[PATCH] drm/amdkfd: Reject zero-sized AQL queue allocations after size halving

KFD_IOC_ALLOC_MEMORY_OF_GPU with flag
KFD_IOC_ALLOC_MEM_FLAGS_AQL_QUEUE_MEM and size=1 triggers the AQL
wraparound workaround (size >>= 1), reducing size to 0. The resulting
zero passes through PAGE_ALIGN(0) = 0 without validation, bypassing the
per-process VRAM quota check in reserve_mem_limit()
(vram_used + 0 > vram_available is always false).

The fix adds post-halving zero-size validation in the primary
allocation path (amdgpu_amdkfd_gpuvm.c). The check happens after size
halving but before reserve_mem_limit(), and uses err_alignment_size
error path to properly clean up the allocated kgd_mem structure and
mutex.

Signed-off-by: Sunday Clement <[email protected]>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 6 ++++++
 drivers/gpu/drm/amd/amdkfd/kfd_chardev.c         | 3 ++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
index 1e71829e0fc6..90a4a68478f8 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
@@ -1795,6 +1795,11 @@ int amdgpu_amdkfd_gpuvm_alloc_memory_of_gpu(
 		size >>= 1;
 	aligned_size = PAGE_ALIGN(size);
 
+	if(!aligned_size) { // reject AQL queue with size < 2
+		ret = -EINVAL;
+		goto err_alignment_size;
+	}
+
 	(*mem)->alloc_flags = flags;
 
 	amdgpu_sync_create(&(*mem)->sync);
@@ -1886,6 +1891,7 @@ int amdgpu_amdkfd_gpuvm_alloc_memory_of_gpu(
 	amdgpu_amdkfd_unreserve_mem_limit(adev, aligned_size, flags, xcp_id);
 err_reserve_limit:
 	amdgpu_sync_free(&(*mem)->sync);
+err_alignment_size:
 	mutex_destroy(&(*mem)->lock);
 	if (gobj)
 		drm_gem_object_put(gobj);
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
index 309510e23315..bb0a2c615326 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
@@ -1200,7 +1200,8 @@ static int kfd_ioctl_alloc_memory_of_gpu(struct file *filep,
 
 		if (flags & KFD_IOC_ALLOC_MEM_FLAGS_AQL_QUEUE_MEM)
 			size >>= 1;
-		atomic64_add(PAGE_ALIGN(size), &pdd->vram_usage);
+		size = PAGE_ALIGN(size);
+		atomic64_add(size, &pdd->vram_usage);
 	}
 
 	mutex_unlock(&p->mutex);
-- 
2.43.0