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

Tue Sep 8 00:30:57 PDT 2026

On 09/08 06:46, Suzuki K Poulose wrote:
> 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.

Thank you for pointing me in the right direction and Ccing Mathieu and
Lorenzo. 
I'll wait for their response.

> 
> On 08/09/2026 05:09, Kohei Enju wrote:
> > Hi Suzuki,
> > 
> > On 09/07 10:59, Suzuki K Poulose wrote:
> > > 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
> > 
> > > [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
> > > 
> > > -- 
> > > 2.43.0
> > > 
> 