KVM: arm64: Add helper for swapping guest descriptor

Implementing FEAT_HAFDBS in KVM's software PTWs requires the ability to
CAS a descriptor to update the in-memory value. Add an accessor to do
exactly that, coping with the fact that guest descriptors are in user
memory (duh).

While FEAT_LSE required on any system that implements NV, KVM now uses
the stage-1 PTW for non-nested use cases meaning an LL/SC implementation
is necessary as well.

Reviewed-by: Marc Zyngier <maz@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Link: https://msgid.link/20251124190158.177318-11-oupton@kernel.org
Signed-off-by: Oliver Upton <oupton@kernel.org>

0 files changed, 0 insertions, 0 deletions