Commit 5cc33255 authored by Thomas Hellström's avatar Thomas Hellström
Browse files

drm/xe: Rework eviction rejection of bound external bos 



For preempt_fence mode VM's we're rejecting eviction of
shared bos during VM_BIND. However, since we do this in the
move() callback, we're getting an eviction failure warning from
TTM. The TTM callback intended for these things is
eviction_valuable().

However, the latter doesn't pass in the struct ttm_operation_ctx
needed to determine whether the caller needs this.

Instead, attach the needed information to the vm under the
vm->resv, until we've been able to update TTM to provide the
needed information. And add sufficient lockdep checks to prevent
misuse and races.

v2:
- Fix a copy-paste error in xe_vm_clear_validating()
v3:
- Fix kerneldoc errors.

Signed-off-by: default avatarThomas Hellström <thomas.hellstrom@linux.intel.com>
Fixes: 0af944f0 ("drm/xe: Reject BO eviction if BO is bound to current VM")
Reviewed-by: default avatarMatthew Brost <matthew.brost@intel.com>
Link: https://lore.kernel.org/r/20250528164105.234718-1-thomas.hellstrom@linux.intel.com


(cherry picked from commit 9d555864)
Signed-off-by: default avatarThomas Hellström <thomas.hellstrom@linux.intel.com>
parent 2182f358

drivers/gpu/drm/xe/xe_bo.c

+28 −18
Original line number Diff line number Diff line
@@ -841,21 +841,6 @@ 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.
@@ -1013,6 +998,25 @@ static long xe_bo_shrink_purge(struct ttm_operation_ctx *ctx, 
	return lret;

}



static bool

xe_bo_eviction_valuable(struct ttm_buffer_object *bo, const struct ttm_place *place)

{

	struct drm_gpuvm_bo *vm_bo;



	if (!ttm_bo_eviction_valuable(bo, place))

		return false;



	if (!xe_bo_is_xe_bo(bo))

		return true;



	drm_gem_for_each_gpuvm_bo(vm_bo, &bo->base) {

		if (xe_vm_is_validating(gpuvm_to_vm(vm_bo->vm)))

			return false;

	}



	return true;

}



/**

 * xe_bo_shrink() - Try to shrink an xe bo.

 * @ctx: The struct ttm_operation_ctx used for shrinking.
@@ -1047,7 +1051,7 @@ long xe_bo_shrink(struct ttm_operation_ctx *ctx, struct ttm_buffer_object *bo, 
	    (flags.purge && !xe_tt->purgeable))

		return -EBUSY;



	if (!ttm_bo_eviction_valuable(bo, &place))

	if (!xe_bo_eviction_valuable(bo, &place))

		return -EBUSY;



	if (!xe_bo_is_xe_bo(bo) || !xe_bo_get_unless_zero(xe_bo))
@@ -1588,7 +1592,7 @@ const struct ttm_device_funcs xe_ttm_funcs = { 
	.io_mem_pfn = xe_ttm_io_mem_pfn,

	.access_memory = xe_ttm_access_memory,

	.release_notify = xe_ttm_bo_release_notify,

	.eviction_valuable = ttm_bo_eviction_valuable,

	.eviction_valuable = xe_bo_eviction_valuable,

	.delete_mem_notify = xe_ttm_bo_delete_mem_notify,

	.swap_notify = xe_ttm_bo_swap_notify,

};
@@ -2431,6 +2435,8 @@ int xe_bo_validate(struct xe_bo *bo, struct xe_vm *vm, bool allow_res_evict) 
		.no_wait_gpu = false,

		.gfp_retry_mayfail = true,

	};

	struct pin_cookie cookie;

	int ret;



	if (vm) {

		lockdep_assert_held(&vm->lock);
@@ -2440,8 +2446,12 @@ int xe_bo_validate(struct xe_bo *bo, struct xe_vm *vm, bool allow_res_evict) 
		ctx.resv = xe_vm_resv(vm);

	}



	cookie = xe_vm_set_validating(vm, allow_res_evict);

	trace_xe_bo_validate(bo);

	return ttm_bo_validate(&bo->ttm, &bo->placement, &ctx);

	ret = ttm_bo_validate(&bo->ttm, &bo->placement, &ctx);

	xe_vm_clear_validating(vm, allow_res_evict, cookie);



	return ret;

}



bool xe_bo_is_xe_bo(struct ttm_buffer_object *bo)

drivers/gpu/drm/xe/xe_vm.h

+69 −0
Original line number Diff line number Diff line
@@ -301,6 +301,75 @@ void xe_vm_snapshot_capture_delayed(struct xe_vm_snapshot *snap); 
void xe_vm_snapshot_print(struct xe_vm_snapshot *snap, struct drm_printer *p);

void xe_vm_snapshot_free(struct xe_vm_snapshot *snap);



/**

 * xe_vm_set_validating() - Register this task as currently making bos resident

 * @allow_res_evict: Allow eviction of buffer objects bound to @vm when

 * validating.

 * @vm: Pointer to the vm or NULL.

 *

 * Register this task as currently making bos resident for the vm. Intended

 * to avoid eviction by the same task of shared bos bound to the vm.

 * Call with the vm's resv lock held.

 *

 * Return: A pin cookie that should be used for xe_vm_clear_validating().

 */

static inline struct pin_cookie xe_vm_set_validating(struct xe_vm *vm,

						     bool allow_res_evict)

{

	struct pin_cookie cookie = {};



	if (vm && !allow_res_evict) {

		xe_vm_assert_held(vm);

		cookie = lockdep_pin_lock(&xe_vm_resv(vm)->lock.base);

		/* Pairs with READ_ONCE in xe_vm_is_validating() */

		WRITE_ONCE(vm->validating, current);

	}



	return cookie;

}



/**

 * xe_vm_clear_validating() - Unregister this task as currently making bos resident

 * @vm: Pointer to the vm or NULL

 * @allow_res_evict: Eviction from @vm was allowed. Must be set to the same

 * value as for xe_vm_set_validation().

 * @cookie: Cookie obtained from xe_vm_set_validating().

 *

 * Register this task as currently making bos resident for the vm. Intended

 * to avoid eviction by the same task of shared bos bound to the vm.

 * Call with the vm's resv lock held.

 */

static inline void xe_vm_clear_validating(struct xe_vm *vm, bool allow_res_evict,

					  struct pin_cookie cookie)

{

	if (vm && !allow_res_evict) {

		lockdep_unpin_lock(&xe_vm_resv(vm)->lock.base, cookie);

		/* Pairs with READ_ONCE in xe_vm_is_validating() */

		WRITE_ONCE(vm->validating, NULL);

	}

}



/**

 * xe_vm_is_validating() - Whether bos bound to the vm are currently being made resident

 * by the current task.

 * @vm: Pointer to the vm.

 *

 * If this function returns %true, we should be in a vm resv locked region, since

 * the current process is the same task that called xe_vm_set_validating().

 * The function asserts that that's indeed the case.

 *

 * Return: %true if the task is currently making bos resident, %false otherwise.

 */

static inline bool xe_vm_is_validating(struct xe_vm *vm)

{

	/* Pairs with WRITE_ONCE in xe_vm_is_validating() */

	if (READ_ONCE(vm->validating) == current) {

		xe_vm_assert_held(vm);

		return true;

	}

	return false;

}



#if IS_ENABLED(CONFIG_DRM_XE_USERPTR_INVAL_INJECT)

void xe_vma_userptr_force_invalidate(struct xe_userptr_vma *uvma);

#else

drivers/gpu/drm/xe/xe_vm_types.h

+8 −0
Original line number Diff line number Diff line
@@ -310,6 +310,14 @@ struct xe_vm { 
	 * protected by the vm resv.

	 */

	u64 tlb_flush_seqno;

	/**

	 * @validating: The task that is currently making bos resident for this vm.

	 * Protected by the VM's resv for writing. Opportunistic reading can be done

	 * using READ_ONCE. Note: This is a workaround for the

	 * TTM eviction_valuable() callback not being passed a struct

	 * ttm_operation_context(). Future work might want to address this.

	 */

	struct task_struct *validating;

	/** @batch_invalidate_tlb: Always invalidate TLB before batch start */

	bool batch_invalidate_tlb;

	/** @xef: XE file handle for tracking this VM's drm client */