[PATCH 1/1] firmware: smccc: add support for Live Firmware Activation (LFA)

[Trilok Soni]

On 2/20/2026 9:39 AM, Andre Przywara wrote:
> On Mon, 19 Jan 2026 12:27:29 +0000
> Salman Nabi <salman.nabi at arm.com> wrote:
> 
> Hey,
> 
> for the records: while working on improving the patch and during internal
> review, we found some bugs and issues in there. I will mark them below for
> the benefit of others. I will send a v2 after -rc1, with those things
> fixed and some improvements, and will include Vedashree's patches, so
> that we have everything in one series.
> 
>> The Arm Live Firmware Activation (LFA) is a specification [1] to describe
>> activating firmware components without a reboot. Those components
>> (like TF-A's BL31, EDK-II, TF-RMM, secure paylods) would be updated the
>> usual way: via fwupd, FF-A or other secure storage methods, or via some
>> IMPDEF Out-Of-Bound method. The user can then activate this new firmware,
>> at system runtime, without requiring a reboot.
>> The specification covers the SMCCC interface to list and query available
>> components and eventually trigger the activation.
>>
>> Add a new directory under /sys/firmware to present firmware components
>> capable of live activation. Each of them is a directory under lfa/,
>> and is identified via its GUID. The activation will be triggered by echoing
>> "1" into the "activate" file:
>> ==========================================
>> /sys/firmware/lfa # ls -l . 6c*
>> .:
>> total 0
>> drwxr-xr-x    2 0 0         0 Jan 19 11:33 47d4086d-4cfe-9846-9b95-2950cbbd5a00
>> drwxr-xr-x    2 0 0         0 Jan 19 11:33 6c0762a6-12f2-4b56-92cb-ba8f633606d9
>> drwxr-xr-x    2 0 0         0 Jan 19 11:33 d6d0eea7-fcea-d54b-9782-9934f234b6e4
>>
>> 6c0762a6-12f2-4b56-92cb-ba8f633606d9:
>> total 0
>> --w-------    1 0        0             4096 Jan 19 11:33 activate
>> -r--r--r--    1 0        0             4096 Jan 19 11:33 activation_capable
>> -r--r--r--    1 0        0             4096 Jan 19 11:33 activation_pending
>> --w-------    1 0        0             4096 Jan 19 11:33 cancel
>> -r--r--r--    1 0        0             4096 Jan 19 11:33 cpu_rendezvous
>> -r--r--r--    1 0        0             4096 Jan 19 11:33 current_version
>> -rw-r--r--    1 0        0             4096 Jan 19 11:33 force_cpu_rendezvous
>> -r--r--r--    1 0        0             4096 Jan 19 11:33 may_reset_cpu
>> -r--r--r--    1 0        0             4096 Jan 19 11:33 name
>> -r--r--r--    1 0        0             4096 Jan 19 11:33 pending_version
>> /sys/firmware/lfa/6c0762a6-12f2-4b56-92cb-ba8f633606d9 # grep . *
>> grep: activate: Permission denied
>> activation_capable:1
>> activation_pending:1
>> grep: cancel: Permission denied
>> cpu_rendezvous:1
>> current_version:0.0
>> force_cpu_rendezvous:1
>> may_reset_cpu:0
>> name:TF-RMM
>> pending_version:0.0
>> /sys/firmware/lfa/6c0762a6-12f2-4b56-92cb-ba8f633606d9 # echo 1 > activate
>> [ 2825.797871] Arm LFA: firmware activation succeeded.
>> /sys/firmware/lfa/6c0762a6-12f2-4b56-92cb-ba8f633606d9 #
>> ==========================================
>>
>> [1] https://developer.arm.com/documentation/den0147/latest/
>>
>> Signed-off-by: Salman Nabi <salman.nabi at arm.com>
>> ---
>>  drivers/firmware/smccc/Kconfig  |   8 +
>>  drivers/firmware/smccc/Makefile |   1 +
>>  drivers/firmware/smccc/lfa_fw.c | 668 ++++++++++++++++++++++++++++++++
>>  3 files changed, 677 insertions(+)
>>  create mode 100644 drivers/firmware/smccc/lfa_fw.c
>>
>> diff --git a/drivers/firmware/smccc/Kconfig b/drivers/firmware/smccc/Kconfig
>> index 15e7466179a6..ff7ca49486b0 100644
>> --- a/drivers/firmware/smccc/Kconfig
>> +++ b/drivers/firmware/smccc/Kconfig
>> @@ -23,3 +23,11 @@ config ARM_SMCCC_SOC_ID
>>  	help
>>  	  Include support for the SoC bus on the ARM SMCCC firmware based
>>  	  platforms providing some sysfs information about the SoC variant.
>> +
>> +config ARM_LFA
>> +	tristate "Arm Live Firmware activation support"
>> +	depends on HAVE_ARM_SMCCC_DISCOVERY
> 
> As the kernel test robot correctly pointed out, this only works on ARM64.
> SMCCC v1.2 is only defined for AArch64, and the LFA spec documents
> actually explicitly mentions AArch64-only at the beginning.


Thank you for the update. How to test these patches outside of NVIDIA devices?
Is it possible to test them on the QEMU or FVP? Any instructions on doing
these tests will be helpful w/ the virtual platforms. 

---Trilok Soni