/* SPDX-License-Identifier: GPL-2.0 OR MIT */
/**************************************************************************
 *
 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sub license, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 * USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 **************************************************************************/
/*
 * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
 */

#define pr_fmt(fmt) "[TTM] " fmt

#include <drm/ttm/ttm_bo_driver.h>
#include <drm/ttm/ttm_placement.h>
#include <drm/drm_vma_manager.h>
#include <drm/drm_drv.h>
#include <drm/drm_managed.h>
#include <linux/mm.h>
#include <linux/pfn_t.h>
#include <linux/rbtree.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <linux/mem_encrypt.h>

static vm_fault_t ttm_bo_vm_fault_idle(struct ttm_buffer_object *bo,
                                struct vm_fault *vmf)
{
        vm_fault_t ret = 0;
        int err = 0;

        if (likely(!bo->moving))
                goto out_unlock;

        /*
         * Quick non-stalling check for idle.
         */
        if (dma_fence_is_signaled(bo->moving))
                goto out_clear;

        /*
         * If possible, avoid waiting for GPU with mmap_lock
         * held.  We only do this if the fault allows retry and this
         * is the first attempt.
         */
        if (fault_flag_allow_retry_first(vmf->flags)) {
                ret = VM_FAULT_RETRY;
                if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT)
                        goto out_unlock;

                ttm_bo_get(bo);
                mmap_read_unlock(vmf->vma->vm_mm);
                (void) dma_fence_wait(bo->moving, true);
                dma_resv_unlock(bo->base.resv);
                ttm_bo_put(bo);
                goto out_unlock;
        }

        /*
         * Ordinary wait.
         */
        err = dma_fence_wait(bo->moving, true);
        if (unlikely(err != 0)) {
                ret = (err != -ERESTARTSYS) ? VM_FAULT_SIGBUS :
                        VM_FAULT_NOPAGE;
                goto out_unlock;
        }

out_clear:
        dma_fence_put(bo->moving);
        bo->moving = NULL;

out_unlock:
        return ret;
}

static unsigned long ttm_bo_io_mem_pfn(struct ttm_buffer_object *bo,
                                       unsigned long page_offset)
{
        struct ttm_device *bdev = bo->bdev;

        if (bdev->funcs->io_mem_pfn)
                return bdev->funcs->io_mem_pfn(bo, page_offset);

        return (bo->resource->bus.offset >> PAGE_SHIFT) + page_offset;
}

/**
 * ttm_bo_vm_reserve - Reserve a buffer object in a retryable vm callback
 * @bo: The buffer object
 * @vmf: The fault structure handed to the callback
 *
 * vm callbacks like fault() and *_mkwrite() allow for the mm_sem to be dropped
 * during long waits, and after the wait the callback will be restarted. This
 * is to allow other threads using the same virtual memory space concurrent
 * access to map(), unmap() completely unrelated buffer objects. TTM buffer
 * object reservations sometimes wait for GPU and should therefore be
 * considered long waits. This function reserves the buffer object interruptibly
 * taking this into account. Starvation is avoided by the vm system not
 * allowing too many repeated restarts.
 * This function is intended to be used in customized fault() and _mkwrite()
 * handlers.
 *
 * Return:
 *    0 on success and the bo was reserved.
 *    VM_FAULT_RETRY if blocking wait.
 *    VM_FAULT_NOPAGE if blocking wait and retrying was not allowed.
 */
vm_fault_t ttm_bo_vm_reserve(struct ttm_buffer_object *bo,
                             struct vm_fault *vmf)
{
        /*
         * Work around locking order reversal in fault / nopfn
         * between mmap_lock and bo_reserve: Perform a trylock operation
         * for reserve, and if it fails, retry the fault after waiting
         * for the buffer to become unreserved.
         */
        if (unlikely(!dma_resv_trylock(bo->base.resv))) {
                /*
                 * If the fault allows retry and this is the first
                 * fault attempt, we try to release the mmap_lock
                 * before waiting
                 */
                if (fault_flag_allow_retry_first(vmf->flags)) {
                        if (!(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) {
                                ttm_bo_get(bo);
                                mmap_read_unlock(vmf->vma->vm_mm);
                                if (!dma_resv_lock_interruptible(bo->base.resv,
                                                                 NULL))
                                        dma_resv_unlock(bo->base.resv);
                                ttm_bo_put(bo);
                        }

                        return VM_FAULT_RETRY;
                }

                if (dma_resv_lock_interruptible(bo->base.resv, NULL))
                        return VM_FAULT_NOPAGE;
        }

        /*
         * Refuse to fault imported pages. This should be handled
         * (if at all) by redirecting mmap to the exporter.
         */
        if (bo->ttm && (bo->ttm->page_flags & TTM_PAGE_FLAG_SG)) {
                dma_resv_unlock(bo->base.resv);
                return VM_FAULT_SIGBUS;
        }

        return 0;
}
EXPORT_SYMBOL(ttm_bo_vm_reserve);

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
/**
 * ttm_bo_vm_insert_huge - Insert a pfn for PUD or PMD faults
 * @vmf: Fault data
 * @bo: The buffer object
 * @page_offset: Page offset from bo start
 * @fault_page_size: The size of the fault in pages.
 * @pgprot: The page protections.
 * Does additional checking whether it's possible to insert a PUD or PMD
 * pfn and performs the insertion.
 *
 * Return: VM_FAULT_NOPAGE on successful insertion, VM_FAULT_FALLBACK if
 * a huge fault was not possible, or on insertion error.
 */
static vm_fault_t ttm_bo_vm_insert_huge(struct vm_fault *vmf,
                                        struct ttm_buffer_object *bo,
                                        pgoff_t page_offset,
                                        pgoff_t fault_page_size,
                                        pgprot_t pgprot)
{
        pgoff_t i;
        vm_fault_t ret;
        unsigned long pfn;
        pfn_t pfnt;
        struct ttm_tt *ttm = bo->ttm;
        bool write = vmf->flags & FAULT_FLAG_WRITE;

        /* Fault should not cross bo boundary. */
        page_offset &= ~(fault_page_size - 1);
        if (page_offset + fault_page_size > bo->resource->num_pages)
                goto out_fallback;

        if (bo->resource->bus.is_iomem)
                pfn = ttm_bo_io_mem_pfn(bo, page_offset);
        else
                pfn = page_to_pfn(ttm->pages[page_offset]);

        /* pfn must be fault_page_size aligned. */
        if ((pfn & (fault_page_size - 1)) != 0)
                goto out_fallback;

        /* Check that memory is contiguous. */
        if (!bo->resource->bus.is_iomem) {
                for (i = 1; i < fault_page_size; ++i) {
                        if (page_to_pfn(ttm->pages[page_offset + i]) != pfn + i)
                                goto out_fallback;
                }
        } else if (bo->bdev->funcs->io_mem_pfn) {
                for (i = 1; i < fault_page_size; ++i) {
                        if (ttm_bo_io_mem_pfn(bo, page_offset + i) != pfn + i)
                                goto out_fallback;
                }
        }

        pfnt = __pfn_to_pfn_t(pfn, PFN_DEV);
        if (fault_page_size == (HPAGE_PMD_SIZE >> PAGE_SHIFT))
                ret = vmf_insert_pfn_pmd_prot(vmf, pfnt, pgprot, write);
#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
        else if (fault_page_size == (HPAGE_PUD_SIZE >> PAGE_SHIFT))
                ret = vmf_insert_pfn_pud_prot(vmf, pfnt, pgprot, write);
#endif
        else
                WARN_ON_ONCE(ret = VM_FAULT_FALLBACK);

        if (ret != VM_FAULT_NOPAGE)
                goto out_fallback;

        return VM_FAULT_NOPAGE;
out_fallback:
        count_vm_event(THP_FAULT_FALLBACK);
        return VM_FAULT_FALLBACK;
}
#else
static vm_fault_t ttm_bo_vm_insert_huge(struct vm_fault *vmf,
                                        struct ttm_buffer_object *bo,
                                        pgoff_t page_offset,
                                        pgoff_t fault_page_size,
                                        pgprot_t pgprot)
{
        return VM_FAULT_FALLBACK;
}
#endif

/**
 * ttm_bo_vm_fault_reserved - TTM fault helper
 * @vmf: The struct vm_fault given as argument to the fault callback
 * @prot: The page protection to be used for this memory area.
 * @num_prefault: Maximum number of prefault pages. The caller may want to
 * specify this based on madvice settings and the size of the GPU object
 * backed by the memory.
 * @fault_page_size: The size of the fault in pages.
 *
 * This function inserts one or more page table entries pointing to the
 * memory backing the buffer object, and then returns a return code
 * instructing the caller to retry the page access.
 *
 * Return:
 *   VM_FAULT_NOPAGE on success or pending signal
 *   VM_FAULT_SIGBUS on unspecified error
 *   VM_FAULT_OOM on out-of-memory
 *   VM_FAULT_RETRY if retryable wait
 */
vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
                                    pgprot_t prot,
                                    pgoff_t num_prefault,
                                    pgoff_t fault_page_size)
{
        struct vm_area_struct *vma = vmf->vma;
        struct ttm_buffer_object *bo = vma->vm_private_data;
        struct ttm_device *bdev = bo->bdev;
        unsigned long page_offset;
        unsigned long page_last;
        unsigned long pfn;
        struct ttm_tt *ttm = NULL;
        struct page *page;
        int err;
        pgoff_t i;
        vm_fault_t ret = VM_FAULT_NOPAGE;
        unsigned long address = vmf->address;

        /*
         * Wait for buffer data in transit, due to a pipelined
         * move.
         */
        ret = ttm_bo_vm_fault_idle(bo, vmf);
        if (unlikely(ret != 0))
                return ret;

        err = ttm_mem_io_reserve(bdev, bo->resource);
        if (unlikely(err != 0))
                return VM_FAULT_SIGBUS;

        page_offset = ((address - vma->vm_start) >> PAGE_SHIFT) +
                vma->vm_pgoff - drm_vma_node_start(&bo->base.vma_node);
        page_last = vma_pages(vma) + vma->vm_pgoff -
                drm_vma_node_start(&bo->base.vma_node);

        if (unlikely(page_offset >= bo->resource->num_pages))
                return VM_FAULT_SIGBUS;

        prot = ttm_io_prot(bo, bo->resource, prot);
        if (!bo->resource->bus.is_iomem) {
                struct ttm_operation_ctx ctx = {
                        .interruptible = false,
                        .no_wait_gpu = false,
                        .force_alloc = true
                };

                ttm = bo->ttm;
                if (ttm_tt_populate(bdev, bo->ttm, &ctx))
                        return VM_FAULT_OOM;
        } else {
                /* Iomem should not be marked encrypted */
                prot = pgprot_decrypted(prot);
        }

        /* We don't prefault on huge faults. Yet. */
        if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && fault_page_size != 1)
                return ttm_bo_vm_insert_huge(vmf, bo, page_offset,
                                             fault_page_size, prot);

        /*
         * Speculatively prefault a number of pages. Only error on
         * first page.
         */
        for (i = 0; i < num_prefault; ++i) {
                if (bo->resource->bus.is_iomem) {
                        pfn = ttm_bo_io_mem_pfn(bo, page_offset);
                } else {
                        page = ttm->pages[page_offset];
                        if (unlikely(!page && i == 0)) {
                                return VM_FAULT_OOM;
                        } else if (unlikely(!page)) {
                                break;
                        }
                        page->index = drm_vma_node_start(&bo->base.vma_node) +
                                page_offset;
                        pfn = page_to_pfn(page);
                }

                /*
                 * Note that the value of @prot at this point may differ from
                 * the value of @vma->vm_page_prot in the caching- and
                 * encryption bits. This is because the exact location of the
                 * data may not be known at mmap() time and may also change
                 * at arbitrary times while the data is mmap'ed.
                 * See vmf_insert_mixed_prot() for a discussion.
                 */
                ret = vmf_insert_pfn_prot(vma, address, pfn, prot);

                /* Never error on prefaulted PTEs */
                if (unlikely((ret & VM_FAULT_ERROR))) {
                        if (i == 0)
                                return VM_FAULT_NOPAGE;
                        else
                                break;
                }

                address += PAGE_SIZE;
                if (unlikely(++page_offset >= page_last))
                        break;
        }
        return ret;
}
EXPORT_SYMBOL(ttm_bo_vm_fault_reserved);

static void ttm_bo_release_dummy_page(struct drm_device *dev, void *res)
{
        struct page *dummy_page = (struct page *)res;

        __free_page(dummy_page);
}

vm_fault_t ttm_bo_vm_dummy_page(struct vm_fault *vmf, pgprot_t prot)
{
        struct vm_area_struct *vma = vmf->vma;
        struct ttm_buffer_object *bo = vma->vm_private_data;
        struct drm_device *ddev = bo->base.dev;
        vm_fault_t ret = VM_FAULT_NOPAGE;
        unsigned long address;
        unsigned long pfn;
        struct page *page;

        /* Allocate new dummy page to map all the VA range in this VMA to it*/
        page = alloc_page(GFP_KERNEL | __GFP_ZERO);
        if (!page)
                return VM_FAULT_OOM;

        /* Set the page to be freed using drmm release action */
        if (drmm_add_action_or_reset(ddev, ttm_bo_release_dummy_page, page))
                return VM_FAULT_OOM;

        pfn = page_to_pfn(page);

        /* Prefault the entire VMA range right away to avoid further faults */
        for (address = vma->vm_start; address < vma->vm_end;
             address += PAGE_SIZE)
                ret = vmf_insert_pfn_prot(vma, address, pfn, prot);

        return ret;
}
EXPORT_SYMBOL(ttm_bo_vm_dummy_page);

vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
{
        struct vm_area_struct *vma = vmf->vma;
        pgprot_t prot;
        struct ttm_buffer_object *bo = vma->vm_private_data;
        struct drm_device *ddev = bo->base.dev;
        vm_fault_t ret;
        int idx;

        ret = ttm_bo_vm_reserve(bo, vmf);
        if (ret)
                return ret;

        prot = vma->vm_page_prot;
        if (drm_dev_enter(ddev, &idx)) {
                ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT, 1);
                drm_dev_exit(idx);
        } else {
                ret = ttm_bo_vm_dummy_page(vmf, prot);
        }
        if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
                return ret;

        dma_resv_unlock(bo->base.resv);

        return ret;
}
EXPORT_SYMBOL(ttm_bo_vm_fault);

void ttm_bo_vm_open(struct vm_area_struct *vma)
{
        struct ttm_buffer_object *bo = vma->vm_private_data;

        WARN_ON(bo->bdev->dev_mapping != vma->vm_file->f_mapping);

        ttm_bo_get(bo);
}
EXPORT_SYMBOL(ttm_bo_vm_open);

void ttm_bo_vm_close(struct vm_area_struct *vma)
{
        struct ttm_buffer_object *bo = vma->vm_private_data;

        ttm_bo_put(bo);
        vma->vm_private_data = NULL;
}
EXPORT_SYMBOL(ttm_bo_vm_close);

static int ttm_bo_vm_access_kmap(struct ttm_buffer_object *bo,
                                 unsigned long offset,
                                 uint8_t *buf, int len, int write)
{
        unsigned long page = offset >> PAGE_SHIFT;
        unsigned long bytes_left = len;
        int ret;

        /* Copy a page at a time, that way no extra virtual address
         * mapping is needed
         */
        offset -= page << PAGE_SHIFT;
        do {
                unsigned long bytes = min(bytes_left, PAGE_SIZE - offset);
                struct ttm_bo_kmap_obj map;
                void *ptr;
                bool is_iomem;

                ret = ttm_bo_kmap(bo, page, 1, &map);
                if (ret)
                        return ret;

                ptr = (uint8_t *)ttm_kmap_obj_virtual(&map, &is_iomem) + offset;
                WARN_ON_ONCE(is_iomem);
                if (write)
                        memcpy(ptr, buf, bytes);
                else
                        memcpy(buf, ptr, bytes);
                ttm_bo_kunmap(&map);

                page++;
                buf += bytes;
                bytes_left -= bytes;
                offset = 0;
        } while (bytes_left);

        return len;
}

int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
                     void *buf, int len, int write)
{
        struct ttm_buffer_object *bo = vma->vm_private_data;
        unsigned long offset = (addr) - vma->vm_start +
                ((vma->vm_pgoff - drm_vma_node_start(&bo->base.vma_node))
                 << PAGE_SHIFT);
        int ret;

        if (len < 1 || (offset + len) >> PAGE_SHIFT > bo->resource->num_pages)
                return -EIO;

        ret = ttm_bo_reserve(bo, true, false, NULL);
        if (ret)
                return ret;

        switch (bo->resource->mem_type) {
        case TTM_PL_SYSTEM:
                if (unlikely(bo->ttm->page_flags & TTM_PAGE_FLAG_SWAPPED)) {
                        ret = ttm_tt_swapin(bo->ttm);
                        if (unlikely(ret != 0))
                                return ret;
                }
                fallthrough;
        case TTM_PL_TT:
                ret = ttm_bo_vm_access_kmap(bo, offset, buf, len, write);
                break;
        default:
                if (bo->bdev->funcs->access_memory)
                        ret = bo->bdev->funcs->access_memory(
                                bo, offset, buf, len, write);
                else
                        ret = -EIO;
        }

        ttm_bo_unreserve(bo);

        return ret;
}
EXPORT_SYMBOL(ttm_bo_vm_access);

static const struct vm_operations_struct ttm_bo_vm_ops = {
        .fault = ttm_bo_vm_fault,
        .open = ttm_bo_vm_open,
        .close = ttm_bo_vm_close,
        .access = ttm_bo_vm_access,
};

int ttm_bo_mmap_obj(struct vm_area_struct *vma, struct ttm_buffer_object *bo)
{
        /* Enforce no COW since would have really strange behavior with it. */
        if (is_cow_mapping(vma->vm_flags))
                return -EINVAL;

        ttm_bo_get(bo);

        /*
         * Drivers may want to override the vm_ops field. Otherwise we
         * use TTM's default callbacks.
         */
        if (!vma->vm_ops)
                vma->vm_ops = &ttm_bo_vm_ops;

        /*
         * Note: We're transferring the bo reference to
         * vma->vm_private_data here.
         */

        vma->vm_private_data = bo;

        vma->vm_flags |= VM_PFNMAP;
        vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP;
        return 0;
}
EXPORT_SYMBOL(ttm_bo_mmap_obj);