// SPDX-License-Identifier: MIT
/*
 * Copyright © 2025 Intel Corporation
 */

#include "xe_svm.h"
#include "xe_userptr.h"

#include <linux/mm.h>

#include "xe_trace_bo.h"

/**
 * xe_vma_userptr_check_repin() - Advisory check for repin needed
 * @uvma: The userptr vma
 *
 * Check if the userptr vma has been invalidated since last successful
 * repin. The check is advisory only and can the function can be called
 * without the vm->svm.gpusvm.notifier_lock held. There is no guarantee that the
 * vma userptr will remain valid after a lockless check, so typically
 * the call needs to be followed by a proper check under the notifier_lock.
 *
 * Return: 0 if userptr vma is valid, -EAGAIN otherwise; repin recommended.
 */
int xe_vma_userptr_check_repin(struct xe_userptr_vma *uvma)
{
        return mmu_interval_check_retry(&uvma->userptr.notifier,
                                        uvma->userptr.pages.notifier_seq) ?
                -EAGAIN : 0;
}

/**
 * __xe_vm_userptr_needs_repin() - Check whether the VM does have userptrs
 * that need repinning.
 * @vm: The VM.
 *
 * This function checks for whether the VM has userptrs that need repinning,
 * and provides a release-type barrier on the svm.gpusvm.notifier_lock after
 * checking.
 *
 * Return: 0 if there are no userptrs needing repinning, -EAGAIN if there are.
 */
int __xe_vm_userptr_needs_repin(struct xe_vm *vm)
{
        lockdep_assert_held_read(&vm->svm.gpusvm.notifier_lock);

        return (list_empty(&vm->userptr.repin_list) &&
                list_empty(&vm->userptr.invalidated)) ? 0 : -EAGAIN;
}

int xe_vma_userptr_pin_pages(struct xe_userptr_vma *uvma)
{
        struct xe_vma *vma = &uvma->vma;
        struct xe_vm *vm = xe_vma_vm(vma);
        struct xe_device *xe = vm->xe;
        struct drm_gpusvm_ctx ctx = {
                .read_only = xe_vma_read_only(vma),
                .device_private_page_owner = xe_svm_private_page_owner(vm, false),
                .allow_mixed = true,
        };

        lockdep_assert_held(&vm->lock);
        xe_assert(xe, xe_vma_is_userptr(vma));

        if (vma->gpuva.flags & XE_VMA_DESTROYED)
                return 0;

        return drm_gpusvm_get_pages(&vm->svm.gpusvm, &uvma->userptr.pages,
                                    uvma->userptr.notifier.mm,
                                    &uvma->userptr.notifier,
                                    xe_vma_userptr(vma),
                                    xe_vma_userptr(vma) + xe_vma_size(vma),
                                    &ctx);
}

static void __vma_userptr_invalidate(struct xe_vm *vm, struct xe_userptr_vma *uvma)
{
        struct xe_userptr *userptr = &uvma->userptr;
        struct xe_vma *vma = &uvma->vma;
        struct dma_resv_iter cursor;
        struct dma_fence *fence;
        struct drm_gpusvm_ctx ctx = {
                .in_notifier = true,
                .read_only = xe_vma_read_only(vma),
        };
        long err;

        /*
         * Tell exec and rebind worker they need to repin and rebind this
         * userptr.
         */
        if (!xe_vm_in_fault_mode(vm) &&
            !(vma->gpuva.flags & XE_VMA_DESTROYED)) {
                spin_lock(&vm->userptr.invalidated_lock);
                list_move_tail(&userptr->invalidate_link,
                               &vm->userptr.invalidated);
                spin_unlock(&vm->userptr.invalidated_lock);
        }

        /*
         * Preempt fences turn into schedule disables, pipeline these.
         * Note that even in fault mode, we need to wait for binds and
         * unbinds to complete, and those are attached as BOOKMARK fences
         * to the vm.
         */
        dma_resv_iter_begin(&cursor, xe_vm_resv(vm),
                            DMA_RESV_USAGE_BOOKKEEP);
        dma_resv_for_each_fence_unlocked(&cursor, fence)
                dma_fence_enable_sw_signaling(fence);
        dma_resv_iter_end(&cursor);

        err = dma_resv_wait_timeout(xe_vm_resv(vm),
                                    DMA_RESV_USAGE_BOOKKEEP,
                                    false, MAX_SCHEDULE_TIMEOUT);
        XE_WARN_ON(err <= 0);

        if (xe_vm_in_fault_mode(vm) && userptr->initial_bind) {
                err = xe_vm_invalidate_vma(vma);
                XE_WARN_ON(err);
        }

        drm_gpusvm_unmap_pages(&vm->svm.gpusvm, &uvma->userptr.pages,
                               xe_vma_size(vma) >> PAGE_SHIFT, &ctx);
}

static bool vma_userptr_invalidate(struct mmu_interval_notifier *mni,
                                   const struct mmu_notifier_range *range,
                                   unsigned long cur_seq)
{
        struct xe_userptr_vma *uvma = container_of(mni, typeof(*uvma), userptr.notifier);
        struct xe_vma *vma = &uvma->vma;
        struct xe_vm *vm = xe_vma_vm(vma);

        xe_assert(vm->xe, xe_vma_is_userptr(vma));
        trace_xe_vma_userptr_invalidate(vma);

        if (!mmu_notifier_range_blockable(range))
                return false;

        vm_dbg(&xe_vma_vm(vma)->xe->drm,
               "NOTIFIER: addr=0x%016llx, range=0x%016llx",
                xe_vma_start(vma), xe_vma_size(vma));

        down_write(&vm->svm.gpusvm.notifier_lock);
        mmu_interval_set_seq(mni, cur_seq);

        __vma_userptr_invalidate(vm, uvma);
        up_write(&vm->svm.gpusvm.notifier_lock);
        trace_xe_vma_userptr_invalidate_complete(vma);

        return true;
}

static const struct mmu_interval_notifier_ops vma_userptr_notifier_ops = {
        .invalidate = vma_userptr_invalidate,
};

#if IS_ENABLED(CONFIG_DRM_XE_USERPTR_INVAL_INJECT)
/**
 * xe_vma_userptr_force_invalidate() - force invalidate a userptr
 * @uvma: The userptr vma to invalidate
 *
 * Perform a forced userptr invalidation for testing purposes.
 */
void xe_vma_userptr_force_invalidate(struct xe_userptr_vma *uvma)
{
        struct xe_vm *vm = xe_vma_vm(&uvma->vma);

        /* Protect against concurrent userptr pinning */
        lockdep_assert_held(&vm->lock);
        /* Protect against concurrent notifiers */
        lockdep_assert_held(&vm->svm.gpusvm.notifier_lock);
        /*
         * Protect against concurrent instances of this function and
         * the critical exec sections
         */
        xe_vm_assert_held(vm);

        if (!mmu_interval_read_retry(&uvma->userptr.notifier,
                                     uvma->userptr.pages.notifier_seq))
                uvma->userptr.pages.notifier_seq -= 2;
        __vma_userptr_invalidate(vm, uvma);
}
#endif

int xe_vm_userptr_pin(struct xe_vm *vm)
{
        struct xe_userptr_vma *uvma, *next;
        int err = 0;

        xe_assert(vm->xe, !xe_vm_in_fault_mode(vm));
        lockdep_assert_held_write(&vm->lock);

        /* Collect invalidated userptrs */
        spin_lock(&vm->userptr.invalidated_lock);
        xe_assert(vm->xe, list_empty(&vm->userptr.repin_list));
        list_for_each_entry_safe(uvma, next, &vm->userptr.invalidated,
                                 userptr.invalidate_link) {
                list_del_init(&uvma->userptr.invalidate_link);
                list_add_tail(&uvma->userptr.repin_link,
                              &vm->userptr.repin_list);
        }
        spin_unlock(&vm->userptr.invalidated_lock);

        /* Pin and move to bind list */
        list_for_each_entry_safe(uvma, next, &vm->userptr.repin_list,
                                 userptr.repin_link) {
                err = xe_vma_userptr_pin_pages(uvma);
                if (err == -EFAULT) {
                        list_del_init(&uvma->userptr.repin_link);
                        /*
                         * We might have already done the pin once already, but
                         * then had to retry before the re-bind happened, due
                         * some other condition in the caller, but in the
                         * meantime the userptr got dinged by the notifier such
                         * that we need to revalidate here, but this time we hit
                         * the EFAULT. In such a case make sure we remove
                         * ourselves from the rebind list to avoid going down in
                         * flames.
                         */
                        if (!list_empty(&uvma->vma.combined_links.rebind))
                                list_del_init(&uvma->vma.combined_links.rebind);

                        /* Wait for pending binds */
                        xe_vm_lock(vm, false);
                        dma_resv_wait_timeout(xe_vm_resv(vm),
                                              DMA_RESV_USAGE_BOOKKEEP,
                                              false, MAX_SCHEDULE_TIMEOUT);

                        down_read(&vm->svm.gpusvm.notifier_lock);
                        err = xe_vm_invalidate_vma(&uvma->vma);
                        up_read(&vm->svm.gpusvm.notifier_lock);
                        xe_vm_unlock(vm);
                        if (err)
                                break;
                } else {
                        if (err)
                                break;

                        list_del_init(&uvma->userptr.repin_link);
                        list_move_tail(&uvma->vma.combined_links.rebind,
                                       &vm->rebind_list);
                }
        }

        if (err) {
                down_write(&vm->svm.gpusvm.notifier_lock);
                spin_lock(&vm->userptr.invalidated_lock);
                list_for_each_entry_safe(uvma, next, &vm->userptr.repin_list,
                                         userptr.repin_link) {
                        list_del_init(&uvma->userptr.repin_link);
                        list_move_tail(&uvma->userptr.invalidate_link,
                                       &vm->userptr.invalidated);
                }
                spin_unlock(&vm->userptr.invalidated_lock);
                up_write(&vm->svm.gpusvm.notifier_lock);
        }
        return err;
}

/**
 * xe_vm_userptr_check_repin() - Check whether the VM might have userptrs
 * that need repinning.
 * @vm: The VM.
 *
 * This function does an advisory check for whether the VM has userptrs that
 * need repinning.
 *
 * Return: 0 if there are no indications of userptrs needing repinning,
 * -EAGAIN if there are.
 */
int xe_vm_userptr_check_repin(struct xe_vm *vm)
{
        return (list_empty_careful(&vm->userptr.repin_list) &&
                list_empty_careful(&vm->userptr.invalidated)) ? 0 : -EAGAIN;
}

int xe_userptr_setup(struct xe_userptr_vma *uvma, unsigned long start,
                     unsigned long range)
{
        struct xe_userptr *userptr = &uvma->userptr;
        int err;

        INIT_LIST_HEAD(&userptr->invalidate_link);
        INIT_LIST_HEAD(&userptr->repin_link);

        err = mmu_interval_notifier_insert(&userptr->notifier, current->mm,
                                           start, range,
                                           &vma_userptr_notifier_ops);
        if (err)
                return err;

        userptr->pages.notifier_seq = LONG_MAX;

        return 0;
}

void xe_userptr_remove(struct xe_userptr_vma *uvma)
{
        struct xe_vm *vm = xe_vma_vm(&uvma->vma);
        struct xe_userptr *userptr = &uvma->userptr;

        drm_gpusvm_free_pages(&vm->svm.gpusvm, &uvma->userptr.pages,
                              xe_vma_size(&uvma->vma) >> PAGE_SHIFT);

        /*
         * Since userptr pages are not pinned, we can't remove
         * the notifier until we're sure the GPU is not accessing
         * them anymore
         */
        mmu_interval_notifier_remove(&userptr->notifier);
}

void xe_userptr_destroy(struct xe_userptr_vma *uvma)
{
        struct xe_vm *vm = xe_vma_vm(&uvma->vma);

        spin_lock(&vm->userptr.invalidated_lock);
        xe_assert(vm->xe, list_empty(&uvma->userptr.repin_link));
        list_del(&uvma->userptr.invalidate_link);
        spin_unlock(&vm->userptr.invalidated_lock);
}