[PATCH v4 00/48] KVM: arm64: Add GICv5 IRS support
Sascha Bischoff
Sascha.Bischoff at arm.com
Fri Jul 24 03:48:25 PDT 2026
Hi all,
This series builds on the initial vGICv5 support [1] and adds support
for the GICv5 IRS, as described by the GICv5 (EAC0) specification [2].
With this, a GICv5 guest is no longer restricted to PPIs, and can make
use of SPIs and LPIs as well.
With SPIs and LPIs available, this series makes it possible to boot a
full Linux guest on the Arm FVP model [3], using the setup described in
Lorenzo's GICv5 Linux software enablement guide [4]. In addition, GICv5
IPIs are typically implemented as LPIs, so LPI support is what makes
guests with more than one vCPU possible.
The corresponding kvmtool changes are available separately [5]. With
these changes, `--irqchip=gicv5` works now. The `--irqchip=gicv5-its`
configuration does not work with this series, as ITS/MSI support is not
included here.
The IRS is created as part of the vgic-v5 device, and is not a separate
KVM device. This is because implementing the CPU interface alone would
limit a guest to a single vCPU and PPIs only. Hence, the IRS is bundled
into the VGIC, much like the distributor for GICv3.
The series adds the host-side plumbing needed for KVM to interact with
the physical IRS, including VM and VPE table management, VPE residency,
and VPE doorbells. It also adds an emulated IRS MMIO interface for the
guest, together with the UAPI needed for userspace to configure the IRS
address and to save/restore the IRS and IST state.
The main pieces are:
* Host IRS capability discovery and configuration frame plumbing.
* Allocation and management of the GICv5 VM table, VPE table, VMTEs,
VPEs, and host-backed guest IST storage.
* VPE residency and doorbell handling, allowing the IRS to select SPIs
and LPIs for resident VPEs and wake non-resident VPEs when required.
* Emulation of the GICv5 IRS MMIO CONFIG_FRAME for guests.
Virtualisation, MPAM, MEC, and SWERR are not supported and are RAZ/WI.
* SPI injection support using GIC VDPEND. Once injected, the GICv5
hardware manages the SPI lifecycle.
* Save/restore support for GICv5 EL1 system registers, IRS MMIO state,
and guest ISTs. SPI and LPI IST state is transferred through
userspace-owned buffers using KVM_DEV_ARM_VGIC_GRP_IST.
* Documentation for the new VGICv5 IRS userspace interfaces and the
required save/restore ordering.
* Selftests for the UAPI components, the PPI, SPI, and LPI support, and
save/restore.
This series keeps SPI, LPI, and save/restore support together
intentionally. SPI and LPI support are needed to run realistic guests,
while the save/restore interface is included at the same time so that the
new userspace ABI is complete from the point it is exposed: userspace
should not be able to create VGICv5 state that it cannot also migrate.
The IST migration selftest restores state into a separate VM, re-saves
the SPI and LPI IST images before the destination runs, and compares
them byte-for-byte with the source images. It also validates restored IRS
MMIO state through SPI/LPI delivery, priority, enable, and affinity
behavior.
LPIs are explicitly driven by the guest through the IRS/IST state. This
series does not add direct LPI injection support, MSI support, or GICv5
ITS emulation.
These changes are based on v7.2-rc4. I've pushed the full set of changes
to a branch at [6].
Changes since v3 [7]:
* Addressed the Sashiko AI reviews [8] for the core implementation, UAPI,
and documentation.
* Dropped the software SPI AP list and in-flight SPI lifecycle tracking.
GICv5 SPI state is now left to the hardware after injection. This will be
revisited in the future.
* Dropped GIC VDRCFG support, including its sysreg encoding and EL2
hypercall. GIC VDPEND remains as the mechanism used to inject SPI and LPI
pending state.
* Reworked IST migration so that both SPI and LPI IST state is transferred
through userspace-owned buffers, exposed through
KVM_DEV_ARM_VGIC_GRP_IST and struct kvm_vgic_v5_ist.
* Updated the IST save/restore implementation and documentation for the
buffer-based interface, including clarified restore ordering and
validation requirements.
* Hardened IRS/VMTE teardown and IRS enable handling, including avoiding
VM-ID reuse after unsuccessful hardware teardown and reloading GICv5
state when the guest changes IRS enablement.
* Expanded VGICv5 device-attribute documentation, including the GICv5
semantics and validation of the NR_IRQS attribute.
* Added KVM selftests for IRS address, NR_IRQS, IRS registers, IST
attributes, userspace PPIs, CPU sysregs, SPI injection, LPI delivery,
and end-to-end IST save/restore.
Thanks for taking the time to look at these changes!
Thanks,
Sascha
[1] https://lore.kernel.org/all/20260319154937.3619520-1-sascha.bischoff@arm.com/
[2] https://developer.arm.com/documentation/aes0070/latest
[3] https://developer.arm.com/documentation/108086/latest
[4] https://linaro.atlassian.net/wiki/x/CQAF-wY
[5] https://lore.kernel.org/all/20260116182606.61856-1-sascha.bischoff@arm.com/
[6] https://gitlab.arm.com/linux-arm/linux-sb/-/tree/gicv5_kvm_irs_support_v4
[7] https://lore.kernel.org/all/20260703154811.3355680-1-sascha.bischoff@arm.com/
[8] https://sashiko.dev/#/patchset/20260703154811.3355680-1-sascha.bischoff@arm.com
Sascha Bischoff (48):
irqchip/gic-v5: Allow KVM setup without a maintenance IRQ
irqchip/gic-v5: Provide OF IRS config frame attrs to KVM
irqchip/gic-v5: Set up gic_kvm_info on ACPI hosts
KVM: arm64: gic-v5: Define remaining IRS MMIO registers
arm64/sysreg: Add GICv5 GIC VDPEND encoding
arm64/sysreg: Update ICC_CR0_EL1 with LINK and LINK_IDLE fields
KVM: arm64: gic-v5: Extract host IRS caps from IRS config frame
KVM: arm64: gic-v5: Add VPE doorbell domain
KVM: arm64: gic-v5: Create and manage VM and VPE tables
KVM: arm64: gic-v5: Introduce guest IST alloc and management
KVM: arm64: gic-v5: Implement VMT/vIST IRS MMIO Ops
KVM: arm64: gic-v5: Keep GICv5 vCPU limit model-specific
KVM: arm64: gic-v5: Implement VPE IRS MMIO Ops
KVM: arm64: gic-v5: Set up VMTEs and VPE doorbells
KVM: arm64: gic-v5: Add resident/non-resident hyp calls
KVM: arm64: gic-v5: Request doorbells when VPEs enter WFI
KVM: arm64: gic-v5: Introduce struct vgic_v5_irs and IRS base address
KVM: arm64: gic-v5: Add IRS IODEV support to MMIO handlers
KVM: arm64: gic-v5: Add KVM_VGIC_V5_ADDR_TYPE_IRS to UAPI
KVM: arm64: gic-v5: Add GICv5 IRS IODEV and MMIO emulation
KVM: arm64: gic-v5: Initialise per-VM IRS state
KVM: arm64: gic-v5: Register the IRS IODEV
KVM: arm64: gic-v5: Set IRICHPPIDIS based on IRS enable state
KVM: arm64: selftests: Update vGICv5 selftest to set IRS address
KVM: arm64: gic-v5: Add GIC VDPEND hyp call
KVM: arm64: gic: Introduce set_pending_state() to irq_op
KVM: arm64: gic-v5: Support SPI injection
Documentation: KVM: Extend VGICv5 device attribute docs
KVM: arm64: gic-v5: Add GICv5 SPI injection to irqfd
KVM: arm64: gic-v5: Mask per-vcpu PPI state in
vgic_v5_finalize_ppi_state()
KVM: arm64: gic-v5: Add GICv5 EL1 sysreg userspace accessors
KVM: arm64: gic-v5: Handle userspace accesses to IRS MMIO region
KVM: arm64: gic-v5: Add CoreSight MMIO regs to IRS
KVM: arm64: gic-v5: Add VGICv5 IST save/restore UAPI
KVM: arm64: gic-v5: Implement save/restore mechanisms for ISTs
Documentation: KVM: Document KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS for
VGICv5
Documentation: KVM: Add KVM_DEV_ARM_VGIC_GRP_IRS_REGS to VGICv5 docs
Documentation: KVM: Add docs for KVM_DEV_ARM_VGIC_GRP_IST
Documentation: KVM: Add the VGICv5 IRS save/restore sequences
KVM: selftests: Add VGICv5 IRS address attribute tests
KVM: selftests: Add VGICv5 NR_IRQS attribute tests
KVM: selftests: Add VGICv5 IRS_REGS attribute tests
KVM: selftests: Add VGICv5 IST attribute tests
KVM: selftests: Add VGICv5 USERSPACE_PPIS tests
KVM: selftests: Add VGICv5 CPU sysreg attribute tests
KVM: selftests: Add VGICv5 SPI injection tests
KVM: selftests: Add VGICv5 LPI delivery tests
KVM: selftests: Add VGICv5 IST save/restore coverage
.../virt/kvm/devices/arm-vgic-v5.rst | 264 ++-
arch/arm64/include/asm/kvm_asm.h | 3 +
arch/arm64/include/asm/kvm_host.h | 1 +
arch/arm64/include/asm/kvm_hyp.h | 3 +
arch/arm64/include/asm/sysreg.h | 13 +-
arch/arm64/include/uapi/asm/kvm.h | 7 +
arch/arm64/kvm/Makefile | 3 +-
arch/arm64/kvm/arm.c | 10 +-
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 26 +
arch/arm64/kvm/hyp/vgic-v5-sr.c | 45 +
arch/arm64/kvm/sys_regs.c | 6 +-
arch/arm64/kvm/vgic-sys-reg-v5.c | 519 +++++
arch/arm64/kvm/vgic/vgic-init.c | 111 +-
arch/arm64/kvm/vgic/vgic-irqfd.c | 11 +-
arch/arm64/kvm/vgic/vgic-irs-v5.c | 1136 +++++++++++
arch/arm64/kvm/vgic/vgic-kvm-device.c | 270 ++-
arch/arm64/kvm/vgic/vgic-mmio.c | 6 +
arch/arm64/kvm/vgic/vgic-mmio.h | 2 +
arch/arm64/kvm/vgic/vgic-v5-tables.c | 1795 ++++++++++++++++
arch/arm64/kvm/vgic/vgic-v5-tables.h | 116 ++
arch/arm64/kvm/vgic/vgic-v5.c | 1142 ++++++++++-
arch/arm64/kvm/vgic/vgic.c | 37 +-
arch/arm64/kvm/vgic/vgic.h | 21 +
arch/arm64/tools/sysreg | 4 +-
drivers/irqchip/irq-gic-v5-irs.c | 19 +-
drivers/irqchip/irq-gic-v5.c | 117 +-
include/kvm/arm_vgic.h | 152 +-
include/linux/irqchip/arm-gic-v5.h | 256 ++-
include/linux/irqchip/arm-vgic-info.h | 5 +
include/uapi/linux/kvm.h | 7 +
tools/arch/arm64/include/uapi/asm/kvm.h | 7 +
tools/testing/selftests/kvm/arm64/vgic_v5.c | 1801 ++++++++++++++++-
.../selftests/kvm/include/arm64/gic_v5.h | 105 +
33 files changed, 7826 insertions(+), 194 deletions(-)
create mode 100644 arch/arm64/kvm/vgic-sys-reg-v5.c
create mode 100644 arch/arm64/kvm/vgic/vgic-irs-v5.c
create mode 100644 arch/arm64/kvm/vgic/vgic-v5-tables.c
create mode 100644 arch/arm64/kvm/vgic/vgic-v5-tables.h
--
2.34.1
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