[PATCH v4 2/5] drm/xe: Merge adjacent default-attribute VMAs during garbage collection

[Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>]

While restoring default memory attributes for VMAs during garbage
collection, extend the target range by checking neighboring VMAs. If
adjacent VMAs are CPU-address-mirrored and have default attributes,
include them in the mergeable range to reduce fragmentation and improve
VMA reuse.

v2
-Rebase

Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
---
 drivers/gpu/drm/xe/xe_svm.c | 62 +++++++++++++++++++++----------------
 1 file changed, 36 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c
index 13af589715a7..585e3eccc876 100644
--- a/drivers/gpu/drm/xe/xe_svm.c
+++ b/drivers/gpu/drm/xe/xe_svm.c
@@ -286,19 +286,21 @@ static int __xe_svm_garbage_collector(struct xe_vm *vm,
 	return 0;
 }
 
-static int xe_svm_range_set_default_attr(struct xe_vm *vm, u64 range_start, u64 range_end)
+static void xe_vma_set_default_attributes(struct xe_vma *vma)
+{
+	vma->attr.preferred_loc.devmem_fd = DRM_XE_PREFERRED_LOC_DEFAULT_DEVICE;
+	vma->attr.preferred_loc.migration_policy = DRM_XE_MIGRATE_ALL_PAGES;
+	vma->attr.pat_index = vma->attr.default_pat_index;
+	vma->attr.atomic_access = DRM_XE_ATOMIC_UNDEFINED;
+}
+
+static int xe_svm_range_set_default_attr(struct xe_vm *vm, u64 start, u64 end)
 {
 	struct xe_vma *vma;
-	struct xe_vma_mem_attr default_attr = {
-		.preferred_loc = {
-			.devmem_fd = DRM_XE_PREFERRED_LOC_DEFAULT_DEVICE,
-			.migration_policy = DRM_XE_MIGRATE_ALL_PAGES,
-		},
-		.atomic_access = DRM_XE_ATOMIC_UNDEFINED,
-	};
-	int err = 0;
+	bool has_default_attr;
+	int err;
 
-	vma = xe_vm_find_vma_by_addr(vm, range_start);
+	vma = xe_vm_find_vma_by_addr(vm, start);
 	if (!vma)
 		return -EINVAL;
 
@@ -307,25 +309,33 @@ static int xe_svm_range_set_default_attr(struct xe_vm *vm, u64 range_start, u64
 		return 0;
 	}
 
-	if (xe_vma_has_default_mem_attrs(vma))
-		return 0;
-
 	vm_dbg(&vm->xe->drm, "Existing VMA start=0x%016llx, vma_end=0x%016llx",
 	       xe_vma_start(vma), xe_vma_end(vma));
 
-	if (xe_vma_start(vma) == range_start && xe_vma_end(vma) == range_end) {
-		default_attr.pat_index = vma->attr.default_pat_index;
-		default_attr.default_pat_index  = vma->attr.default_pat_index;
-		vma->attr = default_attr;
-	} else {
-		vm_dbg(&vm->xe->drm, "Split VMA start=0x%016llx, vma_end=0x%016llx",
-		       range_start, range_end);
-		err = xe_vm_alloc_cpu_addr_mirror_vma(vm, range_start, range_end - range_start);
-		if (err) {
-			drm_warn(&vm->xe->drm, "VMA SPLIT failed: %pe\n", ERR_PTR(err));
-			xe_vm_kill(vm, true);
-			return err;
-		}
+	has_default_attr = xe_vma_has_default_mem_attrs(vma);
+
+	if (has_default_attr) {
+		if (xe_svm_has_mapping(vm, xe_vma_start(vma), xe_vma_end(vma)))
+			return 0;
+
+		start = xe_vma_start(vma);
+		end = xe_vma_end(vma);
+	} else if (xe_vma_start(vma) == start && xe_vma_end(vma) == end) {
+		xe_vma_set_default_attributes(vma);
+	}
+
+	xe_vm_find_cpu_addr_mirror_vma_range(vm, &start, &end);
+
+	if (xe_vma_start(vma) == start && xe_vma_end(vma) == end && has_default_attr)
+		return 0;
+
+	vm_dbg(&vm->xe->drm, "New VMA start=0x%016llx, vma_end=0x%016llx",  start, end);
+
+	err = xe_vm_alloc_cpu_addr_mirror_vma(vm, start, end - start);
+	if (err) {
+		drm_warn(&vm->xe->drm, "New VMA MAP failed: %pe\n", ERR_PTR(err));
+		xe_vm_kill(vm, true);
+		return err;
 	}
 
 	/*
-- 
2.34.1