[PATCH v13 00/48] arm64: Support for Arm CCA in KVM

Steven Price
2026-03-18T15:54:26Z

This series adds support for running protected VMs using KVM under the
Arm Confidential Compute Architecture (CCA).

New major version number! This now targets RMM v2.0-bet0[1]. And unlike
for Linux this represents a significant change.

RMM v2.0 brings with it the ability to configure the RMM to have the
same page size as the host (so no more RMM_PAGE_SIZE and dealing with
granules being different from host pages). It also introduces range
based APIs for many operations which should be more efficient and
simplifies the code in places.

The handling of the GIC has changed, so the system registers are used to
pass the GIC state rather than memory. This means fewer changes to the
KVM code as it looks much like a normal VM in this respect.

And of course the new uAPI introduced in the previous v12 posting is
retained so that also remains simplified compared to earlier postings.

The RMM support for v2.0 is still early and so this series includes a
few hacks to ease the integration. Of note are that there are some RMM
v1.0 SMCs added to paper over areas where the RMM implementation isn't
quite ready for v2.0, and "SROs" (see below) are deferred to the final
patch in the series.

The PMU in RMM v2.0 requires more handling on the RMM-side (and
therefore simplifies the implementation on Linux), but this isn't quite
ready yet. The Linux side is implemented (but untested).

PSCI still requires the VMM to provide the "target" REC for operations
that affect another vCPU. This is likely to change in a future version
of the specification. There's also a desire to force PSCI to be handled
in the VMM for realm guests - this isn't implemented yet as I'm waiting
for the dust to settle on the RMM interface first.

Stateful RMI Operations
-----------------------

The RMM v2.0 spec brings a new concept of Stateful RMI Operations (SROs)
which allow the RMM to complete an operation over several SMC calls and
requesting/returning memory to the host. This has the benefit of
allowing interrupts to be handled in the middle of an operation (by
returning to the host to handle the interrupt without completing the
operation) and enables the RMM to dynamically allocate memory for
internal tracking purposes. One example of this is RMI_REC_CREATE no
longer needs "auxiliary granules" provided upfront but can request the
memory needed during the RMI_REC_CREATE operation.

There are a fairly large number of operations that are defined as SROs
in the specification, but current both Linux and RMM only have support
for RMI_REC_CREATE and RMI_REC_DESTROY. There a number of TODOs/FIXMEs
in the code where support is missing.

Given the early stage support for this, the SRO handling is all confined
to the final patch. This patch can be dropped to return to a pre-SRO
state (albeit a mixture of RMM v1.0 and v2.0 APIs) for testing purposes.

A future posting will reorder the series to move the generic SRO support
to an early patch and will implement the proper support for this in all
RMI SMCs.

One aspect of SROs which is not yet well captured is that in some
circumstances the Linux kernel will need to call an SRO call in a
context where memory allocation is restricted (e.g. because a spinlock
is held). In this case the intention is that the SRO will be cancelled,
the spinlock dropped so the memory allocation can be completed, and then
the SRO restarted (obviously after rechecking the state that the
spinlock was protecting). For this reason the code stores the memory
allocations within a struct rmi_sro_state object - see the final patch
for more details.

This series is based on v7.0-rc1. It is also available as a git
repository:

https://gitlab.arm.com/linux-arm/linux-cca cca-host/v13

Work in progress changes for kvmtool are available from the git
repository below:

https://gitlab.arm.com/linux-arm/kvmtool-cca cca/v11

Note that the kvmtool code has been tidied up (thanks to Suzuki) and
this involves a minor change in flags. The "--restricted_mem" flag is no
longer recognised (or necessary).

The TF-RMM has not yet merged the RMMv2.0 support, so you will need to
use the following branch:

https://git.trustedfirmware.org/TF-RMM/tf-rmm.git topics/rmm-v2.0-poc

[1] https://developer.arm.com/documentation/den0137/2-0bet0/

Jean-Philippe Brucker (7):
arm64: RMI: Propagate number of breakpoints and watchpoints to
userspace
arm64: RMI: Set breakpoint parameters through SET_ONE_REG
arm64: RMI: Initialize PMCR.N with number counter supported by RMM
arm64: RMI: Propagate max SVE vector length from RMM
arm64: RMI: Configure max SVE vector length for a Realm
arm64: RMI: Provide register list for unfinalized RMI RECs
arm64: RMI: Provide accurate register list

Joey Gouly (2):
arm64: RMI: allow userspace to inject aborts
arm64: RMI: support RSI_HOST_CALL

Steven Price (36):
kvm: arm64: Avoid including linux/kvm_host.h in kvm_pgtable.h
arm64: RME: Handle Granule Protection Faults (GPFs)
arm64: RMI: Add SMC definitions for calling the RMM
arm64: RMI: Temporarily add SMCs from RMM v1.0 spec
arm64: RMI: Add wrappers for RMI calls
arm64: RMI: Check for RMI support at KVM init
arm64: RMI: Configure the RMM with the host's page size
arm64: RMI: Check for LPA2 support
arm64: RMI: Ensure that the RMM has GPT entries for memory
arm64: RMI: Define the user ABI
arm64: RMI: Basic infrastructure for creating a realm.
KVM: arm64: Allow passing machine type in KVM creation
arm64: RMI: RTT tear down
arm64: RMI: Activate realm on first VCPU run
arm64: RMI: Allocate/free RECs to match vCPUs
arm64: RMI: Support for the VGIC in realms
KVM: arm64: Support timers in realm RECs
arm64: RMI: Handle realm enter/exit
arm64: RMI: Handle RMI_EXIT_RIPAS_CHANGE
KVM: arm64: Handle realm MMIO emulation
KVM: arm64: Expose support for private memory
arm64: RMI: Allow populating initial contents
arm64: RMI: Set RIPAS of initial memslots
arm64: RMI: Create the realm descriptor
arm64: RMI: Runtime faulting of memory
KVM: arm64: Handle realm VCPU load
KVM: arm64: Validate register access for a Realm VM
KVM: arm64: Handle Realm PSCI requests
KVM: arm64: WARN on injected undef exceptions
arm64: Don't expose stolen time for realm guests
arm64: RMI: Always use 4k pages for realms
arm64: RMI: Prevent Device mappings for Realms
arm64: RMI: Enable PMU support with a realm guest
KVM: arm64: Expose KVM_ARM_VCPU_REC to user space
arm64: RMI: Enable realms to be created
[WIP] arm64: RMI: Add support for SRO

Suzuki K Poulose (3):
kvm: arm64: Include kvm_emulate.h in kvm/arm_psci.h
kvm: arm64: Don't expose unsupported capabilities for realm guests
arm64: RMI: Allow checking SVE on VM instance

Documentation/virt/kvm/api.rst | 86 +-
arch/arm64/include/asm/kvm_emulate.h | 31 +
arch/arm64/include/asm/kvm_host.h | 15 +-
arch/arm64/include/asm/kvm_pgtable.h | 5 +-
arch/arm64/include/asm/kvm_pkvm.h | 2 +-
arch/arm64/include/asm/kvm_rmi.h | 129 ++
arch/arm64/include/asm/rmi_cmds.h | 692 +++++++++
arch/arm64/include/asm/rmi_smc.h | 430 ++++++
arch/arm64/include/asm/virt.h | 1 +
arch/arm64/kernel/cpufeature.c | 1 +
arch/arm64/kvm/Kconfig | 2 +
arch/arm64/kvm/Makefile | 2 +-
arch/arm64/kvm/arch_timer.c | 28 +-
arch/arm64/kvm/arm.c | 178 ++-
arch/arm64/kvm/guest.c | 95 +-
arch/arm64/kvm/hyp/pgtable.c | 1 +
arch/arm64/kvm/hypercalls.c | 4 +-
arch/arm64/kvm/inject_fault.c | 5 +-
arch/arm64/kvm/mmio.c | 16 +-
arch/arm64/kvm/mmu.c | 214 ++-
arch/arm64/kvm/pmu-emul.c | 6 +
arch/arm64/kvm/psci.c | 30 +
arch/arm64/kvm/reset.c | 13 +-
arch/arm64/kvm/rmi-exit.c | 207 +++
arch/arm64/kvm/rmi.c | 1948 ++++++++++++++++++++++++++
arch/arm64/kvm/sys_regs.c | 53 +-
arch/arm64/kvm/vgic/vgic-init.c | 2 +-
arch/arm64/mm/fault.c | 28 +-
include/kvm/arm_arch_timer.h | 2 +
include/kvm/arm_pmu.h | 4 +
include/kvm/arm_psci.h | 2 +
include/uapi/linux/kvm.h | 41 +-
32 files changed, 4176 insertions(+), 97 deletions(-)
create mode 100644 arch/arm64/include/asm/kvm_rmi.h
create mode 100644 arch/arm64/include/asm/rmi_cmds.h
create mode 100644 arch/arm64/include/asm/rmi_smc.h
create mode 100644 arch/arm64/kvm/rmi-exit.c
create mode 100644 arch/arm64/kvm/rmi.c

--
2.43.0