drm/xe/xe_vm_doc.h

1 /* SPDX-License-Identifier: MIT */
15  * Allocate a physical page for root of the page table structure, create default
19  * ------------
33  * ----------
35  * DRM_XE_VM_BIND_OP_MAP		- Create mapping for a BO
36  * DRM_XE_VM_BIND_OP_UNMAP		- Destroy mapping for a BO / userptr
37  * DRM_XE_VM_BIND_OP_MAP_USERPTR	- Create mapping for userptr
54  * .. code-block::
56  *	bind BO0 0x0-0x1000
62  *	bind BO1 0x201000-0x202000
66  *	bind BO2 0x1ff000-0x201000
74  * bind can be done immediately (all in-fences satisfied, VM dma-resv kernel
78  * -------------
83  * ----------
95  * ------------------------
105  * -------------------------
122  * ---------------------
126  * queue, B is now blocked on A's in fences even though it is ready to run. This
135  * is free to pass A. If the engine ID field is omitted, the default bind queue
141  * ------------------------
151  * ----------------------------
155  * .. code-block::
157  *	0x0000-0x2000 and 0x3000-0x5000 have mappings
158  *	Munmap 0x1000-0x4000, results in mappings 0x0000-0x1000 and 0x4000-0x5000
163  * .. code-block::
165  *	unbind 0x0000-0x2000
166  *	unbind 0x3000-0x5000
167  *	rebind 0x0000-0x1000
168  *	rebind 0x4000-0x5000
170  * Why not just do a partial unbind of 0x1000-0x2000 and 0x3000-0x4000? This
178  * In this example there is a window of time where 0x0000-0x1000 and
179  * 0x4000-0x5000 are invalid but the user didn't ask for these addresses to be
186  * VM). The caveat is all dma-resv slots must be updated atomically with respect
188  * vm->lock in write mode from the first operation until the last.
191  * ----------------------------
194  * create mappings are by default deferred to the page fault handler (first
208  * ------------
214  * idle to ensure no faults. This done by waiting on all of VM's dma-resv slots.
217  * -------
219  * Either the next exec (non-compute) or rebind worker (compute mode) will
221  * after the VM dma-resv wait if the VM is in compute mode.
235  * --------------
248  * dma-resv DMA_RESV_USAGE_PREEMPT_FENCE slot. The same preempt fence, for every
249  * engine using the VM, is also installed into the same dma-resv slot of every
253  * -------------
262  * .. code-block::
264  *	<----------------------------------------------------------------------|
268  *	Lock VM dma-resv and external BOs dma-resv                             |
273  *	Wait VM's DMA_RESV_USAGE_KERNEL dma-resv slot                          |
278  *		Wait all VM's dma-resv slots                                   |
279  *		Retry ----------------------------------------------------------
284  * -----------
297  * When VM is created, a default bind engine and PT table structure are created
301  * if this mask is zero then default to all the GTs where the VM has page
305  * various places plus exporting a composite fence for multi-GT binds to the
316  * such, dma fences are not allowed when VM is in fault mode. Because dma-fences
321  * ----------------
323  * By default, on a faulting VM binds just allocate the VMA and the actual
329  * ------------------
354  * .. code-block::
361  *	<----------------------------------------------------------------------|
363  *	Lock VM & BO dma-resv locks                                            |
368  *		Drop VM & BO dma-resv locks                                    |
369  *		Retry ----------------------------------------------------------
375  * ---------------
389  * .. code-block::
395  *	Lock VM & BO dma-resv locks
403  * -------------------------------------------------
425  * -----
427  * VM global lock (vm->lock) - rw semaphore lock. Outer most lock which protects
434  * VM dma-resv lock (vm->gpuvm.r_obj->resv->lock) - WW lock. Protects VM dma-resv
439  * external BO dma-resv lock (bo->ttm.base.resv->lock) - WW lock. Protects
440  * external BO dma-resv slots. Expected to be acquired during VM binds (in
441  * addition to the VM dma-resv lock). All external BO dma-locks within a VM are
442  * expected to be acquired (in addition to the VM dma-resv lock) during execs
447  * -----------------------
450  * time (vm->lock).
453  * executing at the same time (vm->lock).
456  * the same VM is executing (vm->lock).
459  * compute mode rebind worker with the same VM is executing (vm->lock).
462  * executing (dma-resv locks).
465  * with the same VM is executing (dma-resv locks).
467  * dma-resv usage
473  * external BOs dma-resv slots. Let try to make this as clear as possible.
476  * -----------------
482  * 2. In non-compute mode, jobs from execs install themselves into the
485  * 3. In non-compute mode, jobs from execs install themselves into the
501  * ------------
507  * 2. In non-compute mode, the execution of all jobs from rebinds in execs shall
511  * 3. In non-compute mode, the execution of all jobs from execs shall wait on the
524  * -----------------------
526  * 1. New jobs from kernel ops are blocked behind any existing jobs from
527  * non-compute mode execs
529  * 2. New jobs from non-compute mode execs are blocked behind any existing jobs
532  * 3. New jobs from kernel ops are blocked behind all preempt fences signaling in
535  * 4. Compute mode engine resumes are blocked behind any existing jobs from
547  * wait on the dma-resv kernel slots of VM or BO, technically we only have to