[PATCH 2/4] fixup! drm/nouveau: use hmm_range_fault_unlocked_timeout() for SVM faults

[Stanislav Kinsburskii]

nouveau_range_fault() now uses hmm_range_fault_unlocked_timeout() for
the HMM fault path. The timeout passed to that helper is meant to bound
HMM's internal mmu-notifier retry loop, not the whole nouveau retry loop
around mmu_interval_read_retry().

Pass the full relative HMM_RANGE_DEFAULT_TIMEOUT value to
hmm_range_fault_unlocked_timeout() on each attempt, and retry from the
nouveau-side mmu_interval_read_retry() check with a fresh HMM retry
budget. This lets HMM continue when it has made progress, while still
preserving a timeout for repeated notifier invalidation retries inside
one HMM fault attempt.

This also removes the open-coded absolute deadline and remaining-time
calculation from nouveau_range_fault().

Signed-off-by: Stanislav Kinsburskii <skinsburskii@xxxxxxxxx>
---
 drivers/gpu/drm/nouveau/nouveau_svm.c |   30 ++++++++++--------------------
 1 file changed, 10 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c
index 4cfb6eb7c771..b1415c2e49fc 100644
--- a/drivers/gpu/drm/nouveau/nouveau_svm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
@@ -655,8 +655,7 @@ static int nouveau_range_fault(struct nouveau_svmm *svmm,
 			       unsigned long hmm_flags,
 			       struct svm_notifier *notifier)
 {
-	unsigned long timeout =
-		jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
+	unsigned long timeout = msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
 	/* Have HMM fault pages within the fault window to the GPU. */
 	unsigned long hmm_pfns[1];
 	struct hmm_range range = {
@@ -677,25 +676,16 @@ static int nouveau_range_fault(struct nouveau_svmm *svmm,
 	range.start = notifier->notifier.interval_tree.start;
 	range.end = notifier->notifier.interval_tree.last + 1;
 
-	while (true) {
-		if (time_after(jiffies, timeout)) {
-			ret = -EBUSY;
-			goto out;
-		}
-
-		ret = hmm_range_fault_unlocked_timeout(&range,
-						       max(timeout - jiffies,
-							   1L));
-		if (ret)
-			goto out;
+again:
+	ret = hmm_range_fault_unlocked_timeout(&range, timeout);
+	if (ret)
+		goto out;
 
-		mutex_lock(&svmm->mutex);
-		if (mmu_interval_read_retry(range.notifier,
-					    range.notifier_seq)) {
-			mutex_unlock(&svmm->mutex);
-			continue;
-		}
-		break;
+	mutex_lock(&svmm->mutex);
+	if (mmu_interval_read_retry(range.notifier,
+				    range.notifier_seq)) {
+		mutex_unlock(&svmm->mutex);
+		goto again;
 	}
 
 	nouveau_hmm_convert_pfn(drm, &range, args);