[PATCH v3 17/23] kvm: arm64: Extract __do_hyp_init into a helper function

[David Brazdil]

In preparation for adding a CPU entry point in nVHE hyp code, extract
most of __do_hyp_init hypervisor initialization code into a common
helper function. This will be invoked by the entry point to install KVM
on the newly booted CPU.

Signed-off-by: David Brazdil <dbrazdil at google.com>
---
 arch/arm64/kvm/hyp/nvhe/hyp-init.S | 35 ++++++++++++++++++++++--------
 1 file changed, 26 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
index 77c983aa90fa..98ce40e17b42 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
@@ -68,13 +68,32 @@ __do_hyp_init:
 	mov	x0, #SMCCC_RET_NOT_SUPPORTED
 	eret
 
-1:	ldr	x0, [x1, #NVHE_INIT_TPIDR_EL2]
-	msr	tpidr_el2, x0
+1:	mov	x0, x1
+	mov	x4, lr
+	bl	___kvm_hyp_init
+	mov	lr, x4
 
-	ldr	x0, [x1, #NVHE_INIT_STACK_HYP_VA]
-	mov	sp, x0
+	/* Hello, World! */
+	mov	x0, #SMCCC_RET_SUCCESS
+	eret
+SYM_CODE_END(__kvm_hyp_init)
+
+/*
+ * Initialize the hypervisor in EL2.
+ *
+ * Only uses x0..x3 so as to not clobber callee-saved SMCCC registers
+ * and leave x4 for the caller.
+ *
+ * x0: struct kvm_nvhe_init_params PA
+ */
+SYM_CODE_START(___kvm_hyp_init)
+	ldr	x1, [x0, #NVHE_INIT_TPIDR_EL2]
+	msr	tpidr_el2, x1
+
+	ldr	x1, [x0, #NVHE_INIT_STACK_HYP_VA]
+	mov	sp, x1
 
-	ldr	x1, [x1, #NVHE_INIT_PGD_PA]
+	ldr	x1, [x0, #NVHE_INIT_PGD_PA]
 	phys_to_ttbr x0, x1
 alternative_if ARM64_HAS_CNP
 	orr	x0, x0, #TTBR_CNP_BIT
@@ -139,10 +158,8 @@ alternative_else_nop_endif
 	kimg_hyp_va x0, x1
 	msr	vbar_el2, x0
 
-	/* Hello, World! */
-	mov	x0, #SMCCC_RET_SUCCESS
-	eret
-SYM_CODE_END(__kvm_hyp_init)
+	ret
+SYM_CODE_END(___kvm_hyp_init)
 
 SYM_CODE_START(__kvm_handle_stub_hvc)
 	cmp	x0, #HVC_SOFT_RESTART
-- 
2.29.2.454.gaff20da3a2-goog