Lynx framebuffers multidomain implementation.

[linux/elbrus.git] / arch / powerpc / kvm / book3s_64_mmu_hv.c

/*
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Copyright 2010 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
 */

#include <linux/types.h>
#include <linux/string.h>
#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <linux/highmem.h>
#include <linux/gfp.h>
#include <linux/slab.h>
#include <linux/hugetlb.h>
#include <linux/vmalloc.h>
#include <linux/srcu.h>
#include <linux/anon_inodes.h>
#include <linux/file.h>

#include <asm/tlbflush.h>
#include <asm/kvm_ppc.h>
#include <asm/kvm_book3s.h>
#include <asm/mmu-hash64.h>
#include <asm/hvcall.h>
#include <asm/synch.h>
#include <asm/ppc-opcode.h>
#include <asm/cputable.h>

#include "book3s_hv_cma.h"

/* POWER7 has 10-bit LPIDs, PPC970 has 6-bit LPIDs */
#define MAX_LPID_970    63

/* Power architecture requires HPT is at least 256kB */
#define PPC_MIN_HPT_ORDER       18

static long kvmppc_virtmode_do_h_enter(struct kvm *kvm, unsigned long flags,
                                long pte_index, unsigned long pteh,
                                unsigned long ptel, unsigned long *pte_idx_ret);
static void kvmppc_rmap_reset(struct kvm *kvm);

long kvmppc_alloc_hpt(struct kvm *kvm, u32 *htab_orderp)
{
        unsigned long hpt;
        struct revmap_entry *rev;
        struct page *page = NULL;
        long order = KVM_DEFAULT_HPT_ORDER;

        if (htab_orderp) {
                order = *htab_orderp;
                if (order < PPC_MIN_HPT_ORDER)
                        order = PPC_MIN_HPT_ORDER;
        }

        kvm->arch.hpt_cma_alloc = 0;
        /*
         * try first to allocate it from the kernel page allocator.
         * We keep the CMA reserved for failed allocation.
         */
        hpt = __get_free_pages(GFP_KERNEL | __GFP_ZERO | __GFP_REPEAT |
                               __GFP_NOWARN, order - PAGE_SHIFT);

        /* Next try to allocate from the preallocated pool */
        if (!hpt) {
                VM_BUG_ON(order < KVM_CMA_CHUNK_ORDER);
                page = kvm_alloc_hpt(1 << (order - PAGE_SHIFT));
                if (page) {
                        hpt = (unsigned long)pfn_to_kaddr(page_to_pfn(page));
                        kvm->arch.hpt_cma_alloc = 1;
                } else
                        --order;
        }

        /* Lastly try successively smaller sizes from the page allocator */
        while (!hpt && order > PPC_MIN_HPT_ORDER) {
                hpt = __get_free_pages(GFP_KERNEL|__GFP_ZERO|__GFP_REPEAT|
                                       __GFP_NOWARN, order - PAGE_SHIFT);
                if (!hpt)
                        --order;
        }

        if (!hpt)
                return -ENOMEM;

        kvm->arch.hpt_virt = hpt;
        kvm->arch.hpt_order = order;
        /* HPTEs are 2**4 bytes long */
        kvm->arch.hpt_npte = 1ul << (order - 4);
        /* 128 (2**7) bytes in each HPTEG */
        kvm->arch.hpt_mask = (1ul << (order - 7)) - 1;

        /* Allocate reverse map array */
        rev = vmalloc(sizeof(struct revmap_entry) * kvm->arch.hpt_npte);
        if (!rev) {
                pr_err("kvmppc_alloc_hpt: Couldn't alloc reverse map array\n");
                goto out_freehpt;
        }
        kvm->arch.revmap = rev;
        kvm->arch.sdr1 = __pa(hpt) | (order - 18);

        pr_info("KVM guest htab at %lx (order %ld), LPID %x\n",
                hpt, order, kvm->arch.lpid);

        if (htab_orderp)
                *htab_orderp = order;
        return 0;

 out_freehpt:
        if (kvm->arch.hpt_cma_alloc)
                kvm_release_hpt(page, 1 << (order - PAGE_SHIFT));
        else
                free_pages(hpt, order - PAGE_SHIFT);
        return -ENOMEM;
}

long kvmppc_alloc_reset_hpt(struct kvm *kvm, u32 *htab_orderp)
{
        long err = -EBUSY;
        long order;

        mutex_lock(&kvm->lock);
        if (kvm->arch.rma_setup_done) {
                kvm->arch.rma_setup_done = 0;
                /* order rma_setup_done vs. vcpus_running */
                smp_mb();
                if (atomic_read(&kvm->arch.vcpus_running)) {
                        kvm->arch.rma_setup_done = 1;
                        goto out;
                }
        }
        if (kvm->arch.hpt_virt) {
                order = kvm->arch.hpt_order;
                /* Set the entire HPT to 0, i.e. invalid HPTEs */
                memset((void *)kvm->arch.hpt_virt, 0, 1ul << order);
                /*
                 * Reset all the reverse-mapping chains for all memslots
                 */
                kvmppc_rmap_reset(kvm);
                /* Ensure that each vcpu will flush its TLB on next entry. */
                cpumask_setall(&kvm->arch.need_tlb_flush);
                *htab_orderp = order;
                err = 0;
        } else {
                err = kvmppc_alloc_hpt(kvm, htab_orderp);
                order = *htab_orderp;
        }
 out:
        mutex_unlock(&kvm->lock);
        return err;
}

void kvmppc_free_hpt(struct kvm *kvm)
{
        kvmppc_free_lpid(kvm->arch.lpid);
        vfree(kvm->arch.revmap);
        if (kvm->arch.hpt_cma_alloc)
                kvm_release_hpt(virt_to_page(kvm->arch.hpt_virt),
                                1 << (kvm->arch.hpt_order - PAGE_SHIFT));
        else
                free_pages(kvm->arch.hpt_virt,
                           kvm->arch.hpt_order - PAGE_SHIFT);
}

/* Bits in first HPTE dword for pagesize 4k, 64k or 16M */
static inline unsigned long hpte0_pgsize_encoding(unsigned long pgsize)
{
        return (pgsize > 0x1000) ? HPTE_V_LARGE : 0;
}

/* Bits in second HPTE dword for pagesize 4k, 64k or 16M */
static inline unsigned long hpte1_pgsize_encoding(unsigned long pgsize)
{
        return (pgsize == 0x10000) ? 0x1000 : 0;
}

void kvmppc_map_vrma(struct kvm_vcpu *vcpu, struct kvm_memory_slot *memslot,
                     unsigned long porder)
{
        unsigned long i;
        unsigned long npages;
        unsigned long hp_v, hp_r;
        unsigned long addr, hash;
        unsigned long psize;
        unsigned long hp0, hp1;
        unsigned long idx_ret;
        long ret;
        struct kvm *kvm = vcpu->kvm;

        psize = 1ul << porder;
        npages = memslot->npages >> (porder - PAGE_SHIFT);

        /* VRMA can't be > 1TB */
        if (npages > 1ul << (40 - porder))
                npages = 1ul << (40 - porder);
        /* Can't use more than 1 HPTE per HPTEG */
        if (npages > kvm->arch.hpt_mask + 1)
                npages = kvm->arch.hpt_mask + 1;

        hp0 = HPTE_V_1TB_SEG | (VRMA_VSID << (40 - 16)) |
                HPTE_V_BOLTED | hpte0_pgsize_encoding(psize);
        hp1 = hpte1_pgsize_encoding(psize) |
                HPTE_R_R | HPTE_R_C | HPTE_R_M | PP_RWXX;

        for (i = 0; i < npages; ++i) {
                addr = i << porder;
                /* can't use hpt_hash since va > 64 bits */
                hash = (i ^ (VRMA_VSID ^ (VRMA_VSID << 25))) & kvm->arch.hpt_mask;
                /*
                 * We assume that the hash table is empty and no
                 * vcpus are using it at this stage.  Since we create
                 * at most one HPTE per HPTEG, we just assume entry 7
                 * is available and use it.
                 */
                hash = (hash << 3) + 7;
                hp_v = hp0 | ((addr >> 16) & ~0x7fUL);
                hp_r = hp1 | addr;
                ret = kvmppc_virtmode_do_h_enter(kvm, H_EXACT, hash, hp_v, hp_r,
                                                 &idx_ret);
                if (ret != H_SUCCESS) {
                        pr_err("KVM: map_vrma at %lx failed, ret=%ld\n",
                               addr, ret);
                        break;
                }
        }
}

int kvmppc_mmu_hv_init(void)
{
        unsigned long host_lpid, rsvd_lpid;

        if (!cpu_has_feature(CPU_FTR_HVMODE))
                return -EINVAL;

        /* POWER7 has 10-bit LPIDs, PPC970 and e500mc have 6-bit LPIDs */
        if (cpu_has_feature(CPU_FTR_ARCH_206)) {
                host_lpid = mfspr(SPRN_LPID);   /* POWER7 */
                rsvd_lpid = LPID_RSVD;
        } else {
                host_lpid = 0;                  /* PPC970 */
                rsvd_lpid = MAX_LPID_970;
        }

        kvmppc_init_lpid(rsvd_lpid + 1);

        kvmppc_claim_lpid(host_lpid);
        /* rsvd_lpid is reserved for use in partition switching */
        kvmppc_claim_lpid(rsvd_lpid);

        return 0;
}

static void kvmppc_mmu_book3s_64_hv_reset_msr(struct kvm_vcpu *vcpu)
{
        kvmppc_set_msr(vcpu, vcpu->arch.intr_msr);
}

/*
 * This is called to get a reference to a guest page if there isn't
 * one already in the memslot->arch.slot_phys[] array.
 */
static long kvmppc_get_guest_page(struct kvm *kvm, unsigned long gfn,
                                  struct kvm_memory_slot *memslot,
                                  unsigned long psize)
{
        unsigned long start;
        long np, err;
        struct page *page, *hpage, *pages[1];
        unsigned long s, pgsize;
        unsigned long *physp;
        unsigned int is_io, got, pgorder;
        struct vm_area_struct *vma;
        unsigned long pfn, i, npages;

        physp = memslot->arch.slot_phys;
        if (!physp)
                return -EINVAL;
        if (physp[gfn - memslot->base_gfn])
                return 0;

        is_io = 0;
        got = 0;
        page = NULL;
        pgsize = psize;
        err = -EINVAL;
        start = gfn_to_hva_memslot(memslot, gfn);

        /* Instantiate and get the page we want access to */
        np = get_user_pages_fast(start, 1, 1, pages);
        if (np != 1) {
                /* Look up the vma for the page */
                down_read(&current->mm->mmap_sem);
                vma = find_vma(current->mm, start);
                if (!vma || vma->vm_start > start ||
                    start + psize > vma->vm_end ||
                    !(vma->vm_flags & VM_PFNMAP))
                        goto up_err;
                is_io = hpte_cache_bits(pgprot_val(vma->vm_page_prot));
                pfn = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
                /* check alignment of pfn vs. requested page size */
                if (psize > PAGE_SIZE && (pfn & ((psize >> PAGE_SHIFT) - 1)))
                        goto up_err;
                up_read(&current->mm->mmap_sem);

        } else {
                page = pages[0];
                got = KVMPPC_GOT_PAGE;

                /* See if this is a large page */
                s = PAGE_SIZE;
                if (PageHuge(page)) {
                        hpage = compound_head(page);
                        s <<= compound_order(hpage);
                        /* Get the whole large page if slot alignment is ok */
                        if (s > psize && slot_is_aligned(memslot, s) &&
                            !(memslot->userspace_addr & (s - 1))) {
                                start &= ~(s - 1);
                                pgsize = s;
                                get_page(hpage);
                                put_page(page);
                                page = hpage;
                        }
                }
                if (s < psize)
                        goto out;
                pfn = page_to_pfn(page);
        }

        npages = pgsize >> PAGE_SHIFT;
        pgorder = __ilog2(npages);
        physp += (gfn - memslot->base_gfn) & ~(npages - 1);
        spin_lock(&kvm->arch.slot_phys_lock);
        for (i = 0; i < npages; ++i) {
                if (!physp[i]) {
                        physp[i] = ((pfn + i) << PAGE_SHIFT) +
                                got + is_io + pgorder;
                        got = 0;
                }
        }
        spin_unlock(&kvm->arch.slot_phys_lock);
        err = 0;

 out:
        if (got)
                put_page(page);
        return err;

 up_err:
        up_read(&current->mm->mmap_sem);
        return err;
}

long kvmppc_virtmode_do_h_enter(struct kvm *kvm, unsigned long flags,
                                long pte_index, unsigned long pteh,
                                unsigned long ptel, unsigned long *pte_idx_ret)
{
        unsigned long psize, gpa, gfn;
        struct kvm_memory_slot *memslot;
        long ret;

        if (kvm->arch.using_mmu_notifiers)
                goto do_insert;

        psize = hpte_page_size(pteh, ptel);
        if (!psize)
                return H_PARAMETER;

        pteh &= ~(HPTE_V_HVLOCK | HPTE_V_ABSENT | HPTE_V_VALID);

        /* Find the memslot (if any) for this address */
        gpa = (ptel & HPTE_R_RPN) & ~(psize - 1);
        gfn = gpa >> PAGE_SHIFT;
        memslot = gfn_to_memslot(kvm, gfn);
        if (memslot && !(memslot->flags & KVM_MEMSLOT_INVALID)) {
                if (!slot_is_aligned(memslot, psize))
                        return H_PARAMETER;
                if (kvmppc_get_guest_page(kvm, gfn, memslot, psize) < 0)
                        return H_PARAMETER;
        }

 do_insert:
        /* Protect linux PTE lookup from page table destruction */
        rcu_read_lock_sched();  /* this disables preemption too */
        ret = kvmppc_do_h_enter(kvm, flags, pte_index, pteh, ptel,
                                current->mm->pgd, false, pte_idx_ret);
        rcu_read_unlock_sched();
        if (ret == H_TOO_HARD) {
                /* this can't happen */
                pr_err("KVM: Oops, kvmppc_h_enter returned too hard!\n");
                ret = H_RESOURCE;       /* or something */
        }
        return ret;

}

/*
 * We come here on a H_ENTER call from the guest when we are not
 * using mmu notifiers and we don't have the requested page pinned
 * already.
 */
long kvmppc_virtmode_h_enter(struct kvm_vcpu *vcpu, unsigned long flags,
                             long pte_index, unsigned long pteh,
                             unsigned long ptel)
{
        return kvmppc_virtmode_do_h_enter(vcpu->kvm, flags, pte_index,
                                          pteh, ptel, &vcpu->arch.gpr[4]);
}

static struct kvmppc_slb *kvmppc_mmu_book3s_hv_find_slbe(struct kvm_vcpu *vcpu,
                                                         gva_t eaddr)
{
        u64 mask;
        int i;

        for (i = 0; i < vcpu->arch.slb_nr; i++) {
                if (!(vcpu->arch.slb[i].orige & SLB_ESID_V))
                        continue;

                if (vcpu->arch.slb[i].origv & SLB_VSID_B_1T)
                        mask = ESID_MASK_1T;
                else
                        mask = ESID_MASK;

                if (((vcpu->arch.slb[i].orige ^ eaddr) & mask) == 0)
                        return &vcpu->arch.slb[i];
        }
        return NULL;
}

static unsigned long kvmppc_mmu_get_real_addr(unsigned long v, unsigned long r,
                        unsigned long ea)
{
        unsigned long ra_mask;

        ra_mask = hpte_page_size(v, r) - 1;
        return (r & HPTE_R_RPN & ~ra_mask) | (ea & ra_mask);
}

static int kvmppc_mmu_book3s_64_hv_xlate(struct kvm_vcpu *vcpu, gva_t eaddr,
                        struct kvmppc_pte *gpte, bool data, bool iswrite)
{
        struct kvm *kvm = vcpu->kvm;
        struct kvmppc_slb *slbe;
        unsigned long slb_v;
        unsigned long pp, key;
        unsigned long v, gr;
        unsigned long *hptep;
        int index;
        int virtmode = vcpu->arch.shregs.msr & (data ? MSR_DR : MSR_IR);

        /* Get SLB entry */
        if (virtmode) {
                slbe = kvmppc_mmu_book3s_hv_find_slbe(vcpu, eaddr);
                if (!slbe)
                        return -EINVAL;
                slb_v = slbe->origv;
        } else {
                /* real mode access */
                slb_v = vcpu->kvm->arch.vrma_slb_v;
        }

        preempt_disable();
        /* Find the HPTE in the hash table */
        index = kvmppc_hv_find_lock_hpte(kvm, eaddr, slb_v,
                                         HPTE_V_VALID | HPTE_V_ABSENT);
        if (index < 0) {
                preempt_enable();
                return -ENOENT;
        }
        hptep = (unsigned long *)(kvm->arch.hpt_virt + (index << 4));
        v = hptep[0] & ~HPTE_V_HVLOCK;
        gr = kvm->arch.revmap[index].guest_rpte;

        /* Unlock the HPTE */
        asm volatile("lwsync" : : : "memory");
        hptep[0] = v;
        preempt_enable();

        gpte->eaddr = eaddr;
        gpte->vpage = ((v & HPTE_V_AVPN) << 4) | ((eaddr >> 12) & 0xfff);

        /* Get PP bits and key for permission check */
        pp = gr & (HPTE_R_PP0 | HPTE_R_PP);
        key = (vcpu->arch.shregs.msr & MSR_PR) ? SLB_VSID_KP : SLB_VSID_KS;
        key &= slb_v;

        /* Calculate permissions */
        gpte->may_read = hpte_read_permission(pp, key);
        gpte->may_write = hpte_write_permission(pp, key);
        gpte->may_execute = gpte->may_read && !(gr & (HPTE_R_N | HPTE_R_G));

        /* Storage key permission check for POWER7 */
        if (data && virtmode && cpu_has_feature(CPU_FTR_ARCH_206)) {
                int amrfield = hpte_get_skey_perm(gr, vcpu->arch.amr);
                if (amrfield & 1)
                        gpte->may_read = 0;
                if (amrfield & 2)
                        gpte->may_write = 0;
        }

        /* Get the guest physical address */
        gpte->raddr = kvmppc_mmu_get_real_addr(v, gr, eaddr);
        return 0;
}

/*
 * Quick test for whether an instruction is a load or a store.
 * If the instruction is a load or a store, then this will indicate
 * which it is, at least on server processors.  (Embedded processors
 * have some external PID instructions that don't follow the rule
 * embodied here.)  If the instruction isn't a load or store, then
 * this doesn't return anything useful.
 */
static int instruction_is_store(unsigned int instr)
{
        unsigned int mask;

        mask = 0x10000000;
        if ((instr & 0xfc000000) == 0x7c000000)
                mask = 0x100;           /* major opcode 31 */
        return (instr & mask) != 0;
}

static int kvmppc_hv_emulate_mmio(struct kvm_run *run, struct kvm_vcpu *vcpu,
                                  unsigned long gpa, gva_t ea, int is_store)
{
        int ret;
        u32 last_inst;
        unsigned long srr0 = kvmppc_get_pc(vcpu);

        /* We try to load the last instruction.  We don't let
         * emulate_instruction do it as it doesn't check what
         * kvmppc_ld returns.
         * If we fail, we just return to the guest and try executing it again.
         */
        if (vcpu->arch.last_inst == KVM_INST_FETCH_FAILED) {
                ret = kvmppc_ld(vcpu, &srr0, sizeof(u32), &last_inst, false);
                if (ret != EMULATE_DONE || last_inst == KVM_INST_FETCH_FAILED)
                        return RESUME_GUEST;
                vcpu->arch.last_inst = last_inst;
        }

        /*
         * WARNING: We do not know for sure whether the instruction we just
         * read from memory is the same that caused the fault in the first
         * place.  If the instruction we read is neither an load or a store,
         * then it can't access memory, so we don't need to worry about
         * enforcing access permissions.  So, assuming it is a load or
         * store, we just check that its direction (load or store) is
         * consistent with the original fault, since that's what we
         * checked the access permissions against.  If there is a mismatch
         * we just return and retry the instruction.
         */

        if (instruction_is_store(kvmppc_get_last_inst(vcpu)) != !!is_store)
                return RESUME_GUEST;

        /*
         * Emulated accesses are emulated by looking at the hash for
         * translation once, then performing the access later. The
         * translation could be invalidated in the meantime in which
         * point performing the subsequent memory access on the old
         * physical address could possibly be a security hole for the
         * guest (but not the host).
         *
         * This is less of an issue for MMIO stores since they aren't
         * globally visible. It could be an issue for MMIO loads to
         * a certain extent but we'll ignore it for now.
         */

        vcpu->arch.paddr_accessed = gpa;
        vcpu->arch.vaddr_accessed = ea;
        return kvmppc_emulate_mmio(run, vcpu);
}

int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
                                unsigned long ea, unsigned long dsisr)
{
        struct kvm *kvm = vcpu->kvm;
        unsigned long *hptep, hpte[3], r;
        unsigned long mmu_seq, psize, pte_size;
        unsigned long gpa, gfn, hva, pfn;
        struct kvm_memory_slot *memslot;
        unsigned long *rmap;
        struct revmap_entry *rev;
        struct page *page, *pages[1];
        long index, ret, npages;
        unsigned long is_io;
        unsigned int writing, write_ok;
        struct vm_area_struct *vma;
        unsigned long rcbits;

        /*
         * Real-mode code has already searched the HPT and found the
         * entry we're interested in.  Lock the entry and check that
         * it hasn't changed.  If it has, just return and re-execute the
         * instruction.
         */
        if (ea != vcpu->arch.pgfault_addr)
                return RESUME_GUEST;
        index = vcpu->arch.pgfault_index;
        hptep = (unsigned long *)(kvm->arch.hpt_virt + (index << 4));
        rev = &kvm->arch.revmap[index];
        preempt_disable();
        while (!try_lock_hpte(hptep, HPTE_V_HVLOCK))
                cpu_relax();
        hpte[0] = hptep[0] & ~HPTE_V_HVLOCK;
        hpte[1] = hptep[1];
        hpte[2] = r = rev->guest_rpte;
        asm volatile("lwsync" : : : "memory");
        hptep[0] = hpte[0];
        preempt_enable();

        if (hpte[0] != vcpu->arch.pgfault_hpte[0] ||
            hpte[1] != vcpu->arch.pgfault_hpte[1])
                return RESUME_GUEST;

        /* Translate the logical address and get the page */
        psize = hpte_page_size(hpte[0], r);
        gpa = (r & HPTE_R_RPN & ~(psize - 1)) | (ea & (psize - 1));
        gfn = gpa >> PAGE_SHIFT;
        memslot = gfn_to_memslot(kvm, gfn);

        /* No memslot means it's an emulated MMIO region */
        if (!memslot || (memslot->flags & KVM_MEMSLOT_INVALID))
                return kvmppc_hv_emulate_mmio(run, vcpu, gpa, ea,
                                              dsisr & DSISR_ISSTORE);

        if (!kvm->arch.using_mmu_notifiers)
                return -EFAULT;         /* should never get here */

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

        is_io = 0;
        pfn = 0;
        page = NULL;
        pte_size = PAGE_SIZE;
        writing = (dsisr & DSISR_ISSTORE) != 0;
        /* If writing != 0, then the HPTE must allow writing, if we get here */
        write_ok = writing;
        hva = gfn_to_hva_memslot(memslot, gfn);
        npages = get_user_pages_fast(hva, 1, writing, pages);
        if (npages < 1) {
                /* Check if it's an I/O mapping */
                down_read(&current->mm->mmap_sem);
                vma = find_vma(current->mm, hva);
                if (vma && vma->vm_start <= hva && hva + psize <= vma->vm_end &&
                    (vma->vm_flags & VM_PFNMAP)) {
                        pfn = vma->vm_pgoff +
                                ((hva - vma->vm_start) >> PAGE_SHIFT);
                        pte_size = psize;
                        is_io = hpte_cache_bits(pgprot_val(vma->vm_page_prot));
                        write_ok = vma->vm_flags & VM_WRITE;
                }
                up_read(&current->mm->mmap_sem);
                if (!pfn)
                        return -EFAULT;
        } else {
                page = pages[0];
                pfn = page_to_pfn(page);
                if (PageHuge(page)) {
                        page = compound_head(page);
                        pte_size <<= compound_order(page);
                }
                /* if the guest wants write access, see if that is OK */
                if (!writing && hpte_is_writable(r)) {
                        unsigned int hugepage_shift;
                        pte_t *ptep, pte;

                        /*
                         * We need to protect against page table destruction
                         * while looking up and updating the pte.
                         */
                        rcu_read_lock_sched();
                        ptep = find_linux_pte_or_hugepte(current->mm->pgd,
                                                         hva, &hugepage_shift);
                        if (ptep) {
                                pte = kvmppc_read_update_linux_pte(ptep, 1,
                                                           hugepage_shift);
                                if (pte_write(pte))
                                        write_ok = 1;
                        }
                        rcu_read_unlock_sched();
                }
        }

        ret = -EFAULT;
        if (psize > pte_size)
                goto out_put;

        /* Check WIMG vs. the actual page we're accessing */
        if (!hpte_cache_flags_ok(r, is_io)) {
                if (is_io)
                        return -EFAULT;
                /*
                 * Allow guest to map emulated device memory as
                 * uncacheable, but actually make it cacheable.
                 */
                r = (r & ~(HPTE_R_W|HPTE_R_I|HPTE_R_G)) | HPTE_R_M;
        }

        /*
         * Set the HPTE to point to pfn.
         * Since the pfn is at PAGE_SIZE granularity, make sure we
         * don't mask out lower-order bits if psize < PAGE_SIZE.
         */
        if (psize < PAGE_SIZE)
                psize = PAGE_SIZE;
        r = (r & ~(HPTE_R_PP0 - psize)) | ((pfn << PAGE_SHIFT) & ~(psize - 1));
        if (hpte_is_writable(r) && !write_ok)
                r = hpte_make_readonly(r);
        ret = RESUME_GUEST;
        preempt_disable();
        while (!try_lock_hpte(hptep, HPTE_V_HVLOCK))
                cpu_relax();
        if ((hptep[0] & ~HPTE_V_HVLOCK) != hpte[0] || hptep[1] != hpte[1] ||
            rev->guest_rpte != hpte[2])
                /* HPTE has been changed under us; let the guest retry */
                goto out_unlock;
        hpte[0] = (hpte[0] & ~HPTE_V_ABSENT) | HPTE_V_VALID;

        rmap = &memslot->arch.rmap[gfn - memslot->base_gfn];
        lock_rmap(rmap);

        /* Check if we might have been invalidated; let the guest retry if so */
        ret = RESUME_GUEST;
        if (mmu_notifier_retry(vcpu->kvm, mmu_seq)) {
                unlock_rmap(rmap);
                goto out_unlock;
        }

        /* Only set R/C in real HPTE if set in both *rmap and guest_rpte */
        rcbits = *rmap >> KVMPPC_RMAP_RC_SHIFT;
        r &= rcbits | ~(HPTE_R_R | HPTE_R_C);

        if (hptep[0] & HPTE_V_VALID) {
                /* HPTE was previously valid, so we need to invalidate it */
                unlock_rmap(rmap);
                hptep[0] |= HPTE_V_ABSENT;
                kvmppc_invalidate_hpte(kvm, hptep, index);
                /* don't lose previous R and C bits */
                r |= hptep[1] & (HPTE_R_R | HPTE_R_C);
        } else {
                kvmppc_add_revmap_chain(kvm, rev, rmap, index, 0);
        }

        hptep[1] = r;
        eieio();
        hptep[0] = hpte[0];
        asm volatile("ptesync" : : : "memory");
        preempt_enable();
        if (page && hpte_is_writable(r))
                SetPageDirty(page);

 out_put:
        if (page) {
                /*
                 * We drop pages[0] here, not page because page might
                 * have been set to the head page of a compound, but
                 * we have to drop the reference on the correct tail
                 * page to match the get inside gup()
                 */
                put_page(pages[0]);
        }
        return ret;

 out_unlock:
        hptep[0] &= ~HPTE_V_HVLOCK;
        preempt_enable();
        goto out_put;
}

static void kvmppc_rmap_reset(struct kvm *kvm)
{
        struct kvm_memslots *slots;
        struct kvm_memory_slot *memslot;
        int srcu_idx;

        srcu_idx = srcu_read_lock(&kvm->srcu);
        slots = kvm->memslots;
        kvm_for_each_memslot(memslot, slots) {
                /*
                 * This assumes it is acceptable to lose reference and
                 * change bits across a reset.
                 */
                memset(memslot->arch.rmap, 0,
                       memslot->npages * sizeof(*memslot->arch.rmap));
        }
        srcu_read_unlock(&kvm->srcu, srcu_idx);
}

static int kvm_handle_hva_range(struct kvm *kvm,
                                unsigned long start,
                                unsigned long end,
                                int (*handler)(struct kvm *kvm,
                                               unsigned long *rmapp,
                                               unsigned long gfn))
{
        int ret;
        int retval = 0;
        struct kvm_memslots *slots;
        struct kvm_memory_slot *memslot;

        slots = kvm_memslots(kvm);
        kvm_for_each_memslot(memslot, slots) {
                unsigned long hva_start, hva_end;
                gfn_t gfn, gfn_end;

                hva_start = max(start, memslot->userspace_addr);
                hva_end = min(end, memslot->userspace_addr +
                                        (memslot->npages << PAGE_SHIFT));
                if (hva_start >= hva_end)
                        continue;
                /*
                 * {gfn(page) | page intersects with [hva_start, hva_end)} =
                 * {gfn, gfn+1, ..., gfn_end-1}.
                 */
                gfn = hva_to_gfn_memslot(hva_start, memslot);
                gfn_end = hva_to_gfn_memslot(hva_end + PAGE_SIZE - 1, memslot);

                for (; gfn < gfn_end; ++gfn) {
                        gfn_t gfn_offset = gfn - memslot->base_gfn;

                        ret = handler(kvm, &memslot->arch.rmap[gfn_offset], gfn);
                        retval |= ret;
                }
        }

        return retval;
}

static int kvm_handle_hva(struct kvm *kvm, unsigned long hva,
                          int (*handler)(struct kvm *kvm, unsigned long *rmapp,
                                         unsigned long gfn))
{
        return kvm_handle_hva_range(kvm, hva, hva + 1, handler);
}

static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long *rmapp,
                           unsigned long gfn)
{
        struct revmap_entry *rev = kvm->arch.revmap;
        unsigned long h, i, j;
        unsigned long *hptep;
        unsigned long ptel, psize, rcbits;

        for (;;) {
                lock_rmap(rmapp);
                if (!(*rmapp & KVMPPC_RMAP_PRESENT)) {
                        unlock_rmap(rmapp);
                        break;
                }

                /*
                 * To avoid an ABBA deadlock with the HPTE lock bit,
                 * we can't spin on the HPTE lock while holding the
                 * rmap chain lock.
                 */
                i = *rmapp & KVMPPC_RMAP_INDEX;
                hptep = (unsigned long *) (kvm->arch.hpt_virt + (i << 4));
                if (!try_lock_hpte(hptep, HPTE_V_HVLOCK)) {
                        /* unlock rmap before spinning on the HPTE lock */
                        unlock_rmap(rmapp);
                        while (hptep[0] & HPTE_V_HVLOCK)
                                cpu_relax();
                        continue;
                }
                j = rev[i].forw;
                if (j == i) {
                        /* chain is now empty */
                        *rmapp &= ~(KVMPPC_RMAP_PRESENT | KVMPPC_RMAP_INDEX);
                } else {
                        /* remove i from chain */
                        h = rev[i].back;
                        rev[h].forw = j;
                        rev[j].back = h;
                        rev[i].forw = rev[i].back = i;
                        *rmapp = (*rmapp & ~KVMPPC_RMAP_INDEX) | j;
                }

                /* Now check and modify the HPTE */
                ptel = rev[i].guest_rpte;
                psize = hpte_page_size(hptep[0], ptel);
                if ((hptep[0] & HPTE_V_VALID) &&
                    hpte_rpn(ptel, psize) == gfn) {
                        if (kvm->arch.using_mmu_notifiers)
                                hptep[0] |= HPTE_V_ABSENT;
                        kvmppc_invalidate_hpte(kvm, hptep, i);
                        /* Harvest R and C */
                        rcbits = hptep[1] & (HPTE_R_R | HPTE_R_C);
                        *rmapp |= rcbits << KVMPPC_RMAP_RC_SHIFT;
                        if (rcbits & ~rev[i].guest_rpte) {
                                rev[i].guest_rpte = ptel | rcbits;
                                note_hpte_modification(kvm, &rev[i]);
                        }
                }
                unlock_rmap(rmapp);
                hptep[0] &= ~HPTE_V_HVLOCK;
        }
        return 0;
}

int kvm_unmap_hva_hv(struct kvm *kvm, unsigned long hva)
{
        if (kvm->arch.using_mmu_notifiers)
                kvm_handle_hva(kvm, hva, kvm_unmap_rmapp);
        return 0;
}

int kvm_unmap_hva_range_hv(struct kvm *kvm, unsigned long start, unsigned long end)
{
        if (kvm->arch.using_mmu_notifiers)
                kvm_handle_hva_range(kvm, start, end, kvm_unmap_rmapp);
        return 0;
}

void kvmppc_core_flush_memslot_hv(struct kvm *kvm,
                                  struct kvm_memory_slot *memslot)
{
        unsigned long *rmapp;
        unsigned long gfn;
        unsigned long n;

        rmapp = memslot->arch.rmap;
        gfn = memslot->base_gfn;
        for (n = memslot->npages; n; --n) {
                /*
                 * Testing the present bit without locking is OK because
                 * the memslot has been marked invalid already, and hence
                 * no new HPTEs referencing this page can be created,
                 * thus the present bit can't go from 0 to 1.
                 */
                if (*rmapp & KVMPPC_RMAP_PRESENT)
                        kvm_unmap_rmapp(kvm, rmapp, gfn);
                ++rmapp;
                ++gfn;
        }
}

static int kvm_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
                         unsigned long gfn)
{
        struct revmap_entry *rev = kvm->arch.revmap;
        unsigned long head, i, j;
        unsigned long *hptep;
        int ret = 0;

 retry:
        lock_rmap(rmapp);
        if (*rmapp & KVMPPC_RMAP_REFERENCED) {
                *rmapp &= ~KVMPPC_RMAP_REFERENCED;
                ret = 1;
        }
        if (!(*rmapp & KVMPPC_RMAP_PRESENT)) {
                unlock_rmap(rmapp);
                return ret;
        }

        i = head = *rmapp & KVMPPC_RMAP_INDEX;
        do {
                hptep = (unsigned long *) (kvm->arch.hpt_virt + (i << 4));
                j = rev[i].forw;

                /* If this HPTE isn't referenced, ignore it */
                if (!(hptep[1] & HPTE_R_R))
                        continue;

                if (!try_lock_hpte(hptep, HPTE_V_HVLOCK)) {
                        /* unlock rmap before spinning on the HPTE lock */
                        unlock_rmap(rmapp);
                        while (hptep[0] & HPTE_V_HVLOCK)
                                cpu_relax();
                        goto retry;
                }

                /* Now check and modify the HPTE */
                if ((hptep[0] & HPTE_V_VALID) && (hptep[1] & HPTE_R_R)) {
                        kvmppc_clear_ref_hpte(kvm, hptep, i);
                        if (!(rev[i].guest_rpte & HPTE_R_R)) {
                                rev[i].guest_rpte |= HPTE_R_R;
                                note_hpte_modification(kvm, &rev[i]);
                        }
                        ret = 1;
                }
                hptep[0] &= ~HPTE_V_HVLOCK;
        } while ((i = j) != head);

        unlock_rmap(rmapp);
        return ret;
}

int kvm_age_hva_hv(struct kvm *kvm, unsigned long hva)
{
        if (!kvm->arch.using_mmu_notifiers)
                return 0;
        return kvm_handle_hva(kvm, hva, kvm_age_rmapp);
}

static int kvm_test_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
                              unsigned long gfn)
{
        struct revmap_entry *rev = kvm->arch.revmap;
        unsigned long head, i, j;
        unsigned long *hp;
        int ret = 1;

        if (*rmapp & KVMPPC_RMAP_REFERENCED)
                return 1;

        lock_rmap(rmapp);
        if (*rmapp & KVMPPC_RMAP_REFERENCED)
                goto out;

        if (*rmapp & KVMPPC_RMAP_PRESENT) {
                i = head = *rmapp & KVMPPC_RMAP_INDEX;
                do {
                        hp = (unsigned long *)(kvm->arch.hpt_virt + (i << 4));
                        j = rev[i].forw;
                        if (hp[1] & HPTE_R_R)
                                goto out;
                } while ((i = j) != head);
        }
        ret = 0;

 out:
        unlock_rmap(rmapp);
        return ret;
}

int kvm_test_age_hva_hv(struct kvm *kvm, unsigned long hva)
{
        if (!kvm->arch.using_mmu_notifiers)
                return 0;
        return kvm_handle_hva(kvm, hva, kvm_test_age_rmapp);
}

void kvm_set_spte_hva_hv(struct kvm *kvm, unsigned long hva, pte_t pte)
{
        if (!kvm->arch.using_mmu_notifiers)
                return;
        kvm_handle_hva(kvm, hva, kvm_unmap_rmapp);
}

static int kvm_test_clear_dirty(struct kvm *kvm, unsigned long *rmapp)
{
        struct revmap_entry *rev = kvm->arch.revmap;
        unsigned long head, i, j;
        unsigned long *hptep;
        int ret = 0;

 retry:
        lock_rmap(rmapp);
        if (*rmapp & KVMPPC_RMAP_CHANGED) {
                *rmapp &= ~KVMPPC_RMAP_CHANGED;
                ret = 1;
        }
        if (!(*rmapp & KVMPPC_RMAP_PRESENT)) {
                unlock_rmap(rmapp);
                return ret;
        }

        i = head = *rmapp & KVMPPC_RMAP_INDEX;
        do {
                hptep = (unsigned long *) (kvm->arch.hpt_virt + (i << 4));
                j = rev[i].forw;

                if (!(hptep[1] & HPTE_R_C))
                        continue;

                if (!try_lock_hpte(hptep, HPTE_V_HVLOCK)) {
                        /* unlock rmap before spinning on the HPTE lock */
                        unlock_rmap(rmapp);
                        while (hptep[0] & HPTE_V_HVLOCK)
                                cpu_relax();
                        goto retry;
                }

                /* Now check and modify the HPTE */
                if ((hptep[0] & HPTE_V_VALID) && (hptep[1] & HPTE_R_C)) {
                        /* need to make it temporarily absent to clear C */
                        hptep[0] |= HPTE_V_ABSENT;
                        kvmppc_invalidate_hpte(kvm, hptep, i);
                        hptep[1] &= ~HPTE_R_C;
                        eieio();
                        hptep[0] = (hptep[0] & ~HPTE_V_ABSENT) | HPTE_V_VALID;
                        if (!(rev[i].guest_rpte & HPTE_R_C)) {
                                rev[i].guest_rpte |= HPTE_R_C;
                                note_hpte_modification(kvm, &rev[i]);
                        }
                        ret = 1;
                }
                hptep[0] &= ~HPTE_V_HVLOCK;
        } while ((i = j) != head);

        unlock_rmap(rmapp);
        return ret;
}

static void harvest_vpa_dirty(struct kvmppc_vpa *vpa,
                              struct kvm_memory_slot *memslot,
                              unsigned long *map)
{
        unsigned long gfn;

        if (!vpa->dirty || !vpa->pinned_addr)
                return;
        gfn = vpa->gpa >> PAGE_SHIFT;
        if (gfn < memslot->base_gfn ||
            gfn >= memslot->base_gfn + memslot->npages)
                return;

        vpa->dirty = false;
        if (map)
                __set_bit_le(gfn - memslot->base_gfn, map);
}

long kvmppc_hv_get_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot,
                             unsigned long *map)
{
        unsigned long i;
        unsigned long *rmapp;
        struct kvm_vcpu *vcpu;

        preempt_disable();
        rmapp = memslot->arch.rmap;
        for (i = 0; i < memslot->npages; ++i) {
                if (kvm_test_clear_dirty(kvm, rmapp) && map)
                        __set_bit_le(i, map);
                ++rmapp;
        }

        /* Harvest dirty bits from VPA and DTL updates */
        /* Note: we never modify the SLB shadow buffer areas */
        kvm_for_each_vcpu(i, vcpu, kvm) {
                spin_lock(&vcpu->arch.vpa_update_lock);
                harvest_vpa_dirty(&vcpu->arch.vpa, memslot, map);
                harvest_vpa_dirty(&vcpu->arch.dtl, memslot, map);
                spin_unlock(&vcpu->arch.vpa_update_lock);
        }
        preempt_enable();
        return 0;
}

void *kvmppc_pin_guest_page(struct kvm *kvm, unsigned long gpa,
                            unsigned long *nb_ret)
{
        struct kvm_memory_slot *memslot;
        unsigned long gfn = gpa >> PAGE_SHIFT;
        struct page *page, *pages[1];
        int npages;
        unsigned long hva, offset;
        unsigned long pa;
        unsigned long *physp;
        int srcu_idx;

        srcu_idx = srcu_read_lock(&kvm->srcu);
        memslot = gfn_to_memslot(kvm, gfn);
        if (!memslot || (memslot->flags & KVM_MEMSLOT_INVALID))
                goto err;
        if (!kvm->arch.using_mmu_notifiers) {
                physp = memslot->arch.slot_phys;
                if (!physp)
                        goto err;
                physp += gfn - memslot->base_gfn;
                pa = *physp;
                if (!pa) {
                        if (kvmppc_get_guest_page(kvm, gfn, memslot,
                                                  PAGE_SIZE) < 0)
                                goto err;
                        pa = *physp;
                }
                page = pfn_to_page(pa >> PAGE_SHIFT);
                get_page(page);
        } else {
                hva = gfn_to_hva_memslot(memslot, gfn);
                npages = get_user_pages_fast(hva, 1, 1, pages);
                if (npages < 1)
                        goto err;
                page = pages[0];
        }
        srcu_read_unlock(&kvm->srcu, srcu_idx);

        offset = gpa & (PAGE_SIZE - 1);
        if (nb_ret)
                *nb_ret = PAGE_SIZE - offset;
        return page_address(page) + offset;

 err:
        srcu_read_unlock(&kvm->srcu, srcu_idx);
        return NULL;
}

void kvmppc_unpin_guest_page(struct kvm *kvm, void *va, unsigned long gpa,
                             bool dirty)
{
        struct page *page = virt_to_page(va);
        struct kvm_memory_slot *memslot;
        unsigned long gfn;
        unsigned long *rmap;
        int srcu_idx;

        put_page(page);

        if (!dirty || !kvm->arch.using_mmu_notifiers)
                return;

        /* We need to mark this page dirty in the rmap chain */
        gfn = gpa >> PAGE_SHIFT;
        srcu_idx = srcu_read_lock(&kvm->srcu);
        memslot = gfn_to_memslot(kvm, gfn);
        if (memslot) {
                rmap = &memslot->arch.rmap[gfn - memslot->base_gfn];
                lock_rmap(rmap);
                *rmap |= KVMPPC_RMAP_CHANGED;
                unlock_rmap(rmap);
        }
        srcu_read_unlock(&kvm->srcu, srcu_idx);
}

/*
 * Functions for reading and writing the hash table via reads and
 * writes on a file descriptor.
 *
 * Reads return the guest view of the hash table, which has to be
 * pieced together from the real hash table and the guest_rpte
 * values in the revmap array.
 *
 * On writes, each HPTE written is considered in turn, and if it
 * is valid, it is written to the HPT as if an H_ENTER with the
 * exact flag set was done.  When the invalid count is non-zero
 * in the header written to the stream, the kernel will make
 * sure that that many HPTEs are invalid, and invalidate them
 * if not.
 */

struct kvm_htab_ctx {
        unsigned long   index;
        unsigned long   flags;
        struct kvm      *kvm;
        int             first_pass;
};

#define HPTE_SIZE       (2 * sizeof(unsigned long))

/*
 * Returns 1 if this HPT entry has been modified or has pending
 * R/C bit changes.
 */
static int hpte_dirty(struct revmap_entry *revp, unsigned long *hptp)
{
        unsigned long rcbits_unset;

        if (revp->guest_rpte & HPTE_GR_MODIFIED)
                return 1;

        /* Also need to consider changes in reference and changed bits */
        rcbits_unset = ~revp->guest_rpte & (HPTE_R_R | HPTE_R_C);
        if ((hptp[0] & HPTE_V_VALID) && (hptp[1] & rcbits_unset))
                return 1;

        return 0;
}

static long record_hpte(unsigned long flags, unsigned long *hptp,
                        unsigned long *hpte, struct revmap_entry *revp,
                        int want_valid, int first_pass)
{
        unsigned long v, r;
        unsigned long rcbits_unset;
        int ok = 1;
        int valid, dirty;

        /* Unmodified entries are uninteresting except on the first pass */
        dirty = hpte_dirty(revp, hptp);
        if (!first_pass && !dirty)
                return 0;

        valid = 0;
        if (hptp[0] & (HPTE_V_VALID | HPTE_V_ABSENT)) {
                valid = 1;
                if ((flags & KVM_GET_HTAB_BOLTED_ONLY) &&
                    !(hptp[0] & HPTE_V_BOLTED))
                        valid = 0;
        }
        if (valid != want_valid)
                return 0;

        v = r = 0;
        if (valid || dirty) {
                /* lock the HPTE so it's stable and read it */
                preempt_disable();
                while (!try_lock_hpte(hptp, HPTE_V_HVLOCK))
                        cpu_relax();
                v = hptp[0];

                /* re-evaluate valid and dirty from synchronized HPTE value */
                valid = !!(v & HPTE_V_VALID);
                dirty = !!(revp->guest_rpte & HPTE_GR_MODIFIED);

                /* Harvest R and C into guest view if necessary */
                rcbits_unset = ~revp->guest_rpte & (HPTE_R_R | HPTE_R_C);
                if (valid && (rcbits_unset & hptp[1])) {
                        revp->guest_rpte |= (hptp[1] & (HPTE_R_R | HPTE_R_C)) |
                                HPTE_GR_MODIFIED;
                        dirty = 1;
                }

                if (v & HPTE_V_ABSENT) {
                        v &= ~HPTE_V_ABSENT;
                        v |= HPTE_V_VALID;
                        valid = 1;
                }
                if ((flags & KVM_GET_HTAB_BOLTED_ONLY) && !(v & HPTE_V_BOLTED))
                        valid = 0;

                r = revp->guest_rpte;
                /* only clear modified if this is the right sort of entry */
                if (valid == want_valid && dirty) {
                        r &= ~HPTE_GR_MODIFIED;
                        revp->guest_rpte = r;
                }
                asm volatile(PPC_RELEASE_BARRIER "" : : : "memory");
                hptp[0] &= ~HPTE_V_HVLOCK;
                preempt_enable();
                if (!(valid == want_valid && (first_pass || dirty)))
                        ok = 0;
        }
        hpte[0] = v;
        hpte[1] = r;
        return ok;
}

static ssize_t kvm_htab_read(struct file *file, char __user *buf,
                             size_t count, loff_t *ppos)
{
        struct kvm_htab_ctx *ctx = file->private_data;
        struct kvm *kvm = ctx->kvm;
        struct kvm_get_htab_header hdr;
        unsigned long *hptp;
        struct revmap_entry *revp;
        unsigned long i, nb, nw;
        unsigned long __user *lbuf;
        struct kvm_get_htab_header __user *hptr;
        unsigned long flags;
        int first_pass;
        unsigned long hpte[2];

        if (!access_ok(VERIFY_WRITE, buf, count))
                return -EFAULT;

        first_pass = ctx->first_pass;
        flags = ctx->flags;

        i = ctx->index;
        hptp = (unsigned long *)(kvm->arch.hpt_virt + (i * HPTE_SIZE));
        revp = kvm->arch.revmap + i;
        lbuf = (unsigned long __user *)buf;

        nb = 0;
        while (nb + sizeof(hdr) + HPTE_SIZE < count) {
                /* Initialize header */
                hptr = (struct kvm_get_htab_header __user *)buf;
                hdr.n_valid = 0;
                hdr.n_invalid = 0;
                nw = nb;
                nb += sizeof(hdr);
                lbuf = (unsigned long __user *)(buf + sizeof(hdr));

                /* Skip uninteresting entries, i.e. clean on not-first pass */
                if (!first_pass) {
                        while (i < kvm->arch.hpt_npte &&
                               !hpte_dirty(revp, hptp)) {
                                ++i;
                                hptp += 2;
                                ++revp;
                        }
                }
                hdr.index = i;

                /* Grab a series of valid entries */
                while (i < kvm->arch.hpt_npte &&
                       hdr.n_valid < 0xffff &&
                       nb + HPTE_SIZE < count &&
                       record_hpte(flags, hptp, hpte, revp, 1, first_pass)) {
                        /* valid entry, write it out */
                        ++hdr.n_valid;
                        if (__put_user(hpte[0], lbuf) ||
                            __put_user(hpte[1], lbuf + 1))
                                return -EFAULT;
                        nb += HPTE_SIZE;
                        lbuf += 2;
                        ++i;
                        hptp += 2;
                        ++revp;
                }
                /* Now skip invalid entries while we can */
                while (i < kvm->arch.hpt_npte &&
                       hdr.n_invalid < 0xffff &&
                       record_hpte(flags, hptp, hpte, revp, 0, first_pass)) {
                        /* found an invalid entry */
                        ++hdr.n_invalid;
                        ++i;
                        hptp += 2;
                        ++revp;
                }

                if (hdr.n_valid || hdr.n_invalid) {
                        /* write back the header */
                        if (__copy_to_user(hptr, &hdr, sizeof(hdr)))
                                return -EFAULT;
                        nw = nb;
                        buf = (char __user *)lbuf;
                } else {
                        nb = nw;
                }

                /* Check if we've wrapped around the hash table */
                if (i >= kvm->arch.hpt_npte) {
                        i = 0;
                        ctx->first_pass = 0;
                        break;
                }
        }

        ctx->index = i;

        return nb;
}

static ssize_t kvm_htab_write(struct file *file, const char __user *buf,
                              size_t count, loff_t *ppos)
{
        struct kvm_htab_ctx *ctx = file->private_data;
        struct kvm *kvm = ctx->kvm;
        struct kvm_get_htab_header hdr;
        unsigned long i, j;
        unsigned long v, r;
        unsigned long __user *lbuf;
        unsigned long *hptp;
        unsigned long tmp[2];
        ssize_t nb;
        long int err, ret;
        int rma_setup;

        if (!access_ok(VERIFY_READ, buf, count))
                return -EFAULT;

        /* lock out vcpus from running while we're doing this */
        mutex_lock(&kvm->lock);
        rma_setup = kvm->arch.rma_setup_done;
        if (rma_setup) {
                kvm->arch.rma_setup_done = 0;   /* temporarily */
                /* order rma_setup_done vs. vcpus_running */
                smp_mb();
                if (atomic_read(&kvm->arch.vcpus_running)) {
                        kvm->arch.rma_setup_done = 1;
                        mutex_unlock(&kvm->lock);
                        return -EBUSY;
                }
        }

        err = 0;
        for (nb = 0; nb + sizeof(hdr) <= count; ) {
                err = -EFAULT;
                if (__copy_from_user(&hdr, buf, sizeof(hdr)))
                        break;

                err = 0;
                if (nb + hdr.n_valid * HPTE_SIZE > count)
                        break;

                nb += sizeof(hdr);
                buf += sizeof(hdr);

                err = -EINVAL;
                i = hdr.index;
                if (i >= kvm->arch.hpt_npte ||
                    i + hdr.n_valid + hdr.n_invalid > kvm->arch.hpt_npte)
                        break;

                hptp = (unsigned long *)(kvm->arch.hpt_virt + (i * HPTE_SIZE));
                lbuf = (unsigned long __user *)buf;
                for (j = 0; j < hdr.n_valid; ++j) {
                        err = -EFAULT;
                        if (__get_user(v, lbuf) || __get_user(r, lbuf + 1))
                                goto out;
                        err = -EINVAL;
                        if (!(v & HPTE_V_VALID))
                                goto out;
                        lbuf += 2;
                        nb += HPTE_SIZE;

                        if (hptp[0] & (HPTE_V_VALID | HPTE_V_ABSENT))
                                kvmppc_do_h_remove(kvm, 0, i, 0, tmp);
                        err = -EIO;
                        ret = kvmppc_virtmode_do_h_enter(kvm, H_EXACT, i, v, r,
                                                         tmp);
                        if (ret != H_SUCCESS) {
                                pr_err("kvm_htab_write ret %ld i=%ld v=%lx "
                                       "r=%lx\n", ret, i, v, r);
                                goto out;
                        }
                        if (!rma_setup && is_vrma_hpte(v)) {
                                unsigned long psize = hpte_page_size(v, r);
                                unsigned long senc = slb_pgsize_encoding(psize);
                                unsigned long lpcr;

                                kvm->arch.vrma_slb_v = senc | SLB_VSID_B_1T |
                                        (VRMA_VSID << SLB_VSID_SHIFT_1T);
                                lpcr = senc << (LPCR_VRMASD_SH - 4);
                                kvmppc_update_lpcr(kvm, lpcr, LPCR_VRMASD);
                                rma_setup = 1;
                        }
                        ++i;
                        hptp += 2;
                }

                for (j = 0; j < hdr.n_invalid; ++j) {
                        if (hptp[0] & (HPTE_V_VALID | HPTE_V_ABSENT))
                                kvmppc_do_h_remove(kvm, 0, i, 0, tmp);
                        ++i;
                        hptp += 2;
                }
                err = 0;
        }

 out:
        /* Order HPTE updates vs. rma_setup_done */
        smp_wmb();
        kvm->arch.rma_setup_done = rma_setup;
        mutex_unlock(&kvm->lock);

        if (err)
                return err;
        return nb;
}

static int kvm_htab_release(struct inode *inode, struct file *filp)
{
        struct kvm_htab_ctx *ctx = filp->private_data;

        filp->private_data = NULL;
        if (!(ctx->flags & KVM_GET_HTAB_WRITE))
                atomic_dec(&ctx->kvm->arch.hpte_mod_interest);
        kvm_put_kvm(ctx->kvm);
        kfree(ctx);
        return 0;
}

static const struct file_operations kvm_htab_fops = {
        .read           = kvm_htab_read,
        .write          = kvm_htab_write,
        .llseek         = default_llseek,
        .release        = kvm_htab_release,
};

int kvm_vm_ioctl_get_htab_fd(struct kvm *kvm, struct kvm_get_htab_fd *ghf)
{
        int ret;
        struct kvm_htab_ctx *ctx;
        int rwflag;

        /* reject flags we don't recognize */
        if (ghf->flags & ~(KVM_GET_HTAB_BOLTED_ONLY | KVM_GET_HTAB_WRITE))
                return -EINVAL;
        ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
        if (!ctx)
                return -ENOMEM;
        kvm_get_kvm(kvm);
        ctx->kvm = kvm;
        ctx->index = ghf->start_index;
        ctx->flags = ghf->flags;
        ctx->first_pass = 1;

        rwflag = (ghf->flags & KVM_GET_HTAB_WRITE) ? O_WRONLY : O_RDONLY;
        ret = anon_inode_getfd("kvm-htab", &kvm_htab_fops, ctx, rwflag | O_CLOEXEC);
        if (ret < 0) {
                kvm_put_kvm(kvm);
                return ret;
        }

        if (rwflag == O_RDONLY) {
                mutex_lock(&kvm->slots_lock);
                atomic_inc(&kvm->arch.hpte_mod_interest);
                /* make sure kvmppc_do_h_enter etc. see the increment */
                synchronize_srcu_expedited(&kvm->srcu);
                mutex_unlock(&kvm->slots_lock);
        }

        return ret;
}

void kvmppc_mmu_book3s_hv_init(struct kvm_vcpu *vcpu)
{
        struct kvmppc_mmu *mmu = &vcpu->arch.mmu;

        if (cpu_has_feature(CPU_FTR_ARCH_206))
                vcpu->arch.slb_nr = 32;         /* POWER7 */
        else
                vcpu->arch.slb_nr = 64;

        mmu->xlate = kvmppc_mmu_book3s_64_hv_xlate;
        mmu->reset_msr = kvmppc_mmu_book3s_64_hv_reset_msr;

        vcpu->arch.hflags |= BOOK3S_HFLAG_SLB;
}