6.18-stable review patch. If anyone has any objections, please let me know.

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From: Akash Goel akash.goel@arm.com

[ Upstream commit ce04ec03a9c2c4f3e60e26f21311b25d5a478208 ]

The kernel BOs unnecessarily got added to the external objects list of drm_gpuvm, when mapping to GPU, which would have resulted in few extra CPU cycles being spent at the time of job submission as drm_exec_until_all_locked() loop iterates over all external objects.

Kernel BOs are private to a VM and so they share the dma_resv object of the dummy GEM object created for a VM. Use of DRM_EXEC_IGNORE_DUPLICATES flag ensured the recursive locking of the dummy GEM object was ignored. Also no extra space got allocated to add fences to the dma_resv object of dummy GEM object. So no other impact apart from few extra CPU cycles.

This commit sets the pointer to dma_resv object of GEM object of kernel BOs before they are mapped to GPU, to prevent them from being added to external objects list.

v2: Add R-bs and fixes tags

Fixes: 8a1cc07578bf ("drm/panthor: Add GEM logical block") Signed-off-by: Akash Goel akash.goel@arm.com Reviewed-by: Boris Brezillon boris.brezillon@collabora.com Reviewed-by: Steven Price steven.price@arm.com Link: https://patch.msgid.link/20251120172118.2741724-1-akash.goel@arm.com Signed-off-by: Boris Brezillon boris.brezillon@collabora.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/panthor/panthor_gem.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c index 14ed09d700f2f..43471babff86c 100644 --- a/drivers/gpu/drm/panthor/panthor_gem.c +++ b/drivers/gpu/drm/panthor/panthor_gem.c @@ -144,6 +144,9 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, struct panthor_vm *vm, bo = to_panthor_bo(&obj->base); kbo->obj = &obj->base; bo->flags = bo_flags; + bo->exclusive_vm_root_gem = panthor_vm_root_gem(vm); + drm_gem_object_get(bo->exclusive_vm_root_gem); + bo->base.base.resv = bo->exclusive_vm_root_gem->resv;

if (vm == panthor_fw_vm(ptdev)) debug_flags |= PANTHOR_DEBUGFS_GEM_USAGE_FLAG_FW_MAPPED; @@ -167,9 +170,6 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, struct panthor_vm *vm, goto err_free_va;

kbo->vm = panthor_vm_get(vm); - bo->exclusive_vm_root_gem = panthor_vm_root_gem(vm); - drm_gem_object_get(bo->exclusive_vm_root_gem); - bo->base.base.resv = bo->exclusive_vm_root_gem->resv; return kbo;

err_free_va: