From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.100]) (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 EE125107A5; Fri, 15 Dec 2023 07:55:12 +0000 (UTC) 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="SCZ+6v78" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1702626913; x=1734162913; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version; bh=E3dxP/JeHc7c4fIWBmlsAqRVqJ6RpEEE2GiOPJLY2mw=; b=SCZ+6v7832f/wCK3EDKY6kafK7xkHLO3K+HcbMZEXA/W2sbjK0qQ+/ov Qk8u+rS5l9k1AoUNAXUlF6zOfRqtUgxYwoJfvuTIZcUN4+gwoKaHQi0St pAzwDuyilh6tiefJuiTdiWS1Pu5AUp3HeYDAaXjoT7Zbk53aXI/E4r71d NMHshb0TPFsAqFLTkGx0gRiLevJNWmIrt4mpafzXX83De3f27Lt0n+vEC ZUjFhxiSpWUPoHBUT2Le5eMhtJbCjpA62+Qpn8QsCZa7YYTMvGuoz32kV kH3IeDpFbKQ2q7E9TflpMNcfg5IuJnCuYBwgCeAFrdqitgqwhtoetbhKL A==; X-IronPort-AV: E=McAfee;i="6600,9927,10924"; a="461705868" X-IronPort-AV: E=Sophos;i="6.04,278,1695711600"; d="scan'208";a="461705868" Received: from orviesa002.jf.intel.com ([10.64.159.142]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Dec 2023 23:55:12 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.04,278,1695711600"; d="scan'208";a="16200871" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by orviesa002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Dec 2023 23:55:08 -0800 From: "Huang, Ying" To: Vishal Verma Cc: Dan Williams , Dave Jiang , Andrew Morton , Oscar Salvador , , , , David Hildenbrand , "Dave Hansen" , Greg Kroah-Hartman , , "Li Zhijian" , Jonathan Cameron Subject: Re: [PATCH v6 4/4] dax: add a sysfs knob to control memmap_on_memory behavior In-Reply-To: <20231214-vv-dax_abi-v6-4-ad900d698438@intel.com> (Vishal Verma's message of "Thu, 14 Dec 2023 22:25:29 -0700") References: <20231214-vv-dax_abi-v6-0-ad900d698438@intel.com> <20231214-vv-dax_abi-v6-4-ad900d698438@intel.com> Date: Fri, 15 Dec 2023 15:53:08 +0800 Message-ID: <871qbnrjff.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ascii Vishal Verma writes: > 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 Looks good to me! Thanks! Reviewed-by: "Huang, Ying" > --- > drivers/dax/bus.c | 36 +++++++++++++++++++++++++++++++++ > Documentation/ABI/testing/sysfs-bus-dax | 17 ++++++++++++++++ > 2 files changed, 53 insertions(+) > > diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c > index 6226de131d17..3622b3d1c0de 100644 > --- a/drivers/dax/bus.c > +++ b/drivers/dax/bus.c > @@ -1245,6 +1245,41 @@ 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); > + ssize_t rc; > + bool val; > + > + 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; > + } > + > + guard(device)(dev); > + if (dev_dax->memmap_on_memory != val && dev->driver && > + to_dax_drv(dev->driver)->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 +1306,7 @@ 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'."