On 12/08/2025 20:12, 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.fran...@amd.com>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 84 +++++++++++++++++++++++++
drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h | 5 ++
include/uapi/drm/amdgpu_drm.h | 18 ++++++
3 files changed, 107 insertions(+)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
index 8b44d10a8b57..23a0545a0400 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
@@ -948,6 +948,86 @@ 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;
+
I just realized args->padding probably needs to be checked to allow
potential re-use in the future. Eg.
if (args->padding)
return -EINVAL;
Or make it __u64?
+ vm_buckets = kvcalloc(args->num_entries, sizeof(*vm_buckets),
GFP_KERNEL);
+ if (!vm_buckets)
+ return -ENOMEM;
+
+ 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, 0);
+ 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;
+ }
+
+ if (num_mappings > 0 && num_mappings <= args->num_entries)
+ ret = copy_to_user(u64_to_user_ptr(args->value), vm_buckets,
num_mappings * sizeof(*vm_buckets));
+
+ args->num_entries = num_mappings;
+
+unlock_exec:
+ drm_exec_fini(&exec);
+ kvfree(vm_buckets);
+
+ return ret;
+}
+
int amdgpu_gem_op_ioctl(struct drm_device *dev, void *data,
struct drm_file *filp)
{
@@ -1014,6 +1094,10 @@ 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 59b423883e91..7072959103e6 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;
IMO uapi needs to be a little bit better documented - in this case the
information that value fields holds a pointer to the array of
drm_amdgpu_gem_vm_bucket needs to be explained. Kerneldoc for
amdgpu_gem_list_mappings() is not enough since uapi headers are separate
from kernel sources.
Also, why is drm_amdgpu_gem_vm_bucket a bucket? It contains information
pertaining to a *single* mapping, right? So why a bucket and not for
example mapping info, or entry to align with num_entries naming? Is it
just me who associates a bucket with something storing potentially more
than one of something?
Regards,
Tvrtko
};
#define AMDGPU_GEM_LIST_HANDLES_FLAG_IS_IMPORT (1 << 0)
