On Wed, Feb 11, 2026 at 6:07 AM Pierre-Eric Pelloux-Prayer
<[email protected]> wrote:
>
> Now that we have a worker thread, we can try to access the
> IBs of the job. The process is:
> * get the VM from the PASID
> * get the BO from its VA and the VM
> * map the BO for CPU access
> * copy everything, then add it to the dump
> Each step can fail so we have to be cautious.
> These operations can be slow so when amdgpu_devcoredump_format
> is called only to determine the size of the buffer we skip all
> of them and assume they will succeed.
>
> Signed-off-by: Pierre-Eric Pelloux-Prayer <[email protected]>
> ---
> .../gpu/drm/amd/amdgpu/amdgpu_dev_coredump.c | 84 ++++++++++++++++++-
> 1 file changed, 83 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dev_coredump.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_dev_coredump.c
> index d0af8a294abf..d576518c212d 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dev_coredump.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dev_coredump.c
> @@ -200,12 +200,20 @@ static void amdgpu_devcoredump_fw_info(struct
> amdgpu_device *adev,
> static ssize_t
> amdgpu_devcoredump_format(char *buffer, size_t count, struct
> amdgpu_coredump_info *coredump)
> {
> + struct amdgpu_device *adev = coredump->adev;
> struct drm_printer p;
> struct drm_print_iterator iter;
> struct amdgpu_vm_fault_info *fault_info;
> + struct amdgpu_bo_va_mapping *mapping;
> struct amdgpu_ip_block *ip_block;
> + struct amdgpu_res_cursor cursor;
> + struct amdgpu_bo *abo, *root;
> + uint64_t va_start, offset;
> struct amdgpu_ring *ring;
> - int ver, i, j;
> + struct amdgpu_vm *vm;
> + u32 *ib_content;
> + uint8_t *kptr;
> + int ver, i, j, r;
> u32 ring_idx, off;
>
> iter.data = buffer;
> @@ -323,6 +331,80 @@ amdgpu_devcoredump_format(char *buffer, size_t count,
> struct amdgpu_coredump_inf
> else if (coredump->reset_vram_lost)
> drm_printf(&p, "VRAM is lost due to GPU reset!\n");
>
> + if (coredump->num_ibs) {
> + if (buffer)
> + vm = amdgpu_vm_lock_by_pasid(adev, &root,
> coredump->pasid);
> + else
> + vm = NULL;
Is there any point in doing the loop if the vm is NULL?
> +
> + for (int i = 0; i < coredump->num_ibs && (!buffer || vm);
> i++) {
> + ib_content =
> kvmalloc_array(coredump->ibs[i].ib_size_dw, 4,
> + GFP_KERNEL);
Shouldn't this be GFP_NOWAIT?
Alex
> + if (!ib_content)
> + continue;
> +
> + if (!vm)
> + goto output_ib_content;
> +
> + va_start = coredump->ibs[i].gpu_addr &
> AMDGPU_GMC_HOLE_MASK;
> + mapping = amdgpu_vm_bo_lookup_mapping(vm, va_start /
> AMDGPU_GPU_PAGE_SIZE);
> + if (!mapping)
> + goto free_ib_content;
> +
> + offset = va_start - (mapping->start *
> AMDGPU_GPU_PAGE_SIZE);
> + abo = amdgpu_bo_ref(mapping->bo_va->base.bo);
> + r = amdgpu_bo_reserve(abo, false);
> + if (r)
> + goto free_ib_content;
> +
> + if (abo->flags & AMDGPU_GEM_CREATE_NO_CPU_ACCESS) {
> + off = 0;
> +
> + if (abo->tbo.resource->mem_type !=
> TTM_PL_VRAM)
> + goto unreserve_abo;
> +
> + amdgpu_res_first(abo->tbo.resource, offset,
> + coredump->ibs[i].ib_size_dw
> * 4,
> + &cursor);
> + while (cursor.remaining) {
> + amdgpu_device_mm_access(adev,
> cursor.start / 4,
> +
> &ib_content[off], cursor.size / 4,
> + false);
> + off += cursor.size;
> + amdgpu_res_next(&cursor, cursor.size);
> + }
> + } else {
> + r = ttm_bo_kmap(&abo->tbo, 0,
> + PFN_UP(abo->tbo.base.size),
> + &abo->kmap);
> + if (r)
> + goto unreserve_abo;
> +
> + kptr = amdgpu_bo_kptr(abo);
> + kptr += offset;
> + memcpy(ib_content, kptr,
> + coredump->ibs[i].ib_size_dw * 4);
> +
> + amdgpu_bo_kunmap(abo);
> + }
> +
> +output_ib_content:
> + drm_printf(&p, "\nIB #%d 0x%llx %d dw\n",
> + i, coredump->ibs[i].gpu_addr,
> coredump->ibs[i].ib_size_dw);
> + for (int j = 0; j < coredump->ibs[i].ib_size_dw; j++)
> + drm_printf(&p, "0x%08x\n", ib_content[j]);
> +unreserve_abo:
> + if (vm)
> + amdgpu_bo_unreserve(abo);
> +free_ib_content:
> + kfree(ib_content);
> + }
> + if (vm) {
> + amdgpu_bo_unreserve(root);
> + amdgpu_bo_unref(&root);
> + }
> + }
> +
> return count - iter.remain;
> }
>
> --
> 2.43.0
>
