Re: [PATCH v17 0/7] firmware: arm_rmm: Add RMM v2.0 base RMI support

Hi Kohei-San

Linaro is best suited to answer this. I have Cc'ed Mathieu (and
Lorenzo), who may be able to help you here.

On 08/09/2026 05:09, Kohei Enju wrote:

Hi Suzuki,

On 09/07 10:59, Suzuki K Poulose wrote:

quoted

This series adds the generic firmware layer for talking to the Realm
Management Monitor (RMM), as specified by the RMM v2.0-bet3
specification[1]. It is the first part of the Arm CCA host support that
was previously posted as part of the larger KVM series.

The split allows this RMM support to be used as a base for other work,
including Aneesh's PCI IDE support with Arm CCA RMM as the TSM,
  without depending on the KVM Realm support that will follow as separate
  series. (See more on that below)

The series adds:

  * The RMI SMC definitions and direct-call wrappers.

  * RMM discovery and version checks during firmware init.

  * RMM host configuration, including the host page size.

  * Stateful RMI Operation (SRO) infrastructure for commands which the RMM
    can complete across multiple SMC calls while requesting or returning
    memory to the host.

  * Verification that granule tracking is available at fine granularity.
    Fine-grained tracking allows each granule in the system to be tracked
    independently, which is required before individual granules can be
    delegated. A future series will add support for dynamically supplying
    memory to the RMM for this tracking.

  * Support for fully firmware-managed systems, where the Granule Protection
    Tables for memory regions are allocated and managed by firmware. RMM v2.0
    also allows dynamic GPT creation on demand; support for that will be added
    in a later series.

  * Wrappers for the RMI commands that are used for managing the "Realm VM"
    lifecycle. This is added in to make it easier for the on-going KVM support
    to evolve in parallel pieces.

If the platform firmware cannot manage the granule tracking or the GPTs, we
bail out and deactivate the RMM, reclaiming any memory that we have donated.

The RMM v2.0 spec introduces Stateful RMI Operations (SROs), which allow
the RMM to complete an operation over several SMC calls while requesting
or returning memory to the host. This allows interrupts to be handled in
the middle of an operation and lets the RMM dynamically allocate memory
for internal tracking purposes. For example, RMI_REC_CREATE no longer
needs auxiliary granules to be provided up front, and can instead
request memory during the operation.

This series applies on v7.3-rc1 and a branch is available at [2]. The KVM
CCA support that builds on this series is available at [3] as an integration
branch. The KVM support depends on guest-memfd-in-place conversion support v12
from Ackerley [4], we plan to split that into parts, which apply cleanly on
v7.3-rcx without any dependency and is in progress. This will be made available
as soon as it is ready. Until then [3] shows how this base series enables KVM
CCA support. You may find the tf-RMM [5] and kvmtool support [6] below.

[1] RMM spec : https://support.arm.com/documentation/den0137/2-0bet3/
[2] This series: https://gitlab.arm.com/linux-arm/linux-cca.git cca/cca-host/fw_rmm/v17
[3] KVM CCA v17 integration branch: https://gitlab.arm.com/linux-arm/linux-cca.git cca/cca-host/kvm-integration/v17
[4] Gmem inplace conversion https://github.com/googleprodkernel/linux-cc/tree/guest_memfd-inplace-conversion-v12
[5] TF-RMM https://git.trustedfirmware.org/TF-RMM/tf-rmm.git main (commit: 134266ae)

I understand that QEMU-virt is not intended to model a realistic
production platform and that QEMU-SBSA is generally preferred. However,
I sometimes use QEMU-virt to test functionality quickly because it runs
slightly faster than QEMU-SBSA.

I tested this series with QEMU-virt and found that RMM initialization
failed during boot:

   [...]
   INFO:    BL31: Initializing RMM
   INFO:    RMM init start.
   ERROR:   RMM init failed: -8
   WARNING: BL31: RMM initialization failed

The following TF-A revision was used:
   https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git master (38269bb)

After investigating, I found that the failure was caused by the lack of
a plat_rmmd_reserve_memory() implementation for the QEMU-virt platform
in TF-A. Adding an implementation equivalent to the QEMU-SBSA one
resolved the issue:
     https://git.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a.git/+/9d594743aa4d4e8160cdf025ea7538041648972c

Is QEMU virt still intended to be supported as an RME emulation
platform? In particular, is this functionality simply not implemented
yet, or is there a reason why RME support is not planned for QEMU virt?

If this is not the appropriate place to discuss this, please let me

Mathieu, Lorenzo,

Over to you folks :-)

Cheers
Suzuki

know :)

Thanks,
Kohei

quoted

[6] kvmtool https://gitlab.arm.com/linux-arm/kvmtool-cca.git cca/kvm-v17

Known issues: RMMv2.0
  * RmiOpMemDonateReq:count (Uint14) is incompatible with RmiAddrRangeDesc4KB
   (Uint10) and RmiAddrRangeDesc16KB (Uint12). i.e., a larger contiguous request
   may not be satisfiable by the host. Arm is aware of this defect and a spec fix
   is in progress.


Steven Price (7):
   firmware: arm_rmm: Add SMC definitions for calling the RMM
   firmware: arm_rmm: Check for RMI support at init
   firmware: arm_rmm: Configure the RMM with the host's page size
   firmware: arm_rmm: Add support for SRO
   firmware: arm_rmm: Activate the RMM
   firmware: arm_rmm: Ensure the RMM has GPT entries for memory
   firmware: arm_rmm: Add wrappers for Realm related RMI commands

  arch/arm64/Kconfig                |   1 +
  arch/arm64/kernel/cpufeature.c    |   1 +
  drivers/firmware/Kconfig          |   1 +
  drivers/firmware/Makefile         |   1 +
  drivers/firmware/arm_rmm/Kconfig  |  26 +
  drivers/firmware/arm_rmm/Makefile |   2 +
  drivers/firmware/arm_rmm/rmi.c    | 819 ++++++++++++++++++++++++++++++
  include/linux/arm-rmi-cmds.h      | 678 +++++++++++++++++++++++++
  include/linux/arm-smccc-rmi.h     | 494 ++++++++++++++++++
  9 files changed, 2023 insertions(+)
  create mode 100644 drivers/firmware/arm_rmm/Kconfig
  create mode 100644 drivers/firmware/arm_rmm/Makefile
  create mode 100644 drivers/firmware/arm_rmm/rmi.c
  create mode 100644 include/linux/arm-rmi-cmds.h
  create mode 100644 include/linux/arm-smccc-rmi.h

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2.43.0