1 files changed, 258 insertions, 0 deletions
diff --git a/drivers/gpu/drm/xe/xe_shrinker.c b/drivers/gpu/drm/xe/xe_shrinker.c
new file mode 100644
index 000000000000..8184390f9c7b
--- /dev/null
+++ b/drivers/gpu/drm/xe/xe_shrinker.c
@@ -0,0 +1,258 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2024 Intel Corporation
+ */
+
+#include <linux/shrinker.h>
+
+#include <drm/ttm/ttm_backup.h>
+#include <drm/ttm/ttm_bo.h>
+#include <drm/ttm/ttm_tt.h>
+
+#include "xe_bo.h"
+#include "xe_pm.h"
+#include "xe_shrinker.h"
+
+/**
+ * struct xe_shrinker - per-device shrinker
+ * @xe: Back pointer to the device.
+ * @lock: Lock protecting accounting.
+ * @shrinkable_pages: Number of pages that are currently shrinkable.
+ * @purgeable_pages: Number of pages that are currently purgeable.
+ * @shrink: Pointer to the mm shrinker.
+ * @pm_worker: Worker to wake up the device if required.
+ */
+struct xe_shrinker {
+	struct xe_device *xe;
+	rwlock_t lock;
+	long shrinkable_pages;
+	long purgeable_pages;
+	struct shrinker *shrink;
+	struct work_struct pm_worker;
+};
+
+static struct xe_shrinker *to_xe_shrinker(struct shrinker *shrink)
+{
+	return shrink->private_data;
+}
+
+/**
+ * xe_shrinker_mod_pages() - Modify shrinker page accounting
+ * @shrinker: Pointer to the struct xe_shrinker.
+ * @shrinkable: Shrinkable pages delta. May be negative.
+ * @purgeable: Purgeable page delta. May be negative.
+ *
+ * Modifies the shrinkable and purgeable pages accounting.
+ */
+void
+xe_shrinker_mod_pages(struct xe_shrinker *shrinker, long shrinkable, long purgeable)
+{
+	write_lock(&shrinker->lock);
+	shrinker->shrinkable_pages += shrinkable;
+	shrinker->purgeable_pages += purgeable;
+	write_unlock(&shrinker->lock);
+}
+
+static s64 xe_shrinker_walk(struct xe_device *xe,
+			    struct ttm_operation_ctx *ctx,
+			    const struct xe_bo_shrink_flags flags,
+			    unsigned long to_scan, unsigned long *scanned)
+{
+	unsigned int mem_type;
+	s64 freed = 0, lret;
+
+	for (mem_type = XE_PL_SYSTEM; mem_type <= XE_PL_TT; ++mem_type) {
+		struct ttm_resource_manager *man = ttm_manager_type(&xe->ttm, mem_type);
+		struct ttm_bo_lru_cursor curs;
+		struct ttm_buffer_object *ttm_bo;
+
+		if (!man || !man->use_tt)
+			continue;
+
+		ttm_bo_lru_for_each_reserved_guarded(&curs, man, ctx, ttm_bo) {
+			if (!ttm_bo_shrink_suitable(ttm_bo, ctx))
+				continue;
+
+			lret = xe_bo_shrink(ctx, ttm_bo, flags, scanned);
+			if (lret < 0)
+				return lret;
+
+			freed += lret;
+			if (*scanned >= to_scan)
+				break;
+		}
+	}
+
+	return freed;
+}
+
+static unsigned long
+xe_shrinker_count(struct shrinker *shrink, struct shrink_control *sc)
+{
+	struct xe_shrinker *shrinker = to_xe_shrinker(shrink);
+	unsigned long num_pages;
+	bool can_backup = !!(sc->gfp_mask & __GFP_FS);
+
+	num_pages = ttm_backup_bytes_avail() >> PAGE_SHIFT;
+	read_lock(&shrinker->lock);
+
+	if (can_backup)
+		num_pages = min_t(unsigned long, num_pages, shrinker->shrinkable_pages);
+	else
+		num_pages = 0;
+
+	num_pages += shrinker->purgeable_pages;
+	read_unlock(&shrinker->lock);
+
+	return num_pages ? num_pages : SHRINK_EMPTY;
+}
+
+/*
+ * Check if we need runtime pm, and if so try to grab a reference if
+ * already active. If grabbing a reference fails, queue a worker that
+ * does it for us outside of reclaim, but don't wait for it to complete.
+ * If bo shrinking needs an rpm reference and we don't have it (yet),
+ * that bo will be skipped anyway.
+ */
+static bool xe_shrinker_runtime_pm_get(struct xe_shrinker *shrinker, bool force,
+				       unsigned long nr_to_scan, bool can_backup)
+{
+	struct xe_device *xe = shrinker->xe;
+
+	if (IS_DGFX(xe) || !xe_device_has_flat_ccs(xe) ||
+	    !ttm_backup_bytes_avail())
+		return false;
+
+	if (!force) {
+		read_lock(&shrinker->lock);
+		force = (nr_to_scan > shrinker->purgeable_pages && can_backup);
+		read_unlock(&shrinker->lock);
+		if (!force)
+			return false;
+	}
+
+	if (!xe_pm_runtime_get_if_active(xe)) {
+		if (xe_rpm_reclaim_safe(xe) && !ttm_bo_shrink_avoid_wait()) {
+			xe_pm_runtime_get(xe);
+			return true;
+		}
+		queue_work(xe->unordered_wq, &shrinker->pm_worker);
+		return false;
+	}
+
+	return true;
+}
+
+static void xe_shrinker_runtime_pm_put(struct xe_shrinker *shrinker, bool runtime_pm)
+{
+	if (runtime_pm)
+		xe_pm_runtime_put(shrinker->xe);
+}
+
+static unsigned long xe_shrinker_scan(struct shrinker *shrink, struct shrink_control *sc)
+{
+	struct xe_shrinker *shrinker = to_xe_shrinker(shrink);
+	struct ttm_operation_ctx ctx = {
+		.interruptible = false,
+		.no_wait_gpu = ttm_bo_shrink_avoid_wait(),
+	};
+	unsigned long nr_to_scan, nr_scanned = 0, freed = 0;
+	struct xe_bo_shrink_flags shrink_flags = {
+		.purge = true,
+		/* Don't request writeback without __GFP_IO. */
+		.writeback = !ctx.no_wait_gpu && (sc->gfp_mask & __GFP_IO),
+	};
+	bool runtime_pm;
+	bool purgeable;
+	bool can_backup = !!(sc->gfp_mask & __GFP_FS);
+	s64 lret;
+
+	nr_to_scan = sc->nr_to_scan;
+
+	read_lock(&shrinker->lock);
+	purgeable = !!shrinker->purgeable_pages;
+	read_unlock(&shrinker->lock);
+
+	/* Might need runtime PM. Try to wake early if it looks like it. */
+	runtime_pm = xe_shrinker_runtime_pm_get(shrinker, false, nr_to_scan, can_backup);
+
+	if (purgeable && nr_scanned < nr_to_scan) {
+		lret = xe_shrinker_walk(shrinker->xe, &ctx, shrink_flags,
+					nr_to_scan, &nr_scanned);
+		if (lret >= 0)
+			freed += lret;
+	}
+
+	sc->nr_scanned = nr_scanned;
+	if (nr_scanned >= nr_to_scan || !can_backup)
+		goto out;
+
+	/* If we didn't wake before, try to do it now if needed. */
+	if (!runtime_pm)
+		runtime_pm = xe_shrinker_runtime_pm_get(shrinker, true, 0, can_backup);
+
+	shrink_flags.purge = false;
+	lret = xe_shrinker_walk(shrinker->xe, &ctx, shrink_flags,
+				nr_to_scan, &nr_scanned);
+	if (lret >= 0)
+		freed += lret;
+
+	sc->nr_scanned = nr_scanned;
+out:
+	xe_shrinker_runtime_pm_put(shrinker, runtime_pm);
+	return nr_scanned ? freed : SHRINK_STOP;
+}
+
+/* Wake up the device for shrinking. */
+static void xe_shrinker_pm(struct work_struct *work)
+{
+	struct xe_shrinker *shrinker =
+		container_of(work, typeof(*shrinker), pm_worker);
+
+	xe_pm_runtime_get(shrinker->xe);
+	xe_pm_runtime_put(shrinker->xe);
+}
+
+/**
+ * xe_shrinker_create() - Create an xe per-device shrinker
+ * @xe: Pointer to the xe device.
+ *
+ * Returns: A pointer to the created shrinker on success,
+ * Negative error code on failure.
+ */
+struct xe_shrinker *xe_shrinker_create(struct xe_device *xe)
+{
+	struct xe_shrinker *shrinker = kzalloc(sizeof(*shrinker), GFP_KERNEL);
+
+	if (!shrinker)
+		return ERR_PTR(-ENOMEM);
+
+	shrinker->shrink = shrinker_alloc(0, "xe system shrinker");
+	if (!shrinker->shrink) {
+		kfree(shrinker);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	INIT_WORK(&shrinker->pm_worker, xe_shrinker_pm);
+	shrinker->xe = xe;
+	rwlock_init(&shrinker->lock);
+	shrinker->shrink->count_objects = xe_shrinker_count;
+	shrinker->shrink->scan_objects = xe_shrinker_scan;
+	shrinker->shrink->private_data = shrinker;
+	shrinker_register(shrinker->shrink);
+
+	return shrinker;
+}
+
+/**
+ * xe_shrinker_destroy() - Destroy an xe per-device shrinker
+ * @shrinker: Pointer to the shrinker to destroy.
+ */
+void xe_shrinker_destroy(struct xe_shrinker *shrinker)
+{
+	xe_assert(shrinker->xe, !shrinker->shrinkable_pages);
+	xe_assert(shrinker->xe, !shrinker->purgeable_pages);
+	shrinker_free(shrinker->shrink);
+	flush_work(&shrinker->pm_worker);
+	kfree(shrinker);
+}