[PATCH v11 2/3] drm/amdgpu: Add mapping info option for GEM_OP ioctl
Tvrtko Ursulin
tvrtko.ursulin at igalia.com
Mon Aug 11 11:14:22 UTC 2025
On 07/08/2025 21:22, David Francis wrote:
> Add new GEM_OP_IOCTL option GET_MAPPING_INFO, which
> returns a list of mappings associated with a given bo, along with
> their positions and offsets.
>
> Signed-off-by: David Francis <David.Francis at amd.com>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 96 +++++++++++++++++++++++++
> drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h | 5 ++
> include/uapi/drm/amdgpu_drm.h | 18 +++++
> 3 files changed, 119 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> index 7f55e3b7d8a2..29ee1df37661 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> @@ -956,6 +956,98 @@ int amdgpu_gem_va_ioctl(struct drm_device *dev, void *data,
> return r;
> }
>
> +/**
> + * amdgpu_gem_list_mappings - get information about a buffer's mappings
> + *
> + * @gobj: gem object
> + * @args: gem_op arguments
> + * @fpriv: drm file pointer
> + *
> + * num_entries is set as an input to the size of the user-allocated array of
> + * drm_amdgpu_gem_vm_bucket stored at args->value.
> + * num_entries is sent back as output as the number of mappings the bo has.
> + * If that number is larger than the size of the array, the ioctl must
> + * be retried.
> + *
> + * Returns:
> + * 0 for success, -errno for errors.
> + */
> +static int amdgpu_gem_list_mappings(struct drm_gem_object *gobj, struct amdgpu_fpriv *fpriv,
> + struct drm_amdgpu_gem_op *args)
> +{
> + struct amdgpu_vm *avm = &fpriv->vm;
> + struct amdgpu_bo *bo = gem_to_amdgpu_bo(gobj);
> + struct amdgpu_bo_va *bo_va = amdgpu_vm_bo_find(avm, bo);
> + struct drm_amdgpu_gem_vm_bucket *vm_buckets;
> + struct amdgpu_bo_va_mapping *mapping;
> + struct drm_exec exec;
> + int num_mappings = 0;
> + int ret;
> +
> + vm_buckets = kvcalloc(args->num_entries, sizeof(*vm_buckets), GFP_KERNEL);
> + if (!vm_buckets) {
> + ret = -ENOMEM;
> + goto free_vms;
return -ENOMEM would be enough.
> + }
> +
> + drm_exec_init(&exec, DRM_EXEC_INTERRUPTIBLE_WAIT |
> + DRM_EXEC_IGNORE_DUPLICATES, 0);
> + drm_exec_until_all_locked(&exec) {
> + if (gobj) {
> + ret = drm_exec_lock_obj(&exec, gobj);
> + drm_exec_retry_on_contention(&exec);
> + if (ret)
> + goto unlock_exec;
> + }
> +
> + ret = amdgpu_vm_lock_pd(&fpriv->vm, &exec, 2);
What are the two reserved fence slots for?
> + drm_exec_retry_on_contention(&exec);
> + if (ret)
> + goto unlock_exec;
> + }
> +
> + amdgpu_vm_bo_va_for_each_valid_mapping(bo_va, mapping) {
> + if (num_mappings < args->num_entries) {
> + vm_buckets[num_mappings].start = mapping->start;
> + vm_buckets[num_mappings].last = mapping->last;
> + vm_buckets[num_mappings].offset = mapping->offset;
> + vm_buckets[num_mappings].flags = mapping->flags;
> + }
> + num_mappings += 1;
> + }
> +
> + amdgpu_vm_bo_va_for_each_invalid_mapping(bo_va, mapping) {
> + if (num_mappings < args->num_entries) {
> + vm_buckets[num_mappings].start = mapping->start;
> + vm_buckets[num_mappings].last = mapping->last;
> + vm_buckets[num_mappings].offset = mapping->offset;
> + vm_buckets[num_mappings].flags = mapping->flags;
> + }
> + num_mappings += 1;
> + }
> +
> + drm_exec_fini(&exec);
> +
> + if (num_mappings > 0 && num_mappings <= args->num_entries) {
> + ret = copy_to_user((void __user *)args->value, vm_buckets, num_mappings * sizeof(*vm_buckets));
> + if (ret) {
> + pr_debug("Failed to copy BO information to user\n");
> + ret = -EFAULT;
> + }
Same comment as in the first patch - u64_to_user_pointer and I'd
consider dropping the pr_debug path.
> + }
> + args->num_entries = num_mappings;
> +
> + kvfree(vm_buckets);
> +
> + return ret;
> +unlock_exec:
> + drm_exec_fini(&exec);
> +free_vms:
> + kvfree(vm_buckets);
> +
> + return ret;
I think the success/failure exit paths could be consolidated:
amdgpu_vm_bo_va_for_each_invalid_mapping(bo_va, mapping) {
...
}
args->num_entries = num_mappings;
if (num_mappings > 0 && num_mappings <= args->num_entries)
ret = copy_to_user(...);
unlock_exec:
drm_exec_fini(&exec);
kvfree(vm_buckets);
return ret;
Regards,
Tvrtko
> +}
> +
> int amdgpu_gem_op_ioctl(struct drm_device *dev, void *data,
> struct drm_file *filp)
> {
> @@ -1022,6 +1114,10 @@ int amdgpu_gem_op_ioctl(struct drm_device *dev, void *data,
>
> amdgpu_bo_unreserve(robj);
> break;
> + case AMDGPU_GEM_OP_GET_MAPPING_INFO:
> + amdgpu_bo_unreserve(robj);
> + r = amdgpu_gem_list_mappings(gobj, filp->driver_priv, args);
> + break;
> default:
> amdgpu_bo_unreserve(robj);
> r = -EINVAL;
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
> index f9549f6b3d1f..5a63ae490b0e 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
> @@ -668,4 +668,9 @@ void amdgpu_vm_tlb_fence_create(struct amdgpu_device *adev,
> struct amdgpu_vm *vm,
> struct dma_fence **fence);
>
> +#define amdgpu_vm_bo_va_for_each_valid_mapping(bo_va, mapping) \
> + list_for_each_entry(mapping, &bo_va->valids, list)
> +#define amdgpu_vm_bo_va_for_each_invalid_mapping(bo_va, mapping) \
> + list_for_each_entry(mapping, &bo_va->invalids, list)
> +
> #endif
> diff --git a/include/uapi/drm/amdgpu_drm.h b/include/uapi/drm/amdgpu_drm.h
> index 218a179818d4..6b857f528823 100644
> --- a/include/uapi/drm/amdgpu_drm.h
> +++ b/include/uapi/drm/amdgpu_drm.h
> @@ -802,6 +802,21 @@ union drm_amdgpu_wait_fences {
>
> #define AMDGPU_GEM_OP_GET_GEM_CREATE_INFO 0
> #define AMDGPU_GEM_OP_SET_PLACEMENT 1
> +#define AMDGPU_GEM_OP_GET_MAPPING_INFO 2
> +
> +struct drm_amdgpu_gem_vm_bucket {
> + /* Start of mapping (in number of pages) */
> + __u64 start;
> +
> + /* End of mapping (in number of pages) */
> + __u64 last;
> +
> + /* Mapping offset */
> + __u64 offset;
> +
> + /* flags needed to recreate mapping */
> + __u64 flags;
> +};
>
> /* Sets or returns a value associated with a buffer. */
> struct drm_amdgpu_gem_op {
> @@ -811,6 +826,9 @@ struct drm_amdgpu_gem_op {
> __u32 op;
> /** Input or return value */
> __u64 value;
> + /** For MAPPING_INFO op: number of mappings (in/out) */
> + __u32 num_entries;
> + __u32 padding;
> };
>
> #define AMDGPU_GEM_LIST_HANDLES_FLAG_IS_IMPORT (1 << 0)
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