Merge branch kvm-arm64/spec-ptw into kvmarm-master/next

Merge branch kvm-arm64/spec-ptw into kvmarm-master/next

* kvm-arm64/spec-ptw:
  : .
  : On taking an exception from EL1&0 to EL2(&0), the page table walker is
  : allowed to carry on with speculative walks started from EL1&0 while
  : running at EL2 (see R_LFHQG). Given that the PTW may be actively using
  : the EL1&0 system registers, the only safe way to deal with it is to
  : issue a DSB before changing any of it.
  :
  : We already did the right thing for SPE and TRBE, but ignored the PTW
  : for unknown reasons (probably because the architecture wasn't crystal
  : clear at the time).
  :
  : This requires a bit of surgery in the nvhe code, though most of these
  : patches are comments so that my future self can understand the purpose
  : of these barriers. The VHE code is largely unaffected, thanks to the
  : DSB in the context switch.
  : .
  KVM: arm64: vhe: Drop extra isb() on guest exit
  KVM: arm64: vhe: Synchronise with page table walker on MMU update
  KVM: arm64: pkvm: Document the side effects of kvm_flush_dcache_to_poc()
  KVM: arm64: nvhe: Synchronise with page table walker on TLBI
  KVM: arm64: nvhe: Synchronise with page table walker on vcpu run

Signed-off-by: Marc Zyngier <maz@kernel.org>