On Fri, 9 Feb 2024 at 16:00, Eric Auger <eric.au...@redhat.com> wrote: > > This series adds ARM Nested Virtualization support in KVM mode. > This is a respin of previous contributions from Miguel [1] and Haibo [2]. > > This was tested with Marc's v11 [3] on Ampere HW with fedora L1 guest and > L2 guests booted without EDK2. However it does not work yet with > EDK2 but it looks unrelated to this qemu integration (host hard lockups). > > The host needs to be booted with "kvm-arm.mode=nested" option and > qemu needs to be invoked with : > > -machine virt,virtualization=on > > There is a known issue with hosts supporting SVE. Kernel does not support both > SVE and NV2 and the current qemu integration has an issue with the > scratch_host_vcpu startup because both are enabled if exposed by the kernel. > This is independent on whether sve is disabled on the command line. > Unfortunately > I lost access to the HW that expose that issue so I couldn't fix it in this > version.
You can probably repro that by running the whole setup under QEMU's FEAT_NV emulation, which will be able to give you a CPU with both FEAT_NV and SVE. Personally I think that this is a kernel missing-feature that should really be fixed as part of getting the kernel patches upstreamed. There's no cause to force every userspace VMM to develop extra complications for this. thanks -- PMM
