[PATCH] drm/xe: Reject BO eviction if BO is bound to current VM

[Oak Zeng]

This is a follow up fix for
https://patchwork.freedesktop.org/patch/msgid/20241203021929.1919730-1-oak.zeng@intel.com
The overall goal is to fail vm_bind when there is memory pressure. See more
details in the commit message of above patch. Abbove patch fixes the issue
when user pass in a vm_id parameter during gem_create. If user doesn't pass
in a vm_id during gem_create, above patch doesn't help.

This patch further reject BO eviction (which could be triggered by bo validation)
if BO is bound to the current VM. vm_bind could fail due to the eviction failure.
The BO to VM reverse mapping structure is used to determine whether BO is bound
to VM.

v2:
Move vm_bo definition from function scope to if(evict) clause (Thomas)
Further constraint the condition by adding ctx->resv (Thomas)
Add a short comment describe the change.

Suggested-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
Signed-off-by: Oak Zeng <oak.zeng at intel.com>
---
 drivers/gpu/drm/xe/xe_bo.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
index 4a623a98d9f1f..b024c63d8d296 100644
--- a/drivers/gpu/drm/xe/xe_bo.c
+++ b/drivers/gpu/drm/xe/xe_bo.c
@@ -713,6 +713,21 @@ static int xe_bo_move(struct ttm_buffer_object *ttm_bo, bool evict,
 		goto out;
 	}
 
+	/* Reject BO eviction if BO is bound to current VM. */
+	if (evict && ctx->resv) {
+		struct drm_gpuvm_bo *vm_bo;
+
+		drm_gem_for_each_gpuvm_bo(vm_bo, &bo->ttm.base) {
+			struct xe_vm *vm = gpuvm_to_vm(vm_bo->vm);
+
+			if (xe_vm_resv(vm) == ctx->resv &&
+			    xe_vm_in_preempt_fence_mode(vm)) {
+				ret = -EBUSY;
+				goto out;
+			}
+		}
+	}
+
 	/*
 	 * Failed multi-hop where the old_mem is still marked as
 	 * TTM_PL_FLAG_TEMPORARY, should just be a dummy move.
-- 
2.26.3