On Mon, 24 Jun 2019 11:20:16 -0700 Dan Williams <[email protected]> wrote:
> 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. > > Cc: Vishal Verma <[email protected]> > Cc: Keith Busch <[email protected]> > Cc: Dave Jiang <[email protected]> > Reported-by: kbuild test robot <[email protected]> > Reviewed-by: Dave Hansen <[email protected]> > Signed-off-by: Dan Williams <[email protected]> No need to have a remove function at all. Otherwise this looks good to me. Reviewed-by: Jonathan Cameron <[email protected]> > --- > drivers/dax/Kconfig | 27 +++++++++++++++++++---- > drivers/dax/Makefile | 2 ++ > drivers/dax/hmem.c | 57 > ++++++++++++++++++++++++++++++++++++++++++++++++ > include/linux/ioport.h | 4 +++ > 4 files changed, 85 insertions(+), 5 deletions(-) > create mode 100644 drivers/dax/hmem.c > > diff --git a/drivers/dax/Kconfig b/drivers/dax/Kconfig > index f33c73e4af41..1a59ef86f148 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_APPLICATION_RESERVED > + 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..62f9e3c80e21 > --- /dev/null > +++ b/drivers/dax/hmem.c > @@ -0,0 +1,57 @@ > +// SPDX-License-Identifier: GPL-2.0 > +#include <linux/platform_device.h> > +#include <linux/ioport.h> > +#include <linux/module.h> > +#include <linux/pfn_t.h> > +#include "bus.h" > + > +static int dax_hmem_probe(struct platform_device *pdev) > +{ > + struct dev_pagemap pgmap = { NULL }; > + struct device *dev = &pdev->dev; > + 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; > + pgmap.dev = dev; > + 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; Why have a remove at all? driver/base/platform.c has the appropriate protections to allow you to not provide one. If you want the comment, just put it after .probe = below. > +} > + > +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"); > diff --git a/include/linux/ioport.h b/include/linux/ioport.h > index 72ea690b35a4..0c529c8f8027 100644 > --- a/include/linux/ioport.h > +++ b/include/linux/ioport.h > @@ -294,6 +294,10 @@ static inline bool resource_overlaps(struct resource > *r1, struct resource *r2) > } > > #ifdef CONFIG_MEMREGION > +struct memregion_info { > + int target_node; > +}; > + > extern struct ida memregion_ids; > static inline int memregion_alloc(gfp_t gfp) > { >
