arm64: kvm: stop treating register x18 as caller save

In preparation of reserving x18, stop treating it as caller save in
the KVM guest entry/exit code. Currently, the code assumes there is
no need to preserve it for the host, given that it would have been
assumed clobbered anyway by the function call to __guest_enter().
Instead, preserve its value and restore it upon return.

Link: https://patchwork.kernel.org/patch/9836891/
Signed-off-by: Ard Biesheuvel <[email protected]>
[Sami: updated commit message, switched from x18 to x29 for the guest context]
Signed-off-by: Sami Tolvanen <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Reviewed-by: Marc Zyngier <[email protected]>
Reviewed-by: Mark Rutland <[email protected]>
Signed-off-by: Will Deacon <[email protected]>

0 files changed, 0 insertions, 0 deletions