[PATCH v15 3/4] drm/amdgpu: Add mapping info option for GEM_OP ioctl
Christian König
christian.koenig at amd.com
Mon Aug 25 13:44:51 UTC 2025
On 22.08.25 21:47, 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 | 98 ++++++++++++++++++++++++-
> drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h | 5 ++
> include/uapi/drm/amdgpu_drm.h | 21 +++++-
> 3 files changed, 120 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> index e6741d6c9a55..15d588f7acdf 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> @@ -948,6 +948,70 @@ 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_entry 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_entry *vm_entries;
> + struct amdgpu_bo_va_mapping *mapping;
> + int num_mappings = 0;
> + int ret;
> +
> + if (args->padding)
> + return -EINVAL;
> +
> + vm_entries = kvcalloc(args->num_entries, sizeof(*vm_entries), GFP_KERNEL);
> + if (!vm_entries)
> + return -ENOMEM;
> +
> + amdgpu_vm_bo_va_for_each_valid_mapping(bo_va, mapping) {
> + if (num_mappings < args->num_entries) {
> + vm_entries[num_mappings].addr = mapping->start * AMDGPU_GPU_PAGE_SIZE;
> + vm_entries[num_mappings].size = (mapping->last - mapping->start + 1) * AMDGPU_GPU_PAGE_SIZE;
> + vm_entries[num_mappings].offset = mapping->offset;
> + vm_entries[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_entries[num_mappings].addr = mapping->start * AMDGPU_GPU_PAGE_SIZE;
> + vm_entries[num_mappings].size = (mapping->last - mapping->start + 1) * AMDGPU_GPU_PAGE_SIZE;
> + vm_entries[num_mappings].offset = mapping->offset;
> + vm_entries[num_mappings].flags = mapping->flags;
> + }
> + num_mappings += 1;
> + }
> +
> + if (num_mappings > 0 && num_mappings <= args->num_entries)
> + ret = copy_to_user(u64_to_user_ptr(args->value), vm_entries, num_mappings * sizeof(*vm_entries));
> +
> + args->num_entries = num_mappings;
> +
> + kvfree(vm_entries);
> +
> + return ret;
> +}
> +
> int amdgpu_gem_op_ioctl(struct drm_device *dev, void *data,
> struct drm_file *filp)
> {
> @@ -955,6 +1019,8 @@ int amdgpu_gem_op_ioctl(struct drm_device *dev, void *data,
> struct drm_gem_object *gobj;
> struct amdgpu_vm_bo_base *base;
> struct amdgpu_bo *robj;
> + struct drm_exec exec;
> + struct amdgpu_fpriv *fpriv = filp->driver_priv;
> int r;
>
> gobj = drm_gem_object_lookup(filp, args->handle);
> @@ -963,9 +1029,27 @@ int amdgpu_gem_op_ioctl(struct drm_device *dev, void *data,
>
> robj = gem_to_amdgpu_bo(gobj);
>
> - r = amdgpu_bo_reserve(robj, false);
> - if (unlikely(r))
> - goto out;
> + if (args->op == AMDGPU_GEM_OP_GET_MAPPING_INFO) {
> + drm_exec_init(&exec, DRM_EXEC_INTERRUPTIBLE_WAIT |
> + DRM_EXEC_IGNORE_DUPLICATES, 0);
> + drm_exec_until_all_locked(&exec) {
> + if (gobj) {
> + r = drm_exec_lock_obj(&exec, gobj);
> + drm_exec_retry_on_contention(&exec);
> + if (r)
> + goto out_exec;
> + }
> +
> + r = amdgpu_vm_lock_pd(&fpriv->vm, &exec, 0);
> + drm_exec_retry_on_contention(&exec);
> + if (r)
> + goto out_exec;
> + }
> + } else {
> + r = amdgpu_bo_reserve(robj, false);
> + if (unlikely(r))
> + goto out;
> + }
Just simplify that into:
drm_exec_init(&exec, DRM_EXEC_INTERRUPTIBLE_WAIT | DRM_EXEC_IGNORE_DUPLICATES, 0);
drm_exec_until_all_locked(&exec) {
r = drm_exec_lock_obj(&exec, gobj);
drm_exec_retry_on_contention(&exec);
if (r)
goto out_exec;
switch(args->op) {
...
case AMDGPU_GEM_OP_GET_MAPPING_INFO:
r = amdgpu_vm_lock_pd(&fpriv->vm, &exec, 0);
drm_exec_retry_on_contention(&exec);
if (r)
goto out_exec;
...
}
Regards,
Christian.
>
> switch (args->op) {
> case AMDGPU_GEM_OP_GET_GEM_CREATE_INFO: {
> @@ -1014,6 +1098,10 @@ int amdgpu_gem_op_ioctl(struct drm_device *dev, void *data,
>
> amdgpu_bo_unreserve(robj);
> break;
> + case AMDGPU_GEM_OP_GET_MAPPING_INFO:
> + r = amdgpu_gem_list_mappings(gobj, fpriv, args);
> + drm_exec_fini(&exec);
> + break;
> default:
> amdgpu_bo_unreserve(robj);
> r = -EINVAL;
> @@ -1022,6 +1110,10 @@ int amdgpu_gem_op_ioctl(struct drm_device *dev, void *data,
> out:
> drm_gem_object_put(gobj);
> return r;
> +out_exec:
> + drm_exec_fini(&exec);
> + drm_gem_object_put(gobj);
> + return r;
> }
>
> /**
> 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 e5d1c24cabcb..2e7a4e599e5b 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_entry {
> + /* Start of mapping (in bytes) */
> + __u64 addr;
> +
> + /* Size of mapping (in bytes) */
> + __u64 size;
> +
> + /* 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 {
> @@ -809,8 +824,12 @@ struct drm_amdgpu_gem_op {
> __u32 handle;
> /** AMDGPU_GEM_OP_* */
> __u32 op;
> - /** Input or return value */
> + /** Input or return value. For MAPPING_INFO op: pointer to array of struct drm_amdgpu_gem_vm_entry */
> __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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