// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2020 Google LLC
 * Author: Quentin Perret <qperret@google.com>
 */

#include <linux/kvm_host.h>
#include <asm/kvm_hyp.h>
#include <asm/kvm_mmu.h>
#include <asm/kvm_pgtable.h>
#include <asm/kvm_pkvm.h>

#include <nvhe/early_alloc.h>
#include <nvhe/ffa.h>
#include <nvhe/gfp.h>
#include <nvhe/memory.h>
#include <nvhe/mem_protect.h>
#include <nvhe/mm.h>
#include <nvhe/pkvm.h>
#include <nvhe/trap_handler.h>

unsigned long hyp_nr_cpus;

#define hyp_percpu_size ((unsigned long)__per_cpu_end - \
                         (unsigned long)__per_cpu_start)

static void *vmemmap_base;
static void *vm_table_base;
static void *hyp_pgt_base;
static void *host_s2_pgt_base;
static void *selftest_base;
static void *ffa_proxy_pages;
static struct kvm_pgtable_mm_ops pkvm_pgtable_mm_ops;
static struct hyp_pool hpool;

static int divide_memory_pool(void *virt, unsigned long size)
{
        unsigned long nr_pages;

        hyp_early_alloc_init(virt, size);

        nr_pages = pkvm_selftest_pages();
        selftest_base = hyp_early_alloc_contig(nr_pages);
        if (nr_pages && !selftest_base)
                return -ENOMEM;

        nr_pages = hyp_vmemmap_pages(sizeof(struct hyp_page));
        vmemmap_base = hyp_early_alloc_contig(nr_pages);
        if (!vmemmap_base)
                return -ENOMEM;

        nr_pages = hyp_vm_table_pages();
        vm_table_base = hyp_early_alloc_contig(nr_pages);
        if (!vm_table_base)
                return -ENOMEM;

        nr_pages = hyp_s1_pgtable_pages();
        hyp_pgt_base = hyp_early_alloc_contig(nr_pages);
        if (!hyp_pgt_base)
                return -ENOMEM;

        nr_pages = host_s2_pgtable_pages();
        host_s2_pgt_base = hyp_early_alloc_contig(nr_pages);
        if (!host_s2_pgt_base)
                return -ENOMEM;

        nr_pages = hyp_ffa_proxy_pages();
        ffa_proxy_pages = hyp_early_alloc_contig(nr_pages);
        if (!ffa_proxy_pages)
                return -ENOMEM;

        return 0;
}

static int pkvm_create_host_sve_mappings(void)
{
        void *start, *end;
        int ret, i;

        if (!system_supports_sve())
                return 0;

        for (i = 0; i < hyp_nr_cpus; i++) {
                struct kvm_host_data *host_data = per_cpu_ptr(&kvm_host_data, i);
                struct cpu_sve_state *sve_state = host_data->sve_state;

                start = kern_hyp_va(sve_state);
                end = start + PAGE_ALIGN(pkvm_host_sve_state_size());
                ret = pkvm_create_mappings(start, end, PAGE_HYP);
                if (ret)
                        return ret;
        }

        return 0;
}

static int recreate_hyp_mappings(phys_addr_t phys, unsigned long size,
                                 unsigned long *per_cpu_base,
                                 u32 hyp_va_bits)
{
        void *start, *end, *virt = hyp_phys_to_virt(phys);
        unsigned long pgt_size = hyp_s1_pgtable_pages() << PAGE_SHIFT;
        int ret, i;

        /* Recreate the hyp page-table using the early page allocator */
        hyp_early_alloc_init(hyp_pgt_base, pgt_size);
        ret = kvm_pgtable_hyp_init(&pkvm_pgtable, hyp_va_bits,
                                   &hyp_early_alloc_mm_ops);
        if (ret)
                return ret;

        ret = hyp_create_idmap(hyp_va_bits);
        if (ret)
                return ret;

        ret = hyp_map_vectors();
        if (ret)
                return ret;

        ret = hyp_back_vmemmap(hyp_virt_to_phys(vmemmap_base));
        if (ret)
                return ret;

        ret = pkvm_create_mappings(__hyp_text_start, __hyp_text_end, PAGE_HYP_EXEC);
        if (ret)
                return ret;

        ret = pkvm_create_mappings(__hyp_data_start, __hyp_data_end, PAGE_HYP);
        if (ret)
                return ret;

        ret = pkvm_create_mappings(__hyp_rodata_start, __hyp_rodata_end, PAGE_HYP_RO);
        if (ret)
                return ret;

        ret = pkvm_create_mappings(__hyp_bss_start, __hyp_bss_end, PAGE_HYP);
        if (ret)
                return ret;

        ret = pkvm_create_mappings(virt, virt + size, PAGE_HYP);
        if (ret)
                return ret;

        for (i = 0; i < hyp_nr_cpus; i++) {
                struct kvm_nvhe_init_params *params = per_cpu_ptr(&kvm_init_params, i);

                start = (void *)kern_hyp_va(per_cpu_base[i]);
                end = start + PAGE_ALIGN(hyp_percpu_size);
                ret = pkvm_create_mappings(start, end, PAGE_HYP);
                if (ret)
                        return ret;

                ret = pkvm_create_stack(params->stack_pa, &params->stack_hyp_va);
                if (ret)
                        return ret;
        }

        return pkvm_create_host_sve_mappings();
}

static void update_nvhe_init_params(void)
{
        struct kvm_nvhe_init_params *params;
        unsigned long i;

        for (i = 0; i < hyp_nr_cpus; i++) {
                params = per_cpu_ptr(&kvm_init_params, i);
                params->pgd_pa = __hyp_pa(pkvm_pgtable.pgd);
                dcache_clean_inval_poc((unsigned long)params,
                                    (unsigned long)params + sizeof(*params));
        }
}

static void *hyp_zalloc_hyp_page(void *arg)
{
        return hyp_alloc_pages(&hpool, 0);
}

static void hpool_get_page(void *addr)
{
        hyp_get_page(&hpool, addr);
}

static void hpool_put_page(void *addr)
{
        hyp_put_page(&hpool, addr);
}

static int fix_host_ownership_walker(const struct kvm_pgtable_visit_ctx *ctx,
                                     enum kvm_pgtable_walk_flags visit)
{
        enum pkvm_page_state state;
        struct hyp_page *page;
        phys_addr_t phys;
        enum kvm_pgtable_prot prot;

        if (!kvm_pte_valid(ctx->old))
                return 0;

        if (ctx->level != KVM_PGTABLE_LAST_LEVEL)
                return -EINVAL;

        phys = kvm_pte_to_phys(ctx->old);
        if (!addr_is_memory(phys))
                return -EINVAL;

        page = hyp_phys_to_page(phys);

        /*
         * Adjust the host stage-2 mappings to match the ownership attributes
         * configured in the hypervisor stage-1, and make sure to propagate them
         * to the hyp_vmemmap state.
         */
        prot = kvm_pgtable_hyp_pte_prot(ctx->old);
        state = pkvm_getstate(prot);
        switch (state) {
        case PKVM_PAGE_OWNED:
                set_hyp_state(page, PKVM_PAGE_OWNED);
                /* hyp text is RO in the host stage-2 to be inspected on panic. */
                if (prot == PAGE_HYP_EXEC) {
                        set_host_state(page, PKVM_NOPAGE);
                        return host_stage2_idmap_locked(phys, PAGE_SIZE, KVM_PGTABLE_PROT_R);
                } else {
                        return host_stage2_set_owner_locked(phys, PAGE_SIZE, PKVM_ID_HYP);
                }
        case PKVM_PAGE_SHARED_OWNED:
                set_hyp_state(page, PKVM_PAGE_SHARED_OWNED);
                set_host_state(page, PKVM_PAGE_SHARED_BORROWED);
                break;
        case PKVM_PAGE_SHARED_BORROWED:
                set_hyp_state(page, PKVM_PAGE_SHARED_BORROWED);
                set_host_state(page, PKVM_PAGE_SHARED_OWNED);
                break;
        default:
                return -EINVAL;
        }

        return 0;
}

static int fix_hyp_pgtable_refcnt_walker(const struct kvm_pgtable_visit_ctx *ctx,
                                         enum kvm_pgtable_walk_flags visit)
{
        /*
         * Fix-up the refcount for the page-table pages as the early allocator
         * was unable to access the hyp_vmemmap and so the buddy allocator has
         * initialised the refcount to '1'.
         */
        if (kvm_pte_valid(ctx->old))
                ctx->mm_ops->get_page(ctx->ptep);

        return 0;
}

static int fix_host_ownership(void)
{
        struct kvm_pgtable_walker walker = {
                .cb     = fix_host_ownership_walker,
                .flags  = KVM_PGTABLE_WALK_LEAF,
        };
        int i, ret;

        for (i = 0; i < hyp_memblock_nr; i++) {
                struct memblock_region *reg = &hyp_memory[i];
                u64 start = (u64)hyp_phys_to_virt(reg->base);

                ret = kvm_pgtable_walk(&pkvm_pgtable, start, reg->size, &walker);
                if (ret)
                        return ret;
        }

        return 0;
}

static int fix_hyp_pgtable_refcnt(void)
{
        struct kvm_pgtable_walker walker = {
                .cb     = fix_hyp_pgtable_refcnt_walker,
                .flags  = KVM_PGTABLE_WALK_LEAF | KVM_PGTABLE_WALK_TABLE_POST,
                .arg    = pkvm_pgtable.mm_ops,
        };

        return kvm_pgtable_walk(&pkvm_pgtable, 0, BIT(pkvm_pgtable.ia_bits),
                                &walker);
}

void __noreturn __pkvm_init_finalise(void)
{
        struct kvm_cpu_context *host_ctxt = host_data_ptr(host_ctxt);
        unsigned long nr_pages, reserved_pages, pfn;
        int ret;

        /* Now that the vmemmap is backed, install the full-fledged allocator */
        pfn = hyp_virt_to_pfn(hyp_pgt_base);
        nr_pages = hyp_s1_pgtable_pages();
        reserved_pages = hyp_early_alloc_nr_used_pages();
        ret = hyp_pool_init(&hpool, pfn, nr_pages, reserved_pages);
        if (ret)
                goto out;

        ret = kvm_host_prepare_stage2(host_s2_pgt_base);
        if (ret)
                goto out;

        pkvm_pgtable_mm_ops = (struct kvm_pgtable_mm_ops) {
                .zalloc_page = hyp_zalloc_hyp_page,
                .phys_to_virt = hyp_phys_to_virt,
                .virt_to_phys = hyp_virt_to_phys,
                .get_page = hpool_get_page,
                .put_page = hpool_put_page,
                .page_count = hyp_page_count,
        };
        pkvm_pgtable.mm_ops = &pkvm_pgtable_mm_ops;

        ret = fix_host_ownership();
        if (ret)
                goto out;

        ret = fix_hyp_pgtable_refcnt();
        if (ret)
                goto out;

        ret = hyp_create_fixmap();
        if (ret)
                goto out;

        ret = hyp_ffa_init(ffa_proxy_pages);
        if (ret)
                goto out;

        pkvm_hyp_vm_table_init(vm_table_base);

        pkvm_ownership_selftest(selftest_base);
out:
        /*
         * We tail-called to here from handle___pkvm_init() and will not return,
         * so make sure to propagate the return value to the host.
         */
        cpu_reg(host_ctxt, 1) = ret;

        __host_enter(host_ctxt);
}

int __pkvm_init(phys_addr_t phys, unsigned long size, unsigned long nr_cpus,
                unsigned long *per_cpu_base, u32 hyp_va_bits)
{
        struct kvm_nvhe_init_params *params;
        void *virt = hyp_phys_to_virt(phys);
        typeof(__pkvm_init_switch_pgd) *fn;
        int ret;

        BUG_ON(kvm_check_pvm_sysreg_table());

        if (!PAGE_ALIGNED(phys) || !PAGE_ALIGNED(size))
                return -EINVAL;

        hyp_spin_lock_init(&pkvm_pgd_lock);
        hyp_nr_cpus = nr_cpus;

        ret = divide_memory_pool(virt, size);
        if (ret)
                return ret;

        ret = recreate_hyp_mappings(phys, size, per_cpu_base, hyp_va_bits);
        if (ret)
                return ret;

        update_nvhe_init_params();

        /* Jump in the idmap page to switch to the new page-tables */
        params = this_cpu_ptr(&kvm_init_params);
        fn = (typeof(fn))__hyp_pa(__pkvm_init_switch_pgd);
        fn(params->pgd_pa, params->stack_hyp_va, __pkvm_init_finalise);

        unreachable();
}