// SPDX-License-Identifier: MIT
/*
 * Copyright © 2017 Intel Corporation
 */

#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/fs_context.h>

#include "i915_drv.h"
#include "i915_gemfs.h"
#include "i915_utils.h"

void i915_gemfs_init(struct drm_i915_private *i915)
{
#ifdef __linux__
        struct file_system_type *type;
        struct fs_context *fc;
        struct vfsmount *gemfs;
        int ret;

        /*
         * By creating our own shmemfs mountpoint, we can pass in
         * mount flags that better match our usecase.
         *
         * One example, although it is probably better with a per-file
         * control, is selecting huge page allocations ("huge=within_size").
         * However, we only do so on platforms which benefit from it, or to
         * offset the overhead of iommu lookups, where with latter it is a net
         * win even on platforms which would otherwise see some performance
         * regressions such a slow reads issue on Broadwell and Skylake.
         */

        if (GRAPHICS_VER(i915) < 11 && !i915_vtd_active(i915))
                return;

        if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
                goto err;

        type = get_fs_type("tmpfs");
        if (!type)
                goto err;

        fc = fs_context_for_mount(type, SB_KERNMOUNT);
        if (IS_ERR(fc))
                goto err;
        ret = vfs_parse_fs_string(fc, "source", "tmpfs");
        if (!ret)
                ret = vfs_parse_fs_string(fc, "huge", "within_size");
        if (!ret)
                gemfs = fc_mount_longterm(fc);
        put_fs_context(fc);
        if (ret)
                goto err;

        i915->mm.gemfs = gemfs;
        drm_info(&i915->drm, "Using Transparent Hugepages\n");
        return;

err:
        drm_notice(&i915->drm,
                   "Transparent Hugepage support is recommended for optimal performance%s\n",
                   GRAPHICS_VER(i915) >= 11 ? " on this platform!" :
                                              " when IOMMU is enabled!");
#endif
}

void i915_gemfs_fini(struct drm_i915_private *i915)
{
#ifdef __linux__
        kern_unmount(i915->mm.gemfs);
#endif
}