[PATCH v3 4/4] drm/xe: Move vma rebinding to the drm_exec locking loop
Thomas Hellström
thomas.hellstrom at linux.intel.com
Wed Mar 27 09:11:36 UTC 2024
Rebinding might allocate page-table bos, causing evictions.
To support blocking locking during these evictions,
perform the rebinding in the drm_exec locking loop.
Also Reserve fence slots where actually needed rather than trying to
predict how many fence slots will be needed over a complete
wound-wait transaction.
v2:
- Remove a leftover call to xe_vm_rebind() (Matt Brost)
- Add a helper function xe_vm_validate_rebind() (Matt Brost)
v3:
- Add comments and squash with previous patch (Matt Brost)
Fixes: 24f947d58fe5 ("drm/xe: Use DRM GPUVM helpers for external- and evicted objects")
Fixes: 29f424eb8702 ("drm/xe/exec: move fence reservation")
Cc: Matthew Auld <matthew.auld at intel.com>
Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
Reviewed-by: Matthew Brost <matthew.brost at intel.com>
---
drivers/gpu/drm/xe/xe_exec.c | 52 ++---------------
drivers/gpu/drm/xe/xe_gt_pagefault.c | 3 +-
drivers/gpu/drm/xe/xe_pt.c | 14 +++++
drivers/gpu/drm/xe/xe_vm.c | 83 +++++++++++++++++++---------
drivers/gpu/drm/xe/xe_vm.h | 6 +-
5 files changed, 83 insertions(+), 75 deletions(-)
diff --git a/drivers/gpu/drm/xe/xe_exec.c b/drivers/gpu/drm/xe/xe_exec.c
index b7e26e8e6472..97eeb973e897 100644
--- a/drivers/gpu/drm/xe/xe_exec.c
+++ b/drivers/gpu/drm/xe/xe_exec.c
@@ -94,48 +94,16 @@
* Unlock all
*/
+/*
+ * Add validation and rebinding to the drm_exec locking loop, since both can
+ * trigger eviction which may require sleeping dma_resv locks.
+ */
static int xe_exec_fn(struct drm_gpuvm_exec *vm_exec)
{
struct xe_vm *vm = container_of(vm_exec->vm, struct xe_vm, gpuvm);
- struct drm_gem_object *obj;
- unsigned long index;
- int num_fences;
- int ret;
-
- ret = drm_gpuvm_validate(vm_exec->vm, &vm_exec->exec);
- if (ret)
- return ret;
-
- /*
- * 1 fence slot for the final submit, and 1 more for every per-tile for
- * GPU bind and 1 extra for CPU bind. Note that there are potentially
- * many vma per object/dma-resv, however the fence slot will just be
- * re-used, since they are largely the same timeline and the seqno
- * should be in order. In the case of CPU bind there is dummy fence used
- * for all CPU binds, so no need to have a per-tile slot for that.
- */
- num_fences = 1 + 1 + vm->xe->info.tile_count;
- /*
- * We don't know upfront exactly how many fence slots we will need at
- * the start of the exec, since the TTM bo_validate above can consume
- * numerous fence slots. Also due to how the dma_resv_reserve_fences()
- * works it only ensures that at least that many fence slots are
- * available i.e if there are already 10 slots available and we reserve
- * two more, it can just noop without reserving anything. With this it
- * is quite possible that TTM steals some of the fence slots and then
- * when it comes time to do the vma binding and final exec stage we are
- * lacking enough fence slots, leading to some nasty BUG_ON() when
- * adding the fences. Hence just add our own fences here, after the
- * validate stage.
- */
- drm_exec_for_each_locked_object(&vm_exec->exec, index, obj) {
- ret = dma_resv_reserve_fences(obj->resv, num_fences);
- if (ret)
- return ret;
- }
-
- return 0;
+ /* The fence slot added here is intended for the exec sched job. */
+ return xe_vm_validate_rebind(vm, &vm_exec->exec, 1);
}
int xe_exec_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
@@ -289,14 +257,6 @@ int xe_exec_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
goto err_exec;
}
- /*
- * Rebind any invalidated userptr or evicted BOs in the VM, non-compute
- * VM mode only.
- */
- err = xe_vm_rebind(vm, false);
- if (err)
- goto err_put_job;
-
/* Wait behind rebinds */
if (!xe_vm_in_lr_mode(vm)) {
err = drm_sched_job_add_resv_dependencies(&job->drm,
diff --git a/drivers/gpu/drm/xe/xe_gt_pagefault.c b/drivers/gpu/drm/xe/xe_gt_pagefault.c
index 241c294270d9..fa9e9853c53b 100644
--- a/drivers/gpu/drm/xe/xe_gt_pagefault.c
+++ b/drivers/gpu/drm/xe/xe_gt_pagefault.c
@@ -100,10 +100,9 @@ static int xe_pf_begin(struct drm_exec *exec, struct xe_vma *vma,
{
struct xe_bo *bo = xe_vma_bo(vma);
struct xe_vm *vm = xe_vma_vm(vma);
- unsigned int num_shared = 2; /* slots for bind + move */
int err;
- err = xe_vm_prepare_vma(exec, vma, num_shared);
+ err = xe_vm_lock_vma(exec, vma);
if (err)
return err;
diff --git a/drivers/gpu/drm/xe/xe_pt.c b/drivers/gpu/drm/xe/xe_pt.c
index d1b999dbc906..580fe869b414 100644
--- a/drivers/gpu/drm/xe/xe_pt.c
+++ b/drivers/gpu/drm/xe/xe_pt.c
@@ -1235,6 +1235,13 @@ __xe_pt_bind_vma(struct xe_tile *tile, struct xe_vma *vma, struct xe_exec_queue
err = xe_pt_prepare_bind(tile, vma, entries, &num_entries);
if (err)
goto err;
+
+ err = dma_resv_reserve_fences(xe_vm_resv(vm), 1);
+ if (!err && !xe_vma_has_no_bo(vma) && !xe_vma_bo(vma)->vm)
+ err = dma_resv_reserve_fences(xe_vma_bo(vma)->ttm.base.resv, 1);
+ if (err)
+ goto err;
+
xe_tile_assert(tile, num_entries <= ARRAY_SIZE(entries));
xe_vm_dbg_print_entries(tile_to_xe(tile), entries, num_entries);
@@ -1577,6 +1584,7 @@ __xe_pt_unbind_vma(struct xe_tile *tile, struct xe_vma *vma, struct xe_exec_queu
struct dma_fence *fence = NULL;
struct invalidation_fence *ifence;
struct xe_range_fence *rfence;
+ int err;
LLIST_HEAD(deferred);
@@ -1594,6 +1602,12 @@ __xe_pt_unbind_vma(struct xe_tile *tile, struct xe_vma *vma, struct xe_exec_queu
xe_pt_calc_rfence_interval(vma, &unbind_pt_update, entries,
num_entries);
+ err = dma_resv_reserve_fences(xe_vm_resv(vm), 1);
+ if (!err && !xe_vma_has_no_bo(vma) && !xe_vma_bo(vma)->vm)
+ err = dma_resv_reserve_fences(xe_vma_bo(vma)->ttm.base.resv, 1);
+ if (err)
+ return ERR_PTR(err);
+
ifence = kzalloc(sizeof(*ifence), GFP_KERNEL);
if (!ifence)
return ERR_PTR(-ENOMEM);
diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
index e995196862db..8b32aa5003df 100644
--- a/drivers/gpu/drm/xe/xe_vm.c
+++ b/drivers/gpu/drm/xe/xe_vm.c
@@ -482,17 +482,53 @@ static int xe_gpuvm_validate(struct drm_gpuvm_bo *vm_bo, struct drm_exec *exec)
return 0;
}
+/**
+ * xe_vm_validate_rebind() - Validate buffer objects and rebind vmas
+ * @vm: The vm for which we are rebinding.
+ * @exec: The struct drm_exec with the locked GEM objects.
+ * @num_fences: The number of fences to reserve for the operation, not
+ * including rebinds and validations.
+ *
+ * Validates all evicted gem objects and rebinds their vmas. Note that
+ * rebindings may cause evictions and hence the validation-rebind
+ * sequence is rerun until there are no more objects to validate.
+ *
+ * Return: 0 on success, negative error code on error. In particular,
+ * may return -EINTR or -ERESTARTSYS if interrupted, and -EDEADLK if
+ * the drm_exec transaction needs to be restarted.
+ */
+int xe_vm_validate_rebind(struct xe_vm *vm, struct drm_exec *exec,
+ unsigned int num_fences)
+{
+ struct drm_gem_object *obj;
+ unsigned long index;
+ int ret;
+
+ do {
+ ret = drm_gpuvm_validate(&vm->gpuvm, exec);
+ if (ret)
+ return ret;
+
+ ret = xe_vm_rebind(vm, false);
+ if (ret)
+ return ret;
+ } while (!list_empty(&vm->gpuvm.evict.list));
+
+ drm_exec_for_each_locked_object(exec, index, obj) {
+ ret = dma_resv_reserve_fences(obj->resv, num_fences);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
static int xe_preempt_work_begin(struct drm_exec *exec, struct xe_vm *vm,
bool *done)
{
int err;
- /*
- * 1 fence for each preempt fence plus a fence for each tile from a
- * possible rebind
- */
- err = drm_gpuvm_prepare_vm(&vm->gpuvm, exec, vm->preempt.num_exec_queues +
- vm->xe->info.tile_count);
+ err = drm_gpuvm_prepare_vm(&vm->gpuvm, exec, 0);
if (err)
return err;
@@ -507,7 +543,7 @@ static int xe_preempt_work_begin(struct drm_exec *exec, struct xe_vm *vm,
return 0;
}
- err = drm_gpuvm_prepare_objects(&vm->gpuvm, exec, vm->preempt.num_exec_queues);
+ err = drm_gpuvm_prepare_objects(&vm->gpuvm, exec, 0);
if (err)
return err;
@@ -515,7 +551,13 @@ static int xe_preempt_work_begin(struct drm_exec *exec, struct xe_vm *vm,
if (err)
return err;
- return drm_gpuvm_validate(&vm->gpuvm, exec);
+ /*
+ * Add validation and rebinding to the locking loop since both can
+ * cause evictions which may require blocing dma_resv locks.
+ * The fence reservation here is intended for the new preempt fences
+ * we attach at the end of the rebind work.
+ */
+ return xe_vm_validate_rebind(vm, exec, vm->preempt.num_exec_queues);
}
static void preempt_rebind_work_func(struct work_struct *w)
@@ -1000,35 +1042,26 @@ static void xe_vma_destroy(struct xe_vma *vma, struct dma_fence *fence)
}
/**
- * xe_vm_prepare_vma() - drm_exec utility to lock a vma
+ * xe_vm_lock_vma() - drm_exec utility to lock a vma
* @exec: The drm_exec object we're currently locking for.
* @vma: The vma for witch we want to lock the vm resv and any attached
* object's resv.
- * @num_shared: The number of dma-fence slots to pre-allocate in the
- * objects' reservation objects.
*
* Return: 0 on success, negative error code on error. In particular
* may return -EDEADLK on WW transaction contention and -EINTR if
* an interruptible wait is terminated by a signal.
*/
-int xe_vm_prepare_vma(struct drm_exec *exec, struct xe_vma *vma,
- unsigned int num_shared)
+int xe_vm_lock_vma(struct drm_exec *exec, struct xe_vma *vma)
{
struct xe_vm *vm = xe_vma_vm(vma);
struct xe_bo *bo = xe_vma_bo(vma);
int err;
XE_WARN_ON(!vm);
- if (num_shared)
- err = drm_exec_prepare_obj(exec, xe_vm_obj(vm), num_shared);
- else
- err = drm_exec_lock_obj(exec, xe_vm_obj(vm));
- if (!err && bo && !bo->vm) {
- if (num_shared)
- err = drm_exec_prepare_obj(exec, &bo->ttm.base, num_shared);
- else
- err = drm_exec_lock_obj(exec, &bo->ttm.base);
- }
+
+ err = drm_exec_lock_obj(exec, xe_vm_obj(vm));
+ if (!err && bo && !bo->vm)
+ err = drm_exec_lock_obj(exec, &bo->ttm.base);
return err;
}
@@ -1040,7 +1073,7 @@ static void xe_vma_destroy_unlocked(struct xe_vma *vma)
drm_exec_init(&exec, 0, 0);
drm_exec_until_all_locked(&exec) {
- err = xe_vm_prepare_vma(&exec, vma, 0);
+ err = xe_vm_lock_vma(&exec, vma);
drm_exec_retry_on_contention(&exec);
if (XE_WARN_ON(err))
break;
@@ -2506,7 +2539,7 @@ static int op_execute(struct drm_exec *exec, struct xe_vm *vm,
lockdep_assert_held_write(&vm->lock);
- err = xe_vm_prepare_vma(exec, vma, 1);
+ err = xe_vm_lock_vma(exec, vma);
if (err)
return err;
diff --git a/drivers/gpu/drm/xe/xe_vm.h b/drivers/gpu/drm/xe/xe_vm.h
index 4853354336f2..306cd0934a19 100644
--- a/drivers/gpu/drm/xe/xe_vm.h
+++ b/drivers/gpu/drm/xe/xe_vm.h
@@ -242,8 +242,10 @@ bool xe_vm_validate_should_retry(struct drm_exec *exec, int err, ktime_t *end);
int xe_analyze_vm(struct drm_printer *p, struct xe_vm *vm, int gt_id);
-int xe_vm_prepare_vma(struct drm_exec *exec, struct xe_vma *vma,
- unsigned int num_shared);
+int xe_vm_lock_vma(struct drm_exec *exec, struct xe_vma *vma);
+
+int xe_vm_validate_rebind(struct xe_vm *vm, struct drm_exec *exec,
+ unsigned int num_fences);
/**
* xe_vm_resv() - Return's the vm's reservation object
--
2.44.0
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