make allmodconfig && make W=1 C=1 reports:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/dax/hmem/dax_hmem.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/dax/device_dax.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/dax/kmem.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/dax/dax_pmem.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/dax/dax_cxl.o
Add all missing invocations of the MODULE_DESCRIPTION() macro.
[iweiny: edit descriptions]
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Link: https://patch.msgid.link/r/20240605-md-drivers-dax-v1-1-3d448f3368b4@quicinc.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
While platform firmware takes some responsibility for mapping the RAM
capacity of CXL devices present at boot, the OS is responsible for
mapping the remainder and hot-added devices. Platform firmware is also
responsible for identifying the platform general purpose memory pool,
typically DDR attached DRAM, and arranging for the remainder to be 'Soft
Reserved'. That reservation allows the CXL subsystem to route the memory
to core-mm via memory-hotplug (dax_kmem), or leave it for dedicated
access (device-dax).
The new 'struct cxl_dax_region' object allows for a CXL memory resource
(region) to be published, but also allow for udev and module policy to
act on that event. It also prevents cxl_core.ko from having a module
loading dependency on any drivers/dax/ modules.
Tested-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/167602003896.1924368.10335442077318970468.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
The default mode for device-dax instances is backwards for RAM-regions
as evidenced by the fact that it tends to catch end users by surprise.
"Where is my memory?". Recall that platforms are increasingly shipping
with performance-differentiated memory pools beyond typical DRAM and
NUMA effects. This includes HBM (high-bandwidth-memory) and CXL (dynamic
interleave, varied media types, and future fabric attached
possibilities).
For this reason the EFI_MEMORY_SP (EFI Special Purpose Memory => Linux
'Soft Reserved') attribute is expected to be applied to all memory-pools
that are not the general purpose pool. This designation gives an
Operating System a chance to defer usage of a memory pool until later in
the boot process where its performance properties can be interrogated
and administrator policy can be applied.
'Soft Reserved' memory can be anything from too limited and precious to
be part of the general purpose pool (HBM), too slow to host hot kernel
data structures (some PMEM media), or anything in between. However, in
the absence of an explicit policy, the memory should at least be made
usable by default. The current device-dax default hides all
non-general-purpose memory behind a device interface.
The expectation is that the distribution of users that want the memory
online by default vs device-dedicated-access by default follows the
Pareto principle. A small number of enlightened users may want to do
userspace memory management through a device, but general users just
want the kernel to make the memory available with an option to get more
advanced later.
Arrange for all device-dax instances not backed by PMEM to default to
attaching to the dax_kmem driver. From there the baseline memory hotplug
policy (CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE / memhp_default_state=)
gates whether the memory comes online or stays offline. Where, if it
stays offline, it can be reliably converted back to device-mode where it
can be partitioned, or fronted by a userspace allocator.
So, if someone wants device-dax instances for their 'Soft Reserved'
memory:
1/ Build a kernel with CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=n or boot
with memhp_default_state=offline, or roll the dice and hope that the
kernel has not pinned a page in that memory before step 2.
2/ Write a udev rule to convert the target dax device(s) from
'system-ram' mode to 'devdax' mode:
daxctl reconfigure-device $dax -m devdax -f
Cc: Michal Hocko <mhocko@suse.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Gregory Price <gregory.price@memverge.com>
Tested-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/167602003336.1924368.6809503401422267885.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
In preparation for the CXL region driver to take over the responsibility
of registering device-dax instances for CXL regions, move the
registration of "hmem" devices to dax_hmem.ko.
Previously the builtin component of this enabling
(drivers/dax/hmem/device.o) would register platform devices for each
address range and trigger the dax_hmem.ko module to load and attach
device-dax instances to those devices. Now, the ranges are collected
from the HMAT and EFI memory map walking, but the device creation is
deferred. A new "hmem_platform" device is created which triggers
dax_hmem.ko to load and register the platform devices.
Tested-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/167602002771.1924368.5653558226424530127.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
In preparation for hmem platform devices to be unregistered, stop using
platform_device_add_resources() to convey the address range. The
platform_device_add_resources() API causes an existing "Soft Reserved"
iomem resource to be re-parented under an inserted platform device
resource. When that platform device is deleted it removes the platform
device resource and all children.
Instead, it is sufficient to convey just the address range and let
request_mem_region() insert resources to indicate the devices active in
the range. This allows the "Soft Reserved" resource to be re-enumerated
upon the next probe event.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Tested-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/167602002217.1924368.7036275892522551624.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
So called "soft-reserved" memory is an EFI conventional memory range
with the EFI_MEMORY_SP attribute set. That attribute indicates that the
memory is not part of the platform general purpose memory pool and may
want some consideration from the system administrator about whether to
keep that memory set aside for dedicated access through device-dax (map
a device file), or assigned to the page allocator as another general
purpose memory node target.
Absent an ACPI HMAT table the default device-dax registration creates
coarse grained devices that are delineated by EFI Memory Map entries.
With the HMAT the devices are delineated by the finer grained ranges
associated with the proximity domain of the memory target. I.e. the HMAT
describes the properties of performance differentiated memory and each
unique performance description results in a unique target proximity
domain where each memory proximity domain has an associated SRAT entry
that delineates the address range.
The intent was that SRAT-defined device-dax instances are registered
first. Then any left-over address range with the EFI_MEMORY_SP
attribute, but not covered by the SRAT, would have a coarse grained
device-dax instance established. However, the scheme to detect what
ranges are left to be assigned to a device was buggy and resulted in
multiple overlapping device-dax instances. Fix this by using explicit
tracking for which ranges have been handled.
Now, this new approach may leave memory stranded in the presence of
broken platform firmware that fails to fully describe all EFI_MEMORY_SP
ranges in the HMAT. That requires a deeper fix if it becomes a problem
in practice.
Reported-by: "Tallam Mahendra Kumar" <tallam.mahendra.kumar@intel.com>
Reported-by: Mustafa Hajeer <mustafa.hajeer@intel.com>
Debugged-by: Vishal Verma <vishal.l.verma@intel.com>
Tested-by: Vishal Verma <vishal.l.verma@intel.com>
Link: https://lore.kernel.org/r/166890823379.4183293.15333502171004313377.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Pull nvdimm updates from Dan Williams:
"Some small cleanups and fixes in and around the nvdimm subsystem. The
most significant change is a regression fix for nvdimm namespace
(volume) creation when the namespace size is smaller than 2MB/
Summary:
- Fix nvdimm namespace creation on platforms that do not publish
associated 'DIMM' metadata for a persistent memory region.
- Miscellaneous fixes and cleanups"
* tag 'libnvdimm-for-6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
ACPI: HMAT: Release platform device in case of platform_device_add_data() fails
dax: Remove usage of the deprecated ida_simple_xxx API
libnvdimm/region: Allow setting align attribute on regions without mappings
nvdimm/namespace: Fix comment typo
nvdimm: make __nvdimm_security_overwrite_query static
nvdimm/region: Fix kernel-doc
nvdimm/namespace: drop unneeded temporary variable in size_store()
nvdimm/namespace: return uuid_null only once in nd_dev_to_uuid()
The platform device is not released when platform_device_add_data()
fails. And platform_device_put() perfom one more pointer check than
put_device() to check for errors in the 'pdev' pointer.
Use platform_device_put() to release platform device in
platform_device_add()/platform_device_add_data()/
platform_device_add_resources() error case.
Fixes: c01044cc81 ("ACPI: HMAT: refactor hmat_register_target_device to hmem_register_device")
Signed-off-by: Lin Yujun <linyujun809@huawei.com>
Link: https://lore.kernel.org/r/20220914033755.99924-1-linyujun809@huawei.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
The "hmem" platform-devices that are created to represent the
platform-advertised "Soft Reserved" memory ranges end up inserting a
resource that causes the iomem_resource tree to look like this:
340000000-43fffffff : hmem.0
340000000-43fffffff : Soft Reserved
340000000-43fffffff : dax0.0
This is because insert_resource() reparents ranges when they completely
intersect an existing range.
This matters because code that uses region_intersects() to scan for a
given IORES_DESC will only check that top-level 'hmem.0' resource and
not the 'Soft Reserved' descendant.
So, to support EINJ (via einj_error_inject()) to inject errors into
memory hosted by a dax-device, be sure to describe the memory as
IORES_DESC_SOFT_RESERVED. This is a follow-on to:
commit b13a3e5fd4 ("ACPI: APEI: Fix _EINJ vs EFI_MEMORY_SP")
...that fixed EINJ support for "Soft Reserved" ranges in the first
instance.
Fixes: 262b45ae3a ("x86/efi: EFI soft reservation to E820 enumeration")
Reported-by: Ricardo Sandoval Torres <ricardo.sandoval.torres@intel.com>
Tested-by: Ricardo Sandoval Torres <ricardo.sandoval.torres@intel.com>
Cc: <stable@vger.kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Omar Avelar <omar.avelar@intel.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Mark Gross <markgross@kernel.org>
Link: https://lore.kernel.org/r/166397075670.389916.7435722208896316387.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
