open-gpu-kernel-modules/kernel-open/nvidia-uvm/uvm_test_file.c

/*******************************************************************************
    Copyright (c) 2024 NVIDIA Corporation

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        The above copyright notice and this permission notice shall be
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    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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#include "uvm_common.h"
#include "uvm_fd_type.h"
#include "uvm_linux.h"
#include "uvm_lock.h"
#include "uvm_kvmalloc.h"
#include "uvm_test.h"
#include "uvm_test_ioctl.h"
#include "uvm_test_file.h"

#include <linux/mm.h>
#include <linux/mm_types.h>

NV_STATUS uvm_test_file_initialize(UVM_TEST_FILE_INITIALIZE_PARAMS *params, struct file *filp)
{
    uvm_test_file_t *test_file;
    NV_STATUS status;

    status = uvm_fd_type_init(filp);
    if (status != NV_OK)
        return status;

    test_file = uvm_kvmalloc_zero(sizeof(*test_file));
    if (!test_file)
        goto error;

    INIT_RADIX_TREE(&test_file->page_tree, NV_UVM_GFP_FLAGS);
    uvm_mutex_init(&test_file->mutex, UVM_LOCK_ORDER_LEAF);

    uvm_fd_type_set(filp, UVM_FD_TEST, test_file);
    return NV_OK;

error:
    uvm_fd_type_set(filp, UVM_FD_UNINITIALIZED, NULL);
    return status;
}

// If index (page offset) already has a page allocated, return that page.
// Otherwise allocate, zero, insert, and return the page.
static struct page *test_file_get_page(uvm_test_file_t *test_file, NvU64 index)
{
    struct page *page;

    uvm_assert_mutex_locked(&test_file->mutex);

    page = radix_tree_lookup(&test_file->page_tree, index);
    if (!page) {
        page = alloc_page(NV_UVM_GFP_FLAGS | __GFP_ZERO);
        if (page && radix_tree_insert(&test_file->page_tree, index, page)) {
            __free_page(page);
            page = NULL;
        }
    }

    return page;
}

static struct vm_operations_struct uvm_vm_ops_empty;

int uvm_test_file_mmap(uvm_test_file_t *test_file, struct vm_area_struct *vma)
{
    NvU64 i;
    int ret = 0;

    uvm_mutex_lock(&test_file->mutex);

    // Unlike managed or semaphore vmas, we don't have any state to track
    // associated with the vma. We'll free the pages at file release time. If
    // the user wants to fork() or mremap(), we shouldn't care. The only reason
    // to assign vm_ops instead of leaving it NULL is to prevent
    // vma_is_anonymous() from returning true on this vma, which would cause
    // migrate_pageable_vma() to attempt to migrate instead of falling back to
    // uvm_populate_pageable_vma().
    vma->vm_ops = &uvm_vm_ops_empty;

    for (i = 0; i < vma_pages(vma); i++) {
        struct page *page = test_file_get_page(test_file, vma->vm_pgoff + i);
        if (!page) {
            ret = -ENOMEM;
            break;
        }

        // Let remap_pfn_range() set up our vma flags
        ret = remap_pfn_range(vma, vma->vm_start + i * PAGE_SIZE, page_to_pfn(page), 1, vma->vm_page_prot);
        if (ret) {
            // The kernel will unmap any already-mapped pages on mmap() failure
            break;
        }
    }

    uvm_mutex_unlock(&test_file->mutex);
    return ret;
}

NV_STATUS uvm_test_file_unmap(UVM_TEST_FILE_UNMAP_PARAMS *params, struct file *filp)
{
    if (uvm_fd_type(filp, NULL) != UVM_FD_TEST)
        return NV_ERR_ILLEGAL_ACTION;

    unmap_mapping_range(filp->f_mapping, params->offset, params->length, 1);
    return NV_OK;
}

void uvm_test_file_release(struct file *filp, uvm_test_file_t *test_file)
{
    void **slot;
    struct radix_tree_iter iter;

    radix_tree_for_each_slot(slot, &test_file->page_tree, &iter, 0) {
        void *ret;
        struct page *page = *slot;
        UVM_ASSERT(page);
        ret = radix_tree_delete(&test_file->page_tree, iter.index);
        UVM_ASSERT(ret == page);
        __free_page(page);
    }

    uvm_kvfree(test_file);

    // Allocated by uvm_open for all fd types
    uvm_kvfree(filp->f_mapping);
}