include/linux/arm-rsi-cmds.h

/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright (C) 2023 ARM Ltd.
 */

#ifndef __LINUX_ARM_RSI_CMDS_H_
#define __LINUX_ARM_RSI_CMDS_H_

#include <linux/arm-smccc-rsi.h>
#include <linux/jump_label.h>
#include <linux/string.h>
#include <asm/memory.h>

#ifdef CONFIG_ARM_RMM_RSI
DECLARE_STATIC_KEY_FALSE(rsi_present);

void __init arm64_rsi_init(void);

bool arm64_rsi_is_protected(phys_addr_t base, size_t size);

static inline bool is_realm_world(void)
{
	return static_branch_unlikely(&rsi_present);
}
#else
static inline void arm64_rsi_init(void) { }

static inline bool arm64_rsi_is_protected(phys_addr_t base, size_t size)
{
	return false;
}

static inline bool is_realm_world(void) { return false; }
#endif

#define RSI_GRANULE_SHIFT		12
#define RSI_GRANULE_SIZE		(_AC(1, UL) << RSI_GRANULE_SHIFT)

enum ripas {
	RSI_RIPAS_EMPTY = 0,
	RSI_RIPAS_RAM = 1,
	RSI_RIPAS_DESTROYED = 2,
	RSI_RIPAS_DEV = 3,
};

static inline unsigned long rsi_request_version(unsigned long req,
						unsigned long *out_lower,
						unsigned long *out_higher)
{
	struct arm_smccc_res res;

	arm_smccc_smc(SMC_RSI_ABI_VERSION, req, 0, 0, 0, 0, 0, 0, &res);

	if (out_lower)
		*out_lower = res.a1;
	if (out_higher)
		*out_higher = res.a2;

	return res.a0;
}

static inline unsigned long rsi_get_realm_config(struct realm_config *cfg)
{
	struct arm_smccc_res res;

	arm_smccc_smc(SMC_RSI_REALM_CONFIG, virt_to_phys(cfg),
		      0, 0, 0, 0, 0, 0, &res);
	return res.a0;
}

static inline unsigned long rsi_ipa_state_get(phys_addr_t start,
					      phys_addr_t end,
					      enum ripas *state,
					      phys_addr_t *top)
{
	struct arm_smccc_res res;

	arm_smccc_smc(SMC_RSI_IPA_STATE_GET,
		      start, end, 0, 0, 0, 0, 0,
		      &res);

	if (res.a0 == RSI_SUCCESS) {
		if (top)
			*top = res.a1;
		if (state)
			*state = res.a2;
	}

	return res.a0;
}

static inline long rsi_set_addr_range_state(phys_addr_t start,
					    phys_addr_t end,
					    enum ripas state,
					    unsigned long flags,
					    phys_addr_t *top)
{
	struct arm_smccc_res res;

	arm_smccc_smc(SMC_RSI_IPA_STATE_SET, start, end, state,
		      flags, 0, 0, 0, &res);

	if (top)
		*top = res.a1;

	if (res.a2 != RSI_ACCEPT)
		return -EPERM;

	return res.a0;
}

static inline int rsi_set_memory_range(phys_addr_t start, phys_addr_t end,
				       enum ripas state, unsigned long flags)
{
	unsigned long ret;
	phys_addr_t top;

	while (start != end) {
		ret = rsi_set_addr_range_state(start, end, state, flags, &top);
		if (ret || top < start || top > end)
			return -EINVAL;
		start = top;
	}

	return 0;
}

/*
 * Convert the specified range to RAM. Do not use this if you rely on the
 * contents of a page that may already be in RAM state.
 */
static inline int rsi_set_memory_range_protected(phys_addr_t start,
						 phys_addr_t end)
{
	return rsi_set_memory_range(start, end, RSI_RIPAS_RAM,
				    RSI_CHANGE_DESTROYED);
}

/*
 * Convert the specified range to RAM. Do not convert any pages that may have
 * been DESTROYED, without our permission.
 */
static inline int rsi_set_memory_range_protected_safe(phys_addr_t start,
						      phys_addr_t end)
{
	return rsi_set_memory_range(start, end, RSI_RIPAS_RAM,
				    RSI_NO_CHANGE_DESTROYED);
}

static inline int rsi_set_memory_range_shared(phys_addr_t start,
					      phys_addr_t end)
{
	return rsi_set_memory_range(start, end, RSI_RIPAS_EMPTY,
				    RSI_CHANGE_DESTROYED);
}

#define RSI_ATTEST_CHALLENGE_MIN_SIZE	32
#define RSI_ATTEST_CHALLENGE_MAX_SIZE	64

struct rsi_attestation_token_init_args {
	unsigned long fid;
	u8 challenge[RSI_ATTEST_CHALLENGE_MAX_SIZE];
};

/**
 * rsi_attestation_token_init - Initialise the operation to retrieve an
 * attestation token.
 *
 * @challenge:	The challenge data to be used in the attestation token
 *		generation.
 * @size:	Size of the challenge data in bytes.
 *
 * Initialises the attestation token generation and returns an upper bound
 * on the attestation token size that can be used to allocate an adequate
 * buffer. The caller is expected to subsequently call
 * rsi_attestation_token_continue() to retrieve the attestation token data on
 * the same CPU.
 *
 * Returns:
 *  On success, returns the upper limit of the attestation report size.
 *  Otherwise, -EINVAL
 */
static inline long
rsi_attestation_token_init(const u8 *challenge, unsigned long size)
{
	union {
		struct arm_smccc_1_2_regs regs;
		struct rsi_attestation_token_init_args init;
	} args = { 0 };

	if (!challenge || size < RSI_ATTEST_CHALLENGE_MIN_SIZE ||
	    size > RSI_ATTEST_CHALLENGE_MAX_SIZE)
		return -EINVAL;

	args.init.fid = SMC_RSI_ATTESTATION_TOKEN_INIT;
	memcpy(args.init.challenge, challenge, size);
	arm_smccc_1_2_smc(&args.regs, &args.regs);

	if (args.regs.a0 == RSI_SUCCESS)
		return args.regs.a1;

	return -EINVAL;
}

/**
 * rsi_attestation_token_continue - Continue the operation to retrieve an
 * attestation token.
 *
 * @granule: {I}PA of the Granule to which the token will be written.
 * @offset:  Offset within Granule to start of buffer in bytes.
 * @size:    The size of the buffer.
 * @len:     The number of bytes written to the buffer.
 *
 * Retrieves up to a RSI_GRANULE_SIZE worth of token data per call. The caller
 * is expected to call rsi_attestation_token_init() before calling this
 * function to retrieve the attestation token.
 *
 * Return:
 * * %RSI_SUCCESS     - Attestation token retrieved successfully.
 * * %RSI_INCOMPLETE  - Token generation is not complete.
 * * %RSI_ERROR_INPUT - A parameter was not valid.
 * * %RSI_ERROR_STATE - Attestation not in progress.
 */
static inline unsigned long rsi_attestation_token_continue(phys_addr_t granule,
							   unsigned long offset,
							   unsigned long size,
							   unsigned long *len)
{
	struct arm_smccc_res res;

	arm_smccc_1_1_invoke(SMC_RSI_ATTESTATION_TOKEN_CONTINUE,
			     granule, offset, size, 0, &res);

	if (len)
		*len = res.a1;
	return res.a0;
}

#endif /* __LINUX_ARM_RSI_CMDS_H_ */