[00/12] KVM: arm64: nv: Add support for address translation instructions

Message

Marc Zyngier June 25, 2024, 1:34 p.m. UTC

Another task that a hypervisor supporting NV on arm64 has to deal with
is to emulate the AT instruction, because we multiplex all the S1
translations on a single set of registers, and the guest S2 is never
truly resident on the CPU.

So given that we lie about page tables, we also have to lie about
translation instructions, hence the emulation. Things are made
complicated by the fact that guest S1 page tables can be swapped out,
and that our shadow S2 is likely to be incomplete. So while using AT
to emulate AT is tempting (and useful), it is not going to always
work, and we thus need a fallback in the shape of a SW S1 walker.

This series is built in 4 basic blocks:

- Add missing definition and basic reworking

- Dumb emulation of all relevant AT instructions using AT instructions

- Add a SW S1 walker that is using our S2 walker

- Add FEAT_ATS1A support, which is almost trivial

This has been tested by comparing the output of a HW walker with the
output of the SW one. Obviously, this isn't bullet proof, and I'm
pretty sure there are some nasties in there.

In a departure from my usual habit, this series is on top of
kvmarm/next, as it depends on the NV S2 shadow code.

Joey Gouly (1):
  KVM: arm64: make kvm_at() take an OP_AT_*

Marc Zyngier (11):
  arm64: Add missing APTable and TCR_ELx.HPD masks
  arm64: Add PAR_EL1 field description
  KVM: arm64: nv: Turn upper_attr for S2 walk into the full descriptor
  KVM: arm64: nv: Honor absence of FEAT_PAN2
  KVM: arm64: nv: Add basic emulation of AT S1E{0,1}{R,W}[P]
  KVM: arm64: nv: Add basic emulation of AT S1E2{R,W}
  KVM: arm64: nv: Add emulation of AT S12E{0,1}{R,W}
  KVM: arm64: nv: Make ps_to_output_size() generally available
  KVM: arm64: nv: Add SW walker for AT S1 emulation
  KVM: arm64: nv: Plumb handling of AT S1* traps from EL2
  KVM: arm64: nv: Add support for FEAT_ATS1A

 arch/arm64/include/asm/kvm_arm.h       |    1 +
 arch/arm64/include/asm/kvm_asm.h       |    6 +-
 arch/arm64/include/asm/kvm_nested.h    |   18 +-
 arch/arm64/include/asm/pgtable-hwdef.h |    7 +
 arch/arm64/include/asm/sysreg.h        |   19 +
 arch/arm64/kvm/Makefile                |    2 +-
 arch/arm64/kvm/at.c                    | 1007 ++++++++++++++++++++++++
 arch/arm64/kvm/emulate-nested.c        |    2 +
 arch/arm64/kvm/hyp/include/hyp/fault.h |    2 +-
 arch/arm64/kvm/nested.c                |   26 +-
 arch/arm64/kvm/sys_regs.c              |   60 ++
 11 files changed, 1125 insertions(+), 25 deletions(-)
 create mode 100644 arch/arm64/kvm/at.c