Merge branch kvm-arm64/ffa-proxy into kvmarm/next

Merge branch kvm-arm64/ffa-proxy into kvmarm/next

* kvm-arm64/ffa-proxy:
  : pKVM FF-A Proxy, courtesy Will Deacon and Andrew Walbran
  :
  : From the cover letter:
  :
  : pKVM's primary goal is to protect guest pages from a compromised host by
  : enforcing access control restrictions using stage-2 page-tables. Sadly,
  : this cannot prevent TrustZone from accessing non-secure memory, and a
  : compromised host could, for example, perform a 'confused deputy' attack
  : by asking TrustZone to use pages that have been donated to protected
  : guests. This would effectively allow the host to have TrustZone
  : exfiltrate guest secrets on its behalf, hence breaking the isolation
  : that pKVM intends to provide.
  :
  : This series addresses this problem by providing pKVM with the ability to
  : monitor SMCs following the Arm FF-A protocol. FF-A provides (among other
  : things) a set of memory management APIs allowing the Normal World to
  : share, donate or lend pages with Secure. By monitoring these SMCs, pKVM
  : can ensure that the pages that are shared, lent or donated to Secure by
  : the host kernel are only pages that it owns.
  KVM: arm64: pkvm: Add support for fragmented FF-A descriptors
  KVM: arm64: Handle FFA_FEATURES call from the host
  KVM: arm64: Handle FFA_MEM_LEND calls from the host
  KVM: arm64: Handle FFA_MEM_RECLAIM calls from the host
  KVM: arm64: Handle FFA_MEM_SHARE calls from the host
  KVM: arm64: Add FF-A helpers to share/unshare memory with secure world
  KVM: arm64: Handle FFA_RXTX_MAP and FFA_RXTX_UNMAP calls from the host
  KVM: arm64: Allocate pages for hypervisor FF-A mailboxes
  KVM: arm64: Probe FF-A version and host/hyp partition ID during init
  KVM: arm64: Block unsafe FF-A calls from the host

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