[RFC PATCH 14/28] drm/xe: Do not allow system allocator VMA unbind if the GPU has bindings

[Matthew Brost <matthew.brost@intel.com>]

uAPI is designed with the the use case that only mapping a BO to a
malloc'd address will unbind a system allocator VMA. Thus it doesn't
make tons of sense to allow a system allocator VMA unbind if the GPU has
bindings in the range being unbound. Do not support this as it
simplifies the code. Can always be revisited if a use case for this
arrises.

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
---
 drivers/gpu/drm/xe/xe_svm.c |  5 +++++
 drivers/gpu/drm/xe/xe_svm.h |  1 +
 drivers/gpu/drm/xe/xe_vm.c  | 16 ++++++++++++++++
 3 files changed, 22 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c
index 7188aa590fa5..2339359a1d91 100644
--- a/drivers/gpu/drm/xe/xe_svm.c
+++ b/drivers/gpu/drm/xe/xe_svm.c
@@ -366,3 +366,8 @@ int xe_svm_handle_pagefault(struct xe_vm *vm, struct xe_vma *vma,
 err_out:
 	return err;
 }
+
+bool xe_svm_has_mapping(struct xe_vm *vm, u64 start, u64 end)
+{
+	return drm_gpusvm_has_mapping(&vm->svm.gpusvm, start, end);
+}
diff --git a/drivers/gpu/drm/xe/xe_svm.h b/drivers/gpu/drm/xe/xe_svm.h
index 84fd0d8c3380..a4f764bcd835 100644
--- a/drivers/gpu/drm/xe/xe_svm.h
+++ b/drivers/gpu/drm/xe/xe_svm.h
@@ -25,6 +25,7 @@ void xe_svm_fini(struct xe_vm *vm);
 int xe_svm_handle_pagefault(struct xe_vm *vm, struct xe_vma *vma,
 			    struct xe_tile *tile, u64 fault_addr,
 			    bool atomic);
+bool xe_svm_has_mapping(struct xe_vm *vm, u64 start, u64 end);
 
 static inline bool xe_svm_range_pages_valid(struct xe_svm_range *range)
 {
diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
index 6916cdfe4be3..d9bff07ef8d1 100644
--- a/drivers/gpu/drm/xe/xe_vm.c
+++ b/drivers/gpu/drm/xe/xe_vm.c
@@ -2352,6 +2352,17 @@ static int vm_bind_ioctl_ops_parse(struct xe_vm *vm, struct drm_gpuva_ops *ops,
 			struct xe_vma *old =
 				gpuva_to_vma(op->base.remap.unmap->va);
 			bool skip = xe_vma_is_system_allocator(old);
+			u64 start = xe_vma_start(old), end = xe_vma_end(old);
+
+			if (op->base.remap.prev)
+				start = op->base.remap.prev->va.addr +
+					op->base.remap.prev->va.range;
+			if (op->base.remap.next)
+				end = op->base.remap.next->va.addr;
+
+			if (xe_vma_is_system_allocator(old) &&
+			    xe_svm_has_mapping(vm, start, end))
+				return -EBUSY;
 
 			op->remap.start = xe_vma_start(old);
 			op->remap.range = xe_vma_size(old);
@@ -2434,6 +2445,11 @@ static int vm_bind_ioctl_ops_parse(struct xe_vm *vm, struct drm_gpuva_ops *ops,
 		{
 			struct xe_vma *vma = gpuva_to_vma(op->base.unmap.va);
 
+			if (xe_vma_is_system_allocator(vma) &&
+			    xe_svm_has_mapping(vm, xe_vma_start(vma),
+					       xe_vma_end(vma)))
+				return -EBUSY;
+
 			if (!xe_vma_is_system_allocator(vma))
 				xe_vma_ops_incr_pt_update_ops(vops, op->tile_mask);
 			break;
-- 
2.34.1