[PATCH 00/11] KVM: arm64: nv: Userspace register visibility fixes

[Marc Zyngier]

Peter recently pointed out that we don't expose the EL2 GICv3
registers in a consistent manner, as they are presented through the
ONE_REG interface instead of KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS, despite
the latter already exposing the EL1 GICv3 regs.

While I was looking at this, I ended up finding a small number of
equally small problems:

- RVBAR_EL2 shouldn't be a thing at all

- FEAT_FGT registers should only be exposed to userspace if the
  feature is presented to the guest (and actually exists)

- FEAT_FGT2 registers are not exposed at all, and that's bad (though
  the machine that has FGT2 hasn't been built yet)

- Nothing documents which registers are exposed by
  KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS

So I cooked up a handful of fixes for those. And because I was feeling
generous, I hacked the get-reg-list test to check for the EL2
registers reported via ONE_REG /mindblown/.

Eric, I'd really appreciate if you could give this a go with QEMU to
check that you can now correctly get to the GIC El2 registers via the
expected interface.

Marc Zyngier (11):
  KVM: arm64: Make RVBAR_EL2 accesses UNDEF
  KVM: arm64: Don't advertise ICH_*_EL2 registers through GET_ONE_REG
  KVM: arm64: Define constant value for ICC_SRE_EL2
  KVM: arm64: Define helper for ICH_VTR_EL2
  KVM: arm64: Let GICv3 save/restore honor visibility attribute
  KVM: arm64: Expose GICv3 EL2 registers via
    KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS
  KVM: arm64: Condition FGT registers on feature availability
  KVM: arm64: Advertise FGT2 registers to userspace
  KVM: arm64: selftests: get-reg-list: Simplify feature dependency
  KVM: arm64: selftests: get-reg-list: Add base EL2 registers
  KVM: arm64: Document registers exposed via
    KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS

 .../virt/kvm/devices/arm-vgic-v3.rst          |  63 +++++-
 arch/arm64/kvm/sys_regs.c                     | 111 ++++++----
 arch/arm64/kvm/vgic-sys-reg-v3.c              | 121 ++++++++++-
 arch/arm64/kvm/vgic/vgic.h                    |  18 ++
 .../selftests/kvm/arm64/get-reg-list.c        | 197 +++++++++++++++---
 5 files changed, 432 insertions(+), 78 deletions(-)

-- 
2.39.2