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@dwil...
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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
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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