/*
 * 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/hugetlb.h>
#include <linux/list.h>

#include <asm/tlbflush.h>
#include <asm/kvm_ppc.h>
#include <asm/kvm_book3s.h>
#include <asm/book3s/64/mmu-hash.h>
#include <asm/mmu_context.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/pte-walk.h>

#ifdef CONFIG_BUG

#define WARN_ON_ONCE_RM(condition)      ({                      \
        static bool __section(.data.unlikely) __warned;         \
        int __ret_warn_once = !!(condition);                    \
                                                                \
        if (unlikely(__ret_warn_once && !__warned)) {           \
                __warned = true;                                \
                pr_err("WARN_ON_ONCE_RM: (%s) at %s:%u\n",      \
                                __stringify(condition),         \
                                __func__, __LINE__);            \
                dump_stack();                                   \
        }                                                       \
        unlikely(__ret_warn_once);                              \
})

#else

#define WARN_ON_ONCE_RM(condition) ({                           \
        int __ret_warn_on = !!(condition);                      \
        unlikely(__ret_warn_on);                                \
})

#endif

#define TCES_PER_PAGE   (PAGE_SIZE / sizeof(u64))

/*
 * Finds a TCE table descriptor by LIOBN.
 *
 * WARNING: This will be called in real or virtual mode on HV KVM and virtual
 *          mode on PR KVM
 */
struct kvmppc_spapr_tce_table *kvmppc_find_table(struct kvm *kvm,
                unsigned long liobn)
{
        struct kvmppc_spapr_tce_table *stt;

        list_for_each_entry_lockless(stt, &kvm->arch.spapr_tce_tables, list)
                if (stt->liobn == liobn)
                        return stt;

        return NULL;
}
EXPORT_SYMBOL_GPL(kvmppc_find_table);

/*
 * Validates TCE address.
 * At the moment flags and page mask are validated.
 * As the host kernel does not access those addresses (just puts them
 * to the table and user space is supposed to process them), we can skip
 * checking other things (such as TCE is a guest RAM address or the page
 * was actually allocated).
 *
 * WARNING: This will be called in real-mode on HV KVM and virtual
 *          mode on PR KVM
 */
long kvmppc_tce_validate(struct kvmppc_spapr_tce_table *stt, unsigned long tce)
{
        unsigned long gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
        enum dma_data_direction dir = iommu_tce_direction(tce);

        /* Allow userspace to poison TCE table */
        if (dir == DMA_NONE)
                return H_SUCCESS;

        if (iommu_tce_check_gpa(stt->page_shift, gpa))
                return H_PARAMETER;

        return H_SUCCESS;
}
EXPORT_SYMBOL_GPL(kvmppc_tce_validate);

/* Note on the use of page_address() in real mode,
 *
 * It is safe to use page_address() in real mode on ppc64 because
 * page_address() is always defined as lowmem_page_address()
 * which returns __va(PFN_PHYS(page_to_pfn(page))) which is arithmetic
 * operation and does not access page struct.
 *
 * Theoretically page_address() could be defined different
 * but either WANT_PAGE_VIRTUAL or HASHED_PAGE_VIRTUAL
 * would have to be enabled.
 * WANT_PAGE_VIRTUAL is never enabled on ppc32/ppc64,
 * HASHED_PAGE_VIRTUAL could be enabled for ppc32 only and only
 * if CONFIG_HIGHMEM is defined. As CONFIG_SPARSEMEM_VMEMMAP
 * is not expected to be enabled on ppc32, page_address()
 * is safe for ppc32 as well.
 *
 * WARNING: This will be called in real-mode on HV KVM and virtual
 *          mode on PR KVM
 */
static u64 *kvmppc_page_address(struct page *page)
{
#if defined(HASHED_PAGE_VIRTUAL) || defined(WANT_PAGE_VIRTUAL)
#error TODO: fix to avoid page_address() here
#endif
        return (u64 *) page_address(page);
}

/*
 * Handles TCE requests for emulated devices.
 * Puts guest TCE values to the table and expects user space to convert them.
 * Called in both real and virtual modes.
 * Cannot fail so kvmppc_tce_validate must be called before it.
 *
 * WARNING: This will be called in real-mode on HV KVM and virtual
 *          mode on PR KVM
 */
void kvmppc_tce_put(struct kvmppc_spapr_tce_table *stt,
                unsigned long idx, unsigned long tce)
{
        struct page *page;
        u64 *tbl;

        idx -= stt->offset;
        page = stt->pages[idx / TCES_PER_PAGE];
        tbl = kvmppc_page_address(page);

        tbl[idx % TCES_PER_PAGE] = tce;
}
EXPORT_SYMBOL_GPL(kvmppc_tce_put);

long kvmppc_gpa_to_ua(struct kvm *kvm, unsigned long gpa,
                unsigned long *ua, unsigned long **prmap)
{
        unsigned long gfn = gpa >> PAGE_SHIFT;
        struct kvm_memory_slot *memslot;

        memslot = search_memslots(kvm_memslots(kvm), gfn);
        if (!memslot)
                return -EINVAL;

        *ua = __gfn_to_hva_memslot(memslot, gfn) |
                (gpa & ~(PAGE_MASK | TCE_PCI_READ | TCE_PCI_WRITE));

#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
        if (prmap)
                *prmap = &memslot->arch.rmap[gfn - memslot->base_gfn];
#endif

        return 0;
}
EXPORT_SYMBOL_GPL(kvmppc_gpa_to_ua);

#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
static void kvmppc_rm_clear_tce(struct iommu_table *tbl, unsigned long entry)
{
        unsigned long hpa = 0;
        enum dma_data_direction dir = DMA_NONE;

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

static long kvmppc_rm_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;

        pua = (void *) vmalloc_to_phys(pua);
        if (WARN_ON_ONCE_RM(!pua))
                return H_HARDWARE;

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

        mm_iommu_mapped_dec(mem);

        *pua = 0;

        return H_SUCCESS;
}

static long kvmppc_rm_tce_iommu_do_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 (iommu_tce_xchg_rm(tbl, entry, &hpa, &dir))
                /*
                 * real mode xchg can fail if struct page crosses
                 * a page boundary
                 */
                return H_TOO_HARD;

        if (dir == DMA_NONE)
                return H_SUCCESS;

        ret = kvmppc_rm_tce_iommu_mapped_dec(kvm, tbl, entry);
        if (ret)
                iommu_tce_xchg_rm(tbl, entry, &hpa, &dir);

        return ret;
}

static long kvmppc_rm_tce_iommu_unmap(struct kvm *kvm,
                struct kvmppc_spapr_tce_table *stt, struct iommu_table *tbl,
                unsigned long entry)
{
        unsigned long i, ret = H_SUCCESS;
        unsigned long subpages = 1ULL << (stt->page_shift - tbl->it_page_shift);
        unsigned long io_entry = entry * subpages;

        for (i = 0; i < subpages; ++i) {
                ret = kvmppc_rm_tce_iommu_do_unmap(kvm, tbl, io_entry + i);
                if (ret != H_SUCCESS)
                        break;
        }

        return ret;
}

static long kvmppc_rm_tce_iommu_do_map(struct kvm *kvm, struct iommu_table *tbl,
                unsigned long entry, unsigned long ua,
                enum dma_data_direction dir)
{
        long ret;
        unsigned long hpa = 0;
        unsigned long *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_rm(kvm->mm, ua, 1ULL << tbl->it_page_shift);
        if (!mem)
                return H_TOO_HARD;

        if (WARN_ON_ONCE_RM(mm_iommu_ua_to_hpa_rm(mem, ua, tbl->it_page_shift,
                        &hpa)))
                return H_HARDWARE;

        pua = (void *) vmalloc_to_phys(pua);
        if (WARN_ON_ONCE_RM(!pua))
                return H_HARDWARE;

        if (WARN_ON_ONCE_RM(mm_iommu_mapped_inc(mem)))
                return H_CLOSED;

        ret = iommu_tce_xchg_rm(tbl, entry, &hpa, &dir);
        if (ret) {
                mm_iommu_mapped_dec(mem);
                /*
                 * real mode xchg can fail if struct page crosses
                 * a page boundary
                 */
                return H_TOO_HARD;
        }

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

        *pua = ua;

        return 0;
}

static long kvmppc_rm_tce_iommu_map(struct kvm *kvm,
                struct kvmppc_spapr_tce_table *stt, struct iommu_table *tbl,
                unsigned long entry, unsigned long ua,
                enum dma_data_direction dir)
{
        unsigned long i, pgoff, ret = H_SUCCESS;
        unsigned long subpages = 1ULL << (stt->page_shift - tbl->it_page_shift);
        unsigned long io_entry = entry * subpages;

        for (i = 0, pgoff = 0; i < subpages;
                        ++i, pgoff += IOMMU_PAGE_SIZE(tbl)) {

                ret = kvmppc_rm_tce_iommu_do_map(kvm, tbl,
                                io_entry + i, ua + pgoff, dir);
                if (ret != H_SUCCESS)
                        break;
        }

        return ret;
}

long kvmppc_rm_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
                unsigned long ioba, unsigned long tce)
{
        struct kvmppc_spapr_tce_table *stt;
        long ret;
        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); */

        /* For radix, we might be in virtual mode, so punt */
        if (kvm_is_radix(vcpu->kvm))
                return H_TOO_HARD;

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

        entry = ioba >> stt->page_shift;

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

                if (ret == H_SUCCESS)
                        continue;

                if (ret == H_TOO_HARD)
                        return ret;

                WARN_ON_ONCE_RM(1);
                kvmppc_rm_clear_tce(stit->tbl, entry);
        }

        kvmppc_tce_put(stt, entry, tce);

        return H_SUCCESS;
}

static long kvmppc_rm_ua_to_hpa(struct kvm_vcpu *vcpu,
                unsigned long ua, unsigned long *phpa)
{
        pte_t *ptep, pte;
        unsigned shift = 0;

        /*
         * Called in real mode with MSR_EE = 0. We are safe here.
         * It is ok to do the lookup with arch.pgdir here, because
         * we are doing this on secondary cpus and current task there
         * is not the hypervisor. Also this is safe against THP in the
         * host, because an IPI to primary thread will wait for the secondary
         * to exit which will agains result in the below page table walk
         * to finish.
         */
        ptep = __find_linux_pte(vcpu->arch.pgdir, ua, NULL, &shift);
        if (!ptep || !pte_present(*ptep))
                return -ENXIO;
        pte = *ptep;

        if (!shift)
                shift = PAGE_SHIFT;

        /* Avoid handling anything potentially complicated in realmode */
        if (shift > PAGE_SHIFT)
                return -EAGAIN;

        if (!pte_young(pte))
                return -EAGAIN;

        *phpa = (pte_pfn(pte) << PAGE_SHIFT) | (ua & ((1ULL << shift) - 1)) |
                        (ua & ~PAGE_MASK);

        return 0;
}

long kvmppc_rm_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;
        unsigned long tces, entry, ua = 0;
        unsigned long *rmap = NULL;
        bool prereg = false;
        struct kvmppc_spapr_tce_iommu_table *stit;

        /* For radix, we might be in virtual mode, so punt */
        if (kvm_is_radix(vcpu->kvm))
                return H_TOO_HARD;

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

        entry = ioba >> stt->page_shift;
        /*
         * The spec says that the maximum size of the list is 512 TCEs
         * so the whole table addressed resides 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;

        if (mm_iommu_preregistered(vcpu->kvm->mm)) {
                /*
                 * We get here if guest memory was pre-registered which
                 * is normally VFIO case and gpa->hpa translation does not
                 * depend on hpt.
                 */
                struct mm_iommu_table_group_mem_t *mem;

                if (kvmppc_gpa_to_ua(vcpu->kvm, tce_list, &ua, NULL))
                        return H_TOO_HARD;

                mem = mm_iommu_lookup_rm(vcpu->kvm->mm, ua, IOMMU_PAGE_SIZE_4K);
                if (mem)
                        prereg = mm_iommu_ua_to_hpa_rm(mem, ua,
                                        IOMMU_PAGE_SHIFT_4K, &tces) == 0;
        }

        if (!prereg) {
                /*
                 * This is usually a case of a guest with emulated devices only
                 * when TCE list is not in preregistered memory.
                 * We do not require memory to be preregistered in this case
                 * so lock rmap and do __find_linux_pte_or_hugepte().
                 */
                if (kvmppc_gpa_to_ua(vcpu->kvm, tce_list, &ua, &rmap))
                        return H_TOO_HARD;

                rmap = (void *) vmalloc_to_phys(rmap);
                if (WARN_ON_ONCE_RM(!rmap))
                        return H_HARDWARE;

                /*
                 * Synchronize with the MMU notifier callbacks in
                 * book3s_64_mmu_hv.c (kvm_unmap_hva_range_hv etc.).
                 * While we have the rmap lock, code running on other CPUs
                 * cannot finish unmapping the host real page that backs
                 * this guest real page, so we are OK to access the host
                 * real page.
                 */
                lock_rmap(rmap);
                if (kvmppc_rm_ua_to_hpa(vcpu, ua, &tces)) {
                        ret = H_TOO_HARD;
                        goto unlock_exit;
                }
        }

        for (i = 0; i < npages; ++i) {
                unsigned long tce = be64_to_cpu(((u64 *)tces)[i]);

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

                ua = 0;
                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_rm_tce_iommu_map(vcpu->kvm, stt,
                                        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_RM(1);
                        kvmppc_rm_clear_tce(stit->tbl, entry);
                }

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

unlock_exit:
        if (rmap)
                unlock_rmap(rmap);

        return ret;
}

long kvmppc_rm_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;

        /* For radix, we might be in virtual mode, so punt */
        if (kvm_is_radix(vcpu->kvm))
                return H_TOO_HARD;

        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 >> stt->page_shift;

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

                        if (ret == H_SUCCESS)
                                continue;

                        if (ret == H_TOO_HARD)
                                return ret;

                        WARN_ON_ONCE_RM(1);
                        kvmppc_rm_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;
}

/* This can be called in either virtual mode or real mode */
long kvmppc_h_get_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
                      unsigned long ioba)
{
        struct kvmppc_spapr_tce_table *stt;
        long ret;
        unsigned long idx;
        struct page *page;
        u64 *tbl;

        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;

        idx = (ioba >> stt->page_shift) - stt->offset;
        page = stt->pages[idx / TCES_PER_PAGE];
        tbl = (u64 *)page_address(page);

        vcpu->arch.regs.gpr[4] = tbl[idx % TCES_PER_PAGE];

        return H_SUCCESS;
}
EXPORT_SYMBOL_GPL(kvmppc_h_get_tce);

#endif /* KVM_BOOK3S_HV_POSSIBLE */