drm/amdkfd: support larger svm range allocation

For larger range allocation, if hmm_range_fault return -EBUSY, set retry
timeout based on 1 second for every 512MB, this is safe timeout value.
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>

drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c

@@ -185,7 +185,10 @@ int amdgpu_hmm_range_get_pages(struct mmu_interval_notifier *notifier,
 	hmm_range->hmm_pfns = pfns;
 	hmm_range->start = start;
 	hmm_range->end = start + npages * PAGE_SIZE;
-	timeout = jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
+
+	/* Assuming 512MB takes maxmium 1 second to fault page address */
+	timeout = max(npages >> 17, 1ULL) * HMM_RANGE_DEFAULT_TIMEOUT;
+	timeout = jiffies + msecs_to_jiffies(timeout);
 
 retry:
 	hmm_range->notifier_seq = mmu_interval_read_begin(notifier);