linux/arch/arm64/include/asm/virt.h

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

#ifndef __ASM__VIRT_H
#define __ASM__VIRT_H

/*
 * The arm64 hcall implementation uses x0 to specify the hcall
 * number. A value less than HVC_STUB_HCALL_NR indicates a special
 * hcall, such as set vector. Any other value is handled in a
 * hypervisor specific way.
 *
 * The hypercall is allowed to clobber any of the caller-saved
 * registers (x0-x18), so it is advisable to use it through the
 * indirection of a function call (as implemented in hyp-stub.S).
 */

/*
 * HVC_SET_VECTORS - Set the value of the vbar_el2 register.
 *
 * @x1: Physical address of the new vector table.
 */
#define HVC_SET_VECTORS 0

/*
 * HVC_SOFT_RESTART - CPU soft reset, used by the cpu_soft_restart routine.
 */
#define HVC_SOFT_RESTART 1

/*
 * HVC_RESET_VECTORS - Restore the vectors to the original HYP stubs
 */
#define HVC_RESET_VECTORS 2

/*
 * HVC_FINALISE_EL2 - Upgrade the CPU from EL1 to EL2, if possible
 */
#define HVC_FINALISE_EL2	3

/* Max number of HYP stub hypercalls */
#define HVC_STUB_HCALL_NR 4

/* Error returned when an invalid stub number is passed into x0 */
#define HVC_STUB_ERR	0xbadca11

#define BOOT_CPU_MODE_EL1	(0xe11)
#define BOOT_CPU_MODE_EL2	(0xe12)

/*
 * Flags returned together with the boot mode, but not preserved in
 * __boot_cpu_mode. Used by the idreg override code to work out the
 * boot state.
 */
#define BOOT_CPU_FLAG_E2H	BIT_ULL(32)

#ifndef __ASSEMBLY__

#include <asm/ptrace.h>
#include <asm/sections.h>
#include <asm/sysreg.h>
#include <asm/cpufeature.h>

/*
 * __boot_cpu_mode records what mode CPUs were booted in.
 * A correctly-implemented bootloader must start all CPUs in the same mode:
 * In this case, both 32bit halves of __boot_cpu_mode will contain the
 * same value (either 0 if booted in EL1, BOOT_CPU_MODE_EL2 if booted in EL2).
 *
 * Should the bootloader fail to do this, the two values will be different.
 * This allows the kernel to flag an error when the secondaries have come up.
 */
extern u32 __boot_cpu_mode[2];

#define ARM64_VECTOR_TABLE_LEN	SZ_2K

void __hyp_set_vectors(phys_addr_t phys_vector_base);
void __hyp_reset_vectors(void);
bool is_kvm_arm_initialised(void);

DECLARE_STATIC_KEY_FALSE(kvm_protected_mode_initialized);

/* Reports the availability of HYP mode */
static inline bool is_hyp_mode_available(void)
{
	/*
	 * If KVM protected mode is initialized, all CPUs must have been booted
	 * in EL2. Avoid checking __boot_cpu_mode as CPUs now come up in EL1.
	 */
	if (IS_ENABLED(CONFIG_KVM) &&
	    static_branch_likely(&kvm_protected_mode_initialized))
		return true;

	return (__boot_cpu_mode[0] == BOOT_CPU_MODE_EL2 &&
		__boot_cpu_mode[1] == BOOT_CPU_MODE_EL2);
}

/* Check if the bootloader has booted CPUs in different modes */
static inline bool is_hyp_mode_mismatched(void)
{
	/*
	 * If KVM protected mode is initialized, all CPUs must have been booted
	 * in EL2. Avoid checking __boot_cpu_mode as CPUs now come up in EL1.
	 */
	if (IS_ENABLED(CONFIG_KVM) &&
	    static_branch_likely(&kvm_protected_mode_initialized))
		return false;

	return __boot_cpu_mode[0] != __boot_cpu_mode[1];
}

static __always_inline bool is_kernel_in_hyp_mode(void)
{
	BUILD_BUG_ON(__is_defined(__KVM_NVHE_HYPERVISOR__) ||
		     __is_defined(__KVM_VHE_HYPERVISOR__));
	return read_sysreg(CurrentEL) == CurrentEL_EL2;
}

static __always_inline bool has_vhe(void)
{
	/*
	 * Code only run in VHE/NVHE hyp context can assume VHE is present or
	 * absent. Otherwise fall back to caps.
	 * This allows the compiler to discard VHE-specific code from the
	 * nVHE object, reducing the number of external symbol references
	 * needed to link.
	 */
	if (is_vhe_hyp_code())
		return true;
	else if (is_nvhe_hyp_code())
		return false;
	else
		return cpus_have_final_cap(ARM64_HAS_VIRT_HOST_EXTN);
}

static __always_inline bool is_protected_kvm_enabled(void)
{
	if (is_vhe_hyp_code())
		return false;
	else
		return cpus_have_final_cap(ARM64_KVM_PROTECTED_MODE);
}

static __always_inline bool has_hvhe(void)
{
	if (is_vhe_hyp_code())
		return false;

	return cpus_have_final_cap(ARM64_KVM_HVHE);
}

static inline bool is_hyp_nvhe(void)
{
	return is_hyp_mode_available() && !is_kernel_in_hyp_mode();
}

#endif /* __ASSEMBLY__ */

#endif /* ! __ASM__VIRT_H */