// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright IBM Corporation, 2018
 * Authors Suraj Jitindar Singh <sjitindarsingh@gmail.com>
 *         Paul Mackerras <paulus@ozlabs.org>
 *
 * Description: KVM functions specific to running nested KVM-HV guests
 * on Book3S processors (specifically POWER9 and later).
 */

#include <linux/kernel.h>
#include <linux/kvm_host.h>
#include <linux/llist.h>
#include <linux/pgtable.h>

#include <asm/kvm_ppc.h>
#include <asm/kvm_book3s.h>
#include <asm/mmu.h>
#include <asm/pgalloc.h>
#include <asm/pte-walk.h>
#include <asm/reg.h>

static struct patb_entry *pseries_partition_tb;

static void kvmhv_update_ptbl_cache(struct kvm_nested_guest *gp);
static void kvmhv_free_memslot_nest_rmap(struct kvm_memory_slot *free);

void kvmhv_save_hv_regs(struct kvm_vcpu *vcpu, struct hv_guest_state *hr)
{
        struct kvmppc_vcore *vc = vcpu->arch.vcore;

        hr->pcr = vc->pcr | PCR_MASK;
        hr->dpdes = vc->dpdes;
        hr->hfscr = vcpu->arch.hfscr;
        hr->tb_offset = vc->tb_offset;
        hr->dawr0 = vcpu->arch.dawr;
        hr->dawrx0 = vcpu->arch.dawrx;
        hr->ciabr = vcpu->arch.ciabr;
        hr->purr = vcpu->arch.purr;
        hr->spurr = vcpu->arch.spurr;
        hr->ic = vcpu->arch.ic;
        hr->vtb = vc->vtb;
        hr->srr0 = vcpu->arch.shregs.srr0;
        hr->srr1 = vcpu->arch.shregs.srr1;
        hr->sprg[0] = vcpu->arch.shregs.sprg0;
        hr->sprg[1] = vcpu->arch.shregs.sprg1;
        hr->sprg[2] = vcpu->arch.shregs.sprg2;
        hr->sprg[3] = vcpu->arch.shregs.sprg3;
        hr->pidr = vcpu->arch.pid;
        hr->cfar = vcpu->arch.cfar;
        hr->ppr = vcpu->arch.ppr;
}

static void byteswap_pt_regs(struct pt_regs *regs)
{
        unsigned long *addr = (unsigned long *) regs;

        for (; addr < ((unsigned long *) (regs + 1)); addr++)
                *addr = swab64(*addr);
}

static void byteswap_hv_regs(struct hv_guest_state *hr)
{
        hr->version = swab64(hr->version);
        hr->lpid = swab32(hr->lpid);
        hr->vcpu_token = swab32(hr->vcpu_token);
        hr->lpcr = swab64(hr->lpcr);
        hr->pcr = swab64(hr->pcr) | PCR_MASK;
        hr->amor = swab64(hr->amor);
        hr->dpdes = swab64(hr->dpdes);
        hr->hfscr = swab64(hr->hfscr);
        hr->tb_offset = swab64(hr->tb_offset);
        hr->dawr0 = swab64(hr->dawr0);
        hr->dawrx0 = swab64(hr->dawrx0);
        hr->ciabr = swab64(hr->ciabr);
        hr->hdec_expiry = swab64(hr->hdec_expiry);
        hr->purr = swab64(hr->purr);
        hr->spurr = swab64(hr->spurr);
        hr->ic = swab64(hr->ic);
        hr->vtb = swab64(hr->vtb);
        hr->hdar = swab64(hr->hdar);
        hr->hdsisr = swab64(hr->hdsisr);
        hr->heir = swab64(hr->heir);
        hr->asdr = swab64(hr->asdr);
        hr->srr0 = swab64(hr->srr0);
        hr->srr1 = swab64(hr->srr1);
        hr->sprg[0] = swab64(hr->sprg[0]);
        hr->sprg[1] = swab64(hr->sprg[1]);
        hr->sprg[2] = swab64(hr->sprg[2]);
        hr->sprg[3] = swab64(hr->sprg[3]);
        hr->pidr = swab64(hr->pidr);
        hr->cfar = swab64(hr->cfar);
        hr->ppr = swab64(hr->ppr);
}

static void save_hv_return_state(struct kvm_vcpu *vcpu, int trap,
                                 struct hv_guest_state *hr)
{
        struct kvmppc_vcore *vc = vcpu->arch.vcore;

        hr->dpdes = vc->dpdes;
        hr->hfscr = vcpu->arch.hfscr;
        hr->purr = vcpu->arch.purr;
        hr->spurr = vcpu->arch.spurr;
        hr->ic = vcpu->arch.ic;
        hr->vtb = vc->vtb;
        hr->srr0 = vcpu->arch.shregs.srr0;
        hr->srr1 = vcpu->arch.shregs.srr1;
        hr->sprg[0] = vcpu->arch.shregs.sprg0;
        hr->sprg[1] = vcpu->arch.shregs.sprg1;
        hr->sprg[2] = vcpu->arch.shregs.sprg2;
        hr->sprg[3] = vcpu->arch.shregs.sprg3;
        hr->pidr = vcpu->arch.pid;
        hr->cfar = vcpu->arch.cfar;
        hr->ppr = vcpu->arch.ppr;
        switch (trap) {
        case BOOK3S_INTERRUPT_H_DATA_STORAGE:
                hr->hdar = vcpu->arch.fault_dar;
                hr->hdsisr = vcpu->arch.fault_dsisr;
                hr->asdr = vcpu->arch.fault_gpa;
                break;
        case BOOK3S_INTERRUPT_H_INST_STORAGE:
                hr->asdr = vcpu->arch.fault_gpa;
                break;
        case BOOK3S_INTERRUPT_H_EMUL_ASSIST:
                hr->heir = vcpu->arch.emul_inst;
                break;
        }
}

static void sanitise_hv_regs(struct kvm_vcpu *vcpu, struct hv_guest_state *hr)
{
        /*
         * Don't let L1 enable features for L2 which we've disabled for L1,
         * but preserve the interrupt cause field.
         */
        hr->hfscr &= (HFSCR_INTR_CAUSE | vcpu->arch.hfscr);

        /* Don't let data address watchpoint match in hypervisor state */
        hr->dawrx0 &= ~DAWRX_HYP;

        /* Don't let completed instruction address breakpt match in HV state */
        if ((hr->ciabr & CIABR_PRIV) == CIABR_PRIV_HYPER)
                hr->ciabr &= ~CIABR_PRIV;
}

static void restore_hv_regs(struct kvm_vcpu *vcpu, struct hv_guest_state *hr)
{
        struct kvmppc_vcore *vc = vcpu->arch.vcore;

        vc->pcr = hr->pcr | PCR_MASK;
        vc->dpdes = hr->dpdes;
        vcpu->arch.hfscr = hr->hfscr;
        vcpu->arch.dawr = hr->dawr0;
        vcpu->arch.dawrx = hr->dawrx0;
        vcpu->arch.ciabr = hr->ciabr;
        vcpu->arch.purr = hr->purr;
        vcpu->arch.spurr = hr->spurr;
        vcpu->arch.ic = hr->ic;
        vc->vtb = hr->vtb;
        vcpu->arch.shregs.srr0 = hr->srr0;
        vcpu->arch.shregs.srr1 = hr->srr1;
        vcpu->arch.shregs.sprg0 = hr->sprg[0];
        vcpu->arch.shregs.sprg1 = hr->sprg[1];
        vcpu->arch.shregs.sprg2 = hr->sprg[2];
        vcpu->arch.shregs.sprg3 = hr->sprg[3];
        vcpu->arch.pid = hr->pidr;
        vcpu->arch.cfar = hr->cfar;
        vcpu->arch.ppr = hr->ppr;
}

void kvmhv_restore_hv_return_state(struct kvm_vcpu *vcpu,
                                   struct hv_guest_state *hr)
{
        struct kvmppc_vcore *vc = vcpu->arch.vcore;

        vc->dpdes = hr->dpdes;
        vcpu->arch.hfscr = hr->hfscr;
        vcpu->arch.purr = hr->purr;
        vcpu->arch.spurr = hr->spurr;
        vcpu->arch.ic = hr->ic;
        vc->vtb = hr->vtb;
        vcpu->arch.fault_dar = hr->hdar;
        vcpu->arch.fault_dsisr = hr->hdsisr;
        vcpu->arch.fault_gpa = hr->asdr;
        vcpu->arch.emul_inst = hr->heir;
        vcpu->arch.shregs.srr0 = hr->srr0;
        vcpu->arch.shregs.srr1 = hr->srr1;
        vcpu->arch.shregs.sprg0 = hr->sprg[0];
        vcpu->arch.shregs.sprg1 = hr->sprg[1];
        vcpu->arch.shregs.sprg2 = hr->sprg[2];
        vcpu->arch.shregs.sprg3 = hr->sprg[3];
        vcpu->arch.pid = hr->pidr;
        vcpu->arch.cfar = hr->cfar;
        vcpu->arch.ppr = hr->ppr;
}

static void kvmhv_nested_mmio_needed(struct kvm_vcpu *vcpu, u64 regs_ptr)
{
        /* No need to reflect the page fault to L1, we've handled it */
        vcpu->arch.trap = 0;

        /*
         * Since the L2 gprs have already been written back into L1 memory when
         * we complete the mmio, store the L1 memory location of the L2 gpr
         * being loaded into by the mmio so that the loaded value can be
         * written there in kvmppc_complete_mmio_load()
         */
        if (((vcpu->arch.io_gpr & KVM_MMIO_REG_EXT_MASK) == KVM_MMIO_REG_GPR)
            && (vcpu->mmio_is_write == 0)) {
                vcpu->arch.nested_io_gpr = (gpa_t) regs_ptr +
                                           offsetof(struct pt_regs,
                                                    gpr[vcpu->arch.io_gpr]);
                vcpu->arch.io_gpr = KVM_MMIO_REG_NESTED_GPR;
        }
}

long kvmhv_enter_nested_guest(struct kvm_vcpu *vcpu)
{
        long int err, r;
        struct kvm_nested_guest *l2;
        struct pt_regs l2_regs, saved_l1_regs;
        struct hv_guest_state l2_hv, saved_l1_hv;
        struct kvmppc_vcore *vc = vcpu->arch.vcore;
        u64 hv_ptr, regs_ptr;
        u64 hdec_exp;
        s64 delta_purr, delta_spurr, delta_ic, delta_vtb;
        u64 mask;
        unsigned long lpcr;

        if (vcpu->kvm->arch.l1_ptcr == 0)
                return H_NOT_AVAILABLE;

        /* copy parameters in */
        hv_ptr = kvmppc_get_gpr(vcpu, 4);
        regs_ptr = kvmppc_get_gpr(vcpu, 5);
        vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
        err = kvm_vcpu_read_guest(vcpu, hv_ptr, &l2_hv,
                                  sizeof(struct hv_guest_state)) ||
                kvm_vcpu_read_guest(vcpu, regs_ptr, &l2_regs,
                                    sizeof(struct pt_regs));
        srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
        if (err)
                return H_PARAMETER;

        if (kvmppc_need_byteswap(vcpu))
                byteswap_hv_regs(&l2_hv);
        if (l2_hv.version != HV_GUEST_STATE_VERSION)
                return H_P2;

        if (kvmppc_need_byteswap(vcpu))
                byteswap_pt_regs(&l2_regs);
        if (l2_hv.vcpu_token >= NR_CPUS)
                return H_PARAMETER;

        /* translate lpid */
        l2 = kvmhv_get_nested(vcpu->kvm, l2_hv.lpid, true);
        if (!l2)
                return H_PARAMETER;
        if (!l2->l1_gr_to_hr) {
                mutex_lock(&l2->tlb_lock);
                kvmhv_update_ptbl_cache(l2);
                mutex_unlock(&l2->tlb_lock);
        }

        /* save l1 values of things */
        vcpu->arch.regs.msr = vcpu->arch.shregs.msr;
        saved_l1_regs = vcpu->arch.regs;
        kvmhv_save_hv_regs(vcpu, &saved_l1_hv);

        /* convert TB values/offsets to host (L0) values */
        hdec_exp = l2_hv.hdec_expiry - vc->tb_offset;
        vc->tb_offset += l2_hv.tb_offset;

        /* set L1 state to L2 state */
        vcpu->arch.nested = l2;
        vcpu->arch.nested_vcpu_id = l2_hv.vcpu_token;
        vcpu->arch.regs = l2_regs;
        vcpu->arch.shregs.msr = vcpu->arch.regs.msr;
        mask = LPCR_DPFD | LPCR_ILE | LPCR_TC | LPCR_AIL | LPCR_LD |
                LPCR_LPES | LPCR_MER;
        lpcr = (vc->lpcr & ~mask) | (l2_hv.lpcr & mask);
        sanitise_hv_regs(vcpu, &l2_hv);
        restore_hv_regs(vcpu, &l2_hv);

        vcpu->arch.ret = RESUME_GUEST;
        vcpu->arch.trap = 0;
        do {
                if (mftb() >= hdec_exp) {
                        vcpu->arch.trap = BOOK3S_INTERRUPT_HV_DECREMENTER;
                        r = RESUME_HOST;
                        break;
                }
                r = kvmhv_run_single_vcpu(vcpu, hdec_exp, lpcr);
        } while (is_kvmppc_resume_guest(r));

        /* save L2 state for return */
        l2_regs = vcpu->arch.regs;
        l2_regs.msr = vcpu->arch.shregs.msr;
        delta_purr = vcpu->arch.purr - l2_hv.purr;
        delta_spurr = vcpu->arch.spurr - l2_hv.spurr;
        delta_ic = vcpu->arch.ic - l2_hv.ic;
        delta_vtb = vc->vtb - l2_hv.vtb;
        save_hv_return_state(vcpu, vcpu->arch.trap, &l2_hv);

        /* restore L1 state */
        vcpu->arch.nested = NULL;
        vcpu->arch.regs = saved_l1_regs;
        vcpu->arch.shregs.msr = saved_l1_regs.msr & ~MSR_TS_MASK;
        /* set L1 MSR TS field according to L2 transaction state */
        if (l2_regs.msr & MSR_TS_MASK)
                vcpu->arch.shregs.msr |= MSR_TS_S;
        vc->tb_offset = saved_l1_hv.tb_offset;
        restore_hv_regs(vcpu, &saved_l1_hv);
        vcpu->arch.purr += delta_purr;
        vcpu->arch.spurr += delta_spurr;
        vcpu->arch.ic += delta_ic;
        vc->vtb += delta_vtb;

        kvmhv_put_nested(l2);

        /* copy l2_hv_state and regs back to guest */
        if (kvmppc_need_byteswap(vcpu)) {
                byteswap_hv_regs(&l2_hv);
                byteswap_pt_regs(&l2_regs);
        }
        vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
        err = kvm_vcpu_write_guest(vcpu, hv_ptr, &l2_hv,
                                   sizeof(struct hv_guest_state)) ||
                kvm_vcpu_write_guest(vcpu, regs_ptr, &l2_regs,
                                   sizeof(struct pt_regs));
        srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
        if (err)
                return H_AUTHORITY;

        if (r == -EINTR)
                return H_INTERRUPT;

        if (vcpu->mmio_needed) {
                kvmhv_nested_mmio_needed(vcpu, regs_ptr);
                return H_TOO_HARD;
        }

        return vcpu->arch.trap;
}

long kvmhv_nested_init(void)
{
        long int ptb_order;
        unsigned long ptcr;
        long rc;

        if (!kvmhv_on_pseries())
                return 0;
        if (!radix_enabled())
                return -ENODEV;

        /* find log base 2 of KVMPPC_NR_LPIDS, rounding up */
        ptb_order = __ilog2(KVMPPC_NR_LPIDS - 1) + 1;
        if (ptb_order < 8)
                ptb_order = 8;
        pseries_partition_tb = kmalloc(sizeof(struct patb_entry) << ptb_order,
                                       GFP_KERNEL);
        if (!pseries_partition_tb) {
                pr_err("kvm-hv: failed to allocated nested partition table\n");
                return -ENOMEM;
        }

        ptcr = __pa(pseries_partition_tb) | (ptb_order - 8);
        rc = plpar_hcall_norets(H_SET_PARTITION_TABLE, ptcr);
        if (rc != H_SUCCESS) {
                pr_err("kvm-hv: Parent hypervisor does not support nesting (rc=%ld)\n",
                       rc);
                kfree(pseries_partition_tb);
                pseries_partition_tb = NULL;
                return -ENODEV;
        }

        return 0;
}

void kvmhv_nested_exit(void)
{
        /*
         * N.B. the kvmhv_on_pseries() test is there because it enables
         * the compiler to remove the call to plpar_hcall_norets()
         * when CONFIG_PPC_PSERIES=n.
         */
        if (kvmhv_on_pseries() && pseries_partition_tb) {
                plpar_hcall_norets(H_SET_PARTITION_TABLE, 0);
                kfree(pseries_partition_tb);
                pseries_partition_tb = NULL;
        }
}

static void kvmhv_flush_lpid(unsigned int lpid)
{
        long rc;

        if (!kvmhv_on_pseries()) {
                radix__flush_all_lpid(lpid);
                return;
        }

        rc = plpar_hcall_norets(H_TLB_INVALIDATE, H_TLBIE_P1_ENC(2, 0, 1),
                                lpid, TLBIEL_INVAL_SET_LPID);
        if (rc)
                pr_err("KVM: TLB LPID invalidation hcall failed, rc=%ld\n", rc);
}

void kvmhv_set_ptbl_entry(unsigned int lpid, u64 dw0, u64 dw1)
{
        if (!kvmhv_on_pseries()) {
                mmu_partition_table_set_entry(lpid, dw0, dw1, true);
                return;
        }

        pseries_partition_tb[lpid].patb0 = cpu_to_be64(dw0);
        pseries_partition_tb[lpid].patb1 = cpu_to_be64(dw1);
        /* L0 will do the necessary barriers */
        kvmhv_flush_lpid(lpid);
}

static void kvmhv_set_nested_ptbl(struct kvm_nested_guest *gp)
{
        unsigned long dw0;

        dw0 = PATB_HR | radix__get_tree_size() |
                __pa(gp->shadow_pgtable) | RADIX_PGD_INDEX_SIZE;
        kvmhv_set_ptbl_entry(gp->shadow_lpid, dw0, gp->process_table);
}

void kvmhv_vm_nested_init(struct kvm *kvm)
{
        kvm->arch.max_nested_lpid = -1;
}

/*
 * Handle the H_SET_PARTITION_TABLE hcall.
 * r4 = guest real address of partition table + log_2(size) - 12
 * (formatted as for the PTCR).
 */
long kvmhv_set_partition_table(struct kvm_vcpu *vcpu)
{
        struct kvm *kvm = vcpu->kvm;
        unsigned long ptcr = kvmppc_get_gpr(vcpu, 4);
        int srcu_idx;
        long ret = H_SUCCESS;

        srcu_idx = srcu_read_lock(&kvm->srcu);
        /*
         * Limit the partition table to 4096 entries (because that's what
         * hardware supports), and check the base address.
         */
        if ((ptcr & PRTS_MASK) > 12 - 8 ||
            !kvm_is_visible_gfn(vcpu->kvm, (ptcr & PRTB_MASK) >> PAGE_SHIFT))
                ret = H_PARAMETER;
        srcu_read_unlock(&kvm->srcu, srcu_idx);
        if (ret == H_SUCCESS)
                kvm->arch.l1_ptcr = ptcr;
        return ret;
}

/*
 * Handle the H_COPY_TOFROM_GUEST hcall.
 * r4 = L1 lpid of nested guest
 * r5 = pid
 * r6 = eaddr to access
 * r7 = to buffer (L1 gpa)
 * r8 = from buffer (L1 gpa)
 * r9 = n bytes to copy
 */
long kvmhv_copy_tofrom_guest_nested(struct kvm_vcpu *vcpu)
{
        struct kvm_nested_guest *gp;
        int l1_lpid = kvmppc_get_gpr(vcpu, 4);
        int pid = kvmppc_get_gpr(vcpu, 5);
        gva_t eaddr = kvmppc_get_gpr(vcpu, 6);
        gpa_t gp_to = (gpa_t) kvmppc_get_gpr(vcpu, 7);
        gpa_t gp_from = (gpa_t) kvmppc_get_gpr(vcpu, 8);
        void *buf;
        unsigned long n = kvmppc_get_gpr(vcpu, 9);
        bool is_load = !!gp_to;
        long rc;

        if (gp_to && gp_from) /* One must be NULL to determine the direction */
                return H_PARAMETER;

        if (eaddr & (0xFFFUL << 52))
                return H_PARAMETER;

        buf = kzalloc(n, GFP_KERNEL);
        if (!buf)
                return H_NO_MEM;

        gp = kvmhv_get_nested(vcpu->kvm, l1_lpid, false);
        if (!gp) {
                rc = H_PARAMETER;
                goto out_free;
        }

        mutex_lock(&gp->tlb_lock);

        if (is_load) {
                /* Load from the nested guest into our buffer */
                rc = __kvmhv_copy_tofrom_guest_radix(gp->shadow_lpid, pid,
                                                     eaddr, buf, NULL, n);
                if (rc)
                        goto not_found;

                /* Write what was loaded into our buffer back to the L1 guest */
                vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
                rc = kvm_vcpu_write_guest(vcpu, gp_to, buf, n);
                srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
                if (rc)
                        goto not_found;
        } else {
                /* Load the data to be stored from the L1 guest into our buf */
                vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
                rc = kvm_vcpu_read_guest(vcpu, gp_from, buf, n);
                srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
                if (rc)
                        goto not_found;

                /* Store from our buffer into the nested guest */
                rc = __kvmhv_copy_tofrom_guest_radix(gp->shadow_lpid, pid,
                                                     eaddr, NULL, buf, n);
                if (rc)
                        goto not_found;
        }

out_unlock:
        mutex_unlock(&gp->tlb_lock);
        kvmhv_put_nested(gp);
out_free:
        kfree(buf);
        return rc;
not_found:
        rc = H_NOT_FOUND;
        goto out_unlock;
}

/*
 * Reload the partition table entry for a guest.
 * Caller must hold gp->tlb_lock.
 */
static void kvmhv_update_ptbl_cache(struct kvm_nested_guest *gp)
{
        int ret;
        struct patb_entry ptbl_entry;
        unsigned long ptbl_addr;
        struct kvm *kvm = gp->l1_host;

        ret = -EFAULT;
        ptbl_addr = (kvm->arch.l1_ptcr & PRTB_MASK) + (gp->l1_lpid << 4);
        if (gp->l1_lpid < (1ul << ((kvm->arch.l1_ptcr & PRTS_MASK) + 8))) {
                int srcu_idx = srcu_read_lock(&kvm->srcu);
                ret = kvm_read_guest(kvm, ptbl_addr,
                                     &ptbl_entry, sizeof(ptbl_entry));
                srcu_read_unlock(&kvm->srcu, srcu_idx);
        }
        if (ret) {
                gp->l1_gr_to_hr = 0;
                gp->process_table = 0;
        } else {
                gp->l1_gr_to_hr = be64_to_cpu(ptbl_entry.patb0);
                gp->process_table = be64_to_cpu(ptbl_entry.patb1);
        }
        kvmhv_set_nested_ptbl(gp);
}

struct kvm_nested_guest *kvmhv_alloc_nested(struct kvm *kvm, unsigned int lpid)
{
        struct kvm_nested_guest *gp;
        long shadow_lpid;

        gp = kzalloc(sizeof(*gp), GFP_KERNEL);
        if (!gp)
                return NULL;
        gp->l1_host = kvm;
        gp->l1_lpid = lpid;
        mutex_init(&gp->tlb_lock);
        gp->shadow_pgtable = pgd_alloc(kvm->mm);
        if (!gp->shadow_pgtable)
                goto out_free;
        shadow_lpid = kvmppc_alloc_lpid();
        if (shadow_lpid < 0)
                goto out_free2;
        gp->shadow_lpid = shadow_lpid;
        gp->radix = 1;

        memset(gp->prev_cpu, -1, sizeof(gp->prev_cpu));

        return gp;

 out_free2:
        pgd_free(kvm->mm, gp->shadow_pgtable);
 out_free:
        kfree(gp);
        return NULL;
}

/*
 * Free up any resources allocated for a nested guest.
 */
static void kvmhv_release_nested(struct kvm_nested_guest *gp)
{
        struct kvm *kvm = gp->l1_host;

        if (gp->shadow_pgtable) {
                /*
                 * No vcpu is using this struct and no call to
                 * kvmhv_get_nested can find this struct,
                 * so we don't need to hold kvm->mmu_lock.
                 */
                kvmppc_free_pgtable_radix(kvm, gp->shadow_pgtable,
                                          gp->shadow_lpid);
                pgd_free(kvm->mm, gp->shadow_pgtable);
        }
        kvmhv_set_ptbl_entry(gp->shadow_lpid, 0, 0);
        kvmppc_free_lpid(gp->shadow_lpid);
        kfree(gp);
}

static void kvmhv_remove_nested(struct kvm_nested_guest *gp)
{
        struct kvm *kvm = gp->l1_host;
        int lpid = gp->l1_lpid;
        long ref;

        spin_lock(&kvm->mmu_lock);
        if (gp == kvm->arch.nested_guests[lpid]) {
                kvm->arch.nested_guests[lpid] = NULL;
                if (lpid == kvm->arch.max_nested_lpid) {
                        while (--lpid >= 0 && !kvm->arch.nested_guests[lpid])
                                ;
                        kvm->arch.max_nested_lpid = lpid;
                }
                --gp->refcnt;
        }
        ref = gp->refcnt;
        spin_unlock(&kvm->mmu_lock);
        if (ref == 0)
                kvmhv_release_nested(gp);
}

/*
 * Free up all nested resources allocated for this guest.
 * This is called with no vcpus of the guest running, when
 * switching the guest to HPT mode or when destroying the
 * guest.
 */
void kvmhv_release_all_nested(struct kvm *kvm)
{
        int i;
        struct kvm_nested_guest *gp;
        struct kvm_nested_guest *freelist = NULL;
        struct kvm_memory_slot *memslot;
        int srcu_idx;

        spin_lock(&kvm->mmu_lock);
        for (i = 0; i <= kvm->arch.max_nested_lpid; i++) {
                gp = kvm->arch.nested_guests[i];
                if (!gp)
                        continue;
                kvm->arch.nested_guests[i] = NULL;
                if (--gp->refcnt == 0) {
                        gp->next = freelist;
                        freelist = gp;
                }
        }
        kvm->arch.max_nested_lpid = -1;
        spin_unlock(&kvm->mmu_lock);
        while ((gp = freelist) != NULL) {
                freelist = gp->next;
                kvmhv_release_nested(gp);
        }

        srcu_idx = srcu_read_lock(&kvm->srcu);
        kvm_for_each_memslot(memslot, kvm_memslots(kvm))
                kvmhv_free_memslot_nest_rmap(memslot);
        srcu_read_unlock(&kvm->srcu, srcu_idx);
}

/* caller must hold gp->tlb_lock */
static void kvmhv_flush_nested(struct kvm_nested_guest *gp)
{
        struct kvm *kvm = gp->l1_host;

        spin_lock(&kvm->mmu_lock);
        kvmppc_free_pgtable_radix(kvm, gp->shadow_pgtable, gp->shadow_lpid);
        spin_unlock(&kvm->mmu_lock);
        kvmhv_flush_lpid(gp->shadow_lpid);
        kvmhv_update_ptbl_cache(gp);
        if (gp->l1_gr_to_hr == 0)
                kvmhv_remove_nested(gp);
}

struct kvm_nested_guest *kvmhv_get_nested(struct kvm *kvm, int l1_lpid,
                                          bool create)
{
        struct kvm_nested_guest *gp, *newgp;

        if (l1_lpid >= KVM_MAX_NESTED_GUESTS ||
            l1_lpid >= (1ul << ((kvm->arch.l1_ptcr & PRTS_MASK) + 12 - 4)))
                return NULL;

        spin_lock(&kvm->mmu_lock);
        gp = kvm->arch.nested_guests[l1_lpid];
        if (gp)
                ++gp->refcnt;
        spin_unlock(&kvm->mmu_lock);

        if (gp || !create)
                return gp;

        newgp = kvmhv_alloc_nested(kvm, l1_lpid);
        if (!newgp)
                return NULL;
        spin_lock(&kvm->mmu_lock);
        if (kvm->arch.nested_guests[l1_lpid]) {
                /* someone else beat us to it */
                gp = kvm->arch.nested_guests[l1_lpid];
        } else {
                kvm->arch.nested_guests[l1_lpid] = newgp;
                ++newgp->refcnt;
                gp = newgp;
                newgp = NULL;
                if (l1_lpid > kvm->arch.max_nested_lpid)
                        kvm->arch.max_nested_lpid = l1_lpid;
        }
        ++gp->refcnt;
        spin_unlock(&kvm->mmu_lock);

        if (newgp)
                kvmhv_release_nested(newgp);

        return gp;
}

void kvmhv_put_nested(struct kvm_nested_guest *gp)
{
        struct kvm *kvm = gp->l1_host;
        long ref;

        spin_lock(&kvm->mmu_lock);
        ref = --gp->refcnt;
        spin_unlock(&kvm->mmu_lock);
        if (ref == 0)
                kvmhv_release_nested(gp);
}

static struct kvm_nested_guest *kvmhv_find_nested(struct kvm *kvm, int lpid)
{
        if (lpid > kvm->arch.max_nested_lpid)
                return NULL;
        return kvm->arch.nested_guests[lpid];
}

pte_t *find_kvm_nested_guest_pte(struct kvm *kvm, unsigned long lpid,
                                 unsigned long ea, unsigned *hshift)
{
        struct kvm_nested_guest *gp;
        pte_t *pte;

        gp = kvmhv_find_nested(kvm, lpid);
        if (!gp)
                return NULL;

        VM_WARN(!spin_is_locked(&kvm->mmu_lock),
                "%s called with kvm mmu_lock not held \n", __func__);
        pte = __find_linux_pte(gp->shadow_pgtable, ea, NULL, hshift);

        return pte;
}

static inline bool kvmhv_n_rmap_is_equal(u64 rmap_1, u64 rmap_2)
{
        return !((rmap_1 ^ rmap_2) & (RMAP_NESTED_LPID_MASK |
                                       RMAP_NESTED_GPA_MASK));
}

void kvmhv_insert_nest_rmap(struct kvm *kvm, unsigned long *rmapp,
                            struct rmap_nested **n_rmap)
{
        struct llist_node *entry = ((struct llist_head *) rmapp)->first;
        struct rmap_nested *cursor;
        u64 rmap, new_rmap = (*n_rmap)->rmap;

        /* Are there any existing entries? */
        if (!(*rmapp)) {
                /* No -> use the rmap as a single entry */
                *rmapp = new_rmap | RMAP_NESTED_IS_SINGLE_ENTRY;
                return;
        }

        /* Do any entries match what we're trying to insert? */
        for_each_nest_rmap_safe(cursor, entry, &rmap) {
                if (kvmhv_n_rmap_is_equal(rmap, new_rmap))
                        return;
        }

        /* Do we need to create a list or just add the new entry? */
        rmap = *rmapp;
        if (rmap & RMAP_NESTED_IS_SINGLE_ENTRY) /* Not previously a list */
                *rmapp = 0UL;
        llist_add(&((*n_rmap)->list), (struct llist_head *) rmapp);
        if (rmap & RMAP_NESTED_IS_SINGLE_ENTRY) /* Not previously a list */
                (*n_rmap)->list.next = (struct llist_node *) rmap;

        /* Set NULL so not freed by caller */
        *n_rmap = NULL;
}

static void kvmhv_update_nest_rmap_rc(struct kvm *kvm, u64 n_rmap,
                                      unsigned long clr, unsigned long set,
                                      unsigned long hpa, unsigned long mask)
{
        unsigned long gpa;
        unsigned int shift, lpid;
        pte_t *ptep;

        gpa = n_rmap & RMAP_NESTED_GPA_MASK;
        lpid = (n_rmap & RMAP_NESTED_LPID_MASK) >> RMAP_NESTED_LPID_SHIFT;

        /* Find the pte */
        ptep = find_kvm_nested_guest_pte(kvm, lpid, gpa, &shift);
        /*
         * If the pte is present and the pfn is still the same, update the pte.
         * If the pfn has changed then this is a stale rmap entry, the nested
         * gpa actually points somewhere else now, and there is nothing to do.
         * XXX A future optimisation would be to remove the rmap entry here.
         */
        if (ptep && pte_present(*ptep) && ((pte_val(*ptep) & mask) == hpa)) {
                __radix_pte_update(ptep, clr, set);
                kvmppc_radix_tlbie_page(kvm, gpa, shift, lpid);
        }
}

/*
 * For a given list of rmap entries, update the rc bits in all ptes in shadow
 * page tables for nested guests which are referenced by the rmap list.
 */
void kvmhv_update_nest_rmap_rc_list(struct kvm *kvm, unsigned long *rmapp,
                                    unsigned long clr, unsigned long set,
                                    unsigned long hpa, unsigned long nbytes)
{
        struct llist_node *entry = ((struct llist_head *) rmapp)->first;
        struct rmap_nested *cursor;
        unsigned long rmap, mask;

        if ((clr | set) & ~(_PAGE_DIRTY | _PAGE_ACCESSED))
                return;

        mask = PTE_RPN_MASK & ~(nbytes - 1);
        hpa &= mask;

        for_each_nest_rmap_safe(cursor, entry, &rmap)
                kvmhv_update_nest_rmap_rc(kvm, rmap, clr, set, hpa, mask);
}

static void kvmhv_remove_nest_rmap(struct kvm *kvm, u64 n_rmap,
                                   unsigned long hpa, unsigned long mask)
{
        struct kvm_nested_guest *gp;
        unsigned long gpa;
        unsigned int shift, lpid;
        pte_t *ptep;

        gpa = n_rmap & RMAP_NESTED_GPA_MASK;
        lpid = (n_rmap & RMAP_NESTED_LPID_MASK) >> RMAP_NESTED_LPID_SHIFT;
        gp = kvmhv_find_nested(kvm, lpid);
        if (!gp)
                return;

        /* Find and invalidate the pte */
        ptep = find_kvm_nested_guest_pte(kvm, lpid, gpa, &shift);
        /* Don't spuriously invalidate ptes if the pfn has changed */
        if (ptep && pte_present(*ptep) && ((pte_val(*ptep) & mask) == hpa))
                kvmppc_unmap_pte(kvm, ptep, gpa, shift, NULL, gp->shadow_lpid);
}

static void kvmhv_remove_nest_rmap_list(struct kvm *kvm, unsigned long *rmapp,
                                        unsigned long hpa, unsigned long mask)
{
        struct llist_node *entry = llist_del_all((struct llist_head *) rmapp);
        struct rmap_nested *cursor;
        unsigned long rmap;

        for_each_nest_rmap_safe(cursor, entry, &rmap) {
                kvmhv_remove_nest_rmap(kvm, rmap, hpa, mask);
                kfree(cursor);
        }
}

/* called with kvm->mmu_lock held */
void kvmhv_remove_nest_rmap_range(struct kvm *kvm,
                                  const struct kvm_memory_slot *memslot,
                                  unsigned long gpa, unsigned long hpa,
                                  unsigned long nbytes)
{
        unsigned long gfn, end_gfn;
        unsigned long addr_mask;

        if (!memslot)
                return;
        gfn = (gpa >> PAGE_SHIFT) - memslot->base_gfn;
        end_gfn = gfn + (nbytes >> PAGE_SHIFT);

        addr_mask = PTE_RPN_MASK & ~(nbytes - 1);
        hpa &= addr_mask;

        for (; gfn < end_gfn; gfn++) {
                unsigned long *rmap = &memslot->arch.rmap[gfn];
                kvmhv_remove_nest_rmap_list(kvm, rmap, hpa, addr_mask);
        }
}

static void kvmhv_free_memslot_nest_rmap(struct kvm_memory_slot *free)
{
        unsigned long page;

        for (page = 0; page < free->npages; page++) {
                unsigned long rmap, *rmapp = &free->arch.rmap[page];
                struct rmap_nested *cursor;
                struct llist_node *entry;

                entry = llist_del_all((struct llist_head *) rmapp);
                for_each_nest_rmap_safe(cursor, entry, &rmap)
                        kfree(cursor);
        }
}

static bool kvmhv_invalidate_shadow_pte(struct kvm_vcpu *vcpu,
                                        struct kvm_nested_guest *gp,
                                        long gpa, int *shift_ret)
{
        struct kvm *kvm = vcpu->kvm;
        bool ret = false;
        pte_t *ptep;
        int shift;

        spin_lock(&kvm->mmu_lock);
        ptep = find_kvm_nested_guest_pte(kvm, gp->l1_lpid, gpa, &shift);
        if (!shift)
                shift = PAGE_SHIFT;
        if (ptep && pte_present(*ptep)) {
                kvmppc_unmap_pte(kvm, ptep, gpa, shift, NULL, gp->shadow_lpid);
                ret = true;
        }
        spin_unlock(&kvm->mmu_lock);

        if (shift_ret)
                *shift_ret = shift;
        return ret;
}

static inline int get_ric(unsigned int instr)
{
        return (instr >> 18) & 0x3;
}

static inline int get_prs(unsigned int instr)
{
        return (instr >> 17) & 0x1;
}

static inline int get_r(unsigned int instr)
{
        return (instr >> 16) & 0x1;
}

static inline int get_lpid(unsigned long r_val)
{
        return r_val & 0xffffffff;
}

static inline int get_is(unsigned long r_val)
{
        return (r_val >> 10) & 0x3;
}

static inline int get_ap(unsigned long r_val)
{
        return (r_val >> 5) & 0x7;
}

static inline long get_epn(unsigned long r_val)
{
        return r_val >> 12;
}

static int kvmhv_emulate_tlbie_tlb_addr(struct kvm_vcpu *vcpu, int lpid,
                                        int ap, long epn)
{
        struct kvm *kvm = vcpu->kvm;
        struct kvm_nested_guest *gp;
        long npages;
        int shift, shadow_shift;
        unsigned long addr;

        shift = ap_to_shift(ap);
        addr = epn << 12;
        if (shift < 0)
                /* Invalid ap encoding */
                return -EINVAL;

        addr &= ~((1UL << shift) - 1);
        npages = 1UL << (shift - PAGE_SHIFT);

        gp = kvmhv_get_nested(kvm, lpid, false);
        if (!gp) /* No such guest -> nothing to do */
                return 0;
        mutex_lock(&gp->tlb_lock);

        /* There may be more than one host page backing this single guest pte */
        do {
                kvmhv_invalidate_shadow_pte(vcpu, gp, addr, &shadow_shift);

                npages -= 1UL << (shadow_shift - PAGE_SHIFT);
                addr += 1UL << shadow_shift;
        } while (npages > 0);

        mutex_unlock(&gp->tlb_lock);
        kvmhv_put_nested(gp);
        return 0;
}

static void kvmhv_emulate_tlbie_lpid(struct kvm_vcpu *vcpu,
                                     struct kvm_nested_guest *gp, int ric)
{
        struct kvm *kvm = vcpu->kvm;

        mutex_lock(&gp->tlb_lock);
        switch (ric) {
        case 0:
                /* Invalidate TLB */
                spin_lock(&kvm->mmu_lock);
                kvmppc_free_pgtable_radix(kvm, gp->shadow_pgtable,
                                          gp->shadow_lpid);
                kvmhv_flush_lpid(gp->shadow_lpid);
                spin_unlock(&kvm->mmu_lock);
                break;
        case 1:
                /*
                 * Invalidate PWC
                 * We don't cache this -> nothing to do
                 */
                break;
        case 2:
                /* Invalidate TLB, PWC and caching of partition table entries */
                kvmhv_flush_nested(gp);
                break;
        default:
                break;
        }
        mutex_unlock(&gp->tlb_lock);
}

static void kvmhv_emulate_tlbie_all_lpid(struct kvm_vcpu *vcpu, int ric)
{
        struct kvm *kvm = vcpu->kvm;
        struct kvm_nested_guest *gp;
        int i;

        spin_lock(&kvm->mmu_lock);
        for (i = 0; i <= kvm->arch.max_nested_lpid; i++) {
                gp = kvm->arch.nested_guests[i];
                if (gp) {
                        spin_unlock(&kvm->mmu_lock);
                        kvmhv_emulate_tlbie_lpid(vcpu, gp, ric);
                        spin_lock(&kvm->mmu_lock);
                }
        }
        spin_unlock(&kvm->mmu_lock);
}

static int kvmhv_emulate_priv_tlbie(struct kvm_vcpu *vcpu, unsigned int instr,
                                    unsigned long rsval, unsigned long rbval)
{
        struct kvm *kvm = vcpu->kvm;
        struct kvm_nested_guest *gp;
        int r, ric, prs, is, ap;
        int lpid;
        long epn;
        int ret = 0;

        ric = get_ric(instr);
        prs = get_prs(instr);
        r = get_r(instr);
        lpid = get_lpid(rsval);
        is = get_is(rbval);

        /*
         * These cases are invalid and are not handled:
         * r   != 1 -> Only radix supported
         * prs == 1 -> Not HV privileged
         * ric == 3 -> No cluster bombs for radix
         * is  == 1 -> Partition scoped translations not associated with pid
         * (!is) && (ric == 1 || ric == 2) -> Not supported by ISA
         */
        if ((!r) || (prs) || (ric == 3) || (is == 1) ||
            ((!is) && (ric == 1 || ric == 2)))
                return -EINVAL;

        switch (is) {
        case 0:
                /*
                 * We know ric == 0
                 * Invalidate TLB for a given target address
                 */
                epn = get_epn(rbval);
                ap = get_ap(rbval);
                ret = kvmhv_emulate_tlbie_tlb_addr(vcpu, lpid, ap, epn);
                break;
        case 2:
                /* Invalidate matching LPID */
                gp = kvmhv_get_nested(kvm, lpid, false);
                if (gp) {
                        kvmhv_emulate_tlbie_lpid(vcpu, gp, ric);
                        kvmhv_put_nested(gp);
                }
                break;
        case 3:
                /* Invalidate ALL LPIDs */
                kvmhv_emulate_tlbie_all_lpid(vcpu, ric);
                break;
        default:
                ret = -EINVAL;
                break;
        }

        return ret;
}

/*
 * This handles the H_TLB_INVALIDATE hcall.
 * Parameters are (r4) tlbie instruction code, (r5) rS contents,
 * (r6) rB contents.
 */
long kvmhv_do_nested_tlbie(struct kvm_vcpu *vcpu)
{
        int ret;

        ret = kvmhv_emulate_priv_tlbie(vcpu, kvmppc_get_gpr(vcpu, 4),
                        kvmppc_get_gpr(vcpu, 5), kvmppc_get_gpr(vcpu, 6));
        if (ret)
                return H_PARAMETER;
        return H_SUCCESS;
}

/* Used to convert a nested guest real address to a L1 guest real address */
static int kvmhv_translate_addr_nested(struct kvm_vcpu *vcpu,
                                       struct kvm_nested_guest *gp,
                                       unsigned long n_gpa, unsigned long dsisr,
                                       struct kvmppc_pte *gpte_p)
{
        u64 fault_addr, flags = dsisr & DSISR_ISSTORE;
        int ret;

        ret = kvmppc_mmu_walk_radix_tree(vcpu, n_gpa, gpte_p, gp->l1_gr_to_hr,
                                         &fault_addr);

        if (ret) {
                /* We didn't find a pte */
                if (ret == -EINVAL) {
                        /* Unsupported mmu config */
                        flags |= DSISR_UNSUPP_MMU;
                } else if (ret == -ENOENT) {
                        /* No translation found */
                        flags |= DSISR_NOHPTE;
                } else if (ret == -EFAULT) {
                        /* Couldn't access L1 real address */
                        flags |= DSISR_PRTABLE_FAULT;
                        vcpu->arch.fault_gpa = fault_addr;
                } else {
                        /* Unknown error */
                        return ret;
                }
                goto forward_to_l1;
        } else {
                /* We found a pte -> check permissions */
                if (dsisr & DSISR_ISSTORE) {
                        /* Can we write? */
                        if (!gpte_p->may_write) {
                                flags |= DSISR_PROTFAULT;
                                goto forward_to_l1;
                        }
                } else if (vcpu->arch.trap == BOOK3S_INTERRUPT_H_INST_STORAGE) {
                        /* Can we execute? */
                        if (!gpte_p->may_execute) {
                                flags |= SRR1_ISI_N_G_OR_CIP;
                                goto forward_to_l1;
                        }
                } else {
                        /* Can we read? */
                        if (!gpte_p->may_read && !gpte_p->may_write) {
                                flags |= DSISR_PROTFAULT;
                                goto forward_to_l1;
                        }
                }
        }

        return 0;

forward_to_l1:
        vcpu->arch.fault_dsisr = flags;
        if (vcpu->arch.trap == BOOK3S_INTERRUPT_H_INST_STORAGE) {
                vcpu->arch.shregs.msr &= SRR1_MSR_BITS;
                vcpu->arch.shregs.msr |= flags;
        }
        return RESUME_HOST;
}

static long kvmhv_handle_nested_set_rc(struct kvm_vcpu *vcpu,
                                       struct kvm_nested_guest *gp,
                                       unsigned long n_gpa,
                                       struct kvmppc_pte gpte,
                                       unsigned long dsisr)
{
        struct kvm *kvm = vcpu->kvm;
        bool writing = !!(dsisr & DSISR_ISSTORE);
        u64 pgflags;
        long ret;

        /* Are the rc bits set in the L1 partition scoped pte? */
        pgflags = _PAGE_ACCESSED;
        if (writing)
                pgflags |= _PAGE_DIRTY;
        if (pgflags & ~gpte.rc)
                return RESUME_HOST;

        spin_lock(&kvm->mmu_lock);
        /* Set the rc bit in the pte of our (L0) pgtable for the L1 guest */
        ret = kvmppc_hv_handle_set_rc(kvm, false, writing,
                                      gpte.raddr, kvm->arch.lpid);
        if (!ret) {
                ret = -EINVAL;
                goto out_unlock;
        }

        /* Set the rc bit in the pte of the shadow_pgtable for the nest guest */
        ret = kvmppc_hv_handle_set_rc(kvm, true, writing,
                                      n_gpa, gp->l1_lpid);
        if (!ret)
                ret = -EINVAL;
        else
                ret = 0;

out_unlock:
        spin_unlock(&kvm->mmu_lock);
        return ret;
}

static inline int kvmppc_radix_level_to_shift(int level)
{
        switch (level) {
        case 2:
                return PUD_SHIFT;
        case 1:
                return PMD_SHIFT;
        default:
                return PAGE_SHIFT;
        }
}

static inline int kvmppc_radix_shift_to_level(int shift)
{
        if (shift == PUD_SHIFT)
                return 2;
        if (shift == PMD_SHIFT)
                return 1;
        if (shift == PAGE_SHIFT)
                return 0;
        WARN_ON_ONCE(1);
        return 0;
}

/* called with gp->tlb_lock held */
static long int __kvmhv_nested_page_fault(struct kvm_vcpu *vcpu,
                                          struct kvm_nested_guest *gp)
{
        struct kvm *kvm = vcpu->kvm;
        struct kvm_memory_slot *memslot;
        struct rmap_nested *n_rmap;
        struct kvmppc_pte gpte;
        pte_t pte, *pte_p;
        unsigned long mmu_seq;
        unsigned long dsisr = vcpu->arch.fault_dsisr;
        unsigned long ea = vcpu->arch.fault_dar;
        unsigned long *rmapp;
        unsigned long n_gpa, gpa, gfn, perm = 0UL;
        unsigned int shift, l1_shift, level;
        bool writing = !!(dsisr & DSISR_ISSTORE);
        bool kvm_ro = false;
        long int ret;

        if (!gp->l1_gr_to_hr) {
                kvmhv_update_ptbl_cache(gp);
                if (!gp->l1_gr_to_hr)
                        return RESUME_HOST;
        }

        /* Convert the nested guest real address into a L1 guest real address */

        n_gpa = vcpu->arch.fault_gpa & ~0xF000000000000FFFULL;
        if (!(dsisr & DSISR_PRTABLE_FAULT))
                n_gpa |= ea & 0xFFF;
        ret = kvmhv_translate_addr_nested(vcpu, gp, n_gpa, dsisr, &gpte);

        /*
         * If the hardware found a translation but we don't now have a usable
         * translation in the l1 partition-scoped tree, remove the shadow pte
         * and let the guest retry.
         */
        if (ret == RESUME_HOST &&
            (dsisr & (DSISR_PROTFAULT | DSISR_BADACCESS | DSISR_NOEXEC_OR_G |
                      DSISR_BAD_COPYPASTE)))
                goto inval;
        if (ret)
                return ret;

        /* Failed to set the reference/change bits */
        if (dsisr & DSISR_SET_RC) {
                ret = kvmhv_handle_nested_set_rc(vcpu, gp, n_gpa, gpte, dsisr);
                if (ret == RESUME_HOST)
                        return ret;
                if (ret)
                        goto inval;
                dsisr &= ~DSISR_SET_RC;
                if (!(dsisr & (DSISR_BAD_FAULT_64S | DSISR_NOHPTE |
                               DSISR_PROTFAULT)))
                        return RESUME_GUEST;
        }

        /*
         * We took an HISI or HDSI while we were running a nested guest which
         * means we have no partition scoped translation for that. This means
         * we need to insert a pte for the mapping into our shadow_pgtable.
         */

        l1_shift = gpte.page_shift;
        if (l1_shift < PAGE_SHIFT) {
                /* We don't support l1 using a page size smaller than our own */
                pr_err("KVM: L1 guest page shift (%d) less than our own (%d)\n",
                        l1_shift, PAGE_SHIFT);
                return -EINVAL;
        }
        gpa = gpte.raddr;
        gfn = gpa >> PAGE_SHIFT;

        /* 1. Get the corresponding host memslot */

        memslot = gfn_to_memslot(kvm, gfn);
        if (!memslot || (memslot->flags & KVM_MEMSLOT_INVALID)) {
                if (dsisr & (DSISR_PRTABLE_FAULT | DSISR_BADACCESS)) {
                        /* unusual error -> reflect to the guest as a DSI */
                        kvmppc_core_queue_data_storage(vcpu, ea, dsisr);
                        return RESUME_GUEST;
                }

                /* passthrough of emulated MMIO case */
                return kvmppc_hv_emulate_mmio(vcpu, gpa, ea, writing);
        }
        if (memslot->flags & KVM_MEM_READONLY) {
                if (writing) {
                        /* Give the guest a DSI */
                        kvmppc_core_queue_data_storage(vcpu, ea,
                                        DSISR_ISSTORE | DSISR_PROTFAULT);
                        return RESUME_GUEST;
                }
                kvm_ro = true;
        }

        /* 2. Find the host pte for this L1 guest real address */

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

        /* See if can find translation in our partition scoped tables for L1 */
        pte = __pte(0);
        spin_lock(&kvm->mmu_lock);
        pte_p = find_kvm_secondary_pte(kvm, gpa, &shift);
        if (!shift)
                shift = PAGE_SHIFT;
        if (pte_p)
                pte = *pte_p;
        spin_unlock(&kvm->mmu_lock);

        if (!pte_present(pte) || (writing && !(pte_val(pte) & _PAGE_WRITE))) {
                /* No suitable pte found -> try to insert a mapping */
                ret = kvmppc_book3s_instantiate_page(vcpu, gpa, memslot,
                                        writing, kvm_ro, &pte, &level);
                if (ret == -EAGAIN)
                        return RESUME_GUEST;
                else if (ret)
                        return ret;
                shift = kvmppc_radix_level_to_shift(level);
        }
        /* Align gfn to the start of the page */
        gfn = (gpa & ~((1UL << shift) - 1)) >> PAGE_SHIFT;

        /* 3. Compute the pte we need to insert for nest_gpa -> host r_addr */

        /* The permissions is the combination of the host and l1 guest ptes */
        perm |= gpte.may_read ? 0UL : _PAGE_READ;
        perm |= gpte.may_write ? 0UL : _PAGE_WRITE;
        perm |= gpte.may_execute ? 0UL : _PAGE_EXEC;
        /* Only set accessed/dirty (rc) bits if set in host and l1 guest ptes */
        perm |= (gpte.rc & _PAGE_ACCESSED) ? 0UL : _PAGE_ACCESSED;
        perm |= ((gpte.rc & _PAGE_DIRTY) && writing) ? 0UL : _PAGE_DIRTY;
        pte = __pte(pte_val(pte) & ~perm);

        /* What size pte can we insert? */
        if (shift > l1_shift) {
                u64 mask;
                unsigned int actual_shift = PAGE_SHIFT;
                if (PMD_SHIFT < l1_shift)
                        actual_shift = PMD_SHIFT;
                mask = (1UL << shift) - (1UL << actual_shift);
                pte = __pte(pte_val(pte) | (gpa & mask));
                shift = actual_shift;
        }
        level = kvmppc_radix_shift_to_level(shift);
        n_gpa &= ~((1UL << shift) - 1);

        /* 4. Insert the pte into our shadow_pgtable */

        n_rmap = kzalloc(sizeof(*n_rmap), GFP_KERNEL);
        if (!n_rmap)
                return RESUME_GUEST; /* Let the guest try again */
        n_rmap->rmap = (n_gpa & RMAP_NESTED_GPA_MASK) |
                (((unsigned long) gp->l1_lpid) << RMAP_NESTED_LPID_SHIFT);
        rmapp = &memslot->arch.rmap[gfn - memslot->base_gfn];
        ret = kvmppc_create_pte(kvm, gp->shadow_pgtable, pte, n_gpa, level,
                                mmu_seq, gp->shadow_lpid, rmapp, &n_rmap);
        kfree(n_rmap);
        if (ret == -EAGAIN)
                ret = RESUME_GUEST;     /* Let the guest try again */

        return ret;

 inval:
        kvmhv_invalidate_shadow_pte(vcpu, gp, n_gpa, NULL);
        return RESUME_GUEST;
}

long int kvmhv_nested_page_fault(struct kvm_vcpu *vcpu)
{
        struct kvm_nested_guest *gp = vcpu->arch.nested;
        long int ret;

        mutex_lock(&gp->tlb_lock);
        ret = __kvmhv_nested_page_fault(vcpu, gp);
        mutex_unlock(&gp->tlb_lock);
        return ret;
}

int kvmhv_nested_next_lpid(struct kvm *kvm, int lpid)
{
        int ret = -1;

        spin_lock(&kvm->mmu_lock);
        while (++lpid <= kvm->arch.max_nested_lpid) {
                if (kvm->arch.nested_guests[lpid]) {
                        ret = lpid;
                        break;
                }
        }
        spin_unlock(&kvm->mmu_lock);
        return ret;
}