[PATCH v2 00/20] KVM: arm64: Generalise RESx handling

[Marc Zyngier <maz@kernel.org>]

Having spent some time dealing with some dark corners of the
architecture, I have realised that our RESx handling is a bit patchy.
Specially when it comes to RES1 bits, which are not clearly defined in
config.c, and rely on band-aids such as FIXED_VALUE.

This series takes the excuse of adding SCTLR_EL2 sanitisation to bite
the bullet and pursue several goals:

- clearly define bits that are RES1 when a feature is absent

- have a unified data structure to manage both RES0 and RES1 bits

- deal with the annoying complexity of some features being
  conditioned on E2H==1

- allow a single bit to take different RESx values depending on the
  value of E2H

This allows quite a bit of cleanup, including the total removal of the
FIXED_VALUE horror, which was always a bizarre construct. We also get
a new debugfs file to introspect the RESx settings for a given guest.

Overall, this lowers the complexity of expressing the configuration
constraints, for very little code (most of the extra lines are
introduced by the debugfs stuff, and SCTLR_EL2 being added to the
sysreg file).

Patches on top of my kvm-arm64/vtcr branch (which is currently
simmering in -next).

* From v1 [1]

  - Simplified RES0 handling by dropping the RES0_WHEN_E2Hx macros

  - Cleaned up the kvm_{g,s}et_sysreg_resx() helpers

  - Simplified dynamic RESx handling

  - New improved debugfs handling, thanks to Fuad!

  - Various clean-ups and spelling fixes

  - Collected RBs (thanks Fuad and Joey!)

[1] https://lore.kernel.org/all/20260126121655.1641736-1-maz@kernel.org
Marc Zyngier (20):
  arm64: Convert SCTLR_EL2 to sysreg infrastructure
  KVM: arm64: Remove duplicate configuration for SCTLR_EL1.{EE,E0E}
  KVM: arm64: Introduce standalone FGU computing primitive
  KVM: arm64: Introduce data structure tracking both RES0 and RES1 bits
  KVM: arm64: Extend unified RESx handling to runtime sanitisation
  KVM: arm64: Inherit RESx bits from FGT register descriptors
  KVM: arm64: Allow RES1 bits to be inferred from configuration
  KVM: arm64: Correctly handle SCTLR_EL1 RES1 bits for unsupported
    features
  KVM: arm64: Convert HCR_EL2.RW to AS_RES1
  KVM: arm64: Simplify FIXED_VALUE handling
  KVM: arm64: Add REQUIRES_E2H1 constraint as configuration flags
  KVM: arm64: Add RES1_WHEN_E2Hx constraints as configuration flags
  KVM: arm64: Move RESx into individual register descriptors
  KVM: arm64: Simplify handling of HCR_EL2.E2H RESx
  KVM: arm64: Get rid of FIXED_VALUE altogether
  KVM: arm64: Simplify handling of full register invalid constraint
  KVM: arm64: Remove all traces of FEAT_TME
  KVM: arm64: Remove all traces of HCR_EL2.MIOCNCE
  KVM: arm64: Add sanitisation to SCTLR_EL2
  KVM: arm64: Add debugfs file dumping computed RESx values

 arch/arm64/include/asm/kvm_host.h             |  38 +-
 arch/arm64/include/asm/sysreg.h               |   7 -
 arch/arm64/kvm/config.c                       | 427 ++++++++++--------
 arch/arm64/kvm/emulate-nested.c               |  10 +-
 arch/arm64/kvm/nested.c                       | 151 +++----
 arch/arm64/kvm/sys_regs.c                     |  68 +++
 arch/arm64/tools/sysreg                       |  82 +++-
 tools/arch/arm64/include/asm/sysreg.h         |   6 -
 tools/perf/Documentation/perf-arm-spe.txt     |   1 -
 .../testing/selftests/kvm/arm64/set_id_regs.c |   1 -
 10 files changed, 478 insertions(+), 313 deletions(-)

-- 
2.47.3