From patchwork Wed Jan 24 20:03:50 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Verma, Vishal L" X-Patchwork-Id: 13529632 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.15]) (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 D25E41339A1; Wed, 24 Jan 2024 20:04:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.15 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706126670; cv=none; b=e3O5nJdt4MIJ4CNfq4H67cDNEAql4Zd4DO/hNpMhsLUx12Zt+r51ycth0J+IKjvWRwKJ7WbE4so6j0Re5aZ1RlEg9BjfArKNIX/93/m5mJNSFtV/RkoH+h5UxukZWFAa3Bx3wudFot4iNu8KZd+RyPwkuTcsz8LfcHjctaTQgGQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706126670; c=relaxed/simple; bh=LlNwsQ9722KaImXgMJUAbGVELQS9Qj5zVBOISdpjDqE=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=PvyS7mCxYJMx63aqpnqShxOC2gAzRsb48Px3ffQi+XwT1YjlWU/jd314kjUr/xC/Wyi6+4hBF2uty8yN7h4q2hIHGGr9eCE4vFWO4LPo7v+tX1rz0EA2HA0IBcG/EVHw0pJpPjINtUR91ruFPLL4cdPtW9uw5mWxFu+NsxUcYr4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=jFuZahct; arc=none smtp.client-ip=198.175.65.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="jFuZahct" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1706126667; x=1737662667; h=from:date:subject:mime-version:content-transfer-encoding: message-id:references:in-reply-to:to:cc; bh=LlNwsQ9722KaImXgMJUAbGVELQS9Qj5zVBOISdpjDqE=; b=jFuZahctn9V358ON/5NnxJVP3aGmB0Zp54MQRkGjQ5FR0yxZbBmR7fMk h3oaYazLoso+RErHrp3FqeGsPnkxi94FGXt27KNzlVDBOZiOLuNTJ4TM/ vWHOc6w1x8hz6I9tK0Fq62I6iJy8fB8GVkLccbghKOKf2WKEAiYOrUsbM C/2NTfA6vLlxulig55vlx5srSQcOjBstqbFwSBw3IvstTCBe9ox5AfcqY zPmIE4d+HwlPiuqj6zI8LCynuSBrI1H2dfHf4As/rSqczHX66MKVRPf2y dTu9cRsVpnss8c2X9JUI/xvvs/r0Y4bDscjOsg3oSjQ0ode01L8jmQEGe A==; X-IronPort-AV: E=McAfee;i="6600,9927,10962"; a="1836126" X-IronPort-AV: E=Sophos;i="6.05,216,1701158400"; d="scan'208";a="1836126" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orvoesa107.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Jan 2024 12:04:26 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10962"; a="1117735146" X-IronPort-AV: E=Sophos;i="6.05,216,1701158400"; d="scan'208";a="1117735146" Received: from vverma7-mobl3.amr.corp.intel.com (HELO [10.0.0.223]) ([10.251.14.61]) by fmsmga005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Jan 2024 12:04:25 -0800 From: Vishal Verma Date: Wed, 24 Jan 2024 12:03:50 -0800 Subject: [PATCH v7 5/5] 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: <20240124-vv-dax_abi-v7-5-20d16cb8d23d@intel.com> References: <20240124-vv-dax_abi-v7-0-20d16cb8d23d@intel.com> In-Reply-To: <20240124-vv-dax_abi-v7-0-20d16cb8d23d@intel.com> To: Dan Williams , Vishal Verma , Dave Jiang , Andrew Morton , Oscar Salvador Cc: linux-kernel@vger.kernel.org, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, David Hildenbrand , Dave Hansen , Huang Ying , Greg Kroah-Hartman , Matthew Wilcox , linux-mm@kvack.org, Li Zhijian , Jonathan Cameron X-Mailer: b4 0.13-dev-a684c X-Developer-Signature: v=1; a=openpgp-sha256; l=4012; i=vishal.l.verma@intel.com; h=from:subject:message-id; bh=LlNwsQ9722KaImXgMJUAbGVELQS9Qj5zVBOISdpjDqE=; b=owGbwMvMwCXGf25diOft7jLG02pJDKkbc50VeD8v+CjLFhJhfFzu8RSjtH97erzz9l4Qf8Enc LfQ66hyRykLgxgXg6yYIsvfPR8Zj8ltz+cJTHCEmcPKBDKEgYtTACbiH8TwV1Ju2kePSfLnrhke 2viisS8mpjzc/qGgQObvl8E/GFTs9Rn+B7+fyvC/VG61dh1TyJMbdnVpnpttknc4N2ev5nkgpin HBAA= 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 Reviewed-by: Huang, Ying Signed-off-by: Vishal Verma Reviewed-by: Alison Schofield --- drivers/dax/bus.c | 43 +++++++++++++++++++++++++++++++++ Documentation/ABI/testing/sysfs-bus-dax | 17 +++++++++++++ 2 files changed, 60 insertions(+) diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c index 0fd948a4443e..27c86d0ca711 100644 --- a/drivers/dax/bus.c +++ b/drivers/dax/bus.c @@ -1349,6 +1349,48 @@ 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 sysfs_emit(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); + bool val; + int rc; + + rc = kstrtobool(buf, &val); + if (rc) + return rc; + + if (val == true && !mhp_supports_memmap_on_memory()) { + dev_dbg(dev, "memmap_on_memory is not available\n"); + return -EOPNOTSUPP; + } + + rc = down_write_killable(&dax_dev_rwsem); + if (rc) + return rc; + + if (dev_dax->memmap_on_memory != val && dev->driver && + to_dax_drv(dev->driver)->type == DAXDRV_KMEM_TYPE) { + up_write(&dax_dev_rwsem); + return -EBUSY; + } + + dev_dax->memmap_on_memory = val; + up_write(&dax_dev_rwsem); + + 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); @@ -1375,6 +1417,7 @@ 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 6359f7bc9bf4..b34266bfae49 100644 --- a/Documentation/ABI/testing/sysfs-bus-dax +++ b/Documentation/ABI/testing/sysfs-bus-dax @@ -134,3 +134,20 @@ 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: January, 2024 +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'."