// SPDX-License-Identifier: GPL-2.0-only
#include <dirent.h>
#include <fcntl.h>
#include <libgen.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <sys/eventfd.h>
#include <sys/ioctl.h>
#include <sys/mman.h>

#include <linux/iommufd.h>
#include <linux/limits.h>
#include <linux/mman.h>
#include <linux/overflow.h>
#include <linux/types.h>
#include <linux/vfio.h>

#include <libvfio.h>

struct iova_allocator *iova_allocator_init(struct iommu *iommu)
{
        struct iova_allocator *allocator;
        struct iommu_iova_range *ranges;
        u32 nranges;

        ranges = iommu_iova_ranges(iommu, &nranges);
        VFIO_ASSERT_NOT_NULL(ranges);

        allocator = malloc(sizeof(*allocator));
        VFIO_ASSERT_NOT_NULL(allocator);

        *allocator = (struct iova_allocator){
                .ranges = ranges,
                .nranges = nranges,
                .range_idx = 0,
                .range_offset = 0,
        };

        return allocator;
}

void iova_allocator_cleanup(struct iova_allocator *allocator)
{
        free(allocator->ranges);
        free(allocator);
}

iova_t iova_allocator_alloc(struct iova_allocator *allocator, size_t size)
{
        VFIO_ASSERT_GT(size, 0, "Invalid size arg, zero\n");
        VFIO_ASSERT_EQ(size & (size - 1), 0, "Invalid size arg, non-power-of-2\n");

        for (;;) {
                struct iommu_iova_range *range;
                iova_t iova, last;

                VFIO_ASSERT_LT(allocator->range_idx, allocator->nranges,
                               "IOVA allocator out of space\n");

                range = &allocator->ranges[allocator->range_idx];
                iova = range->start + allocator->range_offset;

                /* Check for sufficient space at the current offset */
                if (check_add_overflow(iova, size - 1, &last) ||
                    last > range->last)
                        goto next_range;

                /* Align iova to size */
                iova = last & ~(size - 1);

                /* Check for sufficient space at the aligned iova */
                if (check_add_overflow(iova, size - 1, &last) ||
                    last > range->last)
                        goto next_range;

                if (last == range->last) {
                        allocator->range_idx++;
                        allocator->range_offset = 0;
                } else {
                        allocator->range_offset = last - range->start + 1;
                }

                return iova;

next_range:
                allocator->range_idx++;
                allocator->range_offset = 0;
        }
}