realm/realm_plane.c

/*
 * Copyright (c) 2022-2023, Arm Limited. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 *
 */
#include <stdio.h>
#include <arch.h>
#include <arch_features.h>
#include <assert.h>
#include <debug.h>

#include <host_realm_helper.h>
#include <realm_psi.h>
#include <realm_rsi.h>
#include <sync.h>

static bool is_plane0;
static unsigned int plane_num;

bool realm_is_plane0(void)
{
	return is_plane0;
}

unsigned int realm_get_my_plane_num(void)
{
	return plane_num;
}

void realm_plane_init(void)
{
	u_register_t ret;

	ret = rsi_get_version(RSI_ABI_VERSION_VAL);
	if (ret == RSI_ERROR_STATE) {
		is_plane0 = false;
		plane_num = (unsigned int)psi_get_plane_id();
	} else {
		is_plane0 = true;
		plane_num = PRIMARY_PLANE_ID;
	}
}

static void restore_plane_context(rsi_plane_run *run)
{
	for (unsigned int i = 0U; i < RSI_PLANE_NR_GPRS; i++) {
		run->enter.gprs[i] = run->exit.gprs[i];
	}

	run->enter.pc = run->exit.elr;
}

static u_register_t realm_exit_to_host_as_plane_n(enum host_call_cmd exit_code,
		u_register_t plane_num)
{
	struct rsi_host_call host_cal __aligned(sizeof(struct rsi_host_call));
	smc_ret_values res = {};

	assert(realm_is_p0());
	host_cal.imm = exit_code;
	host_cal.gprs[0] = plane_num;
	host_cal.gprs[1] = read_mpidr_el1();
	res = tftf_smc(&(smc_args) {RSI_HOST_CALL, (u_register_t)&host_cal,
		0UL, 0UL, 0UL, 0UL, 0UL, 0UL});
	return res.ret0;
}

/* return true to re-enter PlaneN, false to exit to P0 */
u_register_t handle_plane_exit(u_register_t plane_index,
		u_register_t perm_index,
		rsi_plane_run *run)
{
	u_register_t ec = EC_BITS(run->exit.esr);
	u_register_t ret;

	if (((run->exit.esr & ISS_FSC_MASK) >= FSC_L0_PERM_FAULT) &&
		((run->exit.esr & ISS_FSC_MASK) <= FSC_L3_PERM_FAULT)) {

		/* If Plane N exit is due to permission fault, change s2ap */
		u_register_t base, new_base, response, ret;
		u_register_t new_cookie = 0UL;

		new_base = base = (run->exit.far & ~PAGE_SIZE_MASK);

		VERBOSE("P0 set s2ap 0x%lx\n", base);
		while (new_base != (base + PAGE_SIZE)) {

			ret = rsi_mem_set_perm_index(new_base, base + PAGE_SIZE,
				perm_index, new_cookie, &new_base,
				&response, &new_cookie);

			if (ret != RSI_SUCCESS || response == RSI_REJECT) {
				ERROR("rsi_mem_set_perm_index failed 0x%lx\n", new_base);
				return PSI_RETURN_TO_P0;
			}
		}

		restore_plane_context(run);
		return PSI_RETURN_TO_PN;
	}

	/* Disallow SMC from Plane N */
	if (ec == EC_AARCH64_SMC) {
		/* TODO Support PSCI in future */
		restore_plane_context(run);
		run->enter.gprs[0] = RSI_ERROR_STATE;
		return PSI_RETURN_TO_PN;
	}

	/* Handle PSI HVC call from Plane N */
	if (ec == EC_AARCH64_HVC) {
		u_register_t hvc_id = run->exit.gprs[0];

		restore_plane_context(run);
		switch (hvc_id) {
		case PSI_CALL_GET_SHARED_BUFF_CMD:
			run->enter.gprs[0] = RSI_SUCCESS;
			run->enter.gprs[1] = (u_register_t)realm_get_my_shared_structure();
			return PSI_RETURN_TO_PN;
		case PSI_CALL_GET_PLANE_ID_CMD:
			run->enter.gprs[0] = RSI_SUCCESS;
			run->enter.gprs[1] = plane_index;
			return PSI_RETURN_TO_PN;
		case PSI_CALL_EXIT_PRINT_CMD:
			/* exit to host to flush buffer, then return to PN */
			ret = realm_exit_to_host_as_plane_n(HOST_CALL_EXIT_PRINT_CMD, plane_index);
			run->enter.gprs[0] = ret;
			return PSI_RETURN_TO_PN;
		case PSI_P0_CALL:
		default:
			return PSI_RETURN_TO_P0;
		}
	}
	return PSI_RETURN_TO_P0;
}

static bool plane_common_init(u_register_t plane_index,
		u_register_t perm_index,
		u_register_t base,
		rsi_plane_run *run)
{
	u_register_t ret;

	memset(run, 0, sizeof(rsi_plane_run));
	run->enter.pc = base;

	/* Perm init */
	ret = rsi_mem_set_perm_value(plane_index, perm_index, PERM_LABEL_RW_upX);
	if (ret != RSI_SUCCESS) {
		ERROR("rsi_mem_set_perm_value failed %u\n", plane_index);
		return false;
	}
	return true;
}

bool realm_plane_enter(u_register_t plane_index,
		u_register_t perm_index,
		u_register_t base,
		u_register_t flags,
		rsi_plane_run *run)
{
	u_register_t ret;
	bool ret1;

	ret1 = plane_common_init(plane_index, perm_index, base, run);
	if (!ret1) {
		return ret1;
	}

	run->enter.flags = flags;

	while (true) {
		ret = rsi_plane_enter(plane_index, (u_register_t)run);
		if (ret != RSI_SUCCESS) {
			ERROR("Plane %u enter failed ret= 0x%lx\n", plane_index, ret);
			return false;
		}

		VERBOSE("plane exit_reason=0x%lx esr=0x%lx hpfar=0x%lx far=0x%lx\n",
				run->exit.exit_reason,
				run->exit.esr,
				run->exit.hpfar,
				run->exit.far);

		ret = handle_plane_exit(plane_index, perm_index, run);

		if (ret != PSI_RETURN_TO_PN) {
			return true;
		}
	}
}