[RFC PATCH 27/28] drm/xe: Add modparam for SVM prefault

[Matthew Brost <matthew.brost@xxxxxxxxx>]

Useful to experiment with SVM prefault and how it affects performance.

Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
---
 drivers/gpu/drm/xe/xe_module.c | 3 +++
 drivers/gpu/drm/xe/xe_module.h | 1 +
 drivers/gpu/drm/xe/xe_svm.c    | 2 ++
 3 files changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_module.c b/drivers/gpu/drm/xe/xe_module.c
index 30cfb76344a1..edda9898f3cf 100644
--- a/drivers/gpu/drm/xe/xe_module.c
+++ b/drivers/gpu/drm/xe/xe_module.c
@@ -29,6 +29,9 @@ struct xe_modparam xe_modparam = {
 module_param_named(svm_notifier_size, xe_modparam.svm_notifier_size, uint, 0600);
 MODULE_PARM_DESC(svm_notifier_size, "Set the svm notifier size(in MiB), must be pow2");
 
+module_param_named(svm_prefault, xe_modparam.svm_prefault, bool, 0444);
+MODULE_PARM_DESC(svm_prefault, "SVM prefault CPU pages upon range allocation");
+
 module_param_named_unsafe(force_execlist, xe_modparam.force_execlist, bool, 0444);
 MODULE_PARM_DESC(force_execlist, "Force Execlist submission");
 
diff --git a/drivers/gpu/drm/xe/xe_module.h b/drivers/gpu/drm/xe/xe_module.h
index 5a3bfea8b7b4..c1571cd8f9fe 100644
--- a/drivers/gpu/drm/xe/xe_module.h
+++ b/drivers/gpu/drm/xe/xe_module.h
@@ -12,6 +12,7 @@
 struct xe_modparam {
 	bool force_execlist;
 	bool probe_display;
+	bool svm_prefault;
 	u32 force_vram_bar_size;
 	int guc_log_level;
 	char *guc_firmware_path;
diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c
index 5e2ec25c3cb2..8e80e8704534 100644
--- a/drivers/gpu/drm/xe/xe_svm.c
+++ b/drivers/gpu/drm/xe/xe_svm.c
@@ -645,9 +645,11 @@ int xe_svm_handle_pagefault(struct xe_vm *vm, struct xe_vma *vma,
 	if (err)
 		return err;
 
+	ctx.prefault = xe_modparam.svm_prefault;
 	r = drm_gpusvm_range_find_or_insert(&vm->svm.gpusvm, fault_addr,
 					    xe_vma_start(vma), xe_vma_end(vma),
 					    &ctx);
+	ctx.prefault = false;
 	if (IS_ERR(r))
 		return PTR_ERR(r);
 
-- 
2.34.1