[PATCH v2 0/2] KVM: arm64: Reject mismatched GICv3 ITS/VGIC models

[Sascha Bischoff]

On a GICv5 host with legacy GICv3 support, KVM exposes both VGIC
models to userspace. A VM can create a GICv3 ITS alongside a GICv5
VGIC, because neither creation path checks the model of the other
device. The ITS sets has_its, but a GICv5 VM cannot use a GICv3 ITS
for MSI translation. Creating the ITS before the VGIC also lets
userspace select an incompatible VGIC model later.

Record the VGIC model required by a GICv3 ITS and reject incompatible
device creation in either order. Drop has_its in favour of using the
newly added its_model instead. The second patch tests both orderings,
skipping the test if the host does not offer a GICv3 ITS.

This series is based on kvmarm/next-7.4+fixes-7.3-2.

Changes since V1:

* Worked in Marc's suggestion to drop has_its.
* Check for its_model being non-zero in vgic_has_its(), allowing us to
  drop has_its.
* Added a comment to explain what we are actually doing. Again, Marc's
  suggestion.
* Changed the type of vgic_model from u32 to enum kvm_device_type.

Thanks,
Sascha

Sascha Bischoff (2):
  KVM: arm64: vgic: Require matching VGIC model for GICv3 ITS
  KVM: selftests: Reject GICv3 ITS with a GICv5 VGIC

 arch/arm64/kvm/vgic/vgic-init.c             | 17 +++++++++++
 arch/arm64/kvm/vgic/vgic-its.c              | 15 +++++++++-
 arch/arm64/kvm/vgic/vgic-mmio-v3.c          |  5 +---
 include/kvm/arm_vgic.h                      |  5 ++--
 tools/testing/selftests/kvm/arm64/vgic_v5.c | 32 +++++++++++++++++++++
 5 files changed, 67 insertions(+), 7 deletions(-)

-- 
2.34.1