[RFC v3 0/5] ARM Nested Virt Support

[Eric Auger]

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

Known issues:
- Does not work on hosts supporting both SVE and NV2. KVM does not
  support both SVE and NV2 and the current qemu integration attempts to
  creates a scracth VM with both if those are exposed by the host.
- L2 guest featuring EDK2 does not work. This produces hard lockups on host
- Migration does not work. After ages one gets on the destination side:
qemu-system-aarch64: error while loading state for instance 0x0 of device 'cpu'
qemu-system-aarch64: Failed to put registers after init: Invalid argument

This series can be found at:
https://github.com/eauger/qemu/tree/v9.0-nv-rfcv3

Previous version from Miguel:
[1] https://lore.kernel.org/all/20230227163718.62003-1-miguel.luis@oracle.com/
Previous version from Haibo:
[2] https://lore.kernel.org/qemu-devel/cover.1617281290.git.haibo.xu@linaro.org/
[3] Based on Marc's kvm-arm64/nv-6.9-sr-enforcement branch
    [PATCH v11 00/43] KVM: arm64: Nested Virtualization support (FEAT_NV2 only)
    
https://lore.kernel.org/linux-arm-kernel/20231120131027.854038-1-maz@kernel.org/T/
    available at: 
https://github.com/eauger/linux/tree/v6.8-rc1-nv2-sr-enforcement

---

v2 -> v3:
- KVM EL2 only is set if virtualization option is set
- fixes regression with virtualization=off
- Add checks against unsupported GIC configs until the kernel does

Haibo Xu (5):
  [Placeholder] headers: Partial headers update for NV2 enablement
  hw/arm: Allow setting KVM vGIC maintenance IRQ
  target/arm/kvm: Add helper to detect EL2 when using KVM
  target/arm: Enable feature ARM_FEATURE_EL2 if EL2 is supported
  hw/arm/virt: Allow virt extensions with KVM

 hw/arm/virt.c                      | 13 ++++++++++++-
 hw/intc/arm_gicv3_common.c         |  1 +
 hw/intc/arm_gicv3_kvm.c            | 21 +++++++++++++++++++++
 include/hw/intc/arm_gicv3_common.h |  1 +
 linux-headers/asm-arm64/kvm.h      |  1 +
 linux-headers/linux/kvm.h          |  1 +
 target/arm/kvm.c                   | 21 +++++++++++++++++++++
 target/arm/kvm_arm.h               | 12 ++++++++++++
 8 files changed, 70 insertions(+), 1 deletion(-)

-- 
2.41.0