[PATCH 00/27] Nested virtualization for KVM RISC-V

[Anup Patel]

On Tue, Jan 20, 2026 at 1:30 PM Anup Patel <anup.patel at oss.qualcomm.com> wrote:
>
> Initial nested virtualization support for KVM RISC-V. Using
> this series, we can boot Xvisor inside KVM guest and KVM RISC-V
> insmod also works inside KVM guest but we can't run nested guest
> at the moment due to work-in-progress G-stage emulation (or
> G-stage page table walker).
>
> Patch01-to-Patch09: Fixes and preparatory changes
> Patch10-to-Patch23: Actual nested virtualization support
> Patch24-to-Patch27: ONE_REG interface and get-reg-list selftest
>
> Upcoming work on-top-of this series include:
>  * Software MMU emulation for nested guest (aka swtlb)
>  * HLV/HSV emulation
>  * Sstc emulation for nested guest
>  * SBI NACL for guest hypervisor
>  * ... and more ...
>
> These patches can also be found in the riscv_kvm_nested_v1
> branch at: https://github.com/avpatel/linux.git
>
> Anup Patel (27):
>   RISC-V: KVM: Fix error code returned for Smstateen ONE_REG
>   RISC-V: KVM: Fix error code returned for Ssaia ONE_REG
>   RISC-V: KVM: Check host Ssaia extension when creating AIA irqchip
>   RISC-V: KVM: Introduce common kvm_riscv_isa_check_host()
>   RISC-V: KVM: Factor-out ISA checks into separate sources
>   RISC-V: KVM: Move timer state defines closer to struct in UAPI header
>   RISC-V: KVM: Add hideleg to struct kvm_vcpu_config
>   RISC-V: KVM: Factor-out VCPU config into separate sources
>   RISC-V: KVM: Don't check hstateen0 when updating sstateen0 CSR
>   RISC-V: KVM: Initial skeletal nested virtualization support
>   RISC-V: KVM: Use half VMID space for nested guest
>   RISC-V: KVM: Extend kvm_riscv_mmu_update_hgatp() for nested
>     virtualization
>   RISC-V: KVM: Extend kvm_riscv_vcpu_config_load() for nested
>     virtualization
>   RISC-V: KVM: Extend kvm_riscv_vcpu_update_timedelta() for nested virt
>   RISC-V: KVM: Extend trap redirection for nested virtualization
>   RISC-V: KVM: Check and inject nested virtual interrupts
>   RISC-V: KVM: Extend kvm_riscv_isa_check_host() for nested virt
>   RISC-V: KVM: Trap-n-emulate SRET for Guest HS-mode
>   RISC-V: KVM: Redirect nested supervisor ecall and breakpoint traps
>   RISC-V: KVM: Redirect nested WFI and WRS traps
>   RISC-V: KVM: Implement remote HFENCE SBI calls for guest
>   RISC-V: KVM: Add CSR emulation for nested virtualization
>   RISC-V: KVM: Add HFENCE emulation for nested virtualization
>   RISC-V: KVM: Add ONE_REG interface for nested virtualization state
>   RISC-V: KVM: selftests: Add nested virt state to get-reg-list test
>   RISC-V: KVM: Add ONE_REG interface for nested virtualization CSRs
>   RISC-V: KVM: selftests: Add nested virt CSRs to get-reg-list test

Patches 1-to-3 are already merged as fixes.

Queued patches 4-to-9 for Linux-7.1

Thanks,
Anup

>
>  arch/riscv/include/asm/csr.h                  |  17 +
>  arch/riscv/include/asm/insn.h                 |   9 +
>  arch/riscv/include/asm/kvm_gstage.h           |   2 +
>  arch/riscv/include/asm/kvm_host.h             |  29 +-
>  arch/riscv/include/asm/kvm_isa.h              |  20 +
>  arch/riscv/include/asm/kvm_mmu.h              |   2 +-
>  arch/riscv/include/asm/kvm_tlb.h              |  37 +-
>  arch/riscv/include/asm/kvm_vcpu_config.h      |  25 ++
>  arch/riscv/include/asm/kvm_vcpu_nested.h      | 163 ++++++++
>  arch/riscv/include/asm/kvm_vcpu_timer.h       |   1 +
>  arch/riscv/include/asm/kvm_vmid.h             |   1 +
>  arch/riscv/include/uapi/asm/kvm.h             |  36 +-
>  arch/riscv/kvm/Makefile                       |   6 +
>  arch/riscv/kvm/aia.c                          |   4 +
>  arch/riscv/kvm/aia_device.c                   |   5 +
>  arch/riscv/kvm/gstage.c                       |  14 +
>  arch/riscv/kvm/isa.c                          | 259 ++++++++++++
>  arch/riscv/kvm/main.c                         |  13 +-
>  arch/riscv/kvm/mmu.c                          |  18 +-
>  arch/riscv/kvm/tlb.c                          | 135 +++++-
>  arch/riscv/kvm/vcpu.c                         | 117 ++----
>  arch/riscv/kvm/vcpu_config.c                  | 130 ++++++
>  arch/riscv/kvm/vcpu_exit.c                    |  62 ++-
>  arch/riscv/kvm/vcpu_fp.c                      |   9 +-
>  arch/riscv/kvm/vcpu_insn.c                    |  46 +++
>  arch/riscv/kvm/vcpu_nested.c                  | 258 ++++++++++++
>  arch/riscv/kvm/vcpu_nested_csr.c              | 389 ++++++++++++++++++
>  arch/riscv/kvm/vcpu_nested_insn.c             | 140 +++++++
>  arch/riscv/kvm/vcpu_nested_swtlb.c            | 146 +++++++
>  arch/riscv/kvm/vcpu_onereg.c                  | 334 +++------------
>  arch/riscv/kvm/vcpu_pmu.c                     |   5 +-
>  arch/riscv/kvm/vcpu_sbi_replace.c             |  63 ++-
>  arch/riscv/kvm/vcpu_timer.c                   |  24 +-
>  arch/riscv/kvm/vcpu_vector.c                  |   5 +-
>  arch/riscv/kvm/vmid.c                         |  33 +-
>  .../selftests/kvm/riscv/get-reg-list.c        | 106 ++++-
>  36 files changed, 2244 insertions(+), 419 deletions(-)
>  create mode 100644 arch/riscv/include/asm/kvm_isa.h
>  create mode 100644 arch/riscv/include/asm/kvm_vcpu_config.h
>  create mode 100644 arch/riscv/include/asm/kvm_vcpu_nested.h
>  create mode 100644 arch/riscv/kvm/isa.c
>  create mode 100644 arch/riscv/kvm/vcpu_config.c
>  create mode 100644 arch/riscv/kvm/vcpu_nested.c
>  create mode 100644 arch/riscv/kvm/vcpu_nested_csr.c
>  create mode 100644 arch/riscv/kvm/vcpu_nested_insn.c
>  create mode 100644 arch/riscv/kvm/vcpu_nested_swtlb.c
>
> --
> 2.43.0
>