/*
 * 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>
 * Copyright 2011 David Gibson, IBM Corporation <dwg@au1.ibm.com>
 * Copyright 2016 Alexey Kardashevskiy, IBM Corporation <aik@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/sched/signal.h>
#include <linux/hugetlb.h>
#include <linux/list.h>
#include <linux/anon_inodes.h>
#include <linux/iommu.h>
#include <linux/file.h>

#include <asm/tlbflush.h>
#include <asm/kvm_ppc.h>
#include <asm/kvm_book3s.h>
#include <asm/book3s/64/mmu-hash.h>
#include <asm/hvcall.h>
#include <asm/synch.h>
#include <asm/ppc-opcode.h>
#include <asm/kvm_host.h>
#include <asm/udbg.h>
#include <asm/iommu.h>
#include <asm/tce.h>
#include <asm/mmu_context.h>

static unsigned long kvmppc_tce_pages(unsigned long iommu_pages)
{
        return ALIGN(iommu_pages * sizeof(u64), PAGE_SIZE) / PAGE_SIZE;
}

static unsigned long kvmppc_stt_pages(unsigned long tce_pages)
{
        unsigned long stt_bytes = sizeof(struct kvmppc_spapr_tce_table) +
                        (tce_pages * sizeof(struct page *));

        return tce_pages + ALIGN(stt_bytes, PAGE_SIZE) / PAGE_SIZE;
}

static long kvmppc_account_memlimit(unsigned long stt_pages, bool inc)
{
        long ret = 0;

        if (!current || !current->mm)
                return ret; /* process exited */

        down_write(&current->mm->mmap_sem);

        if (inc) {
                unsigned long locked, lock_limit;

                locked = current->mm->locked_vm + stt_pages;
                lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
                if (locked > lock_limit && !capable(CAP_IPC_LOCK))
                        ret = -ENOMEM;
                else
                        current->mm->locked_vm += stt_pages;
        } else {
                if (WARN_ON_ONCE(stt_pages > current->mm->locked_vm))
                        stt_pages = current->mm->locked_vm;

                current->mm->locked_vm -= stt_pages;
        }

        pr_debug("[%d] RLIMIT_MEMLOCK KVM %c%ld %ld/%ld%s\n", current->pid,
                        inc ? '+' : '-',
                        stt_pages << PAGE_SHIFT,
                        current->mm->locked_vm << PAGE_SHIFT,
                        rlimit(RLIMIT_MEMLOCK),
                        ret ? " - exceeded" : "");

        up_write(&current->mm->mmap_sem);

        return ret;
}

static void kvm_spapr_tce_iommu_table_free(struct rcu_head *head)
{
        struct kvmppc_spapr_tce_iommu_table *stit = container_of(head,
                        struct kvmppc_spapr_tce_iommu_table, rcu);

        iommu_tce_table_put(stit->tbl);

        kfree(stit);
}

static void kvm_spapr_tce_liobn_put(struct kref *kref)
{
        struct kvmppc_spapr_tce_iommu_table *stit = container_of(kref,
                        struct kvmppc_spapr_tce_iommu_table, kref);

        list_del_rcu(&stit->next);

        call_rcu(&stit->rcu, kvm_spapr_tce_iommu_table_free);
}

extern void kvm_spapr_tce_release_iommu_group(struct kvm *kvm,
                struct iommu_group *grp)
{
        int i;
        struct kvmppc_spapr_tce_table *stt;
        struct kvmppc_spapr_tce_iommu_table *stit, *tmp;
        struct iommu_table_group *table_group = NULL;

        list_for_each_entry_rcu(stt, &kvm->arch.spapr_tce_tables, list) {

                table_group = iommu_group_get_iommudata(grp);
                if (WARN_ON(!table_group))
                        continue;

                list_for_each_entry_safe(stit, tmp, &stt->iommu_tables, next) {
                        for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
                                if (table_group->tables[i] != stit->tbl)
                                        continue;

                                kref_put(&stit->kref, kvm_spapr_tce_liobn_put);
                                return;
                        }
                }
        }
}

extern long kvm_spapr_tce_attach_iommu_group(struct kvm *kvm, int tablefd,
                struct iommu_group *grp)
{
        struct kvmppc_spapr_tce_table *stt = NULL;
        bool found = false;
        struct iommu_table *tbl = NULL;
        struct iommu_table_group *table_group;
        long i;
        struct kvmppc_spapr_tce_iommu_table *stit;
        struct fd f;

        f = fdget(tablefd);
        if (!f.file)
                return -EBADF;

        list_for_each_entry_rcu(stt, &kvm->arch.spapr_tce_tables, list) {
                if (stt == f.file->private_data) {
                        found = true;
                        break;
                }
        }

        fdput(f);

        if (!found)
                return -EINVAL;

        table_group = iommu_group_get_iommudata(grp);
        if (WARN_ON(!table_group))
                return -EFAULT;

        for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
                struct iommu_table *tbltmp = table_group->tables[i];

                if (!tbltmp)
                        continue;
                /*
                 * Make sure hardware table parameters are exactly the same;
                 * this is used in the TCE handlers where boundary checks
                 * use only the first attached table.
                 */
                if ((tbltmp->it_page_shift == stt->page_shift) &&
                                (tbltmp->it_offset == stt->offset) &&
                                (tbltmp->it_size == stt->size)) {
                        /*
                         * Reference the table to avoid races with
                         * add/remove DMA windows.
                         */
                        tbl = iommu_tce_table_get(tbltmp);
                        break;
                }
        }
        if (!tbl)
                return -EINVAL;

        list_for_each_entry_rcu(stit, &stt->iommu_tables, next) {
                if (tbl != stit->tbl)
                        continue;

                if (!kref_get_unless_zero(&stit->kref)) {
                        /* stit is being destroyed */
                        iommu_tce_table_put(tbl);
                        return -ENOTTY;
                }
                /*
                 * The table is already known to this KVM, we just increased
                 * its KVM reference counter and can return.
                 */
                return 0;
        }

        stit = kzalloc(sizeof(*stit), GFP_KERNEL);
        if (!stit) {
                iommu_tce_table_put(tbl);
                return -ENOMEM;
        }

        stit->tbl = tbl;
        kref_init(&stit->kref);

        list_add_rcu(&stit->next, &stt->iommu_tables);

        return 0;
}

static void release_spapr_tce_table(struct rcu_head *head)
{
        struct kvmppc_spapr_tce_table *stt = container_of(head,
                        struct kvmppc_spapr_tce_table, rcu);
        unsigned long i, npages = kvmppc_tce_pages(stt->size);

        for (i = 0; i < npages; i++)
                __free_page(stt->pages[i]);

        kfree(stt);
}

static int kvm_spapr_tce_fault(struct vm_fault *vmf)
{
        struct kvmppc_spapr_tce_table *stt = vmf->vma->vm_file->private_data;
        struct page *page;

        if (vmf->pgoff >= kvmppc_tce_pages(stt->size))
                return VM_FAULT_SIGBUS;

        page = stt->pages[vmf->pgoff];
        get_page(page);
        vmf->page = page;
        return 0;
}

static const struct vm_operations_struct kvm_spapr_tce_vm_ops = {
        .fault = kvm_spapr_tce_fault,
};

static int kvm_spapr_tce_mmap(struct file *file, struct vm_area_struct *vma)
{
        vma->vm_ops = &kvm_spapr_tce_vm_ops;
        return 0;
}

static int kvm_spapr_tce_release(struct inode *inode, struct file *filp)
{
        struct kvmppc_spapr_tce_table *stt = filp->private_data;
        struct kvmppc_spapr_tce_iommu_table *stit, *tmp;
        struct kvm *kvm = stt->kvm;

        mutex_lock(&kvm->lock);
        list_del_rcu(&stt->list);
        mutex_unlock(&kvm->lock);

        list_for_each_entry_safe(stit, tmp, &stt->iommu_tables, next) {
                WARN_ON(!kref_read(&stit->kref));
                while (1) {
                        if (kref_put(&stit->kref, kvm_spapr_tce_liobn_put))
                                break;
                }
        }

        kvm_put_kvm(stt->kvm);

        kvmppc_account_memlimit(
                kvmppc_stt_pages(kvmppc_tce_pages(stt->size)), false);
        call_rcu(&stt->rcu, release_spapr_tce_table);

        return 0;
}

static const struct file_operations kvm_spapr_tce_fops = {
        .mmap           = kvm_spapr_tce_mmap,
        .release        = kvm_spapr_tce_release,
};

long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm,
                                   struct kvm_create_spapr_tce_64 *args)
{
        struct kvmppc_spapr_tce_table *stt = NULL;
        struct kvmppc_spapr_tce_table *siter;
        unsigned long npages, size;
        int ret = -ENOMEM;
        int i;

        if (!args->size)
                return -EINVAL;

        size = _ALIGN_UP(args->size, PAGE_SIZE >> 3);
        npages = kvmppc_tce_pages(size);
        ret = kvmppc_account_memlimit(kvmppc_stt_pages(npages), true);
        if (ret)
                return ret;

        ret = -ENOMEM;
        stt = kzalloc(sizeof(*stt) + npages * sizeof(struct page *),
                      GFP_KERNEL);
        if (!stt)
                goto fail_acct;

        stt->liobn = args->liobn;
        stt->page_shift = args->page_shift;
        stt->offset = args->offset;
        stt->size = size;
        stt->kvm = kvm;
        INIT_LIST_HEAD_RCU(&stt->iommu_tables);

        for (i = 0; i < npages; i++) {
                stt->pages[i] = alloc_page(GFP_KERNEL | __GFP_ZERO);
                if (!stt->pages[i])
                        goto fail;
        }

        mutex_lock(&kvm->lock);

        /* Check this LIOBN hasn't been previously allocated */
        ret = 0;
        list_for_each_entry(siter, &kvm->arch.spapr_tce_tables, list) {
                if (siter->liobn == args->liobn) {
                        ret = -EBUSY;
                        break;
                }
        }

        if (!ret)
                ret = anon_inode_getfd("kvm-spapr-tce", &kvm_spapr_tce_fops,
                                       stt, O_RDWR | O_CLOEXEC);

        if (ret >= 0) {
                list_add_rcu(&stt->list, &kvm->arch.spapr_tce_tables);
                kvm_get_kvm(kvm);
        }

        mutex_unlock(&kvm->lock);

        if (ret >= 0)
                return ret;

 fail:
        for (i = 0; i < npages; i++)
                if (stt->pages[i])
                        __free_page(stt->pages[i]);

        kfree(stt);
 fail_acct:
        kvmppc_account_memlimit(kvmppc_stt_pages(npages), false);
        return ret;
}

static void kvmppc_clear_tce(struct iommu_table *tbl, unsigned long entry)
{
        unsigned long hpa = 0;
        enum dma_data_direction dir = DMA_NONE;

        iommu_tce_xchg(tbl, entry, &hpa, &dir);
}

static long kvmppc_tce_iommu_mapped_dec(struct kvm *kvm,
                struct iommu_table *tbl, unsigned long entry)
{
        struct mm_iommu_table_group_mem_t *mem = NULL;
        const unsigned long pgsize = 1ULL << tbl->it_page_shift;
        unsigned long *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry);

        if (!pua)
                /* it_userspace allocation might be delayed */
                return H_TOO_HARD;

        mem = mm_iommu_lookup(kvm->mm, *pua, pgsize);
        if (!mem)
                return H_TOO_HARD;

        mm_iommu_mapped_dec(mem);

        *pua = 0;

        return H_SUCCESS;
}

static long kvmppc_tce_iommu_unmap(struct kvm *kvm,
                struct iommu_table *tbl, unsigned long entry)
{
        enum dma_data_direction dir = DMA_NONE;
        unsigned long hpa = 0;
        long ret;

        if (WARN_ON_ONCE(iommu_tce_xchg(tbl, entry, &hpa, &dir)))
                return H_HARDWARE;

        if (dir == DMA_NONE)
                return H_SUCCESS;

        ret = kvmppc_tce_iommu_mapped_dec(kvm, tbl, entry);
        if (ret != H_SUCCESS)
                iommu_tce_xchg(tbl, entry, &hpa, &dir);

        return ret;
}

long kvmppc_tce_iommu_map(struct kvm *kvm, struct iommu_table *tbl,
                unsigned long entry, unsigned long ua,
                enum dma_data_direction dir)
{
        long ret;
        unsigned long hpa, *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry);
        struct mm_iommu_table_group_mem_t *mem;

        if (!pua)
                /* it_userspace allocation might be delayed */
                return H_TOO_HARD;

        mem = mm_iommu_lookup(kvm->mm, ua, 1ULL << tbl->it_page_shift);
        if (!mem)
                /* This only handles v2 IOMMU type, v1 is handled via ioctl() */
                return H_TOO_HARD;

        if (WARN_ON_ONCE(mm_iommu_ua_to_hpa(mem, ua, &hpa)))
                return H_HARDWARE;

        if (mm_iommu_mapped_inc(mem))
                return H_CLOSED;

        ret = iommu_tce_xchg(tbl, entry, &hpa, &dir);
        if (WARN_ON_ONCE(ret)) {
                mm_iommu_mapped_dec(mem);
                return H_HARDWARE;
        }

        if (dir != DMA_NONE)
                kvmppc_tce_iommu_mapped_dec(kvm, tbl, entry);

        *pua = ua;

        return 0;
}

long kvmppc_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
                      unsigned long ioba, unsigned long tce)
{
        struct kvmppc_spapr_tce_table *stt;
        long ret, idx;
        struct kvmppc_spapr_tce_iommu_table *stit;
        unsigned long entry, ua = 0;
        enum dma_data_direction dir;

        /* udbg_printf("H_PUT_TCE(): liobn=0x%lx ioba=0x%lx, tce=0x%lx\n", */
        /*          liobn, ioba, tce); */

        stt = kvmppc_find_table(vcpu->kvm, liobn);
        if (!stt)
                return H_TOO_HARD;

        ret = kvmppc_ioba_validate(stt, ioba, 1);
        if (ret != H_SUCCESS)
                return ret;

        ret = kvmppc_tce_validate(stt, tce);
        if (ret != H_SUCCESS)
                return ret;

        dir = iommu_tce_direction(tce);

        idx = srcu_read_lock(&vcpu->kvm->srcu);

        if ((dir != DMA_NONE) && kvmppc_gpa_to_ua(vcpu->kvm,
                        tce & ~(TCE_PCI_READ | TCE_PCI_WRITE), &ua, NULL)) {
                ret = H_PARAMETER;
                goto unlock_exit;
        }

        entry = ioba >> stt->page_shift;

        list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
                if (dir == DMA_NONE)
                        ret = kvmppc_tce_iommu_unmap(vcpu->kvm,
                                        stit->tbl, entry);
                else
                        ret = kvmppc_tce_iommu_map(vcpu->kvm, stit->tbl,
                                        entry, ua, dir);

                if (ret == H_SUCCESS)
                        continue;

                if (ret == H_TOO_HARD)
                        goto unlock_exit;

                WARN_ON_ONCE(1);
                kvmppc_clear_tce(stit->tbl, entry);
        }

        kvmppc_tce_put(stt, entry, tce);

unlock_exit:
        srcu_read_unlock(&vcpu->kvm->srcu, idx);

        return ret;
}
EXPORT_SYMBOL_GPL(kvmppc_h_put_tce);

long kvmppc_h_put_tce_indirect(struct kvm_vcpu *vcpu,
                unsigned long liobn, unsigned long ioba,
                unsigned long tce_list, unsigned long npages)
{
        struct kvmppc_spapr_tce_table *stt;
        long i, ret = H_SUCCESS, idx;
        unsigned long entry, ua = 0;
        u64 __user *tces;
        u64 tce;
        struct kvmppc_spapr_tce_iommu_table *stit;

        stt = kvmppc_find_table(vcpu->kvm, liobn);
        if (!stt)
                return H_TOO_HARD;

        entry = ioba >> stt->page_shift;
        /*
         * SPAPR spec says that the maximum size of the list is 512 TCEs
         * so the whole table fits in 4K page
         */
        if (npages > 512)
                return H_PARAMETER;

        if (tce_list & (SZ_4K - 1))
                return H_PARAMETER;

        ret = kvmppc_ioba_validate(stt, ioba, npages);
        if (ret != H_SUCCESS)
                return ret;

        idx = srcu_read_lock(&vcpu->kvm->srcu);
        if (kvmppc_gpa_to_ua(vcpu->kvm, tce_list, &ua, NULL)) {
                ret = H_TOO_HARD;
                goto unlock_exit;
        }
        tces = (u64 __user *) ua;

        for (i = 0; i < npages; ++i) {
                if (get_user(tce, tces + i)) {
                        ret = H_TOO_HARD;
                        goto unlock_exit;
                }
                tce = be64_to_cpu(tce);

                ret = kvmppc_tce_validate(stt, tce);
                if (ret != H_SUCCESS)
                        goto unlock_exit;

                if (kvmppc_gpa_to_ua(vcpu->kvm,
                                tce & ~(TCE_PCI_READ | TCE_PCI_WRITE),
                                &ua, NULL))
                        return H_PARAMETER;

                list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
                        ret = kvmppc_tce_iommu_map(vcpu->kvm,
                                        stit->tbl, entry + i, ua,
                                        iommu_tce_direction(tce));

                        if (ret == H_SUCCESS)
                                continue;

                        if (ret == H_TOO_HARD)
                                goto unlock_exit;

                        WARN_ON_ONCE(1);
                        kvmppc_clear_tce(stit->tbl, entry);
                }

                kvmppc_tce_put(stt, entry + i, tce);
        }

unlock_exit:
        srcu_read_unlock(&vcpu->kvm->srcu, idx);

        return ret;
}
EXPORT_SYMBOL_GPL(kvmppc_h_put_tce_indirect);

long kvmppc_h_stuff_tce(struct kvm_vcpu *vcpu,
                unsigned long liobn, unsigned long ioba,
                unsigned long tce_value, unsigned long npages)
{
        struct kvmppc_spapr_tce_table *stt;
        long i, ret;
        struct kvmppc_spapr_tce_iommu_table *stit;

        stt = kvmppc_find_table(vcpu->kvm, liobn);
        if (!stt)
                return H_TOO_HARD;

        ret = kvmppc_ioba_validate(stt, ioba, npages);
        if (ret != H_SUCCESS)
                return ret;

        /* Check permission bits only to allow userspace poison TCE for debug */
        if (tce_value & (TCE_PCI_WRITE | TCE_PCI_READ))
                return H_PARAMETER;

        list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
                unsigned long entry = ioba >> stit->tbl->it_page_shift;

                for (i = 0; i < npages; ++i) {
                        ret = kvmppc_tce_iommu_unmap(vcpu->kvm,
                                        stit->tbl, entry + i);

                        if (ret == H_SUCCESS)
                                continue;

                        if (ret == H_TOO_HARD)
                                return ret;

                        WARN_ON_ONCE(1);
                        kvmppc_clear_tce(stit->tbl, entry);
                }
        }

        for (i = 0; i < npages; ++i, ioba += (1ULL << stt->page_shift))
                kvmppc_tce_put(stt, ioba >> stt->page_shift, tce_value);

        return H_SUCCESS;
}
EXPORT_SYMBOL_GPL(kvmppc_h_stuff_tce);