Commit e500b805 authored by Andrew Scull's avatar Andrew Scull Committed by Marc Zyngier
Browse files

KVM: arm64: Don't clobber x4 in __do_hyp_init 



arm_smccc_1_1_hvc() only adds write contraints for x0-3 in the inline
assembly for the HVC instruction so make sure those are the only
registers that change when __do_hyp_init is called.

Tested-by: default avatarDavid Brazdil <dbrazdil@google.com>
Signed-off-by: default avatarAndrew Scull <ascull@google.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210125145415.122439-3-ascull@google.com
parent 139bc8a6

arch/arm64/kvm/hyp/nvhe/hyp-init.S

+11 −9
Original line number Diff line number Diff line
@@ -47,6 +47,8 @@ __invalid: 
	b	.



	/*

	 * Only uses x0..x3 so as to not clobber callee-saved SMCCC registers.

	 *

	 * x0: SMCCC function ID

	 * x1: struct kvm_nvhe_init_params PA

	 */
@@ -70,9 +72,9 @@ __do_hyp_init: 
	eret



1:	mov	x0, x1

	mov	x4, lr

	bl	___kvm_hyp_init

	mov	lr, x4

	mov	x3, lr

	bl	___kvm_hyp_init			// Clobbers x0..x2

	mov	lr, x3



	/* Hello, World! */

	mov	x0, #SMCCC_RET_SUCCESS
@@ -82,8 +84,8 @@ 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.

 * Only uses x0..x2 so as to not clobber callee-saved SMCCC registers

 * and leave x3 for the caller.

 *

 * x0: struct kvm_nvhe_init_params PA

 */
@@ -112,9 +114,9 @@ alternative_else_nop_endif 
	/*

	 * Set the PS bits in TCR_EL2.

	 */

	ldr	x1, [x0, #NVHE_INIT_TCR_EL2]

	tcr_compute_pa_size x1, #TCR_EL2_PS_SHIFT, x2, x3

	msr	tcr_el2, x1

	ldr	x0, [x0, #NVHE_INIT_TCR_EL2]

	tcr_compute_pa_size x0, #TCR_EL2_PS_SHIFT, x1, x2

	msr	tcr_el2, x0



	isb
@@ -193,7 +195,7 @@ SYM_CODE_START_LOCAL(__kvm_hyp_init_cpu) 


	/* Enable MMU, set vectors and stack. */

	mov	x0, x28

	bl	___kvm_hyp_init			// Clobbers x0..x3

	bl	___kvm_hyp_init			// Clobbers x0..x2



	/* Leave idmap. */

	mov	x0, x29