Re: [PATCH kvmtool v3 0/6] arm64: Nested virtualization support

Marc Zyngier
2025-07-29T10:03:13Z

On Tue, 29 Jul 2025 10:57:39 +0100,
Andre Przywara <andre.przywara@arm.com> wrote:
>
> This is v3 of the nested virt support series, adjusting commit messages
> and adding a check that FEAT_E2H0 is really available.
> ========================================================
>
> 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.

Thanks for going the extra mile on this, much appreciated.

FWIW:

Reviewed-by: Marc Zyngier <maz@kernel.org>

M.

--
Without deviation from the norm, progress is not possible.