arch/powerpc/kvm/book3s_64_mmu_host.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) 2009 SUSE Linux Products GmbH. All rights reserved.
  *
  * Authors:
  *     Alexander Graf <agraf@suse.de>
  *     Kevin Wolf <mail@kevin-wolf.de>
  */

 #include <linux/kvm_host.h>

 #include <asm/kvm_ppc.h>
 #include <asm/kvm_book3s.h>
 #include <asm/book3s/64/mmu-hash.h>
 #include <asm/machdep.h>
 #include <asm/mmu_context.h>
 #include <asm/hw_irq.h>
 #include "trace_pr.h"
 #include "book3s.h"

 #define PTE_SIZE 12

 void kvmppc_mmu_invalidate_pte(struct kvm_vcpu *vcpu, struct hpte_cache *pte)
 {
 	mmu_hash_ops.hpte_invalidate(pte->slot, pte->host_vpn,
 				     pte->pagesize, pte->pagesize,
 				     MMU_SEGSIZE_256M, false);
 }

 /* We keep 512 gvsid->hvsid entries, mapping the guest ones to the array using
  * a hash, so we don't waste cycles on looping */
 static u16 kvmppc_sid_hash(struct kvm_vcpu *vcpu, u64 gvsid)
 {
 	return (u16)(((gvsid >> (SID_MAP_BITS * 7)) & SID_MAP_MASK) ^
 		     ((gvsid >> (SID_MAP_BITS * 6)) & SID_MAP_MASK) ^
 		     ((gvsid >> (SID_MAP_BITS * 5)) & SID_MAP_MASK) ^
 		     ((gvsid >> (SID_MAP_BITS * 4)) & SID_MAP_MASK) ^
 		     ((gvsid >> (SID_MAP_BITS * 3)) & SID_MAP_MASK) ^
 		     ((gvsid >> (SID_MAP_BITS * 2)) & SID_MAP_MASK) ^
 		     ((gvsid >> (SID_MAP_BITS * 1)) & SID_MAP_MASK) ^
 		     ((gvsid >> (SID_MAP_BITS * 0)) & SID_MAP_MASK));
 }


 static struct kvmppc_sid_map *find_sid_vsid(struct kvm_vcpu *vcpu, u64 gvsid)
 {
 	struct kvmppc_sid_map *map;
 	u16 sid_map_mask;

 	if (kvmppc_get_msr(vcpu) & MSR_PR)
 		gvsid |= VSID_PR;

 	sid_map_mask = kvmppc_sid_hash(vcpu, gvsid);
 	map = &to_book3s(vcpu)->sid_map[sid_map_mask];
 	if (map->valid && (map->guest_vsid == gvsid)) {
 		trace_kvm_book3s_slb_found(gvsid, map->host_vsid);
 		return map;
 	}

 	map = &to_book3s(vcpu)->sid_map[SID_MAP_MASK - sid_map_mask];
 	if (map->valid && (map->guest_vsid == gvsid)) {
 		trace_kvm_book3s_slb_found(gvsid, map->host_vsid);
 		return map;
 	}

 	trace_kvm_book3s_slb_fail(sid_map_mask, gvsid);
 	return NULL;
 }

 int kvmppc_mmu_map_page(struct kvm_vcpu *vcpu, struct kvmppc_pte *orig_pte,
 			bool iswrite)
 {
 	unsigned long vpn;
 	kvm_pfn_t hpaddr;
 	ulong hash, hpteg;
 	u64 vsid;
 	int ret;
 	int rflags = 0x192;
 	int vflags = 0;
 	int attempt = 0;
 	struct kvmppc_sid_map *map;
 	int r = 0;
 	int hpsize = MMU_PAGE_4K;
 	bool writable;
 	unsigned long mmu_seq;
 	struct kvm *kvm = vcpu->kvm;
 	struct hpte_cache *cpte;
 	unsigned long gfn = orig_pte->raddr >> PAGE_SHIFT;
 	unsigned long pfn;

 	/* used to check for invalidations in progress */
 	mmu_seq = kvm->mmu_notifier_seq;
 	smp_rmb();

 	/* Get host physical address for gpa */
 	pfn = kvmppc_gpa_to_pfn(vcpu, orig_pte->raddr, iswrite, &writable);
 	if (is_error_noslot_pfn(pfn)) {
 		printk(KERN_INFO "Couldn't get guest page for gpa %lx!\n",
 		       orig_pte->raddr);
 		r = -EINVAL;
 		goto out;
 	}
 	hpaddr = pfn << PAGE_SHIFT;

 	/* and write the mapping ea -> hpa into the pt */
 	vcpu->arch.mmu.esid_to_vsid(vcpu, orig_pte->eaddr >> SID_SHIFT, &vsid);
 	map = find_sid_vsid(vcpu, vsid);
 	if (!map) {
 		ret = kvmppc_mmu_map_segment(vcpu, orig_pte->eaddr);
 		WARN_ON(ret < 0);
 		map = find_sid_vsid(vcpu, vsid);
 	}
 	if (!map) {
 		printk(KERN_ERR "KVM: Segment map for 0x%llx (0x%lx) failed\n",
 				vsid, orig_pte->eaddr);
 		WARN_ON(true);
 		r = -EINVAL;
 		goto out;
 	}

 	vpn = hpt_vpn(orig_pte->eaddr, map->host_vsid, MMU_SEGSIZE_256M);

 	kvm_set_pfn_accessed(pfn);
 	if (!orig_pte->may_write || !writable)
 		rflags |= PP_RXRX;
 	else {
 		mark_page_dirty(vcpu->kvm, gfn);
 		kvm_set_pfn_dirty(pfn);
 	}

 	if (!orig_pte->may_execute)
 		rflags |= HPTE_R_N;
 	else
 		kvmppc_mmu_flush_icache(pfn);

 	rflags = (rflags & ~HPTE_R_WIMG) | orig_pte->wimg;

 	/*
 	 * Use 64K pages if possible; otherwise, on 64K page kernels,
 	 * we need to transfer 4 more bits from guest real to host real addr.
 	 */
 	if (vsid & VSID_64K)
 		hpsize = MMU_PAGE_64K;
 	else
 		hpaddr |= orig_pte->raddr & (~0xfffULL & ~PAGE_MASK);

 	hash = hpt_hash(vpn, mmu_psize_defs[hpsize].shift, MMU_SEGSIZE_256M);

 	cpte = kvmppc_mmu_hpte_cache_next(vcpu);

 	spin_lock(&kvm->mmu_lock);
 	if (!cpte || mmu_notifier_retry(kvm, mmu_seq)) {
 		r = -EAGAIN;
 		goto out_unlock;
 	}

 map_again:
 	hpteg = ((hash & htab_hash_mask) * HPTES_PER_GROUP);

 	/* In case we tried normal mapping already, let's nuke old entries */
 	if (attempt > 1)
 		if (mmu_hash_ops.hpte_remove(hpteg) < 0) {
 			r = -1;
 			goto out_unlock;
 		}

 	ret = mmu_hash_ops.hpte_insert(hpteg, vpn, hpaddr, rflags, vflags,
 				       hpsize, hpsize, MMU_SEGSIZE_256M);

 	if (ret == -1) {
 		/* If we couldn't map a primary PTE, try a secondary */
 		hash = ~hash;
 		vflags ^= HPTE_V_SECONDARY;
 		attempt++;
 		goto map_again;
 	} else if (ret < 0) {
 		r = -EIO;
 		goto out_unlock;
 	} else {
 		trace_kvm_book3s_64_mmu_map(rflags, hpteg,
 					    vpn, hpaddr, orig_pte);

 		/*
 		 * The mmu_hash_ops code may give us a secondary entry even
 		 * though we asked for a primary. Fix up.
 		 */
 		if ((ret & _PTEIDX_SECONDARY) && !(vflags & HPTE_V_SECONDARY)) {
 			hash = ~hash;
 			hpteg = ((hash & htab_hash_mask) * HPTES_PER_GROUP);
 		}

 		cpte->slot = hpteg + (ret & 7);
 		cpte->host_vpn = vpn;
 		cpte->pte = *orig_pte;
 		cpte->pfn = pfn;
 		cpte->pagesize = hpsize;

 		kvmppc_mmu_hpte_cache_map(vcpu, cpte);
 		cpte = NULL;
 	}

 out_unlock:
 	spin_unlock(&kvm->mmu_lock);
 	kvm_release_pfn_clean(pfn);
 	if (cpte)
 		kvmppc_mmu_hpte_cache_free(cpte);

 out:
 	return r;
 }

 void kvmppc_mmu_unmap_page(struct kvm_vcpu *vcpu, struct kvmppc_pte *pte)
 {
 	u64 mask = 0xfffffffffULL;
 	u64 vsid;

 	vcpu->arch.mmu.esid_to_vsid(vcpu, pte->eaddr >> SID_SHIFT, &vsid);
 	if (vsid & VSID_64K)
 		mask = 0xffffffff0ULL;
 	kvmppc_mmu_pte_vflush(vcpu, pte->vpage, mask);
 }

 static struct kvmppc_sid_map *create_sid_map(struct kvm_vcpu *vcpu, u64 gvsid)
 {
 	unsigned long vsid_bits = VSID_BITS_65_256M;
 	struct kvmppc_sid_map *map;
 	struct kvmppc_vcpu_book3s *vcpu_book3s = to_book3s(vcpu);
 	u16 sid_map_mask;
 	static int backwards_map = 0;

 	if (kvmppc_get_msr(vcpu) & MSR_PR)
 		gvsid |= VSID_PR;

 	/* We might get collisions that trap in preceding order, so let's
 	   map them differently */

 	sid_map_mask = kvmppc_sid_hash(vcpu, gvsid);
 	if (backwards_map)
 		sid_map_mask = SID_MAP_MASK - sid_map_mask;

 	map = &to_book3s(vcpu)->sid_map[sid_map_mask];

 	/* Make sure we're taking the other map next time */
 	backwards_map = !backwards_map;

 	/* Uh-oh ... out of mappings. Let's flush! */
 	if (vcpu_book3s->proto_vsid_next == vcpu_book3s->proto_vsid_max) {
 		vcpu_book3s->proto_vsid_next = vcpu_book3s->proto_vsid_first;
 		memset(vcpu_book3s->sid_map, 0,
 		       sizeof(struct kvmppc_sid_map) * SID_MAP_NUM);
 		kvmppc_mmu_pte_flush(vcpu, 0, 0);
 		kvmppc_mmu_flush_segments(vcpu);
 	}

 	if (mmu_has_feature(MMU_FTR_68_BIT_VA))
 		vsid_bits = VSID_BITS_256M;

 	map->host_vsid = vsid_scramble(vcpu_book3s->proto_vsid_next++,
 				       VSID_MULTIPLIER_256M, vsid_bits);

 	map->guest_vsid = gvsid;
 	map->valid = true;

 	trace_kvm_book3s_slb_map(sid_map_mask, gvsid, map->host_vsid);

 	return map;
 }

 static int kvmppc_mmu_next_segment(struct kvm_vcpu *vcpu, ulong esid)
 {
 	struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
 	int i;
 	int max_slb_size = 64;
 	int found_inval = -1;
 	int r;

 	/* Are we overwriting? */
 	for (i = 0; i < svcpu->slb_max; i++) {
 		if (!(svcpu->slb[i].esid & SLB_ESID_V))
 			found_inval = i;
 		else if ((svcpu->slb[i].esid & ESID_MASK) == esid) {
 			r = i;
 			goto out;
 		}
 	}

 	/* Found a spare entry that was invalidated before */
 	if (found_inval >= 0) {
 		r = found_inval;
 		goto out;
 	}

 	/* No spare invalid entry, so create one */

 	if (mmu_slb_size < 64)
 		max_slb_size = mmu_slb_size;

 	/* Overflowing -> purge */
 	if ((svcpu->slb_max) == max_slb_size)
 		kvmppc_mmu_flush_segments(vcpu);

 	r = svcpu->slb_max;
 	svcpu->slb_max++;

 out:
 	svcpu_put(svcpu);
 	return r;
 }

 int kvmppc_mmu_map_segment(struct kvm_vcpu *vcpu, ulong eaddr)
 {
 	struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
 	u64 esid = eaddr >> SID_SHIFT;
 	u64 slb_esid = (eaddr & ESID_MASK) | SLB_ESID_V;
 	u64 slb_vsid = SLB_VSID_USER;
 	u64 gvsid;
 	int slb_index;
 	struct kvmppc_sid_map *map;
 	int r = 0;

 	slb_index = kvmppc_mmu_next_segment(vcpu, eaddr & ESID_MASK);

 	if (vcpu->arch.mmu.esid_to_vsid(vcpu, esid, &gvsid)) {
 		/* Invalidate an entry */
 		svcpu->slb[slb_index].esid = 0;
 		r = -ENOENT;
 		goto out;
 	}

 	map = find_sid_vsid(vcpu, gvsid);
 	if (!map)
 		map = create_sid_map(vcpu, gvsid);

 	map->guest_esid = esid;

 	slb_vsid |= (map->host_vsid << 12);
 	slb_vsid &= ~SLB_VSID_KP;
 	slb_esid |= slb_index;

 #ifdef CONFIG_PPC_64K_PAGES
 	/* Set host segment base page size to 64K if possible */
 	if (gvsid & VSID_64K)
 		slb_vsid |= mmu_psize_defs[MMU_PAGE_64K].sllp;
 #endif

 	svcpu->slb[slb_index].esid = slb_esid;
 	svcpu->slb[slb_index].vsid = slb_vsid;

 	trace_kvm_book3s_slbmte(slb_vsid, slb_esid);

 out:
 	svcpu_put(svcpu);
 	return r;
 }

 void kvmppc_mmu_flush_segment(struct kvm_vcpu *vcpu, ulong ea, ulong seg_size)
 {
 	struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
 	ulong seg_mask = -seg_size;
 	int i;

 	for (i = 0; i < svcpu->slb_max; i++) {
 		if ((svcpu->slb[i].esid & SLB_ESID_V) &&
 		    (svcpu->slb[i].esid & seg_mask) == ea) {
 			/* Invalidate this entry */
 			svcpu->slb[i].esid = 0;
 		}
 	}

 	svcpu_put(svcpu);
 }

 void kvmppc_mmu_flush_segments(struct kvm_vcpu *vcpu)
 {
 	struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
 	svcpu->slb_max = 0;
 	svcpu->slb[0].esid = 0;
 	svcpu_put(svcpu);
 }

 void kvmppc_mmu_destroy_pr(struct kvm_vcpu *vcpu)
 {
 	kvmppc_mmu_hpte_destroy(vcpu);
 	__destroy_context(to_book3s(vcpu)->context_id[0]);
 }

 int kvmppc_mmu_init_pr(struct kvm_vcpu *vcpu)
 {
 	struct kvmppc_vcpu_book3s *vcpu3s = to_book3s(vcpu);
 	int err;

 	err = hash__alloc_context_id();
 	if (err < 0)
 		return -1;
 	vcpu3s->context_id[0] = err;

 	vcpu3s->proto_vsid_max = ((u64)(vcpu3s->context_id[0] + 1)
 				  << ESID_BITS) - 1;
 	vcpu3s->proto_vsid_first = (u64)vcpu3s->context_id[0] << ESID_BITS;
 	vcpu3s->proto_vsid_next = vcpu3s->proto_vsid_first;

 	kvmppc_mmu_hpte_init(vcpu);

 	return 0;
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Copyright (C) 2009 SUSE Linux Products GmbH. All rights reserved.
	*
	* Authors:
	* Alexander Graf <agraf@suse.de>
	* Kevin Wolf <mail@kevin-wolf.de>
	*/

	#include <linux/kvm_host.h>

	#include <asm/kvm_ppc.h>
	#include <asm/kvm_book3s.h>
	#include <asm/book3s/64/mmu-hash.h>
	#include <asm/machdep.h>
	#include <asm/mmu_context.h>
	#include <asm/hw_irq.h>
	#include "trace_pr.h"
	#include "book3s.h"

	#define PTE_SIZE 12

	void kvmppc_mmu_invalidate_pte(struct kvm_vcpu vcpu, struct hpte_cache pte)
	{
	mmu_hash_ops.hpte_invalidate(pte->slot, pte->host_vpn,
	pte->pagesize, pte->pagesize,
	MMU_SEGSIZE_256M, false);
	}

	/* We keep 512 gvsid->hvsid entries, mapping the guest ones to the array using
	* a hash, so we don't waste cycles on looping */
	static u16 kvmppc_sid_hash(struct kvm_vcpu *vcpu, u64 gvsid)
	{
	return (u16)(((gvsid >> (SID_MAP_BITS * 7)) & SID_MAP_MASK) ^
	((gvsid >> (SID_MAP_BITS * 6)) & SID_MAP_MASK) ^
	((gvsid >> (SID_MAP_BITS * 5)) & SID_MAP_MASK) ^
	((gvsid >> (SID_MAP_BITS * 4)) & SID_MAP_MASK) ^
	((gvsid >> (SID_MAP_BITS * 3)) & SID_MAP_MASK) ^
	((gvsid >> (SID_MAP_BITS * 2)) & SID_MAP_MASK) ^
	((gvsid >> (SID_MAP_BITS * 1)) & SID_MAP_MASK) ^
	((gvsid >> (SID_MAP_BITS * 0)) & SID_MAP_MASK));
	}


	static struct kvmppc_sid_map find_sid_vsid(struct kvm_vcpu vcpu, u64 gvsid)
	{
	struct kvmppc_sid_map *map;
	u16 sid_map_mask;

	if (kvmppc_get_msr(vcpu) & MSR_PR)
	gvsid \|= VSID_PR;

	sid_map_mask = kvmppc_sid_hash(vcpu, gvsid);
	map = &to_book3s(vcpu)->sid_map[sid_map_mask];
	if (map->valid && (map->guest_vsid == gvsid)) {
	trace_kvm_book3s_slb_found(gvsid, map->host_vsid);
	return map;
	}

	map = &to_book3s(vcpu)->sid_map[SID_MAP_MASK - sid_map_mask];
	if (map->valid && (map->guest_vsid == gvsid)) {
	trace_kvm_book3s_slb_found(gvsid, map->host_vsid);
	return map;
	}

	trace_kvm_book3s_slb_fail(sid_map_mask, gvsid);
	return NULL;
	}

	int kvmppc_mmu_map_page(struct kvm_vcpu vcpu, struct kvmppc_pte orig_pte,
	bool iswrite)
	{
	unsigned long vpn;
	kvm_pfn_t hpaddr;
	ulong hash, hpteg;
	u64 vsid;
	int ret;
	int rflags = 0x192;
	int vflags = 0;
	int attempt = 0;
	struct kvmppc_sid_map *map;
	int r = 0;
	int hpsize = MMU_PAGE_4K;
	bool writable;
	unsigned long mmu_seq;
	struct kvm *kvm = vcpu->kvm;
	struct hpte_cache *cpte;
	unsigned long gfn = orig_pte->raddr >> PAGE_SHIFT;
	unsigned long pfn;

	/* used to check for invalidations in progress */
	mmu_seq = kvm->mmu_notifier_seq;
	smp_rmb();

	/* Get host physical address for gpa */
	pfn = kvmppc_gpa_to_pfn(vcpu, orig_pte->raddr, iswrite, &writable);
	if (is_error_noslot_pfn(pfn)) {
	printk(KERN_INFO "Couldn't get guest page for gpa %lx!\n",
	orig_pte->raddr);
	r = -EINVAL;
	goto out;
	}
	hpaddr = pfn << PAGE_SHIFT;

	/* and write the mapping ea -> hpa into the pt */
	vcpu->arch.mmu.esid_to_vsid(vcpu, orig_pte->eaddr >> SID_SHIFT, &vsid);
	map = find_sid_vsid(vcpu, vsid);
	if (!map) {
	ret = kvmppc_mmu_map_segment(vcpu, orig_pte->eaddr);
	WARN_ON(ret < 0);
	map = find_sid_vsid(vcpu, vsid);
	}
	if (!map) {
	printk(KERN_ERR "KVM: Segment map for 0x%llx (0x%lx) failed\n",
	vsid, orig_pte->eaddr);
	WARN_ON(true);
	r = -EINVAL;
	goto out;
	}

	vpn = hpt_vpn(orig_pte->eaddr, map->host_vsid, MMU_SEGSIZE_256M);

	kvm_set_pfn_accessed(pfn);
	if (!orig_pte->may_write \|\| !writable)
	rflags \|= PP_RXRX;
	else {
	mark_page_dirty(vcpu->kvm, gfn);
	kvm_set_pfn_dirty(pfn);
	}

	if (!orig_pte->may_execute)
	rflags \|= HPTE_R_N;
	else
	kvmppc_mmu_flush_icache(pfn);

	rflags = (rflags & ~HPTE_R_WIMG) \| orig_pte->wimg;

	/*
	* Use 64K pages if possible; otherwise, on 64K page kernels,
	* we need to transfer 4 more bits from guest real to host real addr.
	*/
	if (vsid & VSID_64K)
	hpsize = MMU_PAGE_64K;
	else
	hpaddr \|= orig_pte->raddr & (~0xfffULL & ~PAGE_MASK);

	hash = hpt_hash(vpn, mmu_psize_defs[hpsize].shift, MMU_SEGSIZE_256M);

	cpte = kvmppc_mmu_hpte_cache_next(vcpu);

	spin_lock(&kvm->mmu_lock);
	if (!cpte \|\| mmu_notifier_retry(kvm, mmu_seq)) {
	r = -EAGAIN;
	goto out_unlock;
	}

	map_again:
	hpteg = ((hash & htab_hash_mask) * HPTES_PER_GROUP);

	/* In case we tried normal mapping already, let's nuke old entries */
	if (attempt > 1)
	if (mmu_hash_ops.hpte_remove(hpteg) < 0) {
	r = -1;
	goto out_unlock;
	}

	ret = mmu_hash_ops.hpte_insert(hpteg, vpn, hpaddr, rflags, vflags,
	hpsize, hpsize, MMU_SEGSIZE_256M);

	if (ret == -1) {
	/* If we couldn't map a primary PTE, try a secondary */
	hash = ~hash;
	vflags ^= HPTE_V_SECONDARY;
	attempt++;
	goto map_again;
	} else if (ret < 0) {
	r = -EIO;
	goto out_unlock;
	} else {
	trace_kvm_book3s_64_mmu_map(rflags, hpteg,
	vpn, hpaddr, orig_pte);

	/*
	* The mmu_hash_ops code may give us a secondary entry even
	* though we asked for a primary. Fix up.
	*/
	if ((ret & _PTEIDX_SECONDARY) && !(vflags & HPTE_V_SECONDARY)) {
	hash = ~hash;
	hpteg = ((hash & htab_hash_mask) * HPTES_PER_GROUP);
	}

	cpte->slot = hpteg + (ret & 7);
	cpte->host_vpn = vpn;
	cpte->pte = *orig_pte;
	cpte->pfn = pfn;
	cpte->pagesize = hpsize;

	kvmppc_mmu_hpte_cache_map(vcpu, cpte);
	cpte = NULL;
	}

	out_unlock:
	spin_unlock(&kvm->mmu_lock);
	kvm_release_pfn_clean(pfn);
	if (cpte)
	kvmppc_mmu_hpte_cache_free(cpte);

	out:
	return r;
	}

	void kvmppc_mmu_unmap_page(struct kvm_vcpu vcpu, struct kvmppc_pte pte)
	{
	u64 mask = 0xfffffffffULL;
	u64 vsid;

	vcpu->arch.mmu.esid_to_vsid(vcpu, pte->eaddr >> SID_SHIFT, &vsid);
	if (vsid & VSID_64K)
	mask = 0xffffffff0ULL;
	kvmppc_mmu_pte_vflush(vcpu, pte->vpage, mask);
	}

	static struct kvmppc_sid_map create_sid_map(struct kvm_vcpu vcpu, u64 gvsid)
	{
	unsigned long vsid_bits = VSID_BITS_65_256M;
	struct kvmppc_sid_map *map;
	struct kvmppc_vcpu_book3s *vcpu_book3s = to_book3s(vcpu);
	u16 sid_map_mask;
	static int backwards_map = 0;

	if (kvmppc_get_msr(vcpu) & MSR_PR)
	gvsid \|= VSID_PR;

	/* We might get collisions that trap in preceding order, so let's
	map them differently */

	sid_map_mask = kvmppc_sid_hash(vcpu, gvsid);
	if (backwards_map)
	sid_map_mask = SID_MAP_MASK - sid_map_mask;

	map = &to_book3s(vcpu)->sid_map[sid_map_mask];

	/* Make sure we're taking the other map next time */
	backwards_map = !backwards_map;

	/* Uh-oh ... out of mappings. Let's flush! */
	if (vcpu_book3s->proto_vsid_next == vcpu_book3s->proto_vsid_max) {
	vcpu_book3s->proto_vsid_next = vcpu_book3s->proto_vsid_first;
	memset(vcpu_book3s->sid_map, 0,
	sizeof(struct kvmppc_sid_map) * SID_MAP_NUM);
	kvmppc_mmu_pte_flush(vcpu, 0, 0);
	kvmppc_mmu_flush_segments(vcpu);
	}

	if (mmu_has_feature(MMU_FTR_68_BIT_VA))
	vsid_bits = VSID_BITS_256M;

	map->host_vsid = vsid_scramble(vcpu_book3s->proto_vsid_next++,
	VSID_MULTIPLIER_256M, vsid_bits);

	map->guest_vsid = gvsid;
	map->valid = true;

	trace_kvm_book3s_slb_map(sid_map_mask, gvsid, map->host_vsid);

	return map;
	}

	static int kvmppc_mmu_next_segment(struct kvm_vcpu *vcpu, ulong esid)
	{
	struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
	int i;
	int max_slb_size = 64;
	int found_inval = -1;
	int r;

	/* Are we overwriting? */
	for (i = 0; i < svcpu->slb_max; i++) {
	if (!(svcpu->slb[i].esid & SLB_ESID_V))
	found_inval = i;
	else if ((svcpu->slb[i].esid & ESID_MASK) == esid) {
	r = i;
	goto out;
	}
	}

	/* Found a spare entry that was invalidated before */
	if (found_inval >= 0) {
	r = found_inval;
	goto out;
	}

	/* No spare invalid entry, so create one */

	if (mmu_slb_size < 64)
	max_slb_size = mmu_slb_size;

	/* Overflowing -> purge */
	if ((svcpu->slb_max) == max_slb_size)
	kvmppc_mmu_flush_segments(vcpu);

	r = svcpu->slb_max;
	svcpu->slb_max++;

	out:
	svcpu_put(svcpu);
	return r;
	}

	int kvmppc_mmu_map_segment(struct kvm_vcpu *vcpu, ulong eaddr)
	{
	struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
	u64 esid = eaddr >> SID_SHIFT;
	u64 slb_esid = (eaddr & ESID_MASK) \| SLB_ESID_V;
	u64 slb_vsid = SLB_VSID_USER;
	u64 gvsid;
	int slb_index;
	struct kvmppc_sid_map *map;
	int r = 0;

	slb_index = kvmppc_mmu_next_segment(vcpu, eaddr & ESID_MASK);

	if (vcpu->arch.mmu.esid_to_vsid(vcpu, esid, &gvsid)) {
	/* Invalidate an entry */
	svcpu->slb[slb_index].esid = 0;
	r = -ENOENT;
	goto out;
	}

	map = find_sid_vsid(vcpu, gvsid);
	if (!map)
	map = create_sid_map(vcpu, gvsid);

	map->guest_esid = esid;

	slb_vsid \|= (map->host_vsid << 12);
	slb_vsid &= ~SLB_VSID_KP;
	slb_esid \|= slb_index;

	#ifdef CONFIG_PPC_64K_PAGES
	/* Set host segment base page size to 64K if possible */
	if (gvsid & VSID_64K)
	slb_vsid \|= mmu_psize_defs[MMU_PAGE_64K].sllp;
	#endif

	svcpu->slb[slb_index].esid = slb_esid;
	svcpu->slb[slb_index].vsid = slb_vsid;

	trace_kvm_book3s_slbmte(slb_vsid, slb_esid);

	out:
	svcpu_put(svcpu);
	return r;
	}

	void kvmppc_mmu_flush_segment(struct kvm_vcpu *vcpu, ulong ea, ulong seg_size)
	{
	struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
	ulong seg_mask = -seg_size;
	int i;

	for (i = 0; i < svcpu->slb_max; i++) {
	if ((svcpu->slb[i].esid & SLB_ESID_V) &&
	(svcpu->slb[i].esid & seg_mask) == ea) {
	/* Invalidate this entry */
	svcpu->slb[i].esid = 0;
	}
	}

	svcpu_put(svcpu);
	}

	void kvmppc_mmu_flush_segments(struct kvm_vcpu *vcpu)
	{
	struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
	svcpu->slb_max = 0;
	svcpu->slb[0].esid = 0;
	svcpu_put(svcpu);
	}

	void kvmppc_mmu_destroy_pr(struct kvm_vcpu *vcpu)
	{
	kvmppc_mmu_hpte_destroy(vcpu);
	__destroy_context(to_book3s(vcpu)->context_id[0]);
	}

	int kvmppc_mmu_init_pr(struct kvm_vcpu *vcpu)
	{
	struct kvmppc_vcpu_book3s *vcpu3s = to_book3s(vcpu);
	int err;

	err = hash__alloc_context_id();
	if (err < 0)
	return -1;
	vcpu3s->context_id[0] = err;

	vcpu3s->proto_vsid_max = ((u64)(vcpu3s->context_id[0] + 1)
	<< ESID_BITS) - 1;
	vcpu3s->proto_vsid_first = (u64)vcpu3s->context_id[0] << ESID_BITS;
	vcpu3s->proto_vsid_next = vcpu3s->proto_vsid_first;

	kvmppc_mmu_hpte_init(vcpu);

	return 0;
	}