lib/s2tt/src/s2tt.c

/*
 * SPDX-License-Identifier: BSD-3-Clause
 * SPDX-FileCopyrightText: Copyright TF-RMM Contributors.
 */

#include <arch_helpers.h>
#include <assert.h>
#include <bitmap.h>
#include <granule.h>
#include <ripas.h>
#include <s2tt.h>
#include <s2tt_pvt_defs.h>
#include <smc.h>
#include <stdbool.h>
#include <stddef.h>

/*
 * Return a mask for the IPA field on a S2TTE
 */
static unsigned long s2tte_lvl_mask(long level, bool lpa2)
{
	assert(level <= S2TT_PAGE_LEVEL);
	assert(level >= S2TT_MIN_STARTING_LEVEL_LPA2);

	unsigned long mask;
	unsigned long levels = (unsigned long)(S2TT_PAGE_LEVEL - level);
	unsigned long lsb = (levels * S2TTE_STRIDE) + GRANULE_SHIFT;

	mask = BIT_MASK_ULL((S2TTE_OA_BITS - 1U), lsb);

	if (lpa2 == true) {
		mask |= (MASK(LPA2_S2TTE_51_50) | MASK(LPA2_OA_49_48));
	}

	return mask;
}

/*
 * Extracts the PA mapped by an S2TTE, aligned to a given level.
 */
static unsigned long s2tte_to_pa(unsigned long s2tte, long level, bool lpa2)
{
	unsigned long pa = s2tte & s2tte_lvl_mask(level, lpa2);

	if (lpa2 == true) {
		pa &= ~MASK(LPA2_S2TTE_51_50);
		pa |= INPLACE(LPA2_OA_51_50, EXTRACT(LPA2_S2TTE_51_50, s2tte));
	}

	return pa;
}

/*
 * Invalidates S2 TLB entries from [ipa, ipa + size] region tagged with `vmid`.
 */
static void stage2_tlbi_ipa(const struct s2tt_context *s2_ctx,
			    unsigned long ipa,
			    unsigned long size)
{
	/*
	 * Notes:
	 *
	 * - This follows the description provided in the Arm ARM on
	 *   "Invalidation of TLB entries from stage 2 translations".
	 *
	 * - @TODO: Provide additional information to this primitive so that
	 *   we can utilize:
	 *   - The TTL level hint, see FEAT_TTL,
	 *   - Final level lookup only invalidation,
	 *   - Address range invalidation.
	 */

	assert(s2_ctx != NULL);

	/*
	 * Save the current content of vttb_el2.
	 */
	unsigned long old_vttbr_el2 = read_vttbr_el2();

	/*
	 * Make 'vmid' the `current vmid`. Note that the tlbi instructions
	 * bellow target the TLB entries that match the `current vmid`.
	 */
	write_vttbr_el2(INPLACE(VTTBR_EL2_VMID, s2_ctx->vmid));
	isb();

	/*
	 * Invalidate entries in S2 TLB caches that
	 * match both `ipa` & the `current vmid`.
	 */
	while (size != 0UL) {
		tlbiipas2e1is(ipa >> 12);
		size -= GRANULE_SIZE;
		ipa += GRANULE_SIZE;
	}
	dsb(ish);

	/*
	 * The architecture does not require TLB invalidation by IPA to affect
	 * combined Stage-1 + Stage-2 TLBs. Therefore we must invalidate all of
	 * Stage-1 (tagged with the `current vmid`) after invalidating Stage-2.
	 */
	tlbivmalle1is();
	dsb(ish);
	isb();

	/*
	 * Restore the old content of vttb_el2.
	 */
	write_vttbr_el2(old_vttbr_el2);
	isb();
}

/*
 * Returns true if s2tte has 'output address' field, namely, if it is one of:
 * - assigned_empty
 * - assigned_ram
 * - assigned_ns
 * - assigned_destroyed
 * - table
 */
static bool s2tte_has_pa(const struct s2tt_context *s2_ctx,
			 unsigned long s2tte, long level)
{
	unsigned long desc_type = s2tte & S2TT_DESC_TYPE_MASK;

	return ((desc_type != S2TTE_INVALID) ||	/* block, page or table */
		s2tte_is_assigned_empty(s2_ctx, s2tte, level) ||
		s2tte_is_assigned_destroyed(s2_ctx, s2tte, level));
}

/*
 * Creates a TTE containing only the PA.
 * This function expects 'pa' to be aligned and bounded.
 */
static unsigned long pa_to_s2tte(unsigned long pa, bool lpa2)
{
	unsigned long tte = pa;

	if (lpa2 == true) {
		tte &= ~MASK(LPA2_OA_51_50);
		tte |= INPLACE(LPA2_S2TTE_51_50, EXTRACT(LPA2_OA_51_50, pa));
	}

	return tte;
}

/*
 * Invalidate S2 TLB entries with "addr" IPA.
 * Call this function after:
 * 1.  A L3 page desc has been removed.
 */
void s2tt_invalidate_page(const struct s2tt_context *s2_ctx, unsigned long addr)
{
	stage2_tlbi_ipa(s2_ctx, addr, GRANULE_SIZE);
}

/*
 * Invalidate S2 TLB entries with "addr" IPA.
 * Call this function after:
 * 1.  A L2 block desc has been removed, or
 * 2a. A L2 table desc has been removed, where
 * 2b. All S2TTEs in L3 table that the L2 table desc was pointed to were invalid.
 */
void s2tt_invalidate_block(const struct s2tt_context *s2_ctx, unsigned long addr)
{
	stage2_tlbi_ipa(s2_ctx, addr, GRANULE_SIZE);
}

/*
 * Invalidate S2 TLB entries with "addr" IPA.
 * Call this function after:
 * 1a. A L2 table desc has been removed, where
 * 1b. Some S2TTEs in the table that the L2 table desc was pointed to were valid.
 */
void s2tt_invalidate_pages_in_block(const struct s2tt_context *s2_ctx,
				    unsigned long addr)
{
	stage2_tlbi_ipa(s2_ctx, addr, BLOCK_L2_SIZE);
}

/*
 * Return the index of the entry describing @addr in the translation table at
 * level @level. This only works for non-concatenated page tables, so should
 * not be called to get the index for the starting level.
 *
 * See the library pseudocode
 * aarch64/translation/vmsa_addrcalc/AArch64.TTEntryAddress on which this is
 * modeled.
 */
static unsigned long s2_addr_to_idx(unsigned long addr, long level)
{
	unsigned int levels, lsb;
	unsigned int s2tte_stride = (level < S2TT_MIN_STARTING_LEVEL) ?
					S2TTE_STRIDE_LM1 : S2TTE_STRIDE;

	levels = (unsigned int)(S2TT_PAGE_LEVEL - level);
	lsb = (levels * S2TTE_STRIDE) + GRANULE_SHIFT;

	addr >>= lsb;
	addr &= (1UL << s2tte_stride) - 1UL;
	return addr;
}

/*
 * Return the index of the entry describing @addr in the translation table
 * starting level. This may return an index >= S2TTES_PER_S2TT when the
 * combination of @start_level and @ipa_bits implies concatenated
 * stage 2 tables.
 *
 * See the library pseudocode
 * aarch64/translation/vmsa_addrcalc/AArch64.S2SLTTEntryAddress on which
 * this is modeled.
 */
static unsigned long s2_sl_addr_to_idx(unsigned long addr, int start_level,
				       unsigned long ipa_bits)
{
	unsigned int levels, lsb;

	levels = (unsigned int)(S2TT_PAGE_LEVEL - start_level);
	lsb = (levels * S2TTE_STRIDE) + GRANULE_SHIFT;

	addr &= ((1UL << ipa_bits) - 1UL);
	addr >>= lsb;
	return addr;
}

static bool entry_is_table(unsigned long entry)
{
	return ((entry & S2TT_DESC_TYPE_MASK) == S2TTE_L012_TABLE);
}

static unsigned long table_get_entry(const struct s2tt_context *s2_ctx,
				     struct granule *g_tbl,
				     unsigned long idx)
{
	unsigned long *table, entry;

	(void)s2_ctx;

	table = granule_map(g_tbl, SLOT_RTT);
	assert(table != NULL);

	entry = s2tte_read(&table[idx]);
	buffer_unmap(table);

	return entry;
}

#define table_entry_to_phys(tte, lpa2)			\
				s2tte_to_pa(tte, S2TT_PAGE_LEVEL, lpa2)

static struct granule *find_next_level_idx(const struct s2tt_context *s2_ctx,
					   struct granule *g_tbl,
					   unsigned long idx)
{
	assert(s2_ctx != NULL);

	const unsigned long entry = table_get_entry(s2_ctx, g_tbl, idx);

	if (!entry_is_table(entry)) {
		return NULL;
	}

	return addr_to_granule(table_entry_to_phys(entry, s2_ctx->enable_lpa2));
}

static struct granule *find_lock_next_level(const struct s2tt_context *s2_ctx,
					    struct granule *g_tbl,
					    unsigned long map_addr,
					    long level)
{
	const unsigned long idx = s2_addr_to_idx(map_addr, level);
	struct granule *g = find_next_level_idx(s2_ctx, g_tbl, idx);

	if (g != NULL) {
		granule_lock(g, GRANULE_STATE_RTT);
	}

	return g;
}

/*
 * Walk an RTT until level @level using @map_addr.
 * @g_root is the root (level 0/-1) table and must be locked before the call.
 * @start_level is the initial lookup level used for the stage 2 translation
 * tables which may depend on the configuration of the realm, factoring in the
 * IPA size of the realm and the desired starting level (within the limits
 * defined by the Armv8 VMSA including options for stage 2 table concatenation).
 * The function uses hand-over-hand locking to avoid race conditions and allow
 * concurrent access to RTT tree which is not part of the current walk; when a
 * next level table is reached it is locked before releasing previously locked
 * table.
 * The walk stops when either:
 * - The entry found is a leaf entry (not an RTT Table entry), or
 * - Level @level is reached.
 *
 * On return:
 * - s2tt_walk::last_level is the last level that has been reached by the walk.
 * - s2tt_walk.g_llt points to the TABLE granule at level @s2tt_walk::level.
 *   The granule is locked.
 * - s2tt_walk::index is the entry index at s2tt_walk.g_llt for @map_addr.i
 *
 * NOTE: This function expects that the root table on the s2 context is
 *	 already locked.
 */
void s2tt_walk_lock_unlock(const struct s2tt_context *s2_ctx,
			   unsigned long map_addr,
			   long level,
			   struct s2tt_walk *wi)
{
	struct granule *g_tbls[NR_RTT_LEVELS_LPA2] = { (struct granule *)NULL };
	struct granule *g_root;
	unsigned long sl_idx, ipa_bits;
	int i, start_level, last_level;

	assert(s2_ctx != NULL);

	start_level = s2_ctx->s2_starting_level;
	ipa_bits = s2_ctx->ipa_bits;

	assert(level >= start_level);
	assert(level <= S2TT_PAGE_LEVEL);
	assert(map_addr < (1UL << ipa_bits));
	assert(wi != NULL);

	g_root = s2_ctx->g_rtt;

	/* Handle concatenated starting level (SL) tables */
	sl_idx = s2_sl_addr_to_idx(map_addr, start_level, ipa_bits);
	if (sl_idx >= S2TTES_PER_S2TT) {
		unsigned int tt_num = (unsigned int)(sl_idx >> S2TTE_STRIDE);
		struct granule *g_concat_root;

		assert(tt_num < S2TTE_MAX_CONCAT_TABLES);

		g_concat_root = (struct granule *)((uintptr_t)g_root +
					(tt_num * sizeof(struct granule)));

		granule_lock(g_concat_root, GRANULE_STATE_RTT);
		granule_unlock(g_root);
		g_root = g_concat_root;
	}

	/* 'start_level' can be '-1', so add 1 when used as an index */
	g_tbls[start_level + 1] = g_root;
	for (i = start_level; i < level; i++) {
		/*
		 * Lock next RTT level. Correct locking order is guaranteed
		 * because reference is obtained from a locked granule
		 * (previous level). Also, hand-over-hand locking/unlocking is
		 * used to avoid race conditions.
		 *
		 * Note that as 'start_level' can be -1, we add '1' to the
		 * index 'i' to compensate for the negative value when we
		 * use it to index then 'g_tbls' list.
		 */
		g_tbls[i + 1 + 1] = find_lock_next_level(s2_ctx, g_tbls[i + 1],
						     map_addr, i);
		if (g_tbls[i + 1 + 1] == NULL) {
			last_level = i;
			goto out;
		}
		granule_unlock(g_tbls[i + 1]);
	}

	last_level = (int)level;
out:
	wi->last_level = last_level;
	wi->g_llt = g_tbls[last_level + 1];
	wi->index = s2_addr_to_idx(map_addr, last_level);
}

/*
 * Creates an unassigned_empty s2tte.
 */
unsigned long s2tte_create_unassigned_empty(const struct s2tt_context *s2_ctx)
{
	(void)s2_ctx;

	return (S2TTE_INVALID_HIPAS_UNASSIGNED | S2TTE_INVALID_RIPAS_EMPTY);
}

/*
 * Creates an unassigned_ram s2tte.
 */
unsigned long s2tte_create_unassigned_ram(const struct s2tt_context *s2_ctx)
{
	(void)s2_ctx;

	return (S2TTE_INVALID_HIPAS_UNASSIGNED | S2TTE_INVALID_RIPAS_RAM);
}

/*
 * Creates an unassigned_destroyed s2tte.
 */
unsigned long s2tte_create_unassigned_destroyed(const struct s2tt_context *s2_ctx)
{
	(void)s2_ctx;

	return (S2TTE_INVALID_HIPAS_UNASSIGNED | S2TTE_INVALID_RIPAS_DESTROYED);
}

/*
 * Creates an unassigned_ns s2tte.
 */
unsigned long s2tte_create_unassigned_ns(const struct s2tt_context *s2_ctx)
{
	(void)s2_ctx;

	return (S2TTE_NS | S2TTE_INVALID_HIPAS_UNASSIGNED |
		S2TTE_INVALID_UNPROTECTED);
}

/*
 * Creates an invalid s2tte with output address @pa, HIPAS=ASSIGNED and
 * RIPAS=@s2tte_ripas, at level @level.
 */
static unsigned long s2tte_create_assigned(const struct s2tt_context *s2_ctx,
					   unsigned long pa, long level,
					   unsigned long s2tte_ripas)
{
	assert(level >= S2TT_MIN_BLOCK_LEVEL);
	assert(level <= S2TT_PAGE_LEVEL);
	assert(s2tte_ripas <= S2TTE_INVALID_RIPAS_DESTROYED);
	assert(s2tte_is_addr_lvl_aligned(s2_ctx, pa, level));
	assert(s2_ctx != NULL);

	unsigned long tte = pa_to_s2tte(pa, s2_ctx->enable_lpa2);
	unsigned long s2tte_page, s2tte_block;

	if (s2_ctx->enable_lpa2 == true) {
		s2tte_page = S2TTE_PAGE_LPA2;
		s2tte_block = S2TTE_BLOCK_LPA2;
	} else {
		s2tte_page = S2TTE_PAGE;
		s2tte_block = S2TTE_BLOCK;
	}

	if (s2tte_ripas == S2TTE_INVALID_RIPAS_RAM) {
		if (level == S2TT_PAGE_LEVEL) {
			return (tte | s2tte_page);
		}
		return (tte | s2tte_block);
	}

	return (tte | S2TTE_INVALID_HIPAS_ASSIGNED | s2tte_ripas);
}

/*
 * Creates and invalid s2tte with output address @pa, HIPAS=ASSIGNED and
 * RIPAS=DESTROYED at level @level.
 */
unsigned long s2tte_create_assigned_destroyed(const struct s2tt_context *s2_ctx,
					      unsigned long pa, long level)
{
	return s2tte_create_assigned(s2_ctx, pa, level,
				     S2TTE_INVALID_RIPAS_DESTROYED);
}

/*
 * Creates an invalid s2tte with output address @pa, HIPAS=ASSIGNED and
 * RIPAS=EMPTY at level @level.
 */
unsigned long s2tte_create_assigned_empty(const struct s2tt_context *s2_ctx,
					  unsigned long pa, long level)
{
	return s2tte_create_assigned(s2_ctx, pa, level,
				     S2TTE_INVALID_RIPAS_EMPTY);
}

/*
 * Creates an assigned_ram s2tte with output address @pa.
 */
unsigned long s2tte_create_assigned_ram(const struct s2tt_context *s2_ctx,
					unsigned long pa, long level)
{
	return s2tte_create_assigned(s2_ctx, pa, level,
				     S2TTE_INVALID_RIPAS_RAM);
}

/*
 * Creates an assigned s2tte with output address @pa and the same
 * RIPAS as passed on @s2tte.
 */
unsigned long s2tte_create_assigned_unchanged(const struct s2tt_context *s2_ctx,
					      unsigned long s2tte,
					      unsigned long pa,
					      long level)
{
	unsigned long current_ripas = s2tte & S2TTE_INVALID_RIPAS_MASK;

	return s2tte_create_assigned(s2_ctx, pa, level, current_ripas);
}

/*
 * Creates an assigned_ns s2tte at level @level.
 *
 * The following S2 TTE fields are provided through @s2tte argument:
 * - The physical address
 * - MemAttr
 * - S2AP
 * - Shareability (when FEAT_LPA2 is disabled)
 */
unsigned long s2tte_create_assigned_ns(const struct s2tt_context *s2_ctx,
				       unsigned long s2tte, long level)
{
	/*
	 * We just mask out the DESC_TYPE below. The Shareability bits
	 * without FEAT_LPA2 are at the same position as OA bits [51:50]
	 * with FEAT_LPA2 enabled, so we don't need to cater for that
	 * separately.
	 */
	unsigned long new_s2tte = s2tte & ~S2TT_DESC_TYPE_MASK;

	(void)s2_ctx;

	assert(level >= S2TT_MIN_BLOCK_LEVEL);
	assert(level <= S2TT_PAGE_LEVEL);

	if (level == S2TT_PAGE_LEVEL) {
		return (new_s2tte | S2TTE_PAGE_NS);
	}
	return (new_s2tte | S2TTE_BLOCK_NS);
}

/*
 * Validate the portion of NS S2TTE that is provided by the host.
 */
bool host_ns_s2tte_is_valid(const struct s2tt_context *s2_ctx,
			    unsigned long s2tte, long level)
{

	bool lpa2;
	unsigned long mask;

	assert(s2_ctx != NULL);
	assert(level >= S2TT_MIN_BLOCK_LEVEL);

	lpa2 = s2_ctx->enable_lpa2;

	mask = s2tte_lvl_mask(level, lpa2);
	if (lpa2 == true) {
		mask |= S2TTE_NS_ATTR_LPA2_MASK;
	} else {
		mask |= S2TTE_NS_ATTR_MASK;

		/* Only SH_IS is allowed */
		if ((s2tte & S2TTE_SH_MASK) != S2TTE_SH_IS) {
			return false;
		}
	}

	/*
	 * Test that all fields that are not controlled by the host are zero
	 * and that the output address is correctly aligned. Note that
	 * the host is permitted to map any physical address outside PAR.
	 */
	if ((s2tte & ~mask) != 0UL) {
		return false;
	}

	/*
	 * Only one value masked by S2TTE_MEMATTR_MASK is invalid/reserved.
	 */
	if ((s2tte & S2TTE_MEMATTR_MASK) == S2TTE_MEMATTR_FWB_RESERVED) {
		return false;
	}

	/*
	 * Note that all the values that are masked by S2TTE_AP_MASK are valid.
	 */
	return true;
}

/*
 * Returns the portion of NS S2TTE that is set by the host.
 */
unsigned long host_ns_s2tte(const struct s2tt_context *s2_ctx,
			    unsigned long s2tte, long level)
{
	assert(s2_ctx != NULL);

	unsigned long mask = s2tte_lvl_mask(level, s2_ctx->enable_lpa2);

	mask |= (s2_ctx->enable_lpa2 == true) ? S2TTE_NS_ATTR_LPA2_MASK :
					     S2TTE_NS_ATTR_MASK;

	assert(level >= S2TT_MIN_BLOCK_LEVEL);

	return (s2tte & mask);
}

/*
 * Creates a table s2tte at level @level with output address @pa.
 */
unsigned long s2tte_create_table(const struct s2tt_context *s2_ctx,
				 unsigned long pa, long level)
{
	__unused int min_starting_level;

	(void)level;

	assert(s2_ctx != NULL);
	min_starting_level = (s2_ctx->enable_lpa2 == true) ?
			S2TT_MIN_STARTING_LEVEL_LPA2 : S2TT_MIN_STARTING_LEVEL;

	assert(level < S2TT_PAGE_LEVEL);
	assert(level >= min_starting_level);
	assert(GRANULE_ALIGNED(pa));

	return (pa_to_s2tte(pa, s2_ctx->enable_lpa2) | S2TTE_TABLE);
}

/*
 * Returns true if s2tte has defined ripas value, namely if it is one of:
 * - unassigned_empty
 * - unassigned_ram
 * - unassigned_destroyed
 * - assigned_empty
 * - assigned_ram
 * - assigned_destroyed
 */
bool s2tte_has_ripas(const struct s2tt_context *s2_ctx,
		     unsigned long s2tte, long level)
{
	return (((s2tte & S2TTE_NS) == 0UL) && !s2tte_is_table(s2_ctx,
							       s2tte, level));
}

/*
 * Returns true if @s2tte has HIPAS=@hipas.
 */
static inline bool s2tte_has_hipas(unsigned long s2tte, unsigned long hipas)
{
	unsigned long desc_type = s2tte & S2TT_DESC_TYPE_MASK;
	unsigned long invalid_desc_hipas = s2tte & S2TTE_INVALID_HIPAS_MASK;

	return ((desc_type == S2TTE_INVALID) && (invalid_desc_hipas == hipas));
}

/*
 * Returns true if @s2tte has HIPAS=UNASSIGNED and RIPAS=@ripas.
 */
static inline bool s2tte_has_unassigned_ripas(unsigned long s2tte,
					      unsigned long ripas)
{
	return (((s2tte & S2TTE_INVALID_RIPAS_MASK) == ripas) &&
		  s2tte_has_hipas(s2tte, S2TTE_INVALID_HIPAS_UNASSIGNED));
}

/*
 * Returns true if @s2tte has HIPAS=ASSIGNED and RIPAS=@ripas.
 */
static inline bool s2tte_has_assigned_ripas(unsigned long s2tte,
					    unsigned long ripas)
{
	return (((s2tte & S2TTE_INVALID_RIPAS_MASK) == ripas) &&
		  s2tte_has_hipas(s2tte, S2TTE_INVALID_HIPAS_ASSIGNED));
}

/*
 * Returns true if @s2tte has HIPAS=UNASSIGNED.
 */
bool s2tte_is_unassigned(const struct s2tt_context *s2_ctx, unsigned long s2tte)
{
	(void)s2_ctx;

	return s2tte_has_hipas(s2tte, S2TTE_INVALID_HIPAS_UNASSIGNED);
}

/*
 * Returns true if @s2tte is an unassigned_empty.
 */
bool s2tte_is_unassigned_empty(const struct s2tt_context *s2_ctx,
			       unsigned long s2tte)
{
	(void)s2_ctx;

	return (((s2tte & S2TTE_NS) == 0UL) &&
		  s2tte_has_unassigned_ripas(s2tte, S2TTE_INVALID_RIPAS_EMPTY));
}

/*
 * Returns true if @s2tte is an unassigned_ram.
 */
bool s2tte_is_unassigned_ram(const struct s2tt_context *s2_ctx,
			     unsigned long s2tte)
{
	(void)s2_ctx;

	return s2tte_has_unassigned_ripas(s2tte, S2TTE_INVALID_RIPAS_RAM);
}

/*
 * Returns true if @s2tte is unassigned_ns.
 */
bool s2tte_is_unassigned_ns(const struct s2tt_context *s2_ctx,
			    unsigned long s2tte)
{
	(void)s2_ctx;

	return (((s2tte & S2TTE_NS) != 0UL) &&
		  s2tte_has_hipas(s2tte, S2TTE_INVALID_HIPAS_UNASSIGNED));
}

/*
 * Returns true if @s2tte has RIPAS=DESTROYED.
 */
bool s2tte_is_unassigned_destroyed(const struct s2tt_context *s2_ctx,
				   unsigned long s2tte)
{
	(void)s2_ctx;

	return s2tte_has_unassigned_ripas(s2tte, S2TTE_INVALID_RIPAS_DESTROYED);
}

/*
 * Returns true if @s2tte is an assigned_destroyed.
 */
bool s2tte_is_assigned_destroyed(const struct s2tt_context *s2_ctx,
				 unsigned long s2tte, long level)
{
	(void)level;
	(void)s2_ctx;

	return s2tte_has_assigned_ripas(s2tte, S2TTE_INVALID_RIPAS_DESTROYED);
}

/*
 * Returns true if @s2tte is an assigned_empty.
 */
bool s2tte_is_assigned_empty(const struct s2tt_context *s2_ctx,
			     unsigned long s2tte, long level)
{
	(void)level;
	(void)s2_ctx;

	return s2tte_has_assigned_ripas(s2tte, S2TTE_INVALID_RIPAS_EMPTY);
}

static bool s2tte_check(const struct s2tt_context *s2_ctx, unsigned long s2tte,
			long level, unsigned long ns)
{
	unsigned long desc_type;

	(void)s2_ctx;

	if ((s2tte & S2TTE_NS) != ns) {
		return false;
	}

	desc_type = s2tte & S2TT_DESC_TYPE_MASK;

	/* Only pages at L3 and valid blocks at L2 and L1 allowed */
	if (((level == S2TT_PAGE_LEVEL) && (desc_type == S2TTE_L3_PAGE)) ||
	    ((level >= S2TT_MIN_BLOCK_LEVEL) && (desc_type == S2TTE_L012_BLOCK))) {
		return true;
	}

	return false;
}

/*
 * Returns true if @s2tte is an assigned_ram.
 */
bool s2tte_is_assigned_ram(const struct s2tt_context *s2_ctx,
			   unsigned long s2tte, long level)
{
	return s2tte_check(s2_ctx, s2tte, level, 0UL);
}

/*
 * Returns true if @s2tte is an assigned_ns s2tte.
 */
bool s2tte_is_assigned_ns(const struct s2tt_context *s2_ctx,
			  unsigned long s2tte, long level)
{
	return s2tte_check(s2_ctx, s2tte, level, S2TTE_NS);
}

/*
 * Returns true if @s2tte is a table at level @level.
 */
bool s2tte_is_table(const struct s2tt_context *s2_ctx, unsigned long s2tte,
		    long level)
{
	(void)s2_ctx;

	return ((level < S2TT_PAGE_LEVEL) &&
		((s2tte & S2TT_DESC_TYPE_MASK) == S2TTE_L012_TABLE));
}

/*
 * Returns RIPAS of @s2tte.
 *
 * Caller should ensure that HIPAS=UNASSIGNED or HIPAS=ASSIGNED.
 * The s2tte, if valid, should correspond to RIPAS_RAM.
 */
enum ripas s2tte_get_ripas(const struct s2tt_context *s2_ctx, unsigned long s2tte)
{
	unsigned long desc_ripas = s2tte & S2TTE_INVALID_RIPAS_MASK;

	(void)s2_ctx;

	/*
	 * If valid s2tte descriptor is passed, then ensure S2AP[0]
	 * bit is 1 (S2AP is set to RW for lower EL), which corresponds
	 * to RIPAS_RAM (bits[6:5] = b01) on a valid descriptor.
	 */
	assert(((s2tte & S2TT_DESC_TYPE_MASK) == S2TTE_INVALID) ||
	       (desc_ripas == S2TTE_INVALID_RIPAS_RAM));

	assert(EXTRACT(S2TTE_INVALID_HIPAS, s2tte) <=
	       EXTRACT(S2TTE_INVALID_HIPAS, S2TTE_INVALID_HIPAS_ASSIGNED));

	desc_ripas = desc_ripas >> S2TTE_INVALID_RIPAS_SHIFT;

	assert(desc_ripas <= (unsigned int)RIPAS_DESTROYED);

	return (enum ripas)desc_ripas;
}

/*
 * Populates @s2tt with unassigned_empty s2ttes.
 *
 * The granule is populated before it is made a table,
 * hence, don't use s2tte_write for access.
 */
void s2tt_init_unassigned_empty(const struct s2tt_context *s2_ctx,
				unsigned long *s2tt)
{
	assert(s2tt != NULL);

	unsigned long s2tte =
		s2tte_create_unassigned_empty(s2_ctx);

	for (unsigned int i = 0U; i < S2TTES_PER_S2TT; i++) {
		s2tt[i] = s2tte;
	}

	dsb(ish);
}

/*
 * Populates @s2tt with unassigned_ram s2ttes.
 *
 * The granule is populated before it is made a table,
 * hence, don't use s2tte_write for access.
 */
void s2tt_init_unassigned_ram(const struct s2tt_context *s2_ctx,
			      unsigned long *s2tt)
{
	assert(s2tt != NULL);

	unsigned long s2tte = s2tte_create_unassigned_ram(s2_ctx);

	for (unsigned int i = 0U; i < S2TTES_PER_S2TT; i++) {
		s2tt[i] = s2tte;
	}

	dsb(ish);
}

/*
 * Populates @s2tt with unassigned_ns s2ttes.
 *
 * The granule is populated before it is made a table,
 * hence, don't use s2tte_write for access.
 */
void s2tt_init_unassigned_ns(const struct s2tt_context *s2_ctx,
			     unsigned long *s2tt)
{
	assert(s2tt != NULL);

	unsigned long s2tte = s2tte_create_unassigned_ns(s2_ctx);

	for (unsigned int i = 0U; i < S2TTES_PER_S2TT; i++) {
		s2tt[i] = s2tte;
	}

	dsb(ish);
}

/*
 * Populates @s2tt with s2ttes which have HIPAS=DESTROYED.
 *
 * The granule is populated before it is made a table,
 * hence, don't use s2tte_write for access.
 */
void s2tt_init_unassigned_destroyed(const struct s2tt_context *s2_ctx,
				    unsigned long *s2tt)
{
	assert(s2tt != NULL);

	unsigned long s2tte =
		s2tte_create_unassigned_destroyed(s2_ctx);

	for (unsigned int i = 0U; i < S2TTES_PER_S2TT; i++) {
		s2tt[i] = s2tte;
	}
	dsb(ish);
}

/*
 * Populates @s2tt with HIPAS=ASSIGNED, RIPAS=DESTROYED s2ttes that refer to a
 * contiguous memory block starting at @pa, and mapped at level @level.
 *
 * The granule is populated before it is made a table,
 * hence, don't use s2tte_write for access.
 */
void s2tt_init_assigned_destroyed(const struct s2tt_context *s2_ctx,
				  unsigned long *s2tt, unsigned long pa,
				  long level)
{
	assert(s2tt != NULL);
	assert(level >= S2TT_MIN_BLOCK_LEVEL);
	assert(level <= S2TT_PAGE_LEVEL);
	assert(s2tte_is_addr_lvl_aligned(s2_ctx, pa, level));

	const unsigned long map_size = s2tte_map_size(level);

	for (unsigned int i = 0U; i < S2TTES_PER_S2TT; i++) {
		s2tt[i] = s2tte_create_assigned_destroyed(s2_ctx, pa, level);
		pa += map_size;
	}
	dsb(ish);
}

/*
 * Populates @s2tt with HIPAS=ASSIGNED, RIPAS=EMPTY s2ttes that refer to a
 * contiguous memory block starting at @pa, and mapped at level @level.
 *
 * The granule is populated before it is made a table,
 * hence, don't use s2tte_write for access.
 */
void s2tt_init_assigned_empty(const struct s2tt_context *s2_ctx,
			      unsigned long *s2tt, unsigned long pa,
			      long level)
{
	assert(level >= S2TT_MIN_BLOCK_LEVEL);
	assert(level <= S2TT_PAGE_LEVEL);
	assert(s2tt != NULL);
	assert(s2tte_is_addr_lvl_aligned(s2_ctx, pa, level));

	const unsigned long map_size = s2tte_map_size(level);

	for (unsigned int i = 0U; i < S2TTES_PER_S2TT; i++) {
		s2tt[i] = s2tte_create_assigned_empty(s2_ctx, pa, level);
		pa += map_size;
	}
	dsb(ish);
}

/*
 * Populates @s2tt with assigned_ram s2ttes that refer to a
 * contiguous memory block starting at @pa, and mapped at level @level.
 *
 * The granule is populated before it is made a table,
 * hence, don't use s2tte_write for access.
 */
void s2tt_init_assigned_ram(const struct s2tt_context *s2_ctx,
			    unsigned long *s2tt, unsigned long pa,
			    long level)
{
	assert(level >= S2TT_MIN_BLOCK_LEVEL);
	assert(level <= S2TT_PAGE_LEVEL);
	assert(s2tt != NULL);
	assert(s2tte_is_addr_lvl_aligned(s2_ctx, pa, level));

	const unsigned long map_size = s2tte_map_size(level);

	for (unsigned int i = 0U; i < S2TTES_PER_S2TT; i++) {
		s2tt[i] = s2tte_create_assigned_ram(s2_ctx, pa, level);
		pa += map_size;
	}
	dsb(ish);
}

/*
 * Populates @s2tt with NS attributes @attrs that refer to a
 * contiguous memory block starting at @pa, and mapped at level @level.
 *
 * The granule is populated before it is made a table,
 * hence, don't use s2tte_write for access.
 */
void s2tt_init_assigned_ns(const struct s2tt_context *s2_ctx,
			   unsigned long *s2tt, unsigned long attrs,
			   unsigned long pa, long level)
{
	assert(level >= S2TT_MIN_BLOCK_LEVEL);
	assert(level <= S2TT_PAGE_LEVEL);
	assert(s2tt != NULL);
	assert(s2tte_is_addr_lvl_aligned(s2_ctx, pa, level));

	const unsigned long map_size = s2tte_map_size(level);
	unsigned long ns_attr_host_mask = (s2_ctx->enable_lpa2 == true) ?
		S2TTE_NS_ATTR_LPA2_MASK : S2TTE_NS_ATTR_MASK;

	for (unsigned int i = 0U; i < S2TTES_PER_S2TT; i++) {
		unsigned long s2tte = attrs & ns_attr_host_mask;

		s2tt[i] = s2tte_create_assigned_ns(s2_ctx,
				s2tte | pa_to_s2tte(pa, s2_ctx->enable_lpa2),
				level);
		pa += map_size;
	}

	dsb(ish);
}

/*
 * Returns true if s2tte is a live RTTE entry. i.e.,
 * HIPAS is ASSIGNED.
 *
 * NOTE: For now, only the RTTE with PA are live.
 * This could change with EXPORT/IMPORT support.
 */
static bool s2tte_is_live(const struct s2tt_context *s2_ctx,
			  unsigned long s2tte, long level)
{
	return s2tte_has_pa(s2_ctx, s2tte, level);
}

/* Returns physical address of a S2TTE */
unsigned long s2tte_pa(const struct s2tt_context *s2_ctx, unsigned long s2tte,
		       long level)
{
	bool lpa2;
	unsigned long pa;
	__unused long min_starting_level;

	assert(s2_ctx != NULL);

	min_starting_level = (s2_ctx->enable_lpa2 == true) ?
		S2TT_MIN_STARTING_LEVEL_LPA2 : S2TT_MIN_STARTING_LEVEL;
	assert(level >= min_starting_level);
	assert(level <= S2TT_PAGE_LEVEL);
	assert(s2tte_has_pa(s2_ctx, s2tte, level));

	lpa2 = s2_ctx->enable_lpa2;

	if (s2tte_is_table(s2_ctx, s2tte, level)) {
		pa = table_entry_to_phys(s2tte, lpa2);
	} else {
		pa = s2tte_to_pa(s2tte, level, lpa2);
	}

	return pa;
}

bool s2tte_is_addr_lvl_aligned(const struct s2tt_context *s2_ctx,
			      unsigned long addr, long level)
{
	assert(s2_ctx != NULL);

	__unused long min_starting_level = (s2_ctx->enable_lpa2 == true) ?
		S2TT_MIN_STARTING_LEVEL_LPA2 : S2TT_MIN_STARTING_LEVEL;
	unsigned long levels = (unsigned long)(S2TT_PAGE_LEVEL - level);
	unsigned long lsb = (levels * S2TTE_STRIDE) + GRANULE_SHIFT;
	unsigned long s2tte_oa_bits = (s2_ctx->enable_lpa2 == true) ?
	       S2TTE_OA_BITS_LPA2 : S2TTE_OA_BITS;

	assert(level <= S2TT_PAGE_LEVEL);
	assert(level >= min_starting_level);

	return (addr == (addr & BIT_MASK_ULL((s2tte_oa_bits - 1U), lsb)));
}

typedef bool (*s2tte_type_checker)(const struct s2tt_context *s2_ctx,
				   unsigned long s2tte);

static bool table_is_uniform_block(const struct s2tt_context *s2_ctx,
				   unsigned long *table,
				   s2tte_type_checker s2tte_is_x)
{
	for (unsigned int i = 0U; i < S2TTES_PER_S2TT; i++) {
		unsigned long s2tte = s2tte_read(&table[i]);

		if (!s2tte_is_x(s2_ctx, s2tte)) {
			return false;
		}
	}

	return true;
}

/*
 * Returns true if all s2ttes in @table are unassigned_empty.
 */
bool s2tt_is_unassigned_empty_block(const struct s2tt_context *s2_ctx,
				    unsigned long *table)
{
	assert(table != NULL);

	return table_is_uniform_block(s2_ctx, table, s2tte_is_unassigned_empty);
}

/*
 * Returns true if all s2ttes in @table are unassigned_ram.
 */
bool s2tt_is_unassigned_ram_block(const struct s2tt_context *s2_ctx,
				  unsigned long *table)
{
	assert(table != NULL);

	return table_is_uniform_block(s2_ctx, table, s2tte_is_unassigned_ram);
}

/*
 * Returns true if all s2ttes in @table are unassigned_ns
 */
bool s2tt_is_unassigned_ns_block(const struct s2tt_context *s2_ctx,
				 unsigned long *table)
{
	assert(table != NULL);

	return table_is_uniform_block(s2_ctx, table, s2tte_is_unassigned_ns);
}

/*
 * Returns true if all s2ttes in @table are unassigned_destroyed
 */
bool s2tt_is_unassigned_destroyed_block(const struct s2tt_context *s2_ctx,
					unsigned long *table)
{
	assert(table != NULL);

	return table_is_uniform_block(s2_ctx, table,
				      s2tte_is_unassigned_destroyed);
}

typedef bool (*s2tte_type_level_checker)(const struct s2tt_context *s2_ctx,
					 unsigned long s2tte, long level);

static bool table_maps_block(const struct s2tt_context *s2_ctx,
			     unsigned long *table,
			     long level,
			     s2tte_type_level_checker s2tte_is_x,
			     bool check_ns_attrs)
{
	assert(table != NULL);
	assert(s2_ctx != NULL);

	unsigned long base_pa, ns_attr_host_mask;
	unsigned long map_size = s2tte_map_size(level);
	unsigned long s2tte = s2tte_read(&table[0]);
	unsigned int i;

	if (!s2tte_is_x(s2_ctx, s2tte, level)) {
		return false;
	}

	base_pa = s2tte_pa(s2_ctx, s2tte, level);
	if (!s2tte_is_addr_lvl_aligned(s2_ctx, base_pa, level - 1L)) {
		return false;
	}

	ns_attr_host_mask = (s2_ctx->enable_lpa2 == true) ?
		S2TTE_NS_ATTR_LPA2_MASK : S2TTE_NS_ATTR_MASK;

	for (i = 1U; i < S2TTES_PER_S2TT; i++) {
		unsigned long expected_pa = base_pa + (i * map_size);

		s2tte = s2tte_read(&table[i]);

		if (!s2tte_is_x(s2_ctx, s2tte, level)) {
			return false;
		}

		if (s2tte_pa(s2_ctx, s2tte, level) != expected_pa) {
			return false;
		}

		if (check_ns_attrs) {
			unsigned long ns_attrs =
					s2tte & ns_attr_host_mask;

			/*
			 * We match all the attributes in the S2TTE
			 * except for the AF bit.
			 */
			if ((s2tte & ns_attr_host_mask) != ns_attrs) {
				return false;
			}
		}
	}

	return true;
}

/*
 * Returns true if all s2ttes are assigned_empty
 * and refer to a contiguous block of granules aligned to @level - 1.
 */
bool s2tt_maps_assigned_empty_block(const struct s2tt_context *s2_ctx,
				    unsigned long *table, long level)
{
	return table_maps_block(s2_ctx, table, level,
				s2tte_is_assigned_empty, false);
}

/*
 * Returns true if all s2ttes are assigned_ram and
 * refer to a contiguous block of granules aligned to @level - 1.
 */
bool s2tt_maps_assigned_ram_block(const struct s2tt_context *s2_ctx,
				  unsigned long *table, long level)
{
	return table_maps_block(s2_ctx, table, level,
				s2tte_is_assigned_ram, false);
}

/*
 * Returns true if
 *    - all s2ttes in @table are assigned_ns s2ttes and
 *    - they refer to a contiguous block of granules aligned to @level - 1 and
 *    - all the s2tte attributes in @table controlled by the host are identical
 *
 * @pre: @table maps IPA outside PAR.
 */
bool s2tt_maps_assigned_ns_block(const struct s2tt_context *s2_ctx,
				 unsigned long *table, long level)
{
	return table_maps_block(s2_ctx, table, level,
				s2tte_is_assigned_ns, true);
}

/*
 * Returns true if all s2ttes are assigned_destroyed and
 * refer to a contiguous block of granules aligned to @level - 1.
 */
bool s2tt_maps_assigned_destroyed_block(const struct s2tt_context *s2_ctx,
					unsigned long *table, long level)
{
	return table_maps_block(s2_ctx, table, level,
				s2tte_is_assigned_destroyed, false);
}

/*
 * Scan the RTT @s2tt (which is @wi.level), from the entry (@wi.index) and
 * skip the non-live entries (i.e., HIPAS=UNASSIGNED).
 * In other words, the scanning stops when a live RTTE is encountered or we
 * reach the end of this RTT.
 *
 * For now an RTTE can be considered non-live if it doesn't have a PA.
 * NOTE: This would change with EXPORT/IMPORT where we may have metadata stored
 * in the RTTE.
 *
 * @addr is not necessarily aligned to the wi.last_level (e.g., if we were called
 * with RMI_ERROR_RTT).
 *
 * Returns:
 * - If the entry @wi.index is live, returns @addr.
 * - If none of the entries in the @s2tt are "live", returns the address of the
 *   first entry in the next table.
 * - Otherwise, the address of the first live entry in @s2tt
 */
unsigned long s2tt_skip_non_live_entries(const struct s2tt_context *s2_ctx,
					 unsigned long addr,
					 unsigned long *table,
					 const struct s2tt_walk *wi)
{
	assert(table != NULL);
	assert(wi != NULL);
	assert(wi->index <= S2TTES_PER_S2TT);
	assert(wi->last_level <= S2TT_PAGE_LEVEL);
	assert(s2_ctx != NULL);

	unsigned long i, index = wi->index;
	long level = wi->last_level;
	unsigned long map_size;
	__unused long min_starting_level = (s2_ctx->enable_lpa2 == true) ?
			S2TT_MIN_STARTING_LEVEL_LPA2 : S2TT_MIN_STARTING_LEVEL;

	assert(wi->last_level >= min_starting_level);

	/*
	 * If the entry for the map_addr is live,
	 * return @addr.
	 */
	if (s2tte_is_live(s2_ctx, s2tte_read(&table[index]), level)) {
		return addr;
	}

	/*
	 * Align the address DOWN to the map_size, as expected for the @level,
	 * so that we can compute the correct address by using the index.
	 */
	map_size = s2tte_map_size(level);
	addr &= ~(map_size - 1UL);

	/* Skip the "index" */
	for (i = index + 1UL; i < S2TTES_PER_S2TT; i++) {
		unsigned long s2tte = s2tte_read(&table[i]);

		if (s2tte_is_live(s2_ctx, s2tte, level)) {
			break;
		}
	}

	return (addr + ((i - index) * map_size));
}