arch/powerpc/mm/book3s64/hash_64k.c - linux - Git at Google

 /*
  * Copyright IBM Corporation, 2015
  * Author Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of version 2 of the GNU Lesser General Public License
  * as published by the Free Software Foundation.
  *
  * This program is distributed in the hope that it would be useful, but
  * WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  *
  */

 #include <linux/mm.h>
 #include <asm/machdep.h>
 #include <asm/mmu.h>

 #include "internal.h"

 /*
  * Return true, if the entry has a slot value which
  * the software considers as invalid.
  */
 static inline bool hpte_soft_invalid(unsigned long hidx)
 {
 	return ((hidx & 0xfUL) == 0xfUL);
 }

 /*
  * index from 0 - 15
  */
 bool __rpte_sub_valid(real_pte_t rpte, unsigned long index)
 {
 	return !(hpte_soft_invalid(__rpte_to_hidx(rpte, index)));
 }

 int __hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid,
 		   pte_t *ptep, unsigned long trap, unsigned long flags,
 		   int ssize, int subpg_prot)
 {
 	real_pte_t rpte;
 	unsigned long hpte_group;
 	unsigned int subpg_index;
 	unsigned long rflags, pa;
 	unsigned long old_pte, new_pte, subpg_pte;
 	unsigned long vpn, hash, slot, gslot;
 	unsigned long shift = mmu_psize_defs[MMU_PAGE_4K].shift;

 	/*
 	 * atomically mark the linux large page PTE busy and dirty
 	 */
 	do {
 		pte_t pte = READ_ONCE(*ptep);

 		old_pte = pte_val(pte);
 		/* If PTE busy, retry the access */
 		if (unlikely(old_pte & H_PAGE_BUSY))
 			return 0;
 		/* If PTE permissions don't match, take page fault */
 		if (unlikely(!check_pte_access(access, old_pte)))
 			return 1;
 		/*
 		 * Try to lock the PTE, add ACCESSED and DIRTY if it was
 		 * a write access. Since this is 4K insert of 64K page size
 		 * also add H_PAGE_COMBO
 		 */
 		new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED | H_PAGE_COMBO;
 		if (access & _PAGE_WRITE)
 			new_pte |= _PAGE_DIRTY;
 	} while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));

 	/*
 	 * Handle the subpage protection bits
 	 */
 	subpg_pte = new_pte & ~subpg_prot;
 	rflags = htab_convert_pte_flags(subpg_pte, flags);

 	if (cpu_has_feature(CPU_FTR_NOEXECUTE) &&
 	    !cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) {

 		/*
 		 * No CPU has hugepages but lacks no execute, so we
 		 * don't need to worry about that case
 		 */
 		rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
 	}

 	subpg_index = (ea & (PAGE_SIZE - 1)) >> shift;
 	vpn  = hpt_vpn(ea, vsid, ssize);
 	rpte = __real_pte(__pte(old_pte), ptep, PTRS_PER_PTE);
 	/*
 	 *None of the sub 4k page is hashed
 	 */
 	if (!(old_pte & H_PAGE_HASHPTE))
 		goto htab_insert_hpte;
 	/*
 	 * Check if the pte was already inserted into the hash table
 	 * as a 64k HW page, and invalidate the 64k HPTE if so.
 	 */
 	if (!(old_pte & H_PAGE_COMBO)) {
 		flush_hash_page(vpn, rpte, MMU_PAGE_64K, ssize, flags);
 		/*
 		 * clear the old slot details from the old and new pte.
 		 * On hash insert failure we use old pte value and we don't
 		 * want slot information there if we have a insert failure.
 		 */
 		old_pte &= ~H_PAGE_HASHPTE;
 		new_pte &= ~H_PAGE_HASHPTE;
 		goto htab_insert_hpte;
 	}
 	/*
 	 * Check for sub page valid and update
 	 */
 	if (__rpte_sub_valid(rpte, subpg_index)) {
 		int ret;

 		gslot = pte_get_hash_gslot(vpn, shift, ssize, rpte,
 					   subpg_index);
 		ret = mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn,
 						 MMU_PAGE_4K, MMU_PAGE_4K,
 						 ssize, flags);

 		/*
 		 * If we failed because typically the HPTE wasn't really here
 		 * we try an insertion.
 		 */
 		if (ret == -1)
 			goto htab_insert_hpte;

 		*ptep = __pte(new_pte & ~H_PAGE_BUSY);
 		return 0;
 	}

 htab_insert_hpte:

 	/*
 	 * Initialize all hidx entries to invalid value, the first time
 	 * the PTE is about to allocate a 4K HPTE.
 	 */
 	if (!(old_pte & H_PAGE_COMBO))
 		rpte.hidx = INVALID_RPTE_HIDX;

 	/*
 	 * handle H_PAGE_4K_PFN case
 	 */
 	if (old_pte & H_PAGE_4K_PFN) {
 		/*
 		 * All the sub 4k page have the same
 		 * physical address.
 		 */
 		pa = pte_pfn(__pte(old_pte)) << HW_PAGE_SHIFT;
 	} else {
 		pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
 		pa += (subpg_index << shift);
 	}
 	hash = hpt_hash(vpn, shift, ssize);
 repeat:
 	hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;

 	/* Insert into the hash table, primary slot */
 	slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0,
 					MMU_PAGE_4K, MMU_PAGE_4K, ssize);
 	/*
 	 * Primary is full, try the secondary
 	 */
 	if (unlikely(slot == -1)) {
 		bool soft_invalid;

 		hpte_group = (~hash & htab_hash_mask) * HPTES_PER_GROUP;
 		slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa,
 						rflags, HPTE_V_SECONDARY,
 						MMU_PAGE_4K, MMU_PAGE_4K,
 						ssize);

 		soft_invalid = hpte_soft_invalid(slot);
 		if (unlikely(soft_invalid)) {
 			/*
 			 * We got a valid slot from a hardware point of view.
 			 * but we cannot use it, because we use this special
 			 * value; as defined by hpte_soft_invalid(), to track
 			 * invalid slots. We cannot use it. So invalidate it.
 			 */
 			gslot = slot & _PTEIDX_GROUP_IX;
 			mmu_hash_ops.hpte_invalidate(hpte_group + gslot, vpn,
 						     MMU_PAGE_4K, MMU_PAGE_4K,
 						     ssize, 0);
 		}

 		if (unlikely(slot == -1 || soft_invalid)) {
 			/*
 			 * For soft invalid slot, let's ensure that we release a
 			 * slot from the primary, with the hope that we will
 			 * acquire that slot next time we try. This will ensure
 			 * that we do not get the same soft-invalid slot.
 			 */
 			if (soft_invalid || (mftb() & 0x1))
 				hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;

 			mmu_hash_ops.hpte_remove(hpte_group);
 			/*
 			 * FIXME!! Should be try the group from which we removed ?
 			 */
 			goto repeat;
 		}
 	}
 	/*
 	 * Hypervisor failure. Restore old pte and return -1
 	 * similar to __hash_page_*
 	 */
 	if (unlikely(slot == -2)) {
 		*ptep = __pte(old_pte);
 		hash_failure_debug(ea, access, vsid, trap, ssize,
 				   MMU_PAGE_4K, MMU_PAGE_4K, old_pte);
 		return -1;
 	}

 	new_pte |= pte_set_hidx(ptep, rpte, subpg_index, slot, PTRS_PER_PTE);
 	new_pte |= H_PAGE_HASHPTE;

 	if (stress_hpt())
 		hpt_do_stress(ea, hpte_group);

 	*ptep = __pte(new_pte & ~H_PAGE_BUSY);
 	return 0;
 }

 int __hash_page_64K(unsigned long ea, unsigned long access,
 		    unsigned long vsid, pte_t *ptep, unsigned long trap,
 		    unsigned long flags, int ssize)
 {
 	real_pte_t rpte;
 	unsigned long hpte_group;
 	unsigned long rflags, pa;
 	unsigned long old_pte, new_pte;
 	unsigned long vpn, hash, slot;
 	unsigned long shift = mmu_psize_defs[MMU_PAGE_64K].shift;

 	/*
 	 * atomically mark the linux large page PTE busy and dirty
 	 */
 	do {
 		pte_t pte = READ_ONCE(*ptep);

 		old_pte = pte_val(pte);
 		/* If PTE busy, retry the access */
 		if (unlikely(old_pte & H_PAGE_BUSY))
 			return 0;
 		/* If PTE permissions don't match, take page fault */
 		if (unlikely(!check_pte_access(access, old_pte)))
 			return 1;
 		/*
 		 * Check if PTE has the cache-inhibit bit set
 		 * If so, bail out and refault as a 4k page
 		 */
 		if (!mmu_has_feature(MMU_FTR_CI_LARGE_PAGE) &&
 		    unlikely(pte_ci(pte)))
 			return 0;
 		/*
 		 * Try to lock the PTE, add ACCESSED and DIRTY if it was
 		 * a write access.
 		 */
 		new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED;
 		if (access & _PAGE_WRITE)
 			new_pte |= _PAGE_DIRTY;
 	} while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));

 	rflags = htab_convert_pte_flags(new_pte, flags);
 	rpte = __real_pte(__pte(old_pte), ptep, PTRS_PER_PTE);

 	if (cpu_has_feature(CPU_FTR_NOEXECUTE) &&
 	    !cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
 		rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);

 	vpn  = hpt_vpn(ea, vsid, ssize);
 	if (unlikely(old_pte & H_PAGE_HASHPTE)) {
 		unsigned long gslot;

 		/*
 		 * There MIGHT be an HPTE for this pte
 		 */
 		gslot = pte_get_hash_gslot(vpn, shift, ssize, rpte, 0);
 		if (mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn, MMU_PAGE_64K,
 					       MMU_PAGE_64K, ssize,
 					       flags) == -1)
 			old_pte &= ~_PAGE_HPTEFLAGS;
 	}

 	if (likely(!(old_pte & H_PAGE_HASHPTE))) {

 		pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
 		hash = hpt_hash(vpn, shift, ssize);

 repeat:
 		hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;

 		/* Insert into the hash table, primary slot */
 		slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0,
 						MMU_PAGE_64K, MMU_PAGE_64K,
 						ssize);
 		/*
 		 * Primary is full, try the secondary
 		 */
 		if (unlikely(slot == -1)) {
 			hpte_group = (~hash & htab_hash_mask) * HPTES_PER_GROUP;
 			slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa,
 							rflags,
 							HPTE_V_SECONDARY,
 							MMU_PAGE_64K,
 							MMU_PAGE_64K, ssize);
 			if (slot == -1) {
 				if (mftb() & 0x1)
 					hpte_group = (hash & htab_hash_mask) *
 							HPTES_PER_GROUP;
 				mmu_hash_ops.hpte_remove(hpte_group);
 				/*
 				 * FIXME!! Should be try the group from which we removed ?
 				 */
 				goto repeat;
 			}
 		}
 		/*
 		 * Hypervisor failure. Restore old pte and return -1
 		 * similar to __hash_page_*
 		 */
 		if (unlikely(slot == -2)) {
 			*ptep = __pte(old_pte);
 			hash_failure_debug(ea, access, vsid, trap, ssize,
 					   MMU_PAGE_64K, MMU_PAGE_64K, old_pte);
 			return -1;
 		}

 		new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | H_PAGE_HASHPTE;
 		new_pte |= pte_set_hidx(ptep, rpte, 0, slot, PTRS_PER_PTE);

 		if (stress_hpt())
 			hpt_do_stress(ea, hpte_group);
 	}

 	*ptep = __pte(new_pte & ~H_PAGE_BUSY);

 	return 0;
 }
	/*
	* Copyright IBM Corporation, 2015
	* Author Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms of version 2 of the GNU Lesser General Public License
	* as published by the Free Software Foundation.
	*
	* This program is distributed in the hope that it would be useful, but
	* WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
	*
	*/

	#include <linux/mm.h>
	#include <asm/machdep.h>
	#include <asm/mmu.h>

	#include "internal.h"

	/*
	* Return true, if the entry has a slot value which
	* the software considers as invalid.
	*/
	static inline bool hpte_soft_invalid(unsigned long hidx)
	{
	return ((hidx & 0xfUL) == 0xfUL);
	}

	/*
	* index from 0 - 15
	*/
	bool __rpte_sub_valid(real_pte_t rpte, unsigned long index)
	{
	return !(hpte_soft_invalid(__rpte_to_hidx(rpte, index)));
	}

	int __hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid,
	pte_t *ptep, unsigned long trap, unsigned long flags,
	int ssize, int subpg_prot)
	{
	real_pte_t rpte;
	unsigned long hpte_group;
	unsigned int subpg_index;
	unsigned long rflags, pa;
	unsigned long old_pte, new_pte, subpg_pte;
	unsigned long vpn, hash, slot, gslot;
	unsigned long shift = mmu_psize_defs[MMU_PAGE_4K].shift;

	/*
	* atomically mark the linux large page PTE busy and dirty
	*/
	do {
	pte_t pte = READ_ONCE(*ptep);

	old_pte = pte_val(pte);
	/* If PTE busy, retry the access */
	if (unlikely(old_pte & H_PAGE_BUSY))
	return 0;
	/* If PTE permissions don't match, take page fault */
	if (unlikely(!check_pte_access(access, old_pte)))
	return 1;
	/*
	* Try to lock the PTE, add ACCESSED and DIRTY if it was
	* a write access. Since this is 4K insert of 64K page size
	* also add H_PAGE_COMBO
	*/
	new_pte = old_pte \| H_PAGE_BUSY \| _PAGE_ACCESSED \| H_PAGE_COMBO;
	if (access & _PAGE_WRITE)
	new_pte \|= _PAGE_DIRTY;
	} while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));

	/*
	* Handle the subpage protection bits
	*/
	subpg_pte = new_pte & ~subpg_prot;
	rflags = htab_convert_pte_flags(subpg_pte, flags);

	if (cpu_has_feature(CPU_FTR_NOEXECUTE) &&
	!cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) {

	/*
	* No CPU has hugepages but lacks no execute, so we
	* don't need to worry about that case
	*/
	rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
	}

	subpg_index = (ea & (PAGE_SIZE - 1)) >> shift;
	vpn = hpt_vpn(ea, vsid, ssize);
	rpte = __real_pte(__pte(old_pte), ptep, PTRS_PER_PTE);
	/*
	*None of the sub 4k page is hashed
	*/
	if (!(old_pte & H_PAGE_HASHPTE))
	goto htab_insert_hpte;
	/*
	* Check if the pte was already inserted into the hash table
	* as a 64k HW page, and invalidate the 64k HPTE if so.
	*/
	if (!(old_pte & H_PAGE_COMBO)) {
	flush_hash_page(vpn, rpte, MMU_PAGE_64K, ssize, flags);
	/*
	* clear the old slot details from the old and new pte.
	* On hash insert failure we use old pte value and we don't
	* want slot information there if we have a insert failure.
	*/
	old_pte &= ~H_PAGE_HASHPTE;
	new_pte &= ~H_PAGE_HASHPTE;
	goto htab_insert_hpte;
	}
	/*
	* Check for sub page valid and update
	*/
	if (__rpte_sub_valid(rpte, subpg_index)) {
	int ret;

	gslot = pte_get_hash_gslot(vpn, shift, ssize, rpte,
	subpg_index);
	ret = mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn,
	MMU_PAGE_4K, MMU_PAGE_4K,
	ssize, flags);

	/*
	* If we failed because typically the HPTE wasn't really here
	* we try an insertion.
	*/
	if (ret == -1)
	goto htab_insert_hpte;

	*ptep = __pte(new_pte & ~H_PAGE_BUSY);
	return 0;
	}

	htab_insert_hpte:

	/*
	* Initialize all hidx entries to invalid value, the first time
	* the PTE is about to allocate a 4K HPTE.
	*/
	if (!(old_pte & H_PAGE_COMBO))
	rpte.hidx = INVALID_RPTE_HIDX;

	/*
	* handle H_PAGE_4K_PFN case
	*/
	if (old_pte & H_PAGE_4K_PFN) {
	/*
	* All the sub 4k page have the same
	* physical address.
	*/
	pa = pte_pfn(__pte(old_pte)) << HW_PAGE_SHIFT;
	} else {
	pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
	pa += (subpg_index << shift);
	}
	hash = hpt_hash(vpn, shift, ssize);
	repeat:
	hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;

	/* Insert into the hash table, primary slot */
	slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0,
	MMU_PAGE_4K, MMU_PAGE_4K, ssize);
	/*
	* Primary is full, try the secondary
	*/
	if (unlikely(slot == -1)) {
	bool soft_invalid;

	hpte_group = (~hash & htab_hash_mask) * HPTES_PER_GROUP;
	slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa,
	rflags, HPTE_V_SECONDARY,
	MMU_PAGE_4K, MMU_PAGE_4K,
	ssize);

	soft_invalid = hpte_soft_invalid(slot);
	if (unlikely(soft_invalid)) {
	/*
	* We got a valid slot from a hardware point of view.
	* but we cannot use it, because we use this special
	* value; as defined by hpte_soft_invalid(), to track
	* invalid slots. We cannot use it. So invalidate it.
	*/
	gslot = slot & _PTEIDX_GROUP_IX;
	mmu_hash_ops.hpte_invalidate(hpte_group + gslot, vpn,
	MMU_PAGE_4K, MMU_PAGE_4K,
	ssize, 0);
	}

	if (unlikely(slot == -1 \|\| soft_invalid)) {
	/*
	* For soft invalid slot, let's ensure that we release a
	* slot from the primary, with the hope that we will
	* acquire that slot next time we try. This will ensure
	* that we do not get the same soft-invalid slot.
	*/
	if (soft_invalid \|\| (mftb() & 0x1))
	hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;

	mmu_hash_ops.hpte_remove(hpte_group);
	/*
	* FIXME!! Should be try the group from which we removed ?
	*/
	goto repeat;
	}
	}
	/*
	* Hypervisor failure. Restore old pte and return -1
	* similar to __hash_page_*
	*/
	if (unlikely(slot == -2)) {
	*ptep = __pte(old_pte);
	hash_failure_debug(ea, access, vsid, trap, ssize,
	MMU_PAGE_4K, MMU_PAGE_4K, old_pte);
	return -1;
	}

	new_pte \|= pte_set_hidx(ptep, rpte, subpg_index, slot, PTRS_PER_PTE);
	new_pte \|= H_PAGE_HASHPTE;

	if (stress_hpt())
	hpt_do_stress(ea, hpte_group);

	*ptep = __pte(new_pte & ~H_PAGE_BUSY);
	return 0;
	}

	int __hash_page_64K(unsigned long ea, unsigned long access,
	unsigned long vsid, pte_t *ptep, unsigned long trap,
	unsigned long flags, int ssize)
	{
	real_pte_t rpte;
	unsigned long hpte_group;
	unsigned long rflags, pa;
	unsigned long old_pte, new_pte;
	unsigned long vpn, hash, slot;
	unsigned long shift = mmu_psize_defs[MMU_PAGE_64K].shift;

	/*
	* atomically mark the linux large page PTE busy and dirty
	*/
	do {
	pte_t pte = READ_ONCE(*ptep);

	old_pte = pte_val(pte);
	/* If PTE busy, retry the access */
	if (unlikely(old_pte & H_PAGE_BUSY))
	return 0;
	/* If PTE permissions don't match, take page fault */
	if (unlikely(!check_pte_access(access, old_pte)))
	return 1;
	/*
	* Check if PTE has the cache-inhibit bit set
	* If so, bail out and refault as a 4k page
	*/
	if (!mmu_has_feature(MMU_FTR_CI_LARGE_PAGE) &&
	unlikely(pte_ci(pte)))
	return 0;
	/*
	* Try to lock the PTE, add ACCESSED and DIRTY if it was
	* a write access.
	*/
	new_pte = old_pte \| H_PAGE_BUSY \| _PAGE_ACCESSED;
	if (access & _PAGE_WRITE)
	new_pte \|= _PAGE_DIRTY;
	} while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));

	rflags = htab_convert_pte_flags(new_pte, flags);
	rpte = __real_pte(__pte(old_pte), ptep, PTRS_PER_PTE);

	if (cpu_has_feature(CPU_FTR_NOEXECUTE) &&
	!cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
	rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);

	vpn = hpt_vpn(ea, vsid, ssize);
	if (unlikely(old_pte & H_PAGE_HASHPTE)) {
	unsigned long gslot;

	/*
	* There MIGHT be an HPTE for this pte
	*/
	gslot = pte_get_hash_gslot(vpn, shift, ssize, rpte, 0);
	if (mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn, MMU_PAGE_64K,
	MMU_PAGE_64K, ssize,
	flags) == -1)
	old_pte &= ~_PAGE_HPTEFLAGS;
	}

	if (likely(!(old_pte & H_PAGE_HASHPTE))) {

	pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
	hash = hpt_hash(vpn, shift, ssize);

	repeat:
	hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;

	/* Insert into the hash table, primary slot */
	slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0,
	MMU_PAGE_64K, MMU_PAGE_64K,
	ssize);
	/*
	* Primary is full, try the secondary
	*/
	if (unlikely(slot == -1)) {
	hpte_group = (~hash & htab_hash_mask) * HPTES_PER_GROUP;
	slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa,
	rflags,
	HPTE_V_SECONDARY,
	MMU_PAGE_64K,
	MMU_PAGE_64K, ssize);
	if (slot == -1) {
	if (mftb() & 0x1)
	hpte_group = (hash & htab_hash_mask) *
	HPTES_PER_GROUP;
	mmu_hash_ops.hpte_remove(hpte_group);
	/*
	* FIXME!! Should be try the group from which we removed ?
	*/
	goto repeat;
	}
	}
	/*
	* Hypervisor failure. Restore old pte and return -1
	* similar to __hash_page_*
	*/
	if (unlikely(slot == -2)) {
	*ptep = __pte(old_pte);
	hash_failure_debug(ea, access, vsid, trap, ssize,
	MMU_PAGE_64K, MMU_PAGE_64K, old_pte);
	return -1;
	}

	new_pte = (new_pte & ~_PAGE_HPTEFLAGS) \| H_PAGE_HASHPTE;
	new_pte \|= pte_set_hidx(ptep, rpte, 0, slot, PTRS_PER_PTE);

	if (stress_hpt())
	hpt_do_stress(ea, hpte_group);
	}

	*ptep = __pte(new_pte & ~H_PAGE_BUSY);

	return 0;
	}