From patchwork Tue Dec 12 19:08:32 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Verma, Vishal L" X-Patchwork-Id: 13489795 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="bSRoxJvm" Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.9]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 99763DB; Tue, 12 Dec 2023 11:08:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1702408130; x=1733944130; h=from:date:subject:mime-version:content-transfer-encoding: message-id:references:in-reply-to:to:cc; bh=vTibnNia0m6NhSJs+iWLq3VahLdeYpQQkT1+4mwIgB4=; b=bSRoxJvmp0ln6eGrvMnjx8ic2mK10FffCg1AoPih5jsrzMmuiAlP+BU9 ffmCLyZ78JGFSCs94RPuZSea8W7mx31d3UXC1ea97fOfY1Q9iS6HB/2t/ NT4UHMp5SgYIQfZMcjuahVh7eFxTmuoIUKhVlA2/Pe2Ih4JXspG15pdw6 vzRhU8ABksDIaw9gVHbbnyv1vfXgX7Tz32DEEKHKpfQEaw5q6ZywTDtXz Znk0p+UJClb+0rfla7GP4mb0X/ixrHc31zNnkgIibjfucKSVRt9UOZY5h nBiwNuFgIfnnYx094NYqPz69v7D7mPH+e/QLGoEliOfCjLSoXUp430oAF Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10922"; a="13550598" X-IronPort-AV: E=Sophos;i="6.04,271,1695711600"; d="scan'208";a="13550598" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orvoesa101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Dec 2023 11:08:48 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10922"; a="844017864" X-IronPort-AV: E=Sophos;i="6.04,271,1695711600"; d="scan'208";a="844017864" Received: from cmperez2-mobl2.amr.corp.intel.com (HELO [192.168.1.200]) ([10.212.66.25]) by fmsmga004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Dec 2023 11:08:47 -0800 From: Vishal Verma Date: Tue, 12 Dec 2023 12:08:32 -0700 Subject: [PATCH v4 3/3] dax: add a sysfs knob to control memmap_on_memory behavior Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20231212-vv-dax_abi-v4-3-1351758f0c92@intel.com> References: <20231212-vv-dax_abi-v4-0-1351758f0c92@intel.com> In-Reply-To: <20231212-vv-dax_abi-v4-0-1351758f0c92@intel.com> To: Dan Williams , Vishal Verma , Dave Jiang Cc: linux-kernel@vger.kernel.org, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, David Hildenbrand , Dave Hansen , Huang Ying , Li Zhijian , Jonathan Cameron X-Mailer: b4 0.13-dev-433a8 X-Developer-Signature: v=1; a=openpgp-sha256; l=3733; i=vishal.l.verma@intel.com; h=from:subject:message-id; bh=vTibnNia0m6NhSJs+iWLq3VahLdeYpQQkT1+4mwIgB4=; b=owGbwMvMwCXGf25diOft7jLG02pJDKkV6/eGzgvpDIjI2VB4MUV8v1HGFaXvqUqPjRxU7QQCG y6fvfmyo5SFQYyLQVZMkeXvno+Mx+S25/MEJjjCzGFlAhnCwMUpABNx2cvwz1j+5PvunqhiqR3P mjfIVipLnm6YtOpDe4iNsoWtxoPzLIwMlx02Ru3YvTtjqfq+sg6NPF3butUeWav+XPN8E+q7c6I 3KwA= X-Developer-Key: i=vishal.l.verma@intel.com; a=openpgp; fpr=F8682BE134C67A12332A2ED07AFA61BEA3B84DFF 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 Tested-by: Li Zhijian Reviewed-by: Jonathan Cameron Reviewed-by: David Hildenbrand Signed-off-by: Vishal Verma --- drivers/dax/bus.c | 32 ++++++++++++++++++++++++++++++++ Documentation/ABI/testing/sysfs-bus-dax | 17 +++++++++++++++++ 2 files changed, 49 insertions(+) diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c index ce1356ac6dc2..423adee6f802 100644 --- a/drivers/dax/bus.c +++ b/drivers/dax/bus.c @@ -1245,6 +1245,37 @@ 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 dax_device_driver *dax_drv = to_dax_drv(dev->driver); + struct dev_dax *dev_dax = to_dev_dax(dev); + ssize_t rc; + bool val; + + rc = kstrtobool(buf, &val); + if (rc) + return rc; + + guard(device)(dev); + if (dev_dax->memmap_on_memory != val && + dax_drv->type == DAXDRV_KMEM_TYPE) + return -EBUSY; + dev_dax->memmap_on_memory = val; + + return len; +} +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); @@ -1271,6 +1302,7 @@ 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..b1fd8bf8a7de 100644 --- a/Documentation/ABI/testing/sysfs-bus-dax +++ b/Documentation/ABI/testing/sysfs-bus-dax @@ -149,3 +149,20 @@ 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). Additionally, this + depends on CONFIG_MHP_MEMMAP_ON_MEMORY, and a globally enabled + memmap_on_memory parameter for memory_hotplug. This is + typically set on the kernel command line - + memory_hotplug.memmap_on_memory set to 'true' or 'force'."