Merge branch kvm-arm64/vm-configuration into kvmarm/next

Merge branch kvm-arm64/vm-configuration into kvmarm/next

* kvm-arm64/vm-configuration: (29 commits)
  : VM configuration enforcement, courtesy of Marc Zyngier
  :
  : Userspace has gained the ability to control the features visible
  : through the ID registers, yet KVM didn't take this into account as the
  : effective feature set when determing trap / emulation behavior. This
  : series adds:
  :
  :  - Mechanism for testing the presence of a particular CPU feature in the
  :    guest's ID registers
  :
  :  - Infrastructure for computing the effective value of VNCR-backed
  :    registers, taking into account the RES0 / RES1 bits for a particular
  :    VM configuration
  :
  :  - Implementation of 'fine-grained UNDEF' controls that shadow the FGT
  :    register definitions.
  KVM: arm64: Don't initialize idreg debugfs w/ preemption disabled
  KVM: arm64: Fail the idreg iterator if idregs aren't initialized
  KVM: arm64: Make build-time check of RES0/RES1 bits optional
  KVM: arm64: Add debugfs file for guest's ID registers
  KVM: arm64: Snapshot all non-zero RES0/RES1 sysreg fields for later checking
  KVM: arm64: Make FEAT_MOPS UNDEF if not advertised to the guest
  KVM: arm64: Make AMU sysreg UNDEF if FEAT_AMU is not advertised to the guest
  KVM: arm64: Make PIR{,E0}_EL1 UNDEF if S1PIE is not advertised to the guest
  KVM: arm64: Make TLBI OS/Range UNDEF if not advertised to the guest
  KVM: arm64: Streamline save/restore of HFG[RW]TR_EL2
  KVM: arm64: Move existing feature disabling over to FGU infrastructure
  KVM: arm64: Propagate and handle Fine-Grained UNDEF bits
  KVM: arm64: Add Fine-Grained UNDEF tracking information
  KVM: arm64: Rename __check_nv_sr_forward() to triage_sysreg_trap()
  KVM: arm64: Use the xarray as the primary sysreg/sysinsn walker
  KVM: arm64: Register AArch64 system register entries with the sysreg xarray
  KVM: arm64: Always populate the trap configuration xarray
  KVM: arm64: nv: Move system instructions to their own sys_reg_desc array
  KVM: arm64: Drop the requirement for XARRAY_MULTI
  KVM: arm64: nv: Turn encoding ranges into discrete XArray stores
  ...

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>