Re: [PATCH kvmtool v5 0/7] arm64: Nested virtualization support

[Itaru Kitayama <itaru.kitayama@fujitsu.com>]

On Fri, Jan 23, 2026 at 02:27:22PM +0000, Andre Przywara wrote:
> This is v5 of the nested virt support series, fixing a corner case when
> some maintenance IRQ setup fails. Also there is now a warning if --e2h0
> is specified without --nested. Many thanks to Sascha for the review!
> ========================================================
> 
> Thanks to the imperturbable efforts from Marc, arm64 support for nested
> virtualization has now reached the mainline kernel, which means the
> respective kvmtool support should now be ready as well.
> 
> Patch 1 updates the kernel headers, to get the new EL2 capability, and
> the VGIC device control to setup the maintenance IRQ.
> Patch 2 introduces the new "--nested" command line option, to let the
> VCPUs start in EL2. To allow KVM guests running in such a guest, we also
> need VGIC support, which patch 3 allows by setting the maintenance IRQ.
> Patch 4 to 6 are picked from Marc's repo, and allow to set the arch
> timer offset, enable non-VHE guests (at the cost of losing recursive
> nested virtualisation), and also advertise the virtual EL2 timer IRQ.
> 
> Tested on the FVP (with some good deal of patience), and some commercial
> (non-fruity) hardware, down to a guest's guest's guest.

Hi Andre,
I wonder if you have also tested this series with the latest QEMU which
has FEAT_NV2 support; I ask because when I tried to create a nested
guest with (again) lkvm it got stuck forever.

Thanks,
Itaru.

> 
> Cheers,
> Andre
> 
> Changelog v4 ... v5:
> - bump kernel headers to v6.19-rc6
> - print a warning if --e2h0 is given without --nested
> - fail if the maintenance IRQ setting attribute is not supported
> 
> Changelog v3 ... v4:
> - pass kvm pointer to gic__generate_fdt_nodes()
> - use macros for PPI offset and DT type identifier
> - properly calculate DT interrupt flags value
> - add patch 7 to fix virtio endianess issues
> - CAPITALISE verbs in commit message
> 
> Changelog v2 ... v3:
> - adjust^Wreplace commit messages for E2H0 and counter-offset patch
> - check for KVM_CAP_ARM_EL2_E2H0 when --e2h0 is requested
> - update kernel headers to v6.16 release
> 
> Changelog v1 ... 2:
> - add three patches from Marc:
>   - add --e2h0 command line option
>   - add --counter-offset command line option
>   - advertise all five arch timer interrupts in DT
> 
> Andre Przywara (3):
>   Sync kernel UAPI headers with v6.19-rc6
>   arm64: Initial nested virt support
>   arm64: nested: Add support for setting maintenance IRQ
> 
> Marc Zyngier (4):
>   arm64: Add counter offset control
>   arm64: Add FEAT_E2H0 support
>   arm64: Generate HYP timer interrupt specifiers
>   arm64: Handle virtio endianness reset when running nested
> 
>  arm64/arm-cpu.c                     |   6 +-
>  arm64/fdt.c                         |   5 +-
>  arm64/gic.c                         |  29 ++++++-
>  arm64/include/asm/kvm.h             |  25 ++++--
>  arm64/include/kvm/gic.h             |   2 +-
>  arm64/include/kvm/kvm-config-arch.h |  11 ++-
>  arm64/include/kvm/kvm-cpu-arch.h    |   5 +-
>  arm64/include/kvm/timer.h           |   2 +-
>  arm64/kvm-cpu.c                     |  64 ++++++++++++---
>  arm64/kvm.c                         |  19 +++++
>  arm64/timer.c                       |  29 +++----
>  include/linux/kvm.h                 |  47 +++++++++++
>  include/linux/virtio_ids.h          |   1 +
>  include/linux/virtio_net.h          |  49 +++++++++++-
>  include/linux/virtio_pci.h          |   3 +-
>  powerpc/include/asm/kvm.h           |  13 ----
>  riscv/include/asm/kvm.h             |  29 ++++++-
>  x86/include/asm/kvm.h               | 116 ++++++++++++++++++++++++++++
>  18 files changed, 394 insertions(+), 61 deletions(-)
> 
> -- 
> 2.43.0
>