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    Subject[PATCH v2 00/12] ACPI/NVDIMM: Runtime Firmware Activation
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    Date
    Changes since v1 [1]:
    - Move the syscore callback from 'suspend' path to the 'hibernate' path
    (Rafael)

    - Add a new PM debug test mode, 'mem-quiet' to disable some unnecessary
    hibernation steps (memory image preparation) and debug sleeps when the
    hibernation code is just being used to quiet the system for firmware
    activation. (Rafael)

    - Greg already applied "driver-core: Introduce
    DEVICE_ATTR_ADMIN_{RO,RW}" to driver-core-next, so I'll need to
    duplicate that commit in nvdimm.git, or work out a common branch
    baseline with Greg for this topic and driver-core-next to share.

    [1]: http://lore.kernel.org/r/159312902033.1850128.1712559453279208264.stgit@dwillia2-desk3.amr.corp.intel.com

    ---

    Quoting the documentation:

    Some persistent memory devices run a firmware locally on the device /
    "DIMM" to perform tasks like media management, capacity provisioning,
    and health monitoring. The process of updating that firmware typically
    involves a reboot because it has implications for in-flight memory
    transactions. However, reboots are disruptive and at least the Intel
    persistent memory platform implementation, described by the Intel ACPI
    DSM specification [1], has added support for activating firmware at
    runtime.

    [1]: https://docs.pmem.io/persistent-memory/

    The approach taken is to abstract the Intel platform specific mechanism
    behind a libnvdimm-generic sysfs interface. The interface could support
    runtime-firmware-activation on another architecture without need to
    change userspace tooling.

    The ACPI NFIT implementation involves a set of device-specific-methods
    (DSMs) to 'arm' individual devices for activation and bus-level
    'trigger' method to execute the activation. Informational / enumeration
    methods are also provided at the bus and device level.

    One complicating aspect of the memory device firmware activation is that
    the memory controller may need to be quiesced, no memory cycles, during
    the activation. While the platform has mechanisms to support holding off
    in-flight DMA during the activation, the device response to that delay
    is potentially undefined. The platform may reject a runtime firmware
    update if, for example a PCI-E device does not support its completion
    timeout value being increased to meet the activation time. Outside of
    device timeouts the quiesce period may also violate application
    timeouts.

    Given the above device and application timeout considerations the
    implementation defaults to hooking into the hibernation path to trigger
    the activation, i.e. that a hibernate-resume cycle (at least up to the
    syscore mem-quiet point) is required. That default policy ensures that
    the system is in a quiescent state before ceasing memory controller
    responses for the activate. However, if desired, runtime activation
    without the hibernate freeze can be forced as an override.

    The ndctl utility grows the following extensions / commands to drive
    this mechanism:

    1/ The existing update-firmware command will 'arm' devices where the
    firmware image is staged by default.

    ndctl update-firmware all -f firmware_image.bin

    2/ The existing ability to enumerate firmware-update capabilities now
    includes firmware activate capabilities at the 'bus' and 'dimm/device'
    level:

    ndctl list -BDF -b nfit_test.0
    [
    {
    "provider":"nfit_test.0",
    "dev":"ndbus2",
    "scrub_state":"idle",
    "firmware":{
    "activate_method":"suspend",
    "activate_state":"idle"
    },
    "dimms":[
    {
    "dev":"nmem1",
    "id":"cdab-0a-07e0-ffffffff",
    "handle":0,
    "phys_id":0,
    "security":"disabled",
    "firmware":{
    "current_version":0,
    "can_update":true
    }
    },
    ...

    3/ When the system can support activation without quiesce, or when the
    hibernate-resume requirement is going to be suppressed, the new
    activate-firmware command wraps that functionality:

    ndctl activate-firmware nfit_test.0 --force

    Otherwise, if activate_method is "suspend" then the activation can be
    triggered by the mem-quiet hibernate debug state, or a full hibernate
    resume:

    echo mem-quiet > /sys/power/pm_debug
    echo disk > /sys/power/state

    ---

    Dan Williams (12):
    libnvdimm: Validate command family indices
    ACPI: NFIT: Move bus_dsm_mask out of generic nvdimm_bus_descriptor
    ACPI: NFIT: Define runtime firmware activation commands
    tools/testing/nvdimm: Cleanup dimm index passing
    tools/testing/nvdimm: Add command debug messages
    tools/testing/nvdimm: Prepare nfit_ctl_test() for ND_CMD_CALL emulation
    tools/testing/nvdimm: Emulate firmware activation commands
    driver-core: Introduce DEVICE_ATTR_ADMIN_{RO,RW}
    libnvdimm: Convert to DEVICE_ATTR_ADMIN_RO()
    libnvdimm: Add runtime firmware activation sysfs interface
    PM, libnvdimm: Add 'mem-quiet' state and callback for firmware activation
    ACPI: NFIT: Add runtime firmware activate support


    Documentation/ABI/testing/sysfs-bus-nfit | 35 ++
    Documentation/ABI/testing/sysfs-bus-nvdimm | 2
    .../driver-api/nvdimm/firmware-activate.rst | 74 +++
    drivers/acpi/nfit/core.c | 146 +++++--
    drivers/acpi/nfit/intel.c | 426 ++++++++++++++++++++
    drivers/acpi/nfit/intel.h | 61 +++
    drivers/acpi/nfit/nfit.h | 39 ++
    drivers/base/syscore.c | 21 +
    drivers/nvdimm/bus.c | 46 ++
    drivers/nvdimm/core.c | 103 +++++
    drivers/nvdimm/dimm_devs.c | 99 +++++
    drivers/nvdimm/namespace_devs.c | 2
    drivers/nvdimm/nd-core.h | 1
    drivers/nvdimm/pfn_devs.c | 2
    drivers/nvdimm/region_devs.c | 2
    include/linux/device.h | 4
    include/linux/libnvdimm.h | 53 ++
    include/linux/syscore_ops.h | 2
    include/linux/sysfs.h | 7
    include/uapi/linux/ndctl.h | 5
    kernel/power/hibernate.c | 17 +
    kernel/power/main.c | 1
    kernel/power/power.h | 7
    kernel/power/snapshot.c | 13 +
    kernel/power/suspend.c | 12 +
    tools/testing/nvdimm/test/nfit.c | 367 ++++++++++++++---
    26 files changed, 1427 insertions(+), 120 deletions(-)
    create mode 100644 Documentation/ABI/testing/sysfs-bus-nvdimm
    create mode 100644 Documentation/driver-api/nvdimm/firmware-activate.rst

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