Per JEDEC Annex L Release 3 the SPD data is:

Bits 9~5 00 000 = Function Undefined
         00 001 = Byte addressable energy backed
         00 010 = Block addressed
         00 011 = Byte addressable, no energy backed
         All other codes reserved
Bits 4~0 0 0000 = Proprietary interface
         0 0001 = Standard interface 1
         All other codes reserved; see Definitions of Functions

...and per the ACPI 6.1 spec:

    byte0: Bits 4~0 (0 or 1)
    byte1: Bits 9~5 (1, 2, or 3)

...so a format interface code displayed as 0x301 should be stored in the
nfit as (0x1, 0x3), little-endian.

Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Robert Moore <robert.moore@intel.com>
Cc: Robert Elliott <elliott@hpe.com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=121161
Fixes: 30ec5fd4 ("nfit: fix format interface code byte order per ACPI6.1")
Fixes: 5ad9a7fd ("acpi/nfit: Update nfit driver to comply with ACPI 6.1")
Reported-by: NKristin Jacque <kristin.jacque@intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

QEMU 2.6 implements nascent support for nvdimm DSMs. Depending on
configuration it may only implement the function0 dsm to indicate that
no other DSMs are available. Commit 31eca76b "nfit, libnvdimm:
limited/whitelisted dimm command marshaling mechanism" breaks QEMU, but
QEMU is spec compliant.  Per the spec the way to indicate that no
functions are supported is:

    If Function Index is zero, the return is a buffer containing one bit
    for each function index, starting with zero. Bit 0 indicates whether
    there is support for any functions other than function 0 for the
    specified UUID and Revision ID. If set to zero, no functions are
    supported (other than function zero) for the specified UUID and
    Revision ID.

Update the nfit driver to determine the family (interface UUID) without
requiring the implementation to define any other functions, i.e.
short-circuit acpi_check_dsm() to succeed per the spec.  The nfit driver
appears to be the only user passing funcs==0 to acpi_check_dsm(), so
this behavior change of the common routine should be limited to the
probing done by the nfit driver.

Cc: Len Brown <lenb@kernel.org>
Cc: Jerry Hoemann <jerry.hoemann@hpe.com>
Acked-by: N"Rafael J. Wysocki" <rafael@kernel.org>
Fixes: 31eca76b ("nfit, libnvdimm: limited/whitelisted dimm command marshaling mechanism")
Reported-by: NXiao Guangrong <guangrong.xiao@linux.intel.com>
Tested-by: NXiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

Communicate the command format and supported functions to userspace
tooling.
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

Module option to limit userspace to the publicly defined command set.
For cases where private DIMM commands may be interfering with the
kernel's handling of DIMM state this option can be set to block vendor
specific commands.

Cc: Jerry Hoemann <jerry.hoemann@hpe.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

When transportation of the command completes successfully, it indicates
that the 'status' result is valid.  Fix the missed checking and
translation of the status field at the end of acpi_nfit_ctl().
Otherwise, we fail to handle reported errors and assume commands
complete successfully.
Reported-by: NLinda Knippers <linda.knippers@hpe.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

Similar to pci-sysfs export the subsystem information available in the
NFIT.  ACPI 6.1 clarifies that this data is copied as an array of bytes
from the DIMM SPD data.
Reported-by: NRyon Jensen <ryon.jensen@intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

There are currently 4 known similar but incompatible definitions of the
command sets that can be sent to an NVDIMM through ACPI.  It is also
clear that future platform generations (ACPI or not) will continue to
revise and extend the DIMM command set as new devices and use cases
arrive.

It is obviously untenable to continue to proliferate divergence
of these command definitions, and to that end a standardization process
has begun to provide for a unified specification.  However, that leaves a
problem about what to do with this first generation where vendors are
already shipping divergence.

The Linux kernel can support these initial diverged platforms without
giving platform-firmware free reign to continue to diverge and compound
kernel maintenance overhead.  The kernel implementation can encourage
standardization in two ways:

1/ Require that any function code that userspace wants to send be
   explicitly white-listed in the implementation.  For ACPI this means
   function codes marked as supported by acpi_check_dsm() may
   only be invoked if they appear in the white-list.  A function must be
   publicly documented before it is added to the white-list.

2/ The above restrictions can be trivially bypassed by using the
   "vendor-specific" payload command.  However, since vendor-specific
   commands are by definition not publicly documented and have the
   potential to corrupt the kernel's view of the dimm state, we provide a
   toggle to disable vendor-specific operations.  Enabling undefined
   behavior is a policy decision that can be made by the platform owner
   and encourages firmware implementations to choose public over
   private command implementations.

Based on an initial patch from Jerry Hoemann
Cc: Jerry Hoemann <jerry.hoemann@hpe.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

Clarify the distinction between "commands", the ioctls userspace calls
to request the kernel take some action on a given dimm device, and
"_DSMs", the actual function numbers used in the firmware interface to
the DIMM.  _DSMs are ACPI specific whereas commands are Linux kernel
generic.

This is in preparation for breaking the 1:1 implicit relationship
between the kernel ioctl number space and the firmware specific function
numbers.

Cc: Jerry Hoemann <jerry.hoemann@hpe.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

ACPI 6.1, section 5.2.25.9, defines an identifier for an NVDIMM.

Change the NFIT driver to add a new sysfs file "id" under nfit
directory.
Signed-off-by: NToshi Kani <toshi.kani@hpe.com>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Robert Moore <robert.moore@intel.com>
Cc: Robert Elliott <elliott@hpe.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

ACPI 6.1, Table 5-133, updates NVDIMM Control Region Structure
as follows.
 - Valid Fields, Manufacturing Location, and Manufacturing Date
   are added from reserved range.  No change in the structure size.
 - IDs (SPD values) are stored as arrays of bytes (i.e. big-endian
   format).  The spec clarifies that they need to be represented
   as arrays of bytes as well.

This patch makes the following changes to support this update.
 - Change the NFIT driver to show SPD ID values in big-endian
   format.
 - Change sprintf format to use "0x" instead of "#" since "%#02x"
   does not prepend '0'.

link: http://www.uefi.org/sites/default/files/resources/ACPI_6_1.pdfSigned-off-by: NToshi Kani <toshi.kani@hpe.com>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Robert Moore <robert.moore@intel.com>
Cc: Robert Elliott <elliott@hpe.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

It's minor but that's still better to use ACPI_SIG_NFIT instead of hard
coded string.

Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: NLee, Chun-Yi <jlee@suse.com>
Acked-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

Starting with ACPI 6.1 an NFIT table will report multiple 'NVDIMM
Control Region Structure' instances per-dimm, one for each supported
format interface.  Report that code in the following format in sysfs:

    nmemX/nfit/formats
    nmemX/nfit/format
    nmemX/nfit/format1
    nmemX/nfit/format2
    ...
    nmemX/nfit/formatN

Where format2 - formatN are theoretical as there are no known DIMMs with
support for more than two interface formats.

This layout is compatible with existing libndctl binaries that only
expect one code per-dimm as they will ignore nmemX/nfit/formats and
nmemX/nfit/formatN.
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

ACPI 6 defines persistent memory (PMEM) ranges in multiple
firmware interfaces, e820, EFI, and ACPI NFIT table.  This EFI
change, however, leads to hit a bug in the grub bootloader, which
treats EFI_PERSISTENT_MEMORY type as regular memory and corrupts
stored user data [1].

Therefore, BIOS may set generic reserved type in e820 and EFI to
cover PMEM ranges.  The kernel can initialize PMEM ranges from
ACPI NFIT table alone.

This scheme causes a problem in the iomem table, though.  On x86,
for instance, e820_reserve_resources() initializes top-level entries
(iomem_resource.child) from the e820 table at early boot-time.
This creates "reserved" entry for a PMEM range, which does not allow
region_intersects() to check with PMEM type.

Change acpi_nfit_register_region() to call acpi_nfit_insert_resource(),
which calls insert_resource() to insert a PMEM entry from NFIT when
the iomem table does not have a PMEM entry already.  That is, when
a PMEM range is marked as reserved type in e820, it inserts
"Persistent Memory" entry, which results as follows.

 + "Persistent Memory"
    + "reserved"

This allows the EINJ driver, which calls region_intersects() to check
PMEM ranges, to work continuously even if BIOS sets reserved type
(or sets nothing) to PMEM ranges in e820 and EFI.

[1]: https://lists.gnu.org/archive/html/grub-devel/2015-11/msg00209.htmlSigned-off-by: NToshi Kani <toshi.kani@hpe.com>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

Add the boiler-plate for a 'clear error' command based on section
9.20.7.6 "Function Index 4 - Clear Uncorrectable Error" from the ACPI
6.1 specification, and add a reference implementation in nfit_test.
Reviewed-by: NVishal Verma <vishal.l.verma@intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

While the nfit driver is issuing address range scrub commands and
reaping the results do not permit an ars_start command issued from
userspace.  The scrub thread assumes that all ars completions are for
scrubs initiated by platform firmware at boot, or by the nfit driver.
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

Address range scrub is a potentially long running process that we want
to complete before any pmem regions are registered.  Perform this
operation asynchronously to allow other drivers to load in the meantime.

Platform firmware may have initiated a partial scrub prior to the driver
loading, so we must be careful to consume those results before kicking
off kernel initiated scrubs on other regions.

This rework also makes the registration path more tolerant of scrub
errors in that it splits scrubbing into 2 phases.  The first phase
synchronously waits for a platform-firmware initiated scrub to complete.
The second phase scans the remaining address ranges asynchronously and
notifies the related driver(s) when the scrub completes.
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

Introduce a workqueue that will be used to run address range scrub
asynchronously with the rest of nvdimm device probing.

Userspace still wants notification when probing operations complete, so
introduce a new callback to flush this workqueue when userspace is
awaiting probe completion.
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

The nvdimm unit test infrastructure performs its own initialization of
an acpi_nfit_desc to specify test overrides over the native
implementation.  Make it clear which attributes and operations it is
overriding by re-using acpi_nfit_init_desc() as a common starting point.
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

The return value from an 'ndctl_fn' reports the command execution
status, i.e. was the command properly formatted and was it successfully
submitted to the bus provider.  The new 'cmd_rc' parameter allows the bus
provider to communicate command specific results, translated into
common error codes.

Convert the ARS commands to this scheme to:

1/ Consolidate status reporting

2/ Prepare for for expanding ars unit test cases

3/ Make the implementation more generic

Cc: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

If firmware doesn't implement any of the ARS commands, take that to
mean that ARS is unsupported, and continue to initialize regions without
bad block lists. We cannot make the assumption that ARS commands will be
unconditionally supported on all NVDIMMs.
Reported-by: NHaozhong Zhang <haozhong.zhang@intel.com>
Signed-off-by: NVishal Verma <vishal.l.verma@intel.com>
Acked-by: NXiao Guangrong <guangrong.xiao@linux.intel.com>
Tested-by: NHaozhong Zhang <haozhong.zhang@intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

The original format of these commands from the "NVDIMM DSM Interface
Example" [1] are superseded by the ACPI 6.1 definition of the "NVDIMM Root
Device _DSMs" [2].

[1]: http://pmem.io/documents/NVDIMM_DSM_Interface_Example.pdf
[2]: http://www.uefi.org/sites/default/files/resources/ACPI_6_1.pdf
     "9.20.7 NVDIMM Root Device _DSMs"

Changes include:
1/ New 'restart' fields in ars_status, unfortunately these are
   implemented in the middle of the existing definition so this change
   is not backwards compatible.  The expectation is that shipping
   platforms will only ever support the ACPI 6.1 definition.

2/ New status values for ars_start ('busy') and ars_status ('overflow').

Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Linda Knippers <linda.knippers@hpe.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

Use the output length specified in the command to size the receive
buffer rather than the arbitrary 4K limit.

This bug was hiding the fact that the ndctl implementation of
ndctl_bus_cmd_new_ars_status() was not specifying an output buffer size.

Cc: <stable@vger.kernel.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

ACPI 6.1 clarified that multi-interface dimms require multiple control
region entries (DCRs) per dimm.  Previously we were assuming that a
control region is only present when block-data-windows are present.
This implementation was done with an eye to be compatibility with the
looser ACPI 6.0 interpretation of this table.

1/ When coalescing the memory device (MEMDEV) tables for a single dimm,
coalesce on device_handle rather than control region index.

2/ Whenever we disocver a control region with non-zero block windows
re-scan for block-data-window (BDW) entries.

We may need to revisit this if a DIMM ever implements a format interface
outside of blk or pmem, but that is not on the foreseeable horizon.

Cc: <stable@vger.kernel.org>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

During region creation, perform Address Range Scrubs (ARS) for the SPA
(System Physical Address) ranges to retrieve known poison locations from
firmware. Add a new data structure 'nd_poison' which is used as a list
in nvdimm_bus to store these poison locations.

When creating a pmem namespace, if there is any known poison associated
with its physical address space, convert the poison ranges to bad sectors
that are exposed using the badblocks interface.
Signed-off-by: NVishal Verma <vishal.l.verma@intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

Even if dev->driver is null because we are being removed,
it is safer to not leave device locked.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: NAlexey Khoroshilov <khoroshilov@ispras.ru>
Reviewed-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: NVishal Verma <vishal.l.verma@intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

When support for _FIT was added, the code presumed that the data
returned by the _FIT method is identical to the NFIT table, which
starts with an acpi_table_header.  However, the _FIT is defined
to return a data in the format of a series of NFIT type structure
entries and as a method, has an acpi_object header rather tahn
an acpi_table_header.

To address the differences, explicitly save the acpi_table_header
from the NFIT, since it is accessible through /sys, and change
the nfit pointer in the acpi_desc structure to point to the
table entries rather than the headers.

Reported-by: Jeff Moyer (jmoyer@redhat.com>
Signed-off-by: NLinda Knippers <linda.knippers@hpe.com>
Acked-by: NVishal Verma <vishal.l.verma@intel.com>
[vishal: fix up unit test for new header assumptions]
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

Missed previously due to a lack of test coverage on a platform that
provided an valid response to _FIT.
Signed-off-by: NLinda Knippers <linda.knippers@hpe.com>
Acked-by: NVishal Verma <vishal.l.verma@intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

The size of NFIT tables don't necessarily match the size of the
data structures that we use for them.  For example, the NVDIMM
Control Region Structure table is shorter for a device with
no block control windows than for a device with block control windows.
Other tables, such as Flush Hint Address Structure and the Interleave
Structure are variable length by definition.

Account for the size difference when comparing table entries by
using the actual table size from the table header if it's less
than the structure size.
Signed-off-by: NLinda Knippers <linda.knippers@hpe.com>
Acked-by: NVishal Verma <vishal.l.verma@intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

Add a .notify callback to the acpi_nfit_driver that gets called on a
hotplug event. From this, evaluate the _FIT ACPI method which returns
the updated NFIT with handles for the hot-plugged NVDIMM.

Iterate over the new NFIT, and add any new tables found, and
register/enable the corresponding regions.

In the nfit test framework, after normal initialization, update the NFIT
with a new hot-plugged NVDIMM, and directly call into the driver to
update its view of the available regions.

Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Elliott, Robert <elliott@hpe.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: <linux-acpi@vger.kernel.org>
Cc: <linux-nvdimm@lists.01.org>
Signed-off-by: NVishal Verma <vishal.l.verma@intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

If acpi_nfit_init is called (such as from nfit_test), with an nfit table
that has more memory allocated than it needs (and a similarly large
'size' field, add_tables would happily keep adding null SPA Range tables
filling up all available memory.

Make it friendlier by breaking out if a 0-length header is found in any
of the tables.

Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: <linux-acpi@vger.kernel.org>
Cc: <linux-nvdimm@lists.01.org>
Signed-off-by: NVishal Verma <vishal.l.verma@intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

ACPICA commit 534deab97fb416a13bfede15c538e2c9eac9384a

Updated one of the memory subtable flags to clarify.

Link: https://github.com/acpica/acpica/commit/534deab9Signed-off-by: NBob Moore <robert.moore@intel.com>
Signed-off-by: NLv Zheng <lv.zheng@intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

These are not implementations of default architecture code but helpers
for drivers. Move them to the place they belong to.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NDarren Hart <dvhart@linux.intel.com>
Acked-by: NHitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>
Signed-off-by: NArnd Bergmann <arnd@arndb.de>

Given that a write-back (WB) mapping plus non-temporal stores is
expected to be the most efficient way to access PMEM, update the
definition of ARCH_HAS_PMEM_API to imply arch support for
WB-mapped-PMEM.  This is needed as a pre-requisite for adding PMEM to
the direct map and mapping it with struct page.

The above clarification for X86_64 means that memcpy_to_pmem() is
permitted to use the non-temporal arch_memcpy_to_pmem() rather than
needlessly fall back to default_memcpy_to_pmem() when the pcommit
instruction is not available.  When arch_memcpy_to_pmem() is not
guaranteed to flush writes out of cache, i.e. on older X86_32
implementations where non-temporal stores may just dirty cache,
ARCH_HAS_PMEM_API is simply disabled.

The default fall back for persistent memory handling remains.  Namely,
map it with the WT (write-through) cache-type and hope for the best.

arch_has_pmem_api() is updated to only indicate whether the arch
provides the proper helpers to meet the minimum "writes are visible
outside the cache hierarchy after memcpy_to_pmem() + wmb_pmem()".  Code
that cares whether wmb_pmem() actually flushes writes to pmem must now
call arch_has_wmb_pmem() directly.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Reviewed-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
[hch: set ARCH_HAS_PMEM_API=n on x86_32]
Reviewed-by: NChristoph Hellwig <hch@lst.de>
[toshi: x86_32 compile fixes]
Signed-off-by: NToshi Kani <toshi.kani@hp.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

This should result in a pretty sizeable performance gain for reads.  For
rough comparison I did some simple read testing using PMEM to compare
reads of write combining (WC) mappings vs write-back (WB).  This was
done on a random lab machine.

PMEM reads from a write combining mapping:
	# dd of=/dev/null if=/dev/pmem0 bs=4096 count=100000
	100000+0 records in
	100000+0 records out
	409600000 bytes (410 MB) copied, 9.2855 s, 44.1 MB/s

PMEM reads from a write-back mapping:
	# dd of=/dev/null if=/dev/pmem0 bs=4096 count=1000000
	1000000+0 records in
	1000000+0 records out
	4096000000 bytes (4.1 GB) copied, 3.44034 s, 1.2 GB/s

To be able to safely support a write-back aperture I needed to add
support for the "read flush" _DSM flag, as outlined in the DSM spec:

http://pmem.io/documents/NVDIMM_DSM_Interface_Example.pdf

This flag tells the ND BLK driver that it needs to flush the cache lines
associated with the aperture after the aperture is moved but before any
new data is read.  This ensures that any stale cache lines from the
previous contents of the aperture will be discarded from the processor
cache, and the new data will be read properly from the DIMM.  We know
that the cache lines are clean and will be discarded without any
writeback because either a) the previous aperture operation was a read,
and we never modified the contents of the aperture, or b) the previous
aperture operation was a write and we must have written back the dirtied
contents of the aperture to the DIMM before the I/O was completed.

In order to add support for the "read flush" flag I needed to add a
generic routine to invalidate cache lines, mmio_flush_range().  This is
protected by the ARCH_HAS_MMIO_FLUSH Kconfig variable, and is currently
only supported on x86.
Signed-off-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

ACPI 6.0 NFIT Memory Device State Flags in Table 5-129 defines
NVDIMM status as follows.  These bits indicate multiple info,
such as failures, pending event, and capability.

  Bit [0] set to 1 to indicate that the previous SAVE to the
  Memory Device failed.
  Bit [1] set to 1 to indicate that the last RESTORE from the
  Memory Device failed.
  Bit [2] set to 1 to indicate that platform flush of data to
  Memory Device failed. As a result, the restored data content
  may be inconsistent even if SAVE and RESTORE do not indicate
  failure.
  Bit [3] set to 1 to indicate that the Memory Device is observed
  to be not armed prior to OSPM hand off. A Memory Device is
  considered armed if it is able to accept persistent writes.
  Bit [4] set to 1 to indicate that the Memory Device observed
  SMART and health events prior to OSPM handoff.

/sys/bus/nd/devices/nmemX/nfit/flags shows this flags info.
The output strings associated with the bits are "save", "restore",
"smart", etc., which can be confusing as they may be interpreted
as positive status, i.e. save succeeded.

Change also the dev_info() message in acpi_nfit_register_dimms()
to be consistent with the sysfs flags strings.
Reported-by: NRobert Elliott <elliott@hp.com>
Signed-off-by: NToshi Kani <toshi.kani@hp.com>
[ross: rename 'not_arm' to 'not_armed']
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
[djbw: defer adding bit5, HEALTH_ENABLED, for now]
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

Only read 32 bits for the BLK status register in read_blk_stat().

The format and size of this register is defined in the
"NVDIMM Driver Writer's guide":

http://pmem.io/documents/NVDIMM_Driver_Writers_Guide.pdfSigned-off-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Reported-by: NNicholas Moulin <nicholas.w.moulin@linux.intel.com>
Tested-by: NNicholas Moulin <nicholas.w.moulin@linux.intel.com>
Reviewed-by: NJeff Moyer <jmoyer@redhat.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

The _STA only applies to the root device, not the individual NVDIMMS,
so don't check here. NVDIMM device state flags are checked elsewhere.
Signed-off-by: NLinda Knippers <linda.knippers@hp.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

Add support for the three ARS DSM commands:
- Query ARS Capabilities - Queries the firmware to check if a given
  range supports scrub, and if so, which type (persistent vs. volatile)
- Start ARS - Starts a scrub for a given range/type
- Query ARS Status - Checks status of a previously started scrub, and
  provides the error logs if any.

  The commands are described by the example DSM spec at:
  http://pmem.io/documents/NVDIMM_DSM_Interface_Example.pdf

Also add these commands to the nfit_test test framework, and return
canned data.
Signed-off-by: NVishal Verma <vishal.l.verma@intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

Add support in the NFIT BLK I/O path for the "latch" flag
defined in the "Get Block NVDIMM Flags" _DSM function:

http://pmem.io/documents/NVDIMM_DSM_Interface_Example.pdf

This flag requires the driver to read back the command register after it
is written in the block I/O path.  This ensures that the hardware has
fully processed the new command and moved the aperture appropriately.
Signed-off-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Acked-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

Update the nfit block I/O path to use the new PMEM API and to adhere to
the read/write flows outlined in the "NVDIMM Block Window Driver
Writer's Guide":

http://pmem.io/documents/NVDIMM_Driver_Writers_Guide.pdf

This includes adding support for targeted NVDIMM flushes called "flush
hints" in the ACPI 6.0 specification:

http://www.uefi.org/sites/default/files/resources/ACPI_6.0.pdf

For performance and media durability the mapping for a BLK aperture is
moved to a write-combining mapping which is consistent with
memcpy_to_pmem() and wmb_blk().
Signed-off-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Acked-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>