Re: [PATCH v18 4/7] firmware: arm_rmm: Add support for SRO

[Suzuki K Poulose <suzuki.poulose@arm.com>]

On 14/09/2026 07:22, Suzuki K Poulose wrote:
> Hi Gavin
> 
> Thank you for the review, I will address most of them. Responses inline.
> 
> On 14/09/2026 06:04, Gavin Shan wrote:
>> On 9/12/26 6:36 PM, Suzuki K Poulose wrote:
>>> RMM v2.0 introduces the concept of "Stateful RMI Operations" (SRO). This
>>> means that an SMC can return with an operation still in progress. The
>>> host is expected to continue the operation until it reaches a conclusion
>>> (either success or failure). During this process the RMM can request
>>> additional memory ('donate') or hand memory back to the host
>>> ('reclaim'). The host can request an in progress operation is cancelled,
>>> but still continue the operation until it has completed (otherwise the
>>> incomplete operation may cause future RMM operations to fail).
>>>
>>> The SRO is tracked using a struct rmi_sro_state object which keeps track
>>> of any memory which has been allocated but not yet consumed by the RMM
>>> or reclaimed from the RMM. This allows the memory to be reused in a
>>> future request within the same operation. It will also permit an
>>> operation to be done in a context where memory allocation may be
>>> difficult (e.g. atomic context) with the option to abort the operation
>>> and retry the memory allocation outside of the atomic context. The
>>> memory stored in the struct rmi_sro_state object can then be reused on
>>> the subsequent attempt.
>>>
>>> Wrappers for SRO RMI commands are also provided here because they depend
>>> on the rmi_sro_execute() implementation added by this patch.
>>> Delegate/undelegate handles are also added here because they now use the
>>> SRO/stateful command infrastructure and are also used for the memory
>>> DONATE/RECLAIM flows.
>>>
>>> Signed-off-by: Steven Price <steven.price@arm.com>
>>> Co-Developed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
>>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> 
> 
> 
>>> ---
>>>   drivers/firmware/arm_rmm/rmi.c | 586 +++++++++++++++++++++++++++++++++
>>>   include/linux/arm-rmi-cmds.h   |  41 +++
>>>   2 files changed, 627 insertions(+)
>>>
>>> diff --git a/drivers/firmware/arm_rmm/rmi.c b/drivers/firmware/ 
>>> arm_rmm/rmi.c
>>> index 5b0e342ce3d58..4f9898ece7547 100644
>>> --- a/drivers/firmware/arm_rmm/rmi.c
>>> +++ b/drivers/firmware/arm_rmm/rmi.c
> 
>>
>> I would drop rmi_granule_range_{delegate, undelegate}() by combining 
>> their logics to
>> their only callers rmi_{delegate, undelegate}_range(). More details 
>> are provided for
>> rmi_{delegate, undelegate}_range() in the below.
> 
> Ack

I have moved them closer, but kept the logic separate, since this is not
a simple RMI call.

Cheers
Suzuki