Commit 0cd99046 authored by Maarten Lankhorst's avatar Maarten Lankhorst
Browse files

drm/xe: Add vm snapshot mutex for easily taking a vm snapshot during devcoredump 



The devcoredump is done in fence signaling context. Because of this, we
cannot take any of the normal mutexes or we would invert.

Normal: Take vm->lock, dma_fence_wait()
Devcoredump: from dma_fence_wait() context, take vm->lock.

This doesn't work, and we only care about integrity, so take the locks
around additions and removals of vma's.

Signed-off-by: default avatarMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: default avatarJosé Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240221133024.898315-5-maarten.lankhorst@linux.intel.com
parent ffb7249d

drivers/gpu/drm/xe/xe_vm.c

+8 −0
Original line number Diff line number Diff line
@@ -1055,7 +1055,9 @@ static int xe_vm_insert_vma(struct xe_vm *vm, struct xe_vma *vma) 
	xe_assert(vm->xe, xe_vma_vm(vma) == vm);

	lockdep_assert_held(&vm->lock);



	mutex_lock(&vm->snap_mutex);

	err = drm_gpuva_insert(&vm->gpuvm, &vma->gpuva);

	mutex_unlock(&vm->snap_mutex);

	XE_WARN_ON(err);	/* Shouldn't be possible */



	return err;
@@ -1066,7 +1068,9 @@ static void xe_vm_remove_vma(struct xe_vm *vm, struct xe_vma *vma) 
	xe_assert(vm->xe, xe_vma_vm(vma) == vm);

	lockdep_assert_held(&vm->lock);



	mutex_lock(&vm->snap_mutex);

	drm_gpuva_remove(&vma->gpuva);

	mutex_unlock(&vm->snap_mutex);

	if (vm->usm.last_fault_vma == vma)

		vm->usm.last_fault_vma = NULL;

}
@@ -1293,6 +1297,7 @@ struct xe_vm *xe_vm_create(struct xe_device *xe, u32 flags) 
	vm->flags = flags;



	init_rwsem(&vm->lock);

	mutex_init(&vm->snap_mutex);



	INIT_LIST_HEAD(&vm->rebind_list);
@@ -1418,6 +1423,7 @@ struct xe_vm *xe_vm_create(struct xe_device *xe, u32 flags) 
	return ERR_PTR(err);



err_no_resv:

	mutex_destroy(&vm->snap_mutex);

	for_each_tile(tile, xe, id)

		xe_range_fence_tree_fini(&vm->rftree[id]);

	kfree(vm);
@@ -1517,6 +1523,8 @@ void xe_vm_close_and_put(struct xe_vm *vm) 


	up_write(&vm->lock);



	mutex_destroy(&vm->snap_mutex);



	mutex_lock(&xe->usm.lock);

	if (vm->flags & XE_VM_FLAG_FAULT_MODE)

		xe->usm.num_vm_in_fault_mode--;

drivers/gpu/drm/xe/xe_vm_types.h

+5 −0
Original line number Diff line number Diff line
@@ -160,6 +160,11 @@ struct xe_vm { 
	 * VM

	 */

	struct rw_semaphore lock;

	/**

	 * @snap_mutex: Mutex used to guard insertions and removals from gpuva,

	 * so we can take a snapshot safely from devcoredump.

	 */

	struct mutex snap_mutex;



	/**

	 * @rebind_list: list of VMAs that need rebinding. Protected by the