/*
 * Copyright (C) 2008-2013 Freescale Semiconductor, Inc. All rights reserved.
 *
 * Author: Yu Liu, yu.liu@freescale.com
 *         Scott Wood, scottwood@freescale.com
 *         Ashish Kalra, ashish.kalra@freescale.com
 *         Varun Sethi, varun.sethi@freescale.com
 *         Alexander Graf, agraf@suse.de
 *
 * Description:
 * This file is based on arch/powerpc/kvm/44x_tlb.c,
 * by Hollis Blanchard <hollisb@us.ibm.com>.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2, as
 * published by the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <linux/highmem.h>
#include <linux/log2.h>
#include <linux/uaccess.h>
#include <linux/sched/mm.h>
#include <linux/rwsem.h>
#include <linux/vmalloc.h>
#include <linux/hugetlb.h>
#include <asm/kvm_ppc.h>
#include <asm/pte-walk.h>

#include "e500.h"
#include "timing.h"
#include "e500_mmu_host.h"

#include "trace_booke.h"

#define to_htlb1_esel(esel) (host_tlb_params[1].entries - (esel) - 1)

static struct kvmppc_e500_tlb_params host_tlb_params[E500_TLB_NUM];

static inline unsigned int tlb1_max_shadow_size(void)
{
        /* reserve one entry for magic page */
        return host_tlb_params[1].entries - tlbcam_index - 1;
}

static inline u32 e500_shadow_mas3_attrib(u32 mas3, int usermode)
{
        /* Mask off reserved bits. */
        mas3 &= MAS3_ATTRIB_MASK;

#ifndef CONFIG_KVM_BOOKE_HV
        if (!usermode) {
                /* Guest is in supervisor mode,
                 * so we need to translate guest
                 * supervisor permissions into user permissions. */
                mas3 &= ~E500_TLB_USER_PERM_MASK;
                mas3 |= (mas3 & E500_TLB_SUPER_PERM_MASK) << 1;
        }
        mas3 |= E500_TLB_SUPER_PERM_MASK;
#endif
        return mas3;
}

/*
 * writing shadow tlb entry to host TLB
 */
static inline void __write_host_tlbe(struct kvm_book3e_206_tlb_entry *stlbe,
                                     uint32_t mas0,
                                     uint32_t lpid)
{
        unsigned long flags;

        local_irq_save(flags);
        mtspr(SPRN_MAS0, mas0);
        mtspr(SPRN_MAS1, stlbe->mas1);
        mtspr(SPRN_MAS2, (unsigned long)stlbe->mas2);
        mtspr(SPRN_MAS3, (u32)stlbe->mas7_3);
        mtspr(SPRN_MAS7, (u32)(stlbe->mas7_3 >> 32));
#ifdef CONFIG_KVM_BOOKE_HV
        mtspr(SPRN_MAS8, MAS8_TGS | get_thread_specific_lpid(lpid));
#endif
        asm volatile("isync; tlbwe" : : : "memory");

#ifdef CONFIG_KVM_BOOKE_HV
        /* Must clear mas8 for other host tlbwe's */
        mtspr(SPRN_MAS8, 0);
        isync();
#endif
        local_irq_restore(flags);

        trace_kvm_booke206_stlb_write(mas0, stlbe->mas8, stlbe->mas1,
                                      stlbe->mas2, stlbe->mas7_3);
}

/*
 * Acquire a mas0 with victim hint, as if we just took a TLB miss.
 *
 * We don't care about the address we're searching for, other than that it's
 * in the right set and is not present in the TLB.  Using a zero PID and a
 * userspace address means we don't have to set and then restore MAS5, or
 * calculate a proper MAS6 value.
 */
static u32 get_host_mas0(unsigned long eaddr)
{
        unsigned long flags;
        u32 mas0;
        u32 mas4;

        local_irq_save(flags);
        mtspr(SPRN_MAS6, 0);
        mas4 = mfspr(SPRN_MAS4);
        mtspr(SPRN_MAS4, mas4 & ~MAS4_TLBSEL_MASK);
        asm volatile("tlbsx 0, %0" : : "b" (eaddr & ~CONFIG_PAGE_OFFSET));
        mas0 = mfspr(SPRN_MAS0);
        mtspr(SPRN_MAS4, mas4);
        local_irq_restore(flags);

        return mas0;
}

/* sesel is for tlb1 only */
static inline void write_host_tlbe(struct kvmppc_vcpu_e500 *vcpu_e500,
                int tlbsel, int sesel, struct kvm_book3e_206_tlb_entry *stlbe)
{
        u32 mas0;

        if (tlbsel == 0) {
                mas0 = get_host_mas0(stlbe->mas2);
                __write_host_tlbe(stlbe, mas0, vcpu_e500->vcpu.kvm->arch.lpid);
        } else {
                __write_host_tlbe(stlbe,
                                  MAS0_TLBSEL(1) |
                                  MAS0_ESEL(to_htlb1_esel(sesel)),
                                  vcpu_e500->vcpu.kvm->arch.lpid);
        }
}

/* sesel is for tlb1 only */
static void write_stlbe(struct kvmppc_vcpu_e500 *vcpu_e500,
                        struct kvm_book3e_206_tlb_entry *gtlbe,
                        struct kvm_book3e_206_tlb_entry *stlbe,
                        int stlbsel, int sesel)
{
        int stid;

        preempt_disable();
        stid = kvmppc_e500_get_tlb_stid(&vcpu_e500->vcpu, gtlbe);

        stlbe->mas1 |= MAS1_TID(stid);
        write_host_tlbe(vcpu_e500, stlbsel, sesel, stlbe);
        preempt_enable();
}

#ifdef CONFIG_KVM_E500V2
/* XXX should be a hook in the gva2hpa translation */
void kvmppc_map_magic(struct kvm_vcpu *vcpu)
{
        struct kvmppc_vcpu_e500 *vcpu_e500 = to_e500(vcpu);
        struct kvm_book3e_206_tlb_entry magic;
        ulong shared_page = ((ulong)vcpu->arch.shared) & PAGE_MASK;
        unsigned int stid;
        kvm_pfn_t pfn;

        pfn = (kvm_pfn_t)virt_to_phys((void *)shared_page) >> PAGE_SHIFT;
        get_page(pfn_to_page(pfn));

        preempt_disable();
        stid = kvmppc_e500_get_sid(vcpu_e500, 0, 0, 0, 0);

        magic.mas1 = MAS1_VALID | MAS1_TS | MAS1_TID(stid) |
                     MAS1_TSIZE(BOOK3E_PAGESZ_4K);
        magic.mas2 = vcpu->arch.magic_page_ea | MAS2_M;
        magic.mas7_3 = ((u64)pfn << PAGE_SHIFT) |
                       MAS3_SW | MAS3_SR | MAS3_UW | MAS3_UR;
        magic.mas8 = 0;

        __write_host_tlbe(&magic, MAS0_TLBSEL(1) | MAS0_ESEL(tlbcam_index), 0);
        preempt_enable();
}
#endif

void inval_gtlbe_on_host(struct kvmppc_vcpu_e500 *vcpu_e500, int tlbsel,
                         int esel)
{
        struct kvm_book3e_206_tlb_entry *gtlbe =
                get_entry(vcpu_e500, tlbsel, esel);
        struct tlbe_ref *ref = &vcpu_e500->gtlb_priv[tlbsel][esel].ref;

        /* Don't bother with unmapped entries */
        if (!(ref->flags & E500_TLB_VALID)) {
                WARN(ref->flags & (E500_TLB_BITMAP | E500_TLB_TLB0),
                     "%s: flags %x\n", __func__, ref->flags);
                WARN_ON(tlbsel == 1 && vcpu_e500->g2h_tlb1_map[esel]);
        }

        if (tlbsel == 1 && ref->flags & E500_TLB_BITMAP) {
                u64 tmp = vcpu_e500->g2h_tlb1_map[esel];
                int hw_tlb_indx;
                unsigned long flags;

                local_irq_save(flags);
                while (tmp) {
                        hw_tlb_indx = __ilog2_u64(tmp & -tmp);
                        mtspr(SPRN_MAS0,
                              MAS0_TLBSEL(1) |
                              MAS0_ESEL(to_htlb1_esel(hw_tlb_indx)));
                        mtspr(SPRN_MAS1, 0);
                        asm volatile("tlbwe");
                        vcpu_e500->h2g_tlb1_rmap[hw_tlb_indx] = 0;
                        tmp &= tmp - 1;
                }
                mb();
                vcpu_e500->g2h_tlb1_map[esel] = 0;
                ref->flags &= ~(E500_TLB_BITMAP | E500_TLB_VALID);
                local_irq_restore(flags);
        }

        if (tlbsel == 1 && ref->flags & E500_TLB_TLB0) {
                /*
                 * TLB1 entry is backed by 4k pages. This should happen
                 * rarely and is not worth optimizing. Invalidate everything.
                 */
                kvmppc_e500_tlbil_all(vcpu_e500);
                ref->flags &= ~(E500_TLB_TLB0 | E500_TLB_VALID);
        }

        /*
         * If TLB entry is still valid then it's a TLB0 entry, and thus
         * backed by at most one host tlbe per shadow pid
         */
        if (ref->flags & E500_TLB_VALID)
                kvmppc_e500_tlbil_one(vcpu_e500, gtlbe);

        /* Mark the TLB as not backed by the host anymore */
        ref->flags = 0;
}

static inline int tlbe_is_writable(struct kvm_book3e_206_tlb_entry *tlbe)
{
        return tlbe->mas7_3 & (MAS3_SW|MAS3_UW);
}

static inline void kvmppc_e500_ref_setup(struct tlbe_ref *ref,
                                         struct kvm_book3e_206_tlb_entry *gtlbe,
                                         kvm_pfn_t pfn, unsigned int wimg)
{
        ref->pfn = pfn;
        ref->flags = E500_TLB_VALID;

        /* Use guest supplied MAS2_G and MAS2_E */
        ref->flags |= (gtlbe->mas2 & MAS2_ATTRIB_MASK) | wimg;

        /* Mark the page accessed */
        kvm_set_pfn_accessed(pfn);

        if (tlbe_is_writable(gtlbe))
                kvm_set_pfn_dirty(pfn);
}

static inline void kvmppc_e500_ref_release(struct tlbe_ref *ref)
{
        if (ref->flags & E500_TLB_VALID) {
                /* FIXME: don't log bogus pfn for TLB1 */
                trace_kvm_booke206_ref_release(ref->pfn, ref->flags);
                ref->flags = 0;
        }
}

static void clear_tlb1_bitmap(struct kvmppc_vcpu_e500 *vcpu_e500)
{
        if (vcpu_e500->g2h_tlb1_map)
                memset(vcpu_e500->g2h_tlb1_map, 0,
                       sizeof(u64) * vcpu_e500->gtlb_params[1].entries);
        if (vcpu_e500->h2g_tlb1_rmap)
                memset(vcpu_e500->h2g_tlb1_rmap, 0,
                       sizeof(unsigned int) * host_tlb_params[1].entries);
}

static void clear_tlb_privs(struct kvmppc_vcpu_e500 *vcpu_e500)
{
        int tlbsel;
        int i;

        for (tlbsel = 0; tlbsel <= 1; tlbsel++) {
                for (i = 0; i < vcpu_e500->gtlb_params[tlbsel].entries; i++) {
                        struct tlbe_ref *ref =
                                &vcpu_e500->gtlb_priv[tlbsel][i].ref;
                        kvmppc_e500_ref_release(ref);
                }
        }
}

void kvmppc_core_flush_tlb(struct kvm_vcpu *vcpu)
{
        struct kvmppc_vcpu_e500 *vcpu_e500 = to_e500(vcpu);
        kvmppc_e500_tlbil_all(vcpu_e500);
        clear_tlb_privs(vcpu_e500);
        clear_tlb1_bitmap(vcpu_e500);
}

/* TID must be supplied by the caller */
static void kvmppc_e500_setup_stlbe(
        struct kvm_vcpu *vcpu,
        struct kvm_book3e_206_tlb_entry *gtlbe,
        int tsize, struct tlbe_ref *ref, u64 gvaddr,
        struct kvm_book3e_206_tlb_entry *stlbe)
{
        kvm_pfn_t pfn = ref->pfn;
        u32 pr = vcpu->arch.shared->msr & MSR_PR;

        BUG_ON(!(ref->flags & E500_TLB_VALID));

        /* Force IPROT=0 for all guest mappings. */
        stlbe->mas1 = MAS1_TSIZE(tsize) | get_tlb_sts(gtlbe) | MAS1_VALID;
        stlbe->mas2 = (gvaddr & MAS2_EPN) | (ref->flags & E500_TLB_MAS2_ATTR);
        stlbe->mas7_3 = ((u64)pfn << PAGE_SHIFT) |
                        e500_shadow_mas3_attrib(gtlbe->mas7_3, pr);
}

static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
        u64 gvaddr, gfn_t gfn, struct kvm_book3e_206_tlb_entry *gtlbe,
        int tlbsel, struct kvm_book3e_206_tlb_entry *stlbe,
        struct tlbe_ref *ref)
{
        struct kvm_memory_slot *slot;
        unsigned long pfn = 0; /* silence GCC warning */
        unsigned long hva;
        int pfnmap = 0;
        int tsize = BOOK3E_PAGESZ_4K;
        int ret = 0;
        unsigned long mmu_seq;
        struct kvm *kvm = vcpu_e500->vcpu.kvm;
        unsigned long tsize_pages = 0;
        pte_t *ptep;
        unsigned int wimg = 0;
        pgd_t *pgdir;
        unsigned long flags;

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

        /*
         * Translate guest physical to true physical, acquiring
         * a page reference if it is normal, non-reserved memory.
         *
         * gfn_to_memslot() must succeed because otherwise we wouldn't
         * have gotten this far.  Eventually we should just pass the slot
         * pointer through from the first lookup.
         */
        slot = gfn_to_memslot(vcpu_e500->vcpu.kvm, gfn);
        hva = gfn_to_hva_memslot(slot, gfn);

        if (tlbsel == 1) {
                struct vm_area_struct *vma;
                down_read(&current->mm->mmap_sem);

                vma = find_vma(current->mm, hva);
                if (vma && hva >= vma->vm_start &&
                    (vma->vm_flags & VM_PFNMAP)) {
                        /*
                         * This VMA is a physically contiguous region (e.g.
                         * /dev/mem) that bypasses normal Linux page
                         * management.  Find the overlap between the
                         * vma and the memslot.
                         */

                        unsigned long start, end;
                        unsigned long slot_start, slot_end;

                        pfnmap = 1;

                        start = vma->vm_pgoff;
                        end = start +
                              vma_pages(vma);

                        pfn = start + ((hva - vma->vm_start) >> PAGE_SHIFT);

                        slot_start = pfn - (gfn - slot->base_gfn);
                        slot_end = slot_start + slot->npages;

                        if (start < slot_start)
                                start = slot_start;
                        if (end > slot_end)
                                end = slot_end;

                        tsize = (gtlbe->mas1 & MAS1_TSIZE_MASK) >>
                                MAS1_TSIZE_SHIFT;

                        /*
                         * e500 doesn't implement the lowest tsize bit,
                         * or 1K pages.
                         */
                        tsize = max(BOOK3E_PAGESZ_4K, tsize & ~1);

                        /*
                         * Now find the largest tsize (up to what the guest
                         * requested) that will cover gfn, stay within the
                         * range, and for which gfn and pfn are mutually
                         * aligned.
                         */

                        for (; tsize > BOOK3E_PAGESZ_4K; tsize -= 2) {
                                unsigned long gfn_start, gfn_end;
                                tsize_pages = 1UL << (tsize - 2);

                                gfn_start = gfn & ~(tsize_pages - 1);
                                gfn_end = gfn_start + tsize_pages;

                                if (gfn_start + pfn - gfn < start)
                                        continue;
                                if (gfn_end + pfn - gfn > end)
                                        continue;
                                if ((gfn & (tsize_pages - 1)) !=
                                    (pfn & (tsize_pages - 1)))
                                        continue;

                                gvaddr &= ~((tsize_pages << PAGE_SHIFT) - 1);
                                pfn &= ~(tsize_pages - 1);
                                break;
                        }
                } else if (vma && hva >= vma->vm_start &&
                           (vma->vm_flags & VM_HUGETLB)) {
                        unsigned long psize = vma_kernel_pagesize(vma);

                        tsize = (gtlbe->mas1 & MAS1_TSIZE_MASK) >>
                                MAS1_TSIZE_SHIFT;

                        /*
                         * Take the largest page size that satisfies both host
                         * and guest mapping
                         */
                        tsize = min(__ilog2(psize) - 10, tsize);

                        /*
                         * e500 doesn't implement the lowest tsize bit,
                         * or 1K pages.
                         */
                        tsize = max(BOOK3E_PAGESZ_4K, tsize & ~1);
                }

                up_read(&current->mm->mmap_sem);
        }

        if (likely(!pfnmap)) {
                tsize_pages = 1UL << (tsize + 10 - PAGE_SHIFT);
                pfn = gfn_to_pfn_memslot(slot, gfn);
                if (is_error_noslot_pfn(pfn)) {
                        if (printk_ratelimit())
                                pr_err("%s: real page not found for gfn %lx\n",
                                       __func__, (long)gfn);
                        return -EINVAL;
                }

                /* Align guest and physical address to page map boundaries */
                pfn &= ~(tsize_pages - 1);
                gvaddr &= ~((tsize_pages << PAGE_SHIFT) - 1);
        }

        spin_lock(&kvm->mmu_lock);
        if (mmu_notifier_retry(kvm, mmu_seq)) {
                ret = -EAGAIN;
                goto out;
        }


        pgdir = vcpu_e500->vcpu.arch.pgdir;
        /*
         * We are just looking at the wimg bits, so we don't
         * care much about the trans splitting bit.
         * We are holding kvm->mmu_lock so a notifier invalidate
         * can't run hence pfn won't change.
         */
        local_irq_save(flags);
        ptep = find_linux_pte(pgdir, hva, NULL, NULL);
        if (ptep) {
                pte_t pte = READ_ONCE(*ptep);

                if (pte_present(pte)) {
                        wimg = (pte_val(pte) >> PTE_WIMGE_SHIFT) &
                                MAS2_WIMGE_MASK;
                        local_irq_restore(flags);
                } else {
                        local_irq_restore(flags);
                        pr_err_ratelimited("%s: pte not present: gfn %lx,pfn %lx\n",
                                           __func__, (long)gfn, pfn);
                        ret = -EINVAL;
                        goto out;
                }
        }
        kvmppc_e500_ref_setup(ref, gtlbe, pfn, wimg);

        kvmppc_e500_setup_stlbe(&vcpu_e500->vcpu, gtlbe, tsize,
                                ref, gvaddr, stlbe);

        /* Clear i-cache for new pages */
        kvmppc_mmu_flush_icache(pfn);

out:
        spin_unlock(&kvm->mmu_lock);

        /* Drop refcount on page, so that mmu notifiers can clear it */
        kvm_release_pfn_clean(pfn);

        return ret;
}

/* XXX only map the one-one case, for now use TLB0 */
static int kvmppc_e500_tlb0_map(struct kvmppc_vcpu_e500 *vcpu_e500, int esel,
                                struct kvm_book3e_206_tlb_entry *stlbe)
{
        struct kvm_book3e_206_tlb_entry *gtlbe;
        struct tlbe_ref *ref;
        int stlbsel = 0;
        int sesel = 0;
        int r;

        gtlbe = get_entry(vcpu_e500, 0, esel);
        ref = &vcpu_e500->gtlb_priv[0][esel].ref;

        r = kvmppc_e500_shadow_map(vcpu_e500, get_tlb_eaddr(gtlbe),
                        get_tlb_raddr(gtlbe) >> PAGE_SHIFT,
                        gtlbe, 0, stlbe, ref);
        if (r)
                return r;

        write_stlbe(vcpu_e500, gtlbe, stlbe, stlbsel, sesel);

        return 0;
}

static int kvmppc_e500_tlb1_map_tlb1(struct kvmppc_vcpu_e500 *vcpu_e500,
                                     struct tlbe_ref *ref,
                                     int esel)
{
        unsigned int sesel = vcpu_e500->host_tlb1_nv++;

        if (unlikely(vcpu_e500->host_tlb1_nv >= tlb1_max_shadow_size()))
                vcpu_e500->host_tlb1_nv = 0;

        if (vcpu_e500->h2g_tlb1_rmap[sesel]) {
                unsigned int idx = vcpu_e500->h2g_tlb1_rmap[sesel] - 1;
                vcpu_e500->g2h_tlb1_map[idx] &= ~(1ULL << sesel);
        }

        vcpu_e500->gtlb_priv[1][esel].ref.flags |= E500_TLB_BITMAP;
        vcpu_e500->g2h_tlb1_map[esel] |= (u64)1 << sesel;
        vcpu_e500->h2g_tlb1_rmap[sesel] = esel + 1;
        WARN_ON(!(ref->flags & E500_TLB_VALID));

        return sesel;
}

/* Caller must ensure that the specified guest TLB entry is safe to insert into
 * the shadow TLB. */
/* For both one-one and one-to-many */
static int kvmppc_e500_tlb1_map(struct kvmppc_vcpu_e500 *vcpu_e500,
                u64 gvaddr, gfn_t gfn, struct kvm_book3e_206_tlb_entry *gtlbe,
                struct kvm_book3e_206_tlb_entry *stlbe, int esel)
{
        struct tlbe_ref *ref = &vcpu_e500->gtlb_priv[1][esel].ref;
        int sesel;
        int r;

        r = kvmppc_e500_shadow_map(vcpu_e500, gvaddr, gfn, gtlbe, 1, stlbe,
                                   ref);
        if (r)
                return r;

        /* Use TLB0 when we can only map a page with 4k */
        if (get_tlb_tsize(stlbe) == BOOK3E_PAGESZ_4K) {
                vcpu_e500->gtlb_priv[1][esel].ref.flags |= E500_TLB_TLB0;
                write_stlbe(vcpu_e500, gtlbe, stlbe, 0, 0);
                return 0;
        }

        /* Otherwise map into TLB1 */
        sesel = kvmppc_e500_tlb1_map_tlb1(vcpu_e500, ref, esel);
        write_stlbe(vcpu_e500, gtlbe, stlbe, 1, sesel);

        return 0;
}

void kvmppc_mmu_map(struct kvm_vcpu *vcpu, u64 eaddr, gpa_t gpaddr,
                    unsigned int index)
{
        struct kvmppc_vcpu_e500 *vcpu_e500 = to_e500(vcpu);
        struct tlbe_priv *priv;
        struct kvm_book3e_206_tlb_entry *gtlbe, stlbe;
        int tlbsel = tlbsel_of(index);
        int esel = esel_of(index);

        gtlbe = get_entry(vcpu_e500, tlbsel, esel);

        switch (tlbsel) {
        case 0:
                priv = &vcpu_e500->gtlb_priv[tlbsel][esel];

                /* Triggers after clear_tlb_privs or on initial mapping */
                if (!(priv->ref.flags & E500_TLB_VALID)) {
                        kvmppc_e500_tlb0_map(vcpu_e500, esel, &stlbe);
                } else {
                        kvmppc_e500_setup_stlbe(vcpu, gtlbe, BOOK3E_PAGESZ_4K,
                                                &priv->ref, eaddr, &stlbe);
                        write_stlbe(vcpu_e500, gtlbe, &stlbe, 0, 0);
                }
                break;

        case 1: {
                gfn_t gfn = gpaddr >> PAGE_SHIFT;
                kvmppc_e500_tlb1_map(vcpu_e500, eaddr, gfn, gtlbe, &stlbe,
                                     esel);
                break;
        }

        default:
                BUG();
                break;
        }
}

#ifdef CONFIG_KVM_BOOKE_HV
int kvmppc_load_last_inst(struct kvm_vcpu *vcpu,
                enum instruction_fetch_type type, u32 *instr)
{
        gva_t geaddr;
        hpa_t addr;
        hfn_t pfn;
        hva_t eaddr;
        u32 mas1, mas2, mas3;
        u64 mas7_mas3;
        struct page *page;
        unsigned int addr_space, psize_shift;
        bool pr;
        unsigned long flags;

        /* Search TLB for guest pc to get the real address */
        geaddr = kvmppc_get_pc(vcpu);

        addr_space = (vcpu->arch.shared->msr & MSR_IS) >> MSR_IR_LG;

        local_irq_save(flags);
        mtspr(SPRN_MAS6, (vcpu->arch.pid << MAS6_SPID_SHIFT) | addr_space);
        mtspr(SPRN_MAS5, MAS5_SGS | get_lpid(vcpu));
        asm volatile("tlbsx 0, %[geaddr]\n" : :
                     [geaddr] "r" (geaddr));
        mtspr(SPRN_MAS5, 0);
        mtspr(SPRN_MAS8, 0);
        mas1 = mfspr(SPRN_MAS1);
        mas2 = mfspr(SPRN_MAS2);
        mas3 = mfspr(SPRN_MAS3);
#ifdef CONFIG_64BIT
        mas7_mas3 = mfspr(SPRN_MAS7_MAS3);
#else
        mas7_mas3 = ((u64)mfspr(SPRN_MAS7) << 32) | mas3;
#endif
        local_irq_restore(flags);

        /*
         * If the TLB entry for guest pc was evicted, return to the guest.
         * There are high chances to find a valid TLB entry next time.
         */
        if (!(mas1 & MAS1_VALID))
                return EMULATE_AGAIN;

        /*
         * Another thread may rewrite the TLB entry in parallel, don't
         * execute from the address if the execute permission is not set
         */
        pr = vcpu->arch.shared->msr & MSR_PR;
        if (unlikely((pr && !(mas3 & MAS3_UX)) ||
                     (!pr && !(mas3 & MAS3_SX)))) {
                pr_err_ratelimited(
                        "%s: Instruction emulation from guest address %08lx without execute permission\n",
                        __func__, geaddr);
                return EMULATE_AGAIN;
        }

        /*
         * The real address will be mapped by a cacheable, memory coherent,
         * write-back page. Check for mismatches when LRAT is used.
         */
        if (has_feature(vcpu, VCPU_FTR_MMU_V2) &&
            unlikely((mas2 & MAS2_I) || (mas2 & MAS2_W) || !(mas2 & MAS2_M))) {
                pr_err_ratelimited(
                        "%s: Instruction emulation from guest address %08lx mismatches storage attributes\n",
                        __func__, geaddr);
                return EMULATE_AGAIN;
        }

        /* Get pfn */
        psize_shift = MAS1_GET_TSIZE(mas1) + 10;
        addr = (mas7_mas3 & (~0ULL << psize_shift)) |
               (geaddr & ((1ULL << psize_shift) - 1ULL));
        pfn = addr >> PAGE_SHIFT;

        /* Guard against emulation from devices area */
        if (unlikely(!page_is_ram(pfn))) {
                pr_err_ratelimited("%s: Instruction emulation from non-RAM host address %08llx is not supported\n",
                         __func__, addr);
                return EMULATE_AGAIN;
        }

        /* Map a page and get guest's instruction */
        page = pfn_to_page(pfn);
        eaddr = (unsigned long)kmap_atomic(page);
        *instr = *(u32 *)(eaddr | (unsigned long)(addr & ~PAGE_MASK));
        kunmap_atomic((u32 *)eaddr);

        return EMULATE_DONE;
}
#else
int kvmppc_load_last_inst(struct kvm_vcpu *vcpu,
                enum instruction_fetch_type type, u32 *instr)
{
        return EMULATE_AGAIN;
}
#endif

/************* MMU Notifiers *************/

static int kvm_unmap_hva(struct kvm *kvm, unsigned long hva)
{
        trace_kvm_unmap_hva(hva);

        /*
         * Flush all shadow tlb entries everywhere. This is slow, but
         * we are 100% sure that we catch the to be unmapped page
         */
        kvm_flush_remote_tlbs(kvm);

        return 0;
}

int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end)
{
        /* kvm_unmap_hva flushes everything anyways */
        kvm_unmap_hva(kvm, start);

        return 0;
}

int kvm_age_hva(struct kvm *kvm, unsigned long start, unsigned long end)
{
        /* XXX could be more clever ;) */
        return 0;
}

int kvm_test_age_hva(struct kvm *kvm, unsigned long hva)
{
        /* XXX could be more clever ;) */
        return 0;
}

int kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte)
{
        /* The page will get remapped properly on its next fault */
        kvm_unmap_hva(kvm, hva);
        return 0;
}

/*****************************************/

int e500_mmu_host_init(struct kvmppc_vcpu_e500 *vcpu_e500)
{
        host_tlb_params[0].entries = mfspr(SPRN_TLB0CFG) & TLBnCFG_N_ENTRY;
        host_tlb_params[1].entries = mfspr(SPRN_TLB1CFG) & TLBnCFG_N_ENTRY;

        /*
         * This should never happen on real e500 hardware, but is
         * architecturally possible -- e.g. in some weird nested
         * virtualization case.
         */
        if (host_tlb_params[0].entries == 0 ||
            host_tlb_params[1].entries == 0) {
                pr_err("%s: need to know host tlb size\n", __func__);
                return -ENODEV;
        }

        host_tlb_params[0].ways = (mfspr(SPRN_TLB0CFG) & TLBnCFG_ASSOC) >>
                                  TLBnCFG_ASSOC_SHIFT;
        host_tlb_params[1].ways = host_tlb_params[1].entries;

        if (!is_power_of_2(host_tlb_params[0].entries) ||
            !is_power_of_2(host_tlb_params[0].ways) ||
            host_tlb_params[0].entries < host_tlb_params[0].ways ||
            host_tlb_params[0].ways == 0) {
                pr_err("%s: bad tlb0 host config: %u entries %u ways\n",
                       __func__, host_tlb_params[0].entries,
                       host_tlb_params[0].ways);
                return -ENODEV;
        }

        host_tlb_params[0].sets =
                host_tlb_params[0].entries / host_tlb_params[0].ways;
        host_tlb_params[1].sets = 1;
        vcpu_e500->h2g_tlb1_rmap = kcalloc(host_tlb_params[1].entries,
                                           sizeof(*vcpu_e500->h2g_tlb1_rmap),
                                           GFP_KERNEL);
        if (!vcpu_e500->h2g_tlb1_rmap)
                return -EINVAL;

        return 0;
}

void e500_mmu_host_uninit(struct kvmppc_vcpu_e500 *vcpu_e500)
{
        kfree(vcpu_e500->h2g_tlb1_rmap);
}