drm/amdkfd: add svm range validate timestamp

With xnack on, add validate timestamp in order to handle GPU vm fault
from multiple GPUs.

If GPU retry fault need migrate the range to the best restore location,
use range validate timestamp to record system timestamp after range is
restored to update GPU page table.

Because multiple pages of same range have multiple retry fault, define
AMDGPU_SVM_RANGE_RETRY_FAULT_PENDING to the long time period that
pending retry fault may still comes after page table update, to skip
duplicate retry fault of same range.

If difference between system timestamp and range last validate timestamp
is bigger than AMDGPU_SVM_RANGE_RETRY_FAULT_PENDING, that means the
retry fault is from another GPU, then continue to handle retry fault
recover.

Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
index 7206e0b7b422..0694211a118b 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
@@ -35,6 +35,11 @@
 
 #define AMDGPU_SVM_RANGE_RESTORE_DELAY_MS 1
 
+/* Long enough to ensure no retry fault comes after svm range is restored and
+ * page table is updated.
+ */
+#define AMDGPU_SVM_RANGE_RETRY_FAULT_PENDING	2000
+
 static void svm_range_evict_svm_bo_worker(struct work_struct *work);
 static bool
 svm_range_cpu_invalidate_pagetables(struct mmu_interval_notifier *mni,
@@ -269,6 +274,7 @@ svm_range *svm_range_new(struct svm_range_list *svms, uint64_t start,
 	INIT_LIST_HEAD(&prange->deferred_list);
 	INIT_LIST_HEAD(&prange->child_list);
 	atomic_set(&prange->invalid, 0);
+	prange->validate_timestamp = ktime_to_us(ktime_get());
 	mutex_init(&prange->migrate_mutex);
 	mutex_init(&prange->lock);
 	svm_range_set_default_attributes(&prange->preferred_loc,
@@ -1392,6 +1398,9 @@ unlock_out:
 unreserve_out:
 	svm_range_unreserve_bos(&ctx);
 
+	if (!r)
+		prange->validate_timestamp = ktime_to_us(ktime_get());
+
 	return r;
 }
 
@@ -2131,6 +2140,7 @@ svm_range_restore_pages(struct amdgpu_device *adev, unsigned int pasid,
 	struct svm_range_list *svms;
 	struct svm_range *prange;
 	struct kfd_process *p;
+	uint64_t timestamp;
 	int32_t best_loc, gpuidx;
 	int r = 0;
 
@@ -2166,6 +2176,13 @@ svm_range_restore_pages(struct amdgpu_device *adev, unsigned int pasid,
 	}
 
 	mutex_lock(&prange->migrate_mutex);
+	timestamp = ktime_to_us(ktime_get()) - prange->validate_timestamp;
+	/* skip duplicate vm fault on different pages of same range */
+	if (timestamp < AMDGPU_SVM_RANGE_RETRY_FAULT_PENDING) {
+		pr_debug("svms 0x%p [0x%lx %lx] already restored\n",
+			 svms, prange->start, prange->last);
+		goto out_unlock_range;
+	}
 
 	best_loc = svm_range_best_restore_location(prange, adev, &gpuidx);
 	if (best_loc == -1) {