path: root/arch/arm64/kvm/hyp.S

/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright (C) 2012,2013 - ARM Ltd
 * Author: Marc Zyngier <marc.zyngier@arm.com>
 */

#include <linux/linkage.h>

#include <asm/alternative.h>
#include <asm/assembler.h>
#include <asm/cpufeature.h>

/*
 * u64 __kvm_call_hyp(void *hypfn, ...);
 *
 * This is not really a variadic function in the classic C-way and care must
 * be taken when calling this to ensure parameters are passed in registers
 * only, since the stack will change between the caller and the callee.
 *
 * Call the function with the first argument containing a pointer to the
 * function you wish to call in Hyp mode, and subsequent arguments will be
 * passed as x0, x1, and x2 (a maximum of 3 arguments in addition to the
 * function pointer can be passed).  The function being called must be mapped
 * in Hyp mode (see init_hyp_mode in arch/arm/kvm/arm.c).  Return values are
 * passed in x0.
 *
 * A function pointer with a value less than 0xfff has a special meaning,
 * and is used to implement hyp stubs in the same way as in
 * arch/arm64/kernel/hyp_stub.S.
 */
SYM_FUNC_START(__kvm_call_hyp)
	hvc	#0
	ret
SYM_FUNC_END(__kvm_call_hyp)