KVM: arm64: Add function to enter host from KVM nVHE hyp code

All nVHE hyp code is currently executed as handlers of host's HVCs. This
will change as nVHE starts intercepting host's PSCI CPU_ON SMCs. The
newly booted CPU will need to initialize EL2 state and then enter the
host. Add __host_enter function that branches into the existing
host state-restoring code after the trap handler would have returned.

Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201202184122.26046-21-dbrazdil@google.com

diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S
index 2b56f0bdf874392a244bcf45e6f0e592869b70e7..a820dfdc9c25d427de46236c0335754323b0bc1a 100644 (file)
--- a/arch/arm64/kvm/hyp/nvhe/host.S
+++ b/arch/arm64/kvm/hyp/nvhe/host.S
@@ -39,6 +39,7 @@ SYM_FUNC_START(__host_exit)
        bl      handle_trap
 
        /* Restore host regs x0-x17 */
+__host_enter_restore_full:
        ldp     x0, x1,   [x29, #CPU_XREG_OFFSET(0)]
        ldp     x2, x3,   [x29, #CPU_XREG_OFFSET(2)]
        ldp     x4, x5,   [x29, #CPU_XREG_OFFSET(4)]
@@ -61,6 +62,14 @@ __host_enter_without_restoring:
        sb
 SYM_FUNC_END(__host_exit)
 
+/*
+ * void __noreturn __host_enter(struct kvm_cpu_context *host_ctxt);
+ */
+SYM_FUNC_START(__host_enter)
+       mov     x29, x0
+       b       __host_enter_restore_full
+SYM_FUNC_END(__host_enter)
+
 /*
  * void __noreturn __hyp_do_panic(bool restore_host, u64 spsr, u64 elr, u64 par);
  */