On 7/15/20 1:51 PM, Chris Wilson wrote:
Acquire all the objects and their backing storage, and page directories,
as used by execbuf under a single common ww_mutex. Albeit we have to
restart the critical section a few times in order to handle various
restrictions (such as avoiding copy_(from|to)_user and mmap_sem).
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
.../gpu/drm/i915/gem/i915_gem_execbuffer.c | 168 +++++++++---------
.../i915/gem/selftests/i915_gem_execbuffer.c | 8 +-
2 files changed, 87 insertions(+), 89 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index ebabc0746d50..db433f3f18ec 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -20,6 +20,7 @@
#include "gt/intel_gt_pm.h"
#include "gt/intel_gt_requests.h"
#include "gt/intel_ring.h"
+#include "mm/i915_acquire_ctx.h"
#include "i915_drv.h"
#include "i915_gem_clflush.h"
@@ -244,6 +245,8 @@ struct i915_execbuffer {
struct intel_context *context; /* logical state for the request */
struct i915_gem_context *gem_context; /** caller's context */
+ struct i915_acquire_ctx acquire; /** lock for _all_ DMA reservations */
+
struct i915_request *request; /** our request to build */
struct eb_vma *batch; /** identity of the batch obj/vma */
@@ -389,42 +392,6 @@ static void eb_vma_array_put(struct eb_vma_array *arr)
kref_put(&arr->kref, eb_vma_array_destroy);
}
-static int
-eb_lock_vma(struct i915_execbuffer *eb, struct ww_acquire_ctx *acquire)
-{
- struct eb_vma *ev;
- int err = 0;
-
- list_for_each_entry(ev, &eb->submit_list, submit_link) {
- struct i915_vma *vma = ev->vma;
-
- err = ww_mutex_lock_interruptible(&vma->resv->lock, acquire);
- if (err == -EDEADLK) {
- struct eb_vma *unlock = ev, *en;
-
- list_for_each_entry_safe_continue_reverse(unlock, en,
-
&eb->submit_list,
- submit_link) {
- ww_mutex_unlock(&unlock->vma->resv->lock);
- list_move_tail(&unlock->submit_link,
&eb->submit_list);
- }
-
- GEM_BUG_ON(!list_is_first(&ev->submit_link,
&eb->submit_list));
- err = ww_mutex_lock_slow_interruptible(&vma->resv->lock,
- acquire);
- }
- if (err) {
- list_for_each_entry_continue_reverse(ev,
- &eb->submit_list,
- submit_link)
- ww_mutex_unlock(&ev->vma->resv->lock);
- break;
- }
- }
-
- return err;
-}
-
static int eb_create(struct i915_execbuffer *eb)
{
/* Allocate an extra slot for use by the sentinel */
@@ -668,6 +635,25 @@ eb_add_vma(struct i915_execbuffer *eb,
}
}
+static int eb_lock_mm(struct i915_execbuffer *eb)
+{
+ struct eb_vma *ev;
+ int err;
+
+ list_for_each_entry(ev, &eb->bind_list, bind_link) {
+ err = i915_acquire_ctx_lock(&eb->acquire, ev->vma->obj);
+ if (err)
+ return err;
+ }
+
+ return 0;
+}
+
+static int eb_acquire_mm(struct i915_execbuffer *eb)
+{
+ return i915_acquire_mm(&eb->acquire);
+}
+
struct eb_vm_work {
struct dma_fence_work base;
struct eb_vma_array *array;
@@ -1390,7 +1376,15 @@ static int eb_reserve_vm(struct i915_execbuffer *eb)
unsigned long count;
struct eb_vma *ev;
unsigned int pass;
- int err = 0;
+ int err;
+
+ err = eb_lock_mm(eb);
+ if (err)
+ return err;
+
+ err = eb_acquire_mm(eb);
+ if (err)
+ return err;
count = 0;
INIT_LIST_HEAD(&unbound);
@@ -1416,10 +1410,15 @@ static int eb_reserve_vm(struct i915_execbuffer *eb)
if (count == 0)
return 0;
+ /* We need to reserve page directories, release all, start over */
+ i915_acquire_ctx_fini(&eb->acquire);
+
pass = 0;
do {
struct eb_vm_work *work;
+ i915_acquire_ctx_init(&eb->acquire);
Couldn't we do a i915_acquire_ctx_rollback() here to avoid losing our
ticket? That would mean deferring i915_acquire_ctx_done() until all
potential rollbacks have been performed.
Or even better if we defer _ctx_done(), couldn't we just continue
locking the pts here instead of dropping and re-acquiring everything?
+
/*
* We need to hold one lock as we bind all the vma so that
* we have a consistent view of the entire vm and can plan
@@ -1436,6 +1435,11 @@ static int eb_reserve_vm(struct i915_execbuffer *eb)
* beneath it, so we have to stage and preallocate all the
* resources we may require before taking the mutex.
*/
+
+ err = eb_lock_mm(eb);
+ if (err)
+ return err;
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