_align.attr, &dev_attr_resource.attr, &dev_attr_numa_node.attr, + &dev_attr_memmap_on_memory.attr, NULL, }; diff --git a/Documentation/ABI/testing/sysfs-bus-dax b/Documentation/ABI/testing/sysfs-bus-dax index a61a7b186017..bb063a004e41 100644 --- a/Documentation/ABI/testing/sysfs-bus-dax +++ b/Documentation/ABI/testing/sysfs-bus-dax @@ -149,3 +149,16 @@ KernelVersion: v5.1 Contact: nvdimm@lists.linux.dev Description: (RO) The id attribute indicates the region id of a dax region. + +What: /sys/bus/dax/devices/daxX.Y/memmap_on_memory +Date: October, 2023 +KernelVersion: v6.8 +Contact: nvdimm@lists.linux.dev +Description: + (RW) Control the memmap_on_memory setting if the dax device + were to be hotplugged as system memory. This determines whether + the 'altmap' for the hotplugged memory will be placed on the + device being hotplugged (memmap_on+memory=1) or if it will be + placed on regular memory (memmap_on_memory=0). This attribute + must be set before the device is handed over to the 'kmem' + driver (i.e. hotplugged into system-ram). -- 2.41.0