KVM: Don't pre-reserve xarray entries when storing empty/NULL attributesgrafted

Skip the xarray reservation loop when clearing all memory attributes, as
storing NULL only erases the entry and never needs to allocate, so no
reservation (and no cleanup of a failed one) is required in that case.

Suggested-by: Sean Christopherson <seanjc@google.com>
Cc: David Ballesteros <davimaba.v@proton.me>
Signed-off-by: Zeng Chi <zengchi@kylinos.cn>
Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>

1 files changed, 174 insertions, 0 deletions

diff --git a/drivers/clk/mediatek/reset.c b/drivers/clk/mediatek/reset.c
new file mode 100644
index 000000000..2e3303975
--- /dev/null
+++ b/drivers/clk/mediatek/reset.c
@@ -0,0 +1,174 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2014 MediaTek Inc.
+ */
+
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#include "reset.h"
+
+static inline struct mtk_clk_rst_data *to_mtk_clk_rst_data(struct reset_controller_dev *rcdev)
+{
+	return container_of(rcdev, struct mtk_clk_rst_data, rcdev);
+}
+
+static int mtk_reset_update(struct reset_controller_dev *rcdev,
+			    unsigned long id, bool deassert)
+{
+	struct mtk_clk_rst_data *data = to_mtk_clk_rst_data(rcdev);
+	unsigned int val = deassert ? 0 : ~0;
+
+	return regmap_update_bits(data->regmap,
+				  data->desc->rst_bank_ofs[id / RST_NR_PER_BANK],
+				  BIT(id % RST_NR_PER_BANK), val);
+}
+
+static int mtk_reset_assert(struct reset_controller_dev *rcdev,
+			    unsigned long id)
+{
+	return mtk_reset_update(rcdev, id, false);
+}
+
+static int mtk_reset_deassert(struct reset_controller_dev *rcdev,
+			      unsigned long id)
+{
+	return mtk_reset_update(rcdev, id, true);
+}
+
+static int mtk_reset(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	int ret;
+
+	ret = mtk_reset_assert(rcdev, id);
+	if (ret)
+		return ret;
+
+	return mtk_reset_deassert(rcdev, id);
+}
+
+static int mtk_reset_update_set_clr(struct reset_controller_dev *rcdev,
+				    unsigned long id, bool deassert)
+{
+	struct mtk_clk_rst_data *data = to_mtk_clk_rst_data(rcdev);
+	unsigned int deassert_ofs = deassert ? 0x4 : 0;
+
+	return regmap_write(data->regmap,
+			    data->desc->rst_bank_ofs[id / RST_NR_PER_BANK] +
+			    deassert_ofs,
+			    BIT(id % RST_NR_PER_BANK));
+}
+
+static int mtk_reset_assert_set_clr(struct reset_controller_dev *rcdev,
+				    unsigned long id)
+{
+	return mtk_reset_update_set_clr(rcdev, id, false);
+}
+
+static int mtk_reset_deassert_set_clr(struct reset_controller_dev *rcdev,
+				      unsigned long id)
+{
+	return mtk_reset_update_set_clr(rcdev, id, true);
+}
+
+static int mtk_reset_set_clr(struct reset_controller_dev *rcdev,
+			     unsigned long id)
+{
+	int ret;
+
+	ret = mtk_reset_assert_set_clr(rcdev, id);
+	if (ret)
+		return ret;
+	return mtk_reset_deassert_set_clr(rcdev, id);
+}
+
+static const struct reset_control_ops mtk_reset_ops = {
+	.assert = mtk_reset_assert,
+	.deassert = mtk_reset_deassert,
+	.reset = mtk_reset,
+};
+
+static const struct reset_control_ops mtk_reset_ops_set_clr = {
+	.assert = mtk_reset_assert_set_clr,
+	.deassert = mtk_reset_deassert_set_clr,
+	.reset = mtk_reset_set_clr,
+};
+
+static int reset_xlate(struct reset_controller_dev *rcdev,
+		       const struct of_phandle_args *reset_spec)
+{
+	struct mtk_clk_rst_data *data = to_mtk_clk_rst_data(rcdev);
+
+	if (reset_spec->args[0] >= rcdev->nr_resets ||
+	    reset_spec->args[0] >= data->desc->rst_idx_map_nr)
+		return -EINVAL;
+
+	return data->desc->rst_idx_map[reset_spec->args[0]];
+}
+
+int mtk_register_reset_controller_with_dev(struct device *dev,
+					   const struct mtk_clk_rst_desc *desc)
+{
+	struct device_node *np = dev->of_node;
+	struct regmap *regmap;
+	const struct reset_control_ops *rcops = NULL;
+	struct mtk_clk_rst_data *data;
+	int ret;
+
+	if (!desc) {
+		dev_err(dev, "mtk clock reset desc is NULL\n");
+		return -EINVAL;
+	}
+
+	switch (desc->version) {
+	case MTK_RST_SIMPLE:
+		rcops = &mtk_reset_ops;
+		break;
+	case MTK_RST_SET_CLR:
+		rcops = &mtk_reset_ops_set_clr;
+		break;
+	default:
+		dev_err(dev, "Unknown reset version %d\n", desc->version);
+		return -EINVAL;
+	}
+
+	regmap = device_node_to_regmap(np);
+	if (IS_ERR(regmap)) {
+		dev_err(dev, "Cannot find regmap %pe\n", regmap);
+		return PTR_ERR(regmap);
+	}
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->desc = desc;
+	data->regmap = regmap;
+	data->rcdev.owner = THIS_MODULE;
+	data->rcdev.ops = rcops;
+	data->rcdev.of_node = np;
+	data->rcdev.dev = dev;
+
+	if (data->desc->rst_idx_map_nr > 0) {
+		data->rcdev.of_reset_n_cells = 1;
+		data->rcdev.nr_resets = desc->rst_idx_map_nr;
+		data->rcdev.of_xlate = reset_xlate;
+	} else {
+		data->rcdev.nr_resets = desc->rst_bank_nr * RST_NR_PER_BANK;
+	}
+
+	ret = devm_reset_controller_register(dev, &data->rcdev);
+	if (ret) {
+		dev_err(dev, "could not register reset controller: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(mtk_register_reset_controller_with_dev);
+
+MODULE_LICENSE("GPL");