Hi, > We are happy to announce the early RFC version of the Arm > Confidential Compute Architecture (CCA) support for the Linux > stack. The intention is to seek early feedback in the following areas: > * KVM integration of the Arm CCA > * KVM UABI for managing the Realms, seeking to generalise the operations > wherever possible with other Confidential Compute solutions. > Note: This version doesn't support Guest Private memory, which will be added > later (see below). > * Linux Guest support for Realms > We have updated the stack for Arm CCA Linux support to RMM-v1.0-EAC2 (See links) We are not posting the patches for review yet, as we plan to update our stack to support the latest RMM-v1.0 specification, which includes some functional changes to support PSCI monitoring by the VMM along with other minor changes. All relevant components are updated on a new branch "rmm-v1.0-eac2" Guest-mem support is not included, but is in progress. Change log : - KVM RMI support updated to v1.0-eac2, with optimisations to stage2 tear down - Guest (Linux and kvm-unit-test) support for RSI compliant to v1.0-eac2 - SVE, PMU support for Realms kvmtool : - Dropped no-compat and switched to --loglevel (merged upstream) - Support for SVE, --sve-vl for vector length > Arm CCA Introduction > ===================== > > The Arm CCA is a reference software architecture and implementation that builds > on the Realm Management Extension (RME), enabling the execution of Virtual > machines, while preventing access by more privileged software, such as hypervisor. > The Arm CCA allows the hypervisor to control the VM, but removes the right for > access to the code, register state or data that is used by VM. > More information on the architecture is available here[0]. > > Arm CCA Reference Software Architecture > > Realm World || Normal World || Secure World || > || | || || > EL0 x-------x || x----x | x------x || || > | Realm | || | | | | | || || > | | || | VM | | | | || || > ----| VM* |---------||-| |---| |-||----------------|| > | | || | | | | H | || || > EL1 x-------x || x----x | | | || || > ^ || | | o | || || > | || | | | || || > ------- R*------------------------| s -|--------------------- > S || | | || || > I || | t | || || > | || | | || || > v || x------x || || > EL2 RMM* || ^ || || > ^ || | || || > ========|=============================|======================== > | | SMC > x--------- *RMI* -------------x > > EL3 Root World > EL3 Firmware > =============================================================== > Where : > RMM - Realm Management Monitor > RMI - Realm Management Interface > RSI - Realm Service Interface > SMC - Secure Monitor Call > > RME introduces a new security state "Realm world", in addition to the > traditional Secure and Non-Secure states. The Arm CCA defines a new component, > Realm Management Monitor (RMM) that runs at R-EL2. This is a standard piece of > firmware, verified, installed and loaded by the EL3 firmware (e.g, TF-A), at > system boot. > > The RMM provides standard interfaces - Realm Management Interface (RMI) - to the > Normal world hypervisor to manage the VMs running in the Realm world (also called > Realms in short). These are exposed via SMC and are routed through the EL3 > firmwre. > The RMI interface includes: > - Move a physical page from the Normal world to the Realm world > - Creating a Realm with requested parameters, tracked via Realm Descriptor (RD) > - Creating VCPUs aka Realm Execution Context (REC), with initial register state. > - Create stage2 translation table at any level. > - Load initial images into Realm Memory from normal world memory > - Schedule RECs (vCPUs) and handle exits > - Inject virtual interrupts into the Realm > - Service stage2 runtime faults with pages (provided by host, scrubbed by RMM). > - Create "shared" mappings that can be accessed by VMM/Hyp. > - Reclaim the memory allocated for the RAM and RTTs (Realm Translation Tables) > > However v1.0 of RMM specifications doesn't support: > - Paging protected memory of a Realm VM. Thus the pages backing the protected > memory region must be pinned. > - Live migration of Realms. > - Trusted Device assignment. > - Physical interrupt backed Virtual interrupts for Realms > > RMM also provides certain services to the Realms via SMC, called Realm Service > Interface (RSI). These include: > - Realm Guest Configuration. > - Attestation & Measurement services > - Managing the state of an Intermediate Physical Address (IPA aka GPA) page. > - Host Call service (Communication with the Normal world Hypervisor) > > The specifications for the RMM software is currently at *v1.0-Beta2* and the > latest version is available here [1]. > > The Trusted Firmware foundation has an implementation of the RMM - TF-RMM - > available here [3]. > > Implementation > ================= > > This version of the stack is based on the RMM specification v1.0-Beta0[2], with > following exceptions : > - TF-RMM/KVM currently doesn't support the optional features of PMU, > SVE and Self-hosted debug (coming soon). > - The RSI_HOST_CALL structure alignment requirement is reduced to match > RMM v1.0 Beta1 > - RMI/RSI version numbers do not match the RMM spec. This will be > resolved once the spec/implementation is complete, across TF-RMM+Linux stack. > > We plan to update the stack to support the latest version of the RMMv1.0 spec > in the coming revisions. > > This release includes the following components : > > a) Linux Kernel > i) Host / KVM support - Support for driving the Realms via RMI. This is > dependent on running in the Kernel at EL2 (aka VHE mode). Also provides > UABI for VMMs to manage the Realm VMs. The support is restricted to 4K page > size, matching the Stage2 granule supported by RMM. The VMM is responsible > for making sure the guest memory is locked. > > TODO: Guest Private memory[10] integration - We have been following the > series and support will be added once it is merged upstream. > > ii) Guest support - Support for a Linux Kernel to run in the Realm VM at > Realm-EL1, using RSI services. This includes virtio support (virtio-v1.0 > only). All I/O are treated as non-secure/shared. > > c) kvmtool - VMM changes required to manage Realm VMs. No guest private memory > as mentioned above. > d) kvm-unit-tests - Support for running in Realms along with additional tests > for RSI ABI. > > Running the stack > ==================== > > To run/test the stack, you would need the following components : > > 1) FVP Base AEM RevC model with FEAT_RME support [4] > 2) TF-A firmware for EL3 [5] > 3) TF-A RMM for R-EL2 [3] > 4) Linux Kernel [6] > 5) kvmtool [7] > 6) kvm-unit-tests [8] > > Instructions for building the firmware components and running the model are > available here [9]. Once, the host kernel is booted, a Realm can be launched by > invoking the `lkvm` commad as follows: > > $ lkvm run --realm \ > --measurement-algo=["sha256", "sha512"] \ > --disable-sve \ As noted above, this is no longer required. > <normal-vm-options> > > Where: > * --measurement-algo (Optional) specifies the algorithm selected for creating the > initial measurements by the RMM for this Realm (defaults to sha256). > * GICv3 is mandatory for the Realms. > * SVE is not yet supported in the TF-RMM, and thus must be disabled using > --disable-sve > > You may also run the kvm-unit-tests inside the Realm world, using the similar > options as above. > > > Links > ============ > > [0] Arm CCA Landing page (See Key Resources section for various documentations) > https://www.arm.com/architecture/security-features/arm-confidential-compute-architecture > > [1] RMM Specification Latest > https://developer.arm.com/documentation/den0137/latest > > [2] RMM v1.0-Beta0 specification > https://developer.arm.com/documentation/den0137/1-0bet0/ EAC2 spec: https://developer.arm.com/documentation/den0137/1-0eac2/ > > [3] Trusted Firmware RMM - TF-RMM > https://www.trustedfirmware.org/projects/tf-rmm/ > GIT: https://git.trustedfirmware.org/TF-RMM/tf-rmm.git > > [4] FVP Base RevC AEM Model (available on x86_64 / Arm64 Linux) > https://developer.arm.com/Tools%20and%20Software/Fixed%20Virtual%20Platforms > > [5] Trusted Firmware for A class > https://www.trustedfirmware.org/projects/tf-a/ > > [6] Linux kernel support for Arm-CCA > https://gitlab.arm.com/linux-arm/linux-cca > Host Support branch: cca-host/rfc-v1 Update branch : cca-host/rmm-v1.0-eac2 > Guest Support branch: cca-guest/rfc-v1 Update branch : cca-guest/rmm-v1.0-eac2 Combined tree for host and guest is also available at: "cca-full/rmm-v1.0-eac2" > > [7] kvmtool support for Arm CCA > https://gitlab.arm.com/linux-arm/kvmtool-cca cca/rfc-v1 Update branch : cca/rmm-v1.0-eac2 > > [8] kvm-unit-tests support for Arm CCA > https://gitlab.arm.com/linux-arm/kvm-unit-tests-cca cca/rfc-v1 > Update branch : cca/rmm-v1.0-eac2 Suzuki > [9] Instructions for Building Firmware components and running the model, see > section 4.19.2 "Building and running TF-A with RME" > https://trustedfirmware-a.readthedocs.io/en/latest/components/realm-management-extension.html#building-and-running-tf-a-with-rme > > [10] fd based Guest Private memory for KVM > https://lkml.kernel.org/r/20221202061347.1070246-1-chao.p.peng@xxxxxxxxxxxxxxx Cc: Alexandru Elisei <alexandru.elisei@xxxxxxx> Cc: Andrew Jones <andrew.jones@xxxxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx> Cc: Christoffer Dall <christoffer.dall@xxxxxxx> Cc: Fuad Tabba <tabba@xxxxxxxxxx> Cc: Jonathan Cameron <jonathan.cameron@xxxxxxxxxx> Cc: James Morse <james.morse@xxxxxxx> Cc: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx> Cc: Joey Gouly <Joey.Gouly@xxxxxxx> Cc: Marc Zyngier <maz@xxxxxxxxxx> Cc: Mark Rutland <mark.rutland@xxxxxxx> Cc: Oliver Upton <oliver.upton@xxxxxxxxx> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> Cc: Quentin Perret <qperret@xxxxxxxxxx> Cc: Sean Christopherson <seanjc@xxxxxxxxxx> Cc: Steven Price <steven.price@xxxxxxx> Cc: Thomas Huth <thuth@xxxxxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Cc: Zenghui Yu <yuzenghui@xxxxxxxxxx> To: linux-coco@xxxxxxxxxxxxxxx To: kvmarm@xxxxxxxxxxxxxxx Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx To: linux-kernel@xxxxxxxxxxxxxxx To: kvm@xxxxxxxxxxxxxxx
