// SPDX-License-Identifier: GPL-2.0 OR MIT
/******************************************************************************
 * grant_table.c
 * x86 specific part
 *
 * Granting foreign access to our memory reservation.
 *
 * Copyright (c) 2005-2006, Christopher Clark
 * Copyright (c) 2004-2005, K A Fraser
 * Copyright (c) 2008 Isaku Yamahata <yamahata at valinux co jp>
 *                    VA Linux Systems Japan. Split out x86 specific part.
 */

#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>

#include <xen/interface/xen.h>
#include <xen/page.h>
#include <xen/grant_table.h>
#include <xen/xen.h>


static struct gnttab_vm_area {
        struct vm_struct *area;
        pte_t **ptes;
        int idx;
} gnttab_shared_vm_area, gnttab_status_vm_area;

int arch_gnttab_map_shared(unsigned long *frames, unsigned long nr_gframes,
                           unsigned long max_nr_gframes,
                           void **__shared)
{
        void *shared = *__shared;
        unsigned long addr;
        unsigned long i;

        if (shared == NULL)
                *__shared = shared = gnttab_shared_vm_area.area->addr;

        addr = (unsigned long)shared;

        for (i = 0; i < nr_gframes; i++) {
                set_pte_at(&init_mm, addr, gnttab_shared_vm_area.ptes[i],
                           mfn_pte(frames[i], PAGE_KERNEL));
                addr += PAGE_SIZE;
        }

        return 0;
}

int arch_gnttab_map_status(uint64_t *frames, unsigned long nr_gframes,
                           unsigned long max_nr_gframes,
                           grant_status_t **__shared)
{
        grant_status_t *shared = *__shared;
        unsigned long addr;
        unsigned long i;

        if (shared == NULL)
                *__shared = shared = gnttab_status_vm_area.area->addr;

        addr = (unsigned long)shared;

        for (i = 0; i < nr_gframes; i++) {
                set_pte_at(&init_mm, addr, gnttab_status_vm_area.ptes[i],
                           mfn_pte(frames[i], PAGE_KERNEL));
                addr += PAGE_SIZE;
        }

        return 0;
}

void arch_gnttab_unmap(void *shared, unsigned long nr_gframes)
{
        pte_t **ptes;
        unsigned long addr;
        unsigned long i;

        if (shared == gnttab_status_vm_area.area->addr)
                ptes = gnttab_status_vm_area.ptes;
        else
                ptes = gnttab_shared_vm_area.ptes;

        addr = (unsigned long)shared;

        for (i = 0; i < nr_gframes; i++) {
                set_pte_at(&init_mm, addr, ptes[i], __pte(0));
                addr += PAGE_SIZE;
        }
}

static int gnttab_apply(pte_t *pte, unsigned long addr, void *data)
{
        struct gnttab_vm_area *area = data;

        area->ptes[area->idx++] = pte;
        return 0;
}

static int arch_gnttab_valloc(struct gnttab_vm_area *area, unsigned nr_frames)
{
        area->ptes = kmalloc_objs(*area->ptes, nr_frames);
        if (area->ptes == NULL)
                return -ENOMEM;
        area->area = get_vm_area(PAGE_SIZE * nr_frames, VM_IOREMAP);
        if (!area->area)
                goto out_free_ptes;
        if (apply_to_page_range(&init_mm, (unsigned long)area->area->addr,
                        PAGE_SIZE * nr_frames, gnttab_apply, area))
                goto out_free_vm_area;
        return 0;
out_free_vm_area:
        free_vm_area(area->area);
out_free_ptes:
        kfree(area->ptes);
        return -ENOMEM;
}

static void arch_gnttab_vfree(struct gnttab_vm_area *area)
{
        free_vm_area(area->area);
        kfree(area->ptes);
}

int arch_gnttab_init(unsigned long nr_shared, unsigned long nr_status)
{
        int ret;

        if (!xen_pv_domain())
                return 0;

        ret = arch_gnttab_valloc(&gnttab_shared_vm_area, nr_shared);
        if (ret < 0)
                return ret;

        /*
         * Always allocate the space for the status frames in case
         * we're migrated to a host with V2 support.
         */
        ret = arch_gnttab_valloc(&gnttab_status_vm_area, nr_status);
        if (ret < 0)
                goto err;

        return 0;
err:
        arch_gnttab_vfree(&gnttab_shared_vm_area);
        return -ENOMEM;
}

#ifdef CONFIG_XEN_PVH
#include <xen/events.h>
#include <xen/xen-ops.h>
static int __init xen_pvh_gnttab_setup(void)
{
        if (!xen_pvh_domain())
                return -ENODEV;

        xen_auto_xlat_grant_frames.count = gnttab_max_grant_frames();

        return xen_xlate_map_ballooned_pages(&xen_auto_xlat_grant_frames.pfn,
                                             &xen_auto_xlat_grant_frames.vaddr,
                                             xen_auto_xlat_grant_frames.count);
}
/* Call it _before_ __gnttab_init as we need to initialize the
 * xen_auto_xlat_grant_frames first. */
core_initcall(xen_pvh_gnttab_setup);
#endif