From a6c7f4c6aea5f4ca6056b06cec7ebd79f8c23e33 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Wed, 6 Nov 2019 17:43:43 -0800 Subject: device-dax: Add a driver for "hmem" devices Platform firmware like EFI/ACPI may publish "hmem" platform devices. Such a device is a performance differentiated memory range likely reserved for an application specific use case. The driver gives access to 100% of the capacity via a device-dax mmap instance by default. However, if over-subscription and other kernel memory management is desired the resulting dax device can be assigned to the core-mm via the kmem driver. This consumes "hmem" devices the producer of "hmem" devices is saved for a follow-on patch so that it can reference the new CONFIG_DEV_DAX_HMEM symbol to gate performing the enumeration work. Reported-by: kbuild test robot Reviewed-by: Dave Hansen Signed-off-by: Dan Williams Acked-by: Thomas Gleixner Signed-off-by: Rafael J. Wysocki --- drivers/dax/Kconfig | 27 ++++++++++++++++++++----- drivers/dax/Makefile | 2 ++ drivers/dax/hmem.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 80 insertions(+), 5 deletions(-) create mode 100644 drivers/dax/hmem.c (limited to 'drivers/dax') diff --git a/drivers/dax/Kconfig b/drivers/dax/Kconfig index f33c73e4af41..3b6c06f07326 100644 --- a/drivers/dax/Kconfig +++ b/drivers/dax/Kconfig @@ -32,19 +32,36 @@ config DEV_DAX_PMEM Say M if unsure +config DEV_DAX_HMEM + tristate "HMEM DAX: direct access to 'specific purpose' memory" + depends on EFI_SOFT_RESERVE + default DEV_DAX + help + EFI 2.8 platforms, and others, may advertise 'specific purpose' + memory. For example, a high bandwidth memory pool. The + indication from platform firmware is meant to reserve the + memory from typical usage by default. This driver creates + device-dax instances for these memory ranges, and that also + enables the possibility to assign them to the DEV_DAX_KMEM + driver to override the reservation and add them to kernel + "System RAM" pool. + + Say M if unsure. + config DEV_DAX_KMEM tristate "KMEM DAX: volatile-use of persistent memory" default DEV_DAX depends on DEV_DAX depends on MEMORY_HOTPLUG # for add_memory() and friends help - Support access to persistent memory as if it were RAM. This - allows easier use of persistent memory by unmodified - applications. + Support access to persistent, or other performance + differentiated memory as if it were System RAM. This allows + easier use of persistent memory by unmodified applications, or + adds core kernel memory services to heterogeneous memory types + (HMEM) marked "reserved" by platform firmware. To use this feature, a DAX device must be unbound from the - device_dax driver (PMEM DAX) and bound to this kmem driver - on each boot. + device_dax driver and bound to this kmem driver on each boot. Say N if unsure. diff --git a/drivers/dax/Makefile b/drivers/dax/Makefile index 81f7d54dadfb..80065b38b3c4 100644 --- a/drivers/dax/Makefile +++ b/drivers/dax/Makefile @@ -2,9 +2,11 @@ obj-$(CONFIG_DAX) += dax.o obj-$(CONFIG_DEV_DAX) += device_dax.o obj-$(CONFIG_DEV_DAX_KMEM) += kmem.o +obj-$(CONFIG_DEV_DAX_HMEM) += dax_hmem.o dax-y := super.o dax-y += bus.o device_dax-y := device.o +dax_hmem-y := hmem.o obj-y += pmem/ diff --git a/drivers/dax/hmem.c b/drivers/dax/hmem.c new file mode 100644 index 000000000000..fe7214daf62e --- /dev/null +++ b/drivers/dax/hmem.c @@ -0,0 +1,56 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include "bus.h" + +static int dax_hmem_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct dev_pagemap pgmap = { }; + struct dax_region *dax_region; + struct memregion_info *mri; + struct dev_dax *dev_dax; + struct resource *res; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (!res) + return -ENOMEM; + + mri = dev->platform_data; + memcpy(&pgmap.res, res, sizeof(*res)); + + dax_region = alloc_dax_region(dev, pdev->id, res, mri->target_node, + PMD_SIZE, PFN_DEV|PFN_MAP); + if (!dax_region) + return -ENOMEM; + + dev_dax = devm_create_dev_dax(dax_region, 0, &pgmap); + if (IS_ERR(dev_dax)) + return PTR_ERR(dev_dax); + + /* child dev_dax instances now own the lifetime of the dax_region */ + dax_region_put(dax_region); + return 0; +} + +static int dax_hmem_remove(struct platform_device *pdev) +{ + /* devm handles teardown */ + return 0; +} + +static struct platform_driver dax_hmem_driver = { + .probe = dax_hmem_probe, + .remove = dax_hmem_remove, + .driver = { + .name = "hmem", + }, +}; + +module_platform_driver(dax_hmem_driver); + +MODULE_ALIAS("platform:hmem*"); +MODULE_LICENSE("GPL v2"); +MODULE_AUTHOR("Intel Corporation"); -- cgit v1.2.3-70-g09d2