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7b4bcaadfe
Ensure cxl_acpi has published CXL Window resources before HMEM walks Soft
Reserved ranges.
Replace MODULE_SOFTDEP("pre: cxl_acpi") with an explicit, synchronous
request_module("cxl_acpi"). MODULE_SOFTDEP() only guarantees eventual
loading, it does not enforce that the dependency has finished init
before the current module runs. This can cause HMEM to start before
cxl_acpi has populated the resource tree, breaking detection of overlaps
between Soft Reserved and CXL Windows.
Also, request cxl_pci before HMEM walks Soft Reserved ranges. Unlike
cxl_acpi, cxl_pci attach is asynchronous and creates dependent devices
that trigger further module loads. Asynchronous probe flushing
(wait_for_device_probe()) is added later in the series in a deferred
context before HMEM makes ownership decisions for Soft Reserved ranges.
Add an additional explicit Kconfig ordering so that CXL_ACPI and CXL_PCI
must be initialized before DEV_DAX_HMEM. This prevents HMEM from consuming
Soft Reserved ranges before CXL drivers have had a chance to claim them.
Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Tested-by: Tomasz Wolski <tomasz.wolski@fujitsu.com>
Link: https://patch.msgid.link/20260322195343.206900-4-Smita.KoralahalliChannabasappa@amd.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
84 lines
2.9 KiB
Plaintext
84 lines
2.9 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0-only
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menuconfig DAX
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tristate "DAX: direct access to differentiated memory"
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default m if NVDIMM_DAX
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if DAX
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config DEV_DAX
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tristate "Device DAX: direct access mapping device"
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depends on TRANSPARENT_HUGEPAGE
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help
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Support raw access to differentiated (persistence, bandwidth,
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latency...) memory via an mmap(2) capable character
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device. Platform firmware or a device driver may identify a
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platform memory resource that is differentiated from the
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baseline memory pool. Mappings of a /dev/daxX.Y device impose
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restrictions that make the mapping behavior deterministic.
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config DEV_DAX_PMEM
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tristate "PMEM DAX: direct access to persistent memory"
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depends on LIBNVDIMM && NVDIMM_DAX && DEV_DAX
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default DEV_DAX
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help
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Support raw access to persistent memory. Note that this
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driver consumes memory ranges allocated and exported by the
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libnvdimm sub-system.
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Say M if unsure
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config DEV_DAX_HMEM
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tristate "HMEM DAX: direct access to 'specific purpose' memory"
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depends on EFI_SOFT_RESERVE
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select NUMA_KEEP_MEMINFO if NUMA_MEMBLKS
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default DEV_DAX
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help
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EFI 2.8 platforms, and others, may advertise 'specific purpose'
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memory. For example, a high bandwidth memory pool. The
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indication from platform firmware is meant to reserve the
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memory from typical usage by default. This driver creates
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device-dax instances for these memory ranges, and that also
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enables the possibility to assign them to the DEV_DAX_KMEM
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driver to override the reservation and add them to kernel
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"System RAM" pool.
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Say M if unsure.
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config DEV_DAX_CXL
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tristate "CXL DAX: direct access to CXL RAM regions"
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depends on CXL_BUS && CXL_REGION && DEV_DAX
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default CXL_REGION && DEV_DAX
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depends on CXL_ACPI >= DEV_DAX_HMEM
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depends on CXL_PCI >= DEV_DAX_HMEM
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help
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CXL RAM regions are either mapped by platform-firmware
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and published in the initial system-memory map as "System RAM", mapped
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by platform-firmware as "Soft Reserved", or dynamically provisioned
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after boot by the CXL driver. In the latter two cases a device-dax
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instance is created to access that unmapped-by-default address range.
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Per usual it can remain as dedicated access via a device interface, or
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converted to "System RAM" via the dax_kmem facility.
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config DEV_DAX_HMEM_DEVICES
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depends on DEV_DAX_HMEM && DAX
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def_bool y
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config DEV_DAX_KMEM
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tristate "KMEM DAX: map dax-devices as System-RAM"
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default DEV_DAX
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depends on DEV_DAX
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depends on MEMORY_HOTPLUG # for add_memory() and friends
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help
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Support access to persistent, or other performance
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differentiated memory as if it were System RAM. This allows
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easier use of persistent memory by unmodified applications, or
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adds core kernel memory services to heterogeneous memory types
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(HMEM) marked "reserved" by platform firmware.
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To use this feature, a DAX device must be unbound from the
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device_dax driver and bound to this kmem driver on each boot.
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Say N if unsure.
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endif
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