KVM: SEV: Do cache maintenance on the source VM during intra-host migrationgrafted

Manually perform cache maintenance on the source VM during intra-host
migration to ensure no stale data is left in CPU caches after the VM is
destroyed.  Because the source VM is "converted" to a non-SEV VM, KVM's
memory reclaim flows won't trigger cache maintenance, e.g. when all guest
memory is reclaimed in response to detaching from the mmu_notifier.

Note, relying on the destination VM to do cache maintenance isn't an option
as KVM doesn't require identical guest memory configurations, i.e. the
source VM may have access to memory that the destination VM does not.
Enforcing equivalent memory configurations is infeasible, as it would
require a *deep* comparison of memslots, e.g. to verify that not only are
the memslot identical, but what the memslots point at is also identical.

Fixes: b56639318bb2 ("KVM: SEV: Add support for SEV intra host migration")
Cc: stable@vger.kernel.org
Reported-by: Stefan Teodorescu <fane@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260923163721.1584779-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 1089 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-hwmon b/Documentation/ABI/testing/sysfs-class-hwmon
new file mode 100644
index 000000000..b185bdfc7
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-hwmon
@@ -0,0 +1,1089 @@
+What:		/sys/class/hwmon/hwmonX/name
+Description:
+		The chip name.
+		This should be a short, lowercase string, not containing
+		whitespace, dashes, or the wildcard character '*'.
+		This attribute represents the chip name. It is the only
+		mandatory attribute.
+		I2C devices get this attribute created automatically.
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/label
+Description:
+		A descriptive label that allows to uniquely identify a
+		device within the system.
+		The contents of the label are free-form.
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/update_interval
+Description:
+		The interval at which the chip will update readings.
+		Unit: millisecond
+
+		RW
+
+		Some devices have a variable update rate or interval.
+		This attribute can be used to change it to the desired value.
+
+What:		/sys/class/hwmon/hwmonX/update_interval_us
+Description:
+		The interval at which the chip will update readings,
+		expressed in microseconds.
+		Unit: microsecond
+
+		RW
+
+		Some devices have a variable update rate or interval and
+		require finer-than-millisecond control.
+		This attribute can be used to change it to the desired value.
+		Drivers implementing this attribute should also implement
+		update_interval for millisecond-based userspace interfaces.
+
+What:		/sys/class/hwmon/hwmonX/inY_min
+Description:
+		Voltage min value.
+
+		Unit: millivolt
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/inY_lcrit
+Description:
+		Voltage critical min value.
+
+		Unit: millivolt
+
+		RW
+
+		If voltage drops to or below this limit, the system may
+		take drastic action such as power down or reset. At the very
+		least, it should report a fault.
+
+What:		/sys/class/hwmon/hwmonX/inY_max
+Description:
+		Voltage max value.
+
+		Unit: millivolt
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/inY_crit
+Description:
+		Voltage critical max value.
+
+		Unit: millivolt
+
+		RW
+
+		If voltage reaches or exceeds this limit, the system may
+		take drastic action such as power down or reset. At the very
+		least, it should report a fault.
+
+What:		/sys/class/hwmon/hwmonX/inY_input
+Description:
+		Voltage input value.
+
+		Unit: millivolt
+
+		RO
+
+		Voltage measured on the chip pin.
+
+		Actual voltage depends on the scaling resistors on the
+		motherboard, as recommended in the chip datasheet.
+
+		This varies by chip and by motherboard.
+		Because of this variation, values are generally NOT scaled
+		by the chip driver, and must be done by the application.
+		However, some drivers (notably lm87 and via686a)
+		do scale, because of internal resistors built into a chip.
+		These drivers will output the actual voltage. Rule of
+		thumb: drivers should report the voltage values at the
+		"pins" of the chip.
+
+What:		/sys/class/hwmon/hwmonX/inY_average
+Description:
+		Average voltage
+
+		Unit: millivolt
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/inY_lowest
+Description:
+		Historical minimum voltage
+
+		Unit: millivolt
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/inY_highest
+Description:
+		Historical maximum voltage
+
+		Unit: millivolt
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/inY_reset_history
+Description:
+		Reset inX_lowest and inX_highest
+
+		WO
+
+What:		/sys/class/hwmon/hwmonX/in_reset_history
+Description:
+		Reset inX_lowest and inX_highest for all sensors
+
+		WO
+
+What:		/sys/class/hwmon/hwmonX/inY_label
+Description:
+		Suggested voltage channel label.
+
+		Text string
+
+		Should only be created if the driver has hints about what
+		this voltage channel is being used for, and user-space
+		doesn't. In all other cases, the label is provided by
+		user-space.
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/inY_enable
+Description:
+		Enable or disable the sensors.
+
+		When disabled the sensor read will return -ENODATA.
+
+		- 1: Enable
+		- 0: Disable
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/inY_fault
+Description:
+		Reports a voltage hard failure (eg: shorted component)
+
+		- 1: Failed
+		- 0: Ok
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/cpuY_vid
+Description:
+		CPU core reference voltage.
+
+		Unit: millivolt
+
+		RO
+
+		Not always correct.
+
+What:		/sys/class/hwmon/hwmonX/vrm
+Description:
+		Voltage Regulator Module version number.
+
+		RW (but changing it should no more be necessary)
+
+		Originally the VRM standard version multiplied by 10, but now
+		an arbitrary number, as not all standards have a version
+		number.
+
+		Affects the way the driver calculates the CPU core reference
+		voltage from the vid pins.
+
+What:		/sys/class/hwmon/hwmonX/inY_rated_min
+Description:
+		Minimum rated voltage.
+
+		Unit: millivolt
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/inY_rated_max
+Description:
+		Maximum rated voltage.
+
+		Unit: millivolt
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/fanY_min
+Description:
+		Fan minimum value
+
+		Unit: revolution/min (RPM)
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/fanY_max
+Description:
+		Fan maximum value
+
+		Unit: revolution/min (RPM)
+
+		Only rarely supported by the hardware.
+		RW
+
+What:		/sys/class/hwmon/hwmonX/fanY_input
+Description:
+		Fan input value.
+
+		Unit: revolution/min (RPM)
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/fanY_div
+Description:
+		Fan divisor.
+
+		Integer value in powers of two (1, 2, 4, 8, 16, 32, 64, 128).
+
+		RW
+
+		Some chips only support values 1, 2, 4 and 8.
+		Note that this is actually an internal clock divisor, which
+		affects the measurable speed range, not the read value.
+
+What:		/sys/class/hwmon/hwmonX/fanY_pulses
+Description:
+		Number of tachometer pulses per fan revolution.
+
+		Integer value, typically between 1 and 4.
+
+		RW
+
+		This value is a characteristic of the fan connected to the
+		device's input, so it has to be set in accordance with the fan
+		model.
+
+		Should only be created if the chip has a register to configure
+		the number of pulses. In the absence of such a register (and
+		thus attribute) the value assumed by all devices is 2 pulses
+		per fan revolution.
+
+What:		/sys/class/hwmon/hwmonX/fanY_target
+Description:
+		Desired fan speed
+
+		Unit: revolution/min (RPM)
+
+		RW
+
+		Only makes sense if the chip supports closed-loop fan speed
+		control based on the measured fan speed.
+
+What:		/sys/class/hwmon/hwmonX/fanY_label
+Description:
+		Suggested fan channel label.
+
+		Text string
+
+		Should only be created if the driver has hints about what
+		this fan channel is being used for, and user-space doesn't.
+		In all other cases, the label is provided by user-space.
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/fanY_enable
+Description:
+		Enable or disable the sensors.
+
+		When disabled the sensor read will return -ENODATA.
+
+		- 1: Enable
+		- 0: Disable
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/fanY_fault
+Description:
+		Reports if a fan has reported failure.
+
+		- 1: Failed
+		- 0: Ok
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/pwmY
+Description:
+		Pulse width modulation fan control.
+
+		Integer value in the range 0 to 255
+
+		RW
+
+		255 is max or 100%.
+
+What:		/sys/class/hwmon/hwmonX/pwmY_enable
+Description:
+		Fan speed control method:
+
+		- 0: no fan speed control (i.e. fan at full speed)
+		- 1: manual fan speed control enabled (using `pwmY`)
+		- 2+: automatic fan speed control enabled
+
+		Check individual chip documentation files for automatic mode
+		details.
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/pwmY_mode
+Description:
+		- 0: DC mode (direct current)
+		- 1: PWM mode (pulse-width modulation)
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/pwmY_freq
+Description:
+		Base PWM frequency in Hz.
+
+		Only possibly available when pwmN_mode is PWM, but not always
+		present even then.
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/pwmY_auto_channels_temp
+Description:
+		Select which temperature channels affect this PWM output in
+		auto mode.
+
+		Bitfield, 1 is temp1, 2 is temp2, 4 is temp3 etc...
+		Which values are possible depend on the chip used.
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/pwmY_auto_pointZ_pwm
+What:		/sys/class/hwmon/hwmonX/pwmY_auto_pointZ_temp
+What:		/sys/class/hwmon/hwmonX/pwmY_auto_pointZ_temp_hyst
+Description:
+		Define the PWM vs temperature curve.
+
+		Number of trip points is chip-dependent. Use this for chips
+		which associate trip points to PWM output channels.
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/tempY_auto_pointZ_pwm
+What:		/sys/class/hwmon/hwmonX/tempY_auto_pointZ_temp
+What:		/sys/class/hwmon/hwmonX/tempY_auto_pointZ_temp_hyst
+Description:
+		Define the PWM vs temperature curve.
+
+		Number of trip points is chip-dependent. Use this for chips
+		which associate trip points to temperature channels.
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/tempY_type
+Description:
+		Sensor type selection.
+
+		Integers 1 to 6
+
+		RW
+
+		- 1: CPU embedded diode
+		- 2: 3904 transistor
+		- 3: thermal diode
+		- 4: thermistor
+		- 5: AMD AMDSI
+		- 6: Intel PECI
+
+		Not all types are supported by all chips
+
+What:		/sys/class/hwmon/hwmonX/tempY_max
+Description:
+		Temperature max value.
+
+		Unit: millidegree Celsius (or millivolt, see below)
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/tempY_max_alarm
+Description:
+		Maximum temperature alarm flag.
+
+		- 0: OK
+		- 1: temperature has reached tempY_max
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/tempY_min
+Description:
+		Temperature min value.
+
+		Unit: millidegree Celsius
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/tempY_min_alarm
+Description:
+		Minimum temperature alarm flag.
+
+		- 0: OK
+		- 1: temperature has reached tempY_min
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/tempY_max_hyst
+Description:
+		Temperature hysteresis value for max limit.
+
+		Unit: millidegree Celsius
+
+		Must be reported as an absolute temperature, NOT a delta
+		from the max value.
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/tempY_min_hyst
+Description:
+		Temperature hysteresis value for min limit.
+		Unit: millidegree Celsius
+
+		Must be reported as an absolute temperature, NOT a delta
+		from the min value.
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/tempY_input
+Description:
+		Temperature input value.
+
+		Unit: millidegree Celsius
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/tempY_crit
+Description:
+		Temperature critical max value, typically greater than
+		corresponding temp_max values.
+
+		Unit: millidegree Celsius
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/tempY_crit_alarm
+Description:
+		Critical high temperature alarm flag.
+
+		- 0: OK
+		- 1: temperature has reached tempY_crit
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/tempY_crit_hyst
+Description:
+		Temperature hysteresis value for critical limit.
+
+		Unit: millidegree Celsius
+
+		Must be reported as an absolute temperature, NOT a delta
+		from the critical value.
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/tempY_emergency
+Description:
+		Temperature emergency max value, for chips supporting more than
+		two upper temperature limits. Must be equal or greater than
+		corresponding temp_crit values.
+
+		Unit: millidegree Celsius
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/tempY_emergency_alarm
+Description:
+		Emergency high temperature alarm flag.
+
+		- 0: OK
+		- 1: temperature has reached tempY_emergency
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/tempY_emergency_hyst
+Description:
+		Temperature hysteresis value for emergency limit.
+
+		Unit: millidegree Celsius
+
+		Must be reported as an absolute temperature, NOT a delta
+		from the emergency value.
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/tempY_lcrit
+Description:
+		Temperature critical min value, typically lower than
+		corresponding temp_min values.
+
+		Unit: millidegree Celsius
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/tempY_lcrit_hyst
+Description:
+		Temperature hysteresis value for critical min limit.
+
+		Unit: millidegree Celsius
+
+		Must be reported as an absolute temperature, NOT a delta
+		from the critical min value.
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/tempY_offset
+Description:
+		Temperature offset which is added to the temperature reading
+		by the chip.
+
+		Unit: millidegree Celsius
+
+		Read/Write value.
+
+What:		/sys/class/hwmon/hwmonX/tempY_label
+Description:
+		Suggested temperature channel label.
+
+		Text string
+
+		Should only be created if the driver has hints about what
+		this temperature channel is being used for, and user-space
+		doesn't. In all other cases, the label is provided by
+		user-space.
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/tempY_lowest
+Description:
+		Historical minimum temperature
+
+		Unit: millidegree Celsius
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/tempY_highest
+Description:
+		Historical maximum temperature
+
+		Unit: millidegree Celsius
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/tempY_reset_history
+Description:
+		Reset temp_lowest and temp_highest
+
+		WO
+
+What:		/sys/class/hwmon/hwmonX/temp_reset_history
+Description:
+		Reset temp_lowest and temp_highest for all sensors
+
+		WO
+
+What:		/sys/class/hwmon/hwmonX/tempY_enable
+Description:
+		Enable or disable the sensors.
+
+		When disabled the sensor read will return -ENODATA.
+
+		- 1: Enable
+		- 0: Disable
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/tempY_rated_min
+Description:
+		Minimum rated temperature.
+
+		Unit: millidegree Celsius
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/tempY_rated_max
+Description:
+		Maximum rated temperature.
+
+		Unit: millidegree Celsius
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/currY_max
+Description:
+		Current max value
+
+		Unit: milliampere
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/currY_min
+Description:
+		Current min value.
+
+		Unit: milliampere
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/currY_lcrit
+Description:
+		Current critical low value
+
+		Unit: milliampere
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/currY_crit
+Description:
+		Current critical high value.
+
+		Unit: milliampere
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/currY_input
+Description:
+		Current input value
+
+		Unit: milliampere
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/currY_average
+Description:
+		Average current use
+
+		Unit: milliampere
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/currY_lowest
+Description:
+		Historical minimum current
+
+		Unit: milliampere
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/currY_highest
+Description:
+		Historical maximum current
+		Unit: milliampere
+		RO
+
+What:		/sys/class/hwmon/hwmonX/currY_reset_history
+Description:
+		Reset currX_lowest and currX_highest
+
+		WO
+
+What:		/sys/class/hwmon/hwmonX/curr_reset_history
+Description:
+		Reset currX_lowest and currX_highest for all sensors
+
+		WO
+
+What:		/sys/class/hwmon/hwmonX/currY_enable
+Description:
+		Enable or disable the sensors.
+
+		When disabled the sensor read will return -ENODATA.
+
+		- 1: Enable
+		- 0: Disable
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/currY_rated_min
+Description:
+		Minimum rated current.
+
+		Unit: milliampere
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/currY_rated_max
+Description:
+		Maximum rated current.
+
+		Unit: milliampere
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/powerY_average
+Description:
+		Average power use
+
+		Unit: microWatt
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/powerY_average_interval
+Description:
+		Power use averaging interval.  A poll
+		notification is sent to this file if the
+		hardware changes the averaging interval.
+
+		Unit: milliseconds
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/powerY_average_interval_max
+Description:
+		Maximum power use averaging interval
+
+		Unit: milliseconds
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/powerY_average_interval_min
+Description:
+		Minimum power use averaging interval
+
+		Unit: milliseconds
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/powerY_average_highest
+Description:
+		Historical average maximum power use
+
+		Unit: microWatt
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/powerY_average_lowest
+Description:
+		Historical average minimum power use
+
+		Unit: microWatt
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/powerY_average_max
+Description:
+		A poll notification is sent to
+		`powerY_average` when power use
+		rises above this value.
+
+		Unit: microWatt
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/powerY_average_min
+Description:
+		A poll notification is sent to
+		`powerY_average` when power use
+		sinks below this value.
+
+		Unit: microWatt
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/powerY_input
+Description:
+		Instantaneous power use
+
+		Unit: microWatt
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/powerY_input_highest
+Description:
+		Historical maximum power use
+
+		Unit: microWatt
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/powerY_input_lowest
+Description:
+		Historical minimum power use
+
+		Unit: microWatt
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/powerY_reset_history
+Description:
+		Reset input_highest, input_lowest,
+		average_highest and average_lowest.
+
+		WO
+
+What:		/sys/class/hwmon/hwmonX/powerY_accuracy
+Description:
+		Accuracy of the power meter.
+
+		Unit: Percent
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/powerY_cap
+Description:
+		If power use rises above this limit, the
+		system should take action to reduce power use.
+		A poll notification is sent to this file if the
+		cap is changed by the hardware.  The `*_cap`
+		files only appear if the cap is known to be
+		enforced by hardware.
+
+		Unit: microWatt
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/powerY_cap_hyst
+Description:
+		Margin of hysteresis built around capping and
+		notification.
+
+		Unit: microWatt
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/powerY_cap_max
+Description:
+		Maximum cap that can be set.
+
+		Unit: microWatt
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/powerY_cap_min
+Description:
+		Minimum cap that can be set.
+
+		Unit: microWatt
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/powerY_max
+Description:
+		Maximum power.
+
+		Unit: microWatt
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/powerY_crit
+Description:
+		Critical maximum power.
+
+		If power rises to or above this limit, the
+		system is expected take drastic action to reduce
+		power consumption, such as a system shutdown or
+		a forced powerdown of some devices.
+
+		Unit: microWatt
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/powerY_enable
+Description:
+		Enable or disable the sensors.
+
+		When disabled the sensor read will return
+		-ENODATA.
+
+		- 1: Enable
+		- 0: Disable
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/powerY_rated_min
+Description:
+		Minimum rated power.
+
+		Unit: microWatt
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/powerY_rated_max
+Description:
+		Maximum rated power.
+
+		Unit: microWatt
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/energyY_input
+Description:
+		Cumulative energy use
+
+		Unit: microJoule
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/energyY_enable
+Description:
+		Enable or disable the sensors.
+
+		When disabled the sensor read will return
+		-ENODATA.
+
+		- 1: Enable
+		- 0: Disable
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/humidityY_alarm
+Description:
+		Humidity limit detection
+
+		- 0: OK
+		- 1: Humidity limit has been reached
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/humidityY_enable
+Description:
+		Enable or disable the sensors
+
+		When disabled the sensor read will return
+		-ENODATA.
+
+		- 1: Enable
+		- 0: Disable
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/humidityY_fault
+Description:
+		Reports a humidity sensor failure.
+
+		- 1: Failed
+		- 0: Ok
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/humidityY_input
+Description:
+		Humidity
+
+		Unit: milli-percent (per cent mille, pcm)
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/humidityY_label
+Description:
+		Suggested humidity channel label.
+
+		Text string
+
+		Should only be created if the driver has hints about what
+		this humidity channel is being used for, and user-space
+		doesn't. In all other cases, the label is provided by
+		user-space.
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/humidityY_max
+Description:
+		Humidity max value.
+
+		Unit: milli-percent (per cent mille, pcm)
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/humidityY_max_alarm
+Description:
+		Maximum humidity detection
+
+		- 0: OK
+		- 1: Maximum humidity detected
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/humidityY_max_hyst
+Description:
+		Humidity hysteresis value for max limit.
+
+		Unit: milli-percent (per cent mille, pcm)
+
+		Must be reported as an absolute humidity, NOT a delta
+		from the max value.
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/humidityY_min
+Description:
+		Humidity min value.
+
+		Unit: milli-percent (per cent mille, pcm)
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/humidityY_min_alarm
+Description:
+		Minimum humidity detection
+
+		- 0: OK
+		- 1: Minimum humidity detected
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/humidityY_min_hyst
+Description:
+		Humidity hysteresis value for min limit.
+
+		Unit: milli-percent (per cent mille, pcm)
+
+		Must be reported as an absolute humidity, NOT a delta
+		from the min value.
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/humidityY_rated_min
+Description:
+		Minimum rated humidity.
+
+		Unit: milli-percent (per cent mille, pcm)
+
+		RO
+
+What:		/sys/class/hwmon/hwmonX/humidityY_rated_max
+Description:
+		Maximum rated humidity.
+
+		Unit: milli-percent (per cent mille, pcm)
+
+		RO
+
+
+What:		/sys/class/hwmon/hwmonX/intrusionY_alarm
+Description:
+		Chassis intrusion detection
+
+		- 0: OK
+		- 1: intrusion detected
+
+		RW
+
+		Contrary to regular alarm flags which clear themselves
+		automatically when read, this one sticks until cleared by
+		the user. This is done by writing 0 to the file. Writing
+		other values is unsupported.
+
+What:		/sys/class/hwmon/hwmonX/intrusionY_beep
+Description:
+		Chassis intrusion beep
+
+		- 0: disable
+		- 1: enable
+
+		RW
+
+What:		/sys/class/hwmon/hwmonX/device/pec
+Description:
+		PEC support on I2C devices
+
+		- 0, off, n: disable
+		- 1, on, y: enable
+
+		RW