> -----Original Message-----
> From: Ankit Agrawal <[email protected]>
> Sent: 30 January 2026 04:07
> To: Ankit Agrawal <[email protected]>; Vikram Sethi <[email protected]>;
> Jason Gunthorpe <[email protected]>; Shameer Kolothum Thodi
> <[email protected]>; [email protected]; [email protected]
> Cc: Aniket Agashe <[email protected]>; Neo Jia <[email protected]>; Kirti
> Wankhede <[email protected]>; Tarun Gupta (SW-GPU)
> <[email protected]>; Zhi Wang <[email protected]>; Matt Ochs
> <[email protected]>; Krishnakant Jaju <[email protected]>; qemu-
> [email protected]
> Subject: [PATCH v1 1/2] hw/vfio: sort and validate sparse mmap regions by
> offset
>
> From: Ankit Agrawal <[email protected]>
>
> Sort sparse mmap regions by offset during region setup to ensure
> predictable mapping order, avoid overlaps and a proper handling
> of the gaps between sub-regions.
>
> Add validation to detect overlapping sparse regions early during
> setup before any mapping operations begin.
>
> The sorting is performed on the subregions ranges during
> vfio_setup_region_sparse_mmaps(). This also ensures that subsequent
> mapping code can rely on subregions being in ascending offset order.
>
> This is preparatory work for alignment adjustments needed to support
> hugepfnmap on systems where device memory (e.g., Grace-based systems)
> may have non-power-of-2 sizes.
>
> cc: Alex Williamson <[email protected]>
> Signed-off-by: Ankit Agrawal <[email protected]>
> ---
> hw/vfio/region.c | 45 ++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 44 insertions(+), 1 deletion(-)
>
> diff --git a/hw/vfio/region.c b/hw/vfio/region.c
> index ab39d77574..7622ae5683 100644
> --- a/hw/vfio/region.c
> +++ b/hw/vfio/region.c
> @@ -149,6 +149,19 @@ static const MemoryRegionOps vfio_region_ops = {
> },
> };
>
> +static int vfio_mmap_compare_offset(const void *a, const void *b)
> +{
> + const VFIOMmap *mmap_a = a;
> + const VFIOMmap *mmap_b = b;
> +
> + if (mmap_a->offset < mmap_b->offset) {
> + return -1;
> + } else if (mmap_a->offset > mmap_b->offset) {
> + return 1;
> + }
> + return 0;
> +}
> +
> static int vfio_setup_region_sparse_mmaps(VFIORegion *region,
> struct vfio_region_info *info)
> {
> @@ -182,6 +195,34 @@ static int
> vfio_setup_region_sparse_mmaps(VFIORegion *region,
> region->nr_mmaps = j;
> region->mmaps = g_realloc(region->mmaps, j * sizeof(VFIOMmap));
>
> + /*
> + * Sort sparse mmaps by offset to ensure proper handling of gaps
> + * and predictable mapping order in vfio_region_mmap().
> + */
> + if (region->nr_mmaps > 1) {
> + qsort(region->mmaps, region->nr_mmaps, sizeof(VFIOMmap),
> + vfio_mmap_compare_offset);
> +
> + /*
> + * Validate that sparse regions dont overlap after sorting.
> + */
> + for (i = 1; i < region->nr_mmaps; i++) {
> + off_t prev_end = region->mmaps[i - 1].offset +
> + region->mmaps[i - 1].size;
> + if (prev_end > region->mmaps[i].offset) {
> + error_report("%s: overlapping sparse mmap regions detected "
> + "in region %d: [0x%lx-0x%lx] overlaps with
> [0x%lx-0x%lx]",
> + __func__, region->nr, region->mmaps[i -
> 1].offset,
> + prev_end - 1, region->mmaps[i].offset,
> + region->mmaps[i].offset + region->mmaps[i].size
> - 1);
> + g_free(region->mmaps);
> + region->mmaps = NULL;
> + region->nr_mmaps = 0;
> + return -EINVAL;
> + }
> + }
> + }
> +
> return 0;
> }
>
> @@ -213,11 +254,13 @@ int vfio_region_setup(Object *obj, VFIODevice
> *vbasedev, VFIORegion *region,
>
> ret = vfio_setup_region_sparse_mmaps(region, info);
>
> - if (ret) {
> + if (ret == -ENODEV) {
> region->nr_mmaps = 1;
> region->mmaps = g_new0(VFIOMmap, region->nr_mmaps);
> region->mmaps[0].offset = 0;
> region->mmaps[0].size = region->size;
> + } else {
> + return ret;
> }
Is this now returns without the trace_xxx , right?
With that fixed:
Reviewed-by: Shameer Kolothum <[email protected]>
Thanks,
Shameer
> }
> }
> --
> 2.34.1
