drm/xe: Add SVM init / close / fini to faulting VMs

Add SVM init / close / fini to faulting VMs. Minimual implementation
acting as a placeholder for follow on patches.

v2:
 - Add close function
v3:
 - Better commit message (Thomas)
 - Kernel doc (Thomas)
 - Update chunk array to be unsigned long (Thomas)
 - Use new drm_gpusvm.h header location (Thomas)
 - Newlines between functions in xe_svm.h (Thomas)
 - Call drm_gpusvm_driver_set_lock in init (Thomas)
v6:
 - Only compile if CONFIG_DRM_GPUSVM selected (CI, Lucas)
v7:
 - Only select CONFIG_DRM_GPUSVM if DEVICE_PRIVATE (CI)

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250306012657.3505757-10-matthew.brost@intel.com

drivers/gpu/drm/xe/Makefile

@@ -124,6 +124,7 @@ xe-y += xe_bb.o \
 	xe_wopcm.o
 
 xe-$(CONFIG_HMM_MIRROR) += xe_hmm.o
+xe-$(CONFIG_DRM_GPUSVM) += xe_svm.o
 
 # graphics hardware monitoring (HWMON) support
 xe-$(CONFIG_HWMON) += xe_hwmon.o

drivers/gpu/drm/xe/xe_svm.c

@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2024 Intel Corporation
+ */
+
+#include "xe_svm.h"
+#include "xe_vm.h"
+#include "xe_vm_types.h"
+
+static void xe_svm_invalidate(struct drm_gpusvm *gpusvm,
+			      struct drm_gpusvm_notifier *notifier,
+			      const struct mmu_notifier_range *mmu_range)
+{
+	/* TODO: Implement */
+}
+
+static const struct drm_gpusvm_ops gpusvm_ops = {
+	.invalidate = xe_svm_invalidate,
+};
+
+static const unsigned long fault_chunk_sizes[] = {
+	SZ_2M,
+	SZ_64K,
+	SZ_4K,
+};
+
+/**
+ * xe_svm_init() - SVM initialize
+ * @vm: The VM.
+ *
+ * Initialize SVM state which is embedded within the VM.
+ *
+ * Return: 0 on success, negative error code on error.
+ */
+int xe_svm_init(struct xe_vm *vm)
+{
+	int err;
+
+	err = drm_gpusvm_init(&vm->svm.gpusvm, "Xe SVM", &vm->xe->drm,
+			      current->mm, NULL, 0, vm->size,
+			      SZ_512M, &gpusvm_ops, fault_chunk_sizes,
+			      ARRAY_SIZE(fault_chunk_sizes));
+	if (err)
+		return err;
+
+	drm_gpusvm_driver_set_lock(&vm->svm.gpusvm, &vm->lock);
+
+	return 0;
+}
+
+/**
+ * xe_svm_close() - SVM close
+ * @vm: The VM.
+ *
+ * Close SVM state (i.e., stop and flush all SVM actions).
+ */
+void xe_svm_close(struct xe_vm *vm)
+{
+	xe_assert(vm->xe, xe_vm_is_closed(vm));
+}
+
+/**
+ * xe_svm_fini() - SVM finalize
+ * @vm: The VM.
+ *
+ * Finalize SVM state which is embedded within the VM.
+ */
+void xe_svm_fini(struct xe_vm *vm)
+{
+	xe_assert(vm->xe, xe_vm_is_closed(vm));
+
+	drm_gpusvm_fini(&vm->svm.gpusvm);
+}

drivers/gpu/drm/xe/xe_svm.h

@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2024 Intel Corporation
+ */
+
+#ifndef _XE_SVM_H_
+#define _XE_SVM_H_
+
+struct xe_vm;
+
+#if IS_ENABLED(CONFIG_DRM_GPUSVM)
+int xe_svm_init(struct xe_vm *vm);
+
+void xe_svm_fini(struct xe_vm *vm);
+
+void xe_svm_close(struct xe_vm *vm);
+#else
+static inline
+int xe_svm_init(struct xe_vm *vm)
+{
+	return 0;
+}
+
+static inline
+void xe_svm_fini(struct xe_vm *vm)
+{
+}
+
+static inline
+void xe_svm_close(struct xe_vm *vm)
+{
+}
+#endif
+
+#endif

drivers/gpu/drm/xe/xe_vm.c

@@ -35,6 +35,7 @@
 #include "xe_pt.h"
 #include "xe_pxp.h"
 #include "xe_res_cursor.h"
+#include "xe_svm.h"
 #include "xe_sync.h"
 #include "xe_trace_bo.h"
 #include "xe_wa.h"
@@ -1582,6 +1583,12 @@ struct xe_vm *xe_vm_create(struct xe_device *xe, u32 flags)
 		}
 	}
 
+	if (flags & XE_VM_FLAG_FAULT_MODE) {
+		err = xe_svm_init(vm);
+		if (err)
+			goto err_close;
+	}
+
 	if (number_tiles > 1)
 		vm->composite_fence_ctx = dma_fence_context_alloc(1);
 
@@ -1627,6 +1634,8 @@ void xe_vm_close_and_put(struct xe_vm *vm)
 	xe_vm_close(vm);
 	if (xe_vm_in_preempt_fence_mode(vm))
 		flush_work(&vm->preempt.rebind_work);
+	if (xe_vm_in_fault_mode(vm))
+		xe_svm_close(vm);
 
 	down_write(&vm->lock);
 	for_each_tile(tile, xe, id) {
@@ -1695,6 +1704,9 @@ void xe_vm_close_and_put(struct xe_vm *vm)
 		xe_vma_destroy_unlocked(vma);
 	}
 
+	if (xe_vm_in_fault_mode(vm))
+		xe_svm_fini(vm);
+
 	up_write(&vm->lock);
 
 	down_write(&xe->usm.lock);

drivers/gpu/drm/xe/xe_vm_types.h

@@ -6,6 +6,7 @@
 #ifndef _XE_VM_TYPES_H_
 #define _XE_VM_TYPES_H_
 
+#include <drm/drm_gpusvm.h>
 #include <drm/drm_gpuvm.h>
 
 #include <linux/dma-resv.h>
@@ -144,6 +145,12 @@ struct xe_vm {
 	/** @gpuvm: base GPUVM used to track VMAs */
 	struct drm_gpuvm gpuvm;
 
+	/** @svm: Shared virtual memory state */
+	struct {
+		/** @svm.gpusvm: base GPUSVM used to track fault allocations */
+		struct drm_gpusvm gpusvm;
+	} svm;
+
 	struct xe_device *xe;
 
 	/* exec queue used for (un)binding vma's */