[PATCH v2 18/24] kvm: arm64: Add function to enter host from KVM nVHE hyp code

David Brazdil
2020-11-16T20:45:13Z

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>
---
arch/arm64/kvm/hyp/nvhe/host.S | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S
index 52dae5cd5a28..170d6f6376ae 100644
--- a/arch/arm64/kvm/hyp/nvhe/host.S
+++ b/arch/arm64/kvm/hyp/nvhe/host.S
@@ -41,6 +41,7 @@ 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)]
@@ -63,6 +64,14 @@ __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);
*/
--
2.29.2.299.gdc1121823c-goog