[Mesa-dev] [PATCH 1/4] intel/dump_gpu: Fix corner cases in PPGTT range calculations

[Lionel Landwerlin]

On 18/07/18 00:05, Jason Ekstrand wrote:
> For large buffers which span an entire l1 page table, we got the range
> calculations wrong.  In this case, we end up with an l1_start which is
> the first byte represented by the given l1 table and an l1_end which is
> the first byte after the range represented by the l1 table.  Then
> l2_start_index == L2_index(l2_end) due to roll-over.  Instead, compute
> lN_end using (1Ull << shift) - 1 so that lN_end is the last byte in the
> range represented by the Nth level page table.  When we do this, we
> don't need the conditional expression anymore.
> ---
>   src/intel/tools/intel_dump_gpu.c | 12 ++++++------
>   1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/src/intel/tools/intel_dump_gpu.c b/src/intel/tools/intel_dump_gpu.c
> index 766ba662d91..5a0283960c1 100644
> --- a/src/intel/tools/intel_dump_gpu.c
> +++ b/src/intel/tools/intel_dump_gpu.c
> @@ -457,28 +457,28 @@ map_ppgtt(uint64_t start, uint64_t size)
>   
>      for (uint64_t l4 = l4_start; l4 < l4_end; l4 += (1ULL << 39)) {
>         uint64_t l3_start = max(l4, start & 0xffffc0000000);
> -      uint64_t l3_end = min(l4 + (1ULL << 39),
> +      uint64_t l3_end = min(l4 + (1ULL << 39) - 1,
>                               ((start + size - 1) | 0x00003fffffff) & 0xffffffffffff);
>         uint64_t l3_start_idx = L3_index(l3_start);
> -      uint64_t l3_end_idx = L3_index(l3_start) >= l3_start_idx ? L3_index(l3_end) : 0x1ff;
> +      uint64_t l3_end_idx = L3_index(l3_start);

uint64_t l3_end_idx = L3_index(l3_end);

>   
>         populate_ppgtt_table(L3_table(l4), l3_start_idx, l3_end_idx, 3);
>   
>         for (uint64_t l3 = l3_start; l3 < l3_end; l3 += (1ULL << 30)) {
>            uint64_t l2_start = max(l3, start & 0xffffffe00000);
> -         uint64_t l2_end = min(l3 + (1ULL << 30),
> +         uint64_t l2_end = min(l3 + (1ULL << 30) - 1,
>                                  ((start + size - 1) | 0x0000001fffff) & 0xffffffffffff);
>            uint64_t l2_start_idx = L2_index(l2_start);
> -         uint64_t l2_end_idx = L2_index(l2_end) >= l2_start_idx ? L2_index(l2_end) : 0x1ff;
> +         uint64_t l2_end_idx = L2_index(l2_end);
>   
>            populate_ppgtt_table(L2_table(l3), l2_start_idx, l2_end_idx, 2);
>   
>            for (uint64_t l2 = l2_start; l2 < l2_end; l2 += (1ULL << 21)) {
>               uint64_t l1_start = max(l2, start & 0xfffffffff000);
> -            uint64_t l1_end = min(l2 + (1ULL << 21),
> +            uint64_t l1_end = min(l2 + (1ULL << 21) - 1,
>                                     ((start + size - 1) | 0x000000000fff) & 0xffffffffffff);
>               uint64_t l1_start_idx = L1_index(l1_start);
> -            uint64_t l1_end_idx = L1_index(l1_end) >= l1_start_idx ? L1_index(l1_end) : 0x1ff;
> +            uint64_t l1_end_idx = L1_index(l1_end);
>   
>               populate_ppgtt_table(L1_table(l2), l1_start_idx, l1_end_idx, 1);
>            }