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, 127 insertions, 0 deletions

diff --git a/drivers/reset/reset-sky1-audss.c b/drivers/reset/reset-sky1-audss.c
new file mode 100644
index 000000000..d9735db68
--- /dev/null
+++ b/drivers/reset/reset-sky1-audss.c
@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Cix Sky1 Audio Subsystem reset controller driver
+ *
+ * Copyright 2026 Cix Technology Group Co., Ltd.
+ */
+
+#include <dt-bindings/reset/cix,sky1-audss-cru.h>
+
+#include <linux/auxiliary_bus.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/reset-controller.h>
+
+#define SKY1_RESET_SLEEP_US			50
+
+#define AUDSS_SW_RST			0x78
+
+struct sky1_audss_reset_map {
+	unsigned int offset;
+	unsigned int mask;
+};
+
+struct sky1_audss_reset {
+	struct reset_controller_dev rcdev;
+	struct regmap *regmap;
+	const struct sky1_audss_reset_map *map;
+};
+
+static const struct sky1_audss_reset_map sky1_audss_reset_map[] = {
+	[AUDSS_I2S0_SW_RST]   = { AUDSS_SW_RST, BIT(0) },
+	[AUDSS_I2S1_SW_RST]   = { AUDSS_SW_RST, BIT(1) },
+	[AUDSS_I2S2_SW_RST]   = { AUDSS_SW_RST, BIT(2) },
+	[AUDSS_I2S3_SW_RST]   = { AUDSS_SW_RST, BIT(3) },
+	[AUDSS_I2S4_SW_RST]   = { AUDSS_SW_RST, BIT(4) },
+	[AUDSS_I2S5_SW_RST]   = { AUDSS_SW_RST, BIT(5) },
+	[AUDSS_I2S6_SW_RST]   = { AUDSS_SW_RST, BIT(6) },
+	[AUDSS_I2S7_SW_RST]   = { AUDSS_SW_RST, BIT(7) },
+	[AUDSS_I2S8_SW_RST]   = { AUDSS_SW_RST, BIT(8) },
+	[AUDSS_I2S9_SW_RST]   = { AUDSS_SW_RST, BIT(9) },
+	[AUDSS_WDT_SW_RST]    = { AUDSS_SW_RST, BIT(10) },
+	[AUDSS_TIMER_SW_RST]  = { AUDSS_SW_RST, BIT(11) },
+	[AUDSS_MB0_SW_RST]    = { AUDSS_SW_RST, BIT(12) },
+	[AUDSS_MB1_SW_RST]    = { AUDSS_SW_RST, BIT(13) },
+	[AUDSS_HDA_SW_RST]    = { AUDSS_SW_RST, BIT(14) },
+	[AUDSS_DMAC_SW_RST]   = { AUDSS_SW_RST, BIT(15) },
+};
+
+static struct sky1_audss_reset *to_sky1_audss_reset(struct reset_controller_dev *rcdev)
+{
+	return container_of(rcdev, struct sky1_audss_reset, rcdev);
+}
+
+static int sky1_audss_reset_set(struct reset_controller_dev *rcdev,
+				unsigned long id, bool assert)
+{
+	struct sky1_audss_reset *priv = to_sky1_audss_reset(rcdev);
+	const struct sky1_audss_reset_map *signal = &priv->map[id];
+	int ret;
+
+	ret = regmap_assign_bits(priv->regmap, signal->offset,
+				 signal->mask, !assert);
+	if (ret)
+		return ret;
+
+	fsleep(SKY1_RESET_SLEEP_US);
+	return 0;
+}
+
+static int sky1_audss_reset_assert(struct reset_controller_dev *rcdev,
+				   unsigned long id)
+{
+	return sky1_audss_reset_set(rcdev, id, true);
+}
+
+static int sky1_audss_reset_deassert(struct reset_controller_dev *rcdev,
+				     unsigned long id)
+{
+	return sky1_audss_reset_set(rcdev, id, false);
+}
+
+static const struct reset_control_ops sky1_audss_reset_ops = {
+	.assert   = sky1_audss_reset_assert,
+	.deassert = sky1_audss_reset_deassert,
+};
+
+static int sky1_audss_reset_probe(struct auxiliary_device *adev,
+				  const struct auxiliary_device_id *id)
+{
+	struct sky1_audss_reset *priv;
+	struct device *dev = &adev->dev;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->regmap = dev_get_regmap(dev->parent, NULL);
+	if (!priv->regmap)
+		return dev_err_probe(dev, -ENODEV, "failed to get parent regmap\n");
+
+	priv->map = sky1_audss_reset_map;
+	priv->rcdev.owner = THIS_MODULE;
+	priv->rcdev.nr_resets = ARRAY_SIZE(sky1_audss_reset_map);
+	priv->rcdev.ops = &sky1_audss_reset_ops;
+	priv->rcdev.of_node = dev->of_node;
+	priv->rcdev.dev = dev;
+
+	return devm_reset_controller_register(dev, &priv->rcdev);
+}
+
+static const struct auxiliary_device_id sky1_audss_reset_ids[] = {
+	{ .name = "clk_sky1_audss.reset" },
+	{ }
+};
+MODULE_DEVICE_TABLE(auxiliary, sky1_audss_reset_ids);
+
+static struct auxiliary_driver sky1_audss_reset_driver = {
+	.probe = sky1_audss_reset_probe,
+	.id_table = sky1_audss_reset_ids,
+};
+module_auxiliary_driver(sky1_audss_reset_driver);
+
+MODULE_AUTHOR("Joakim Zhang <joakim.zhang@cixtech.com>");
+MODULE_DESCRIPTION("Cix Sky1 Audio Subsystem reset driver");
+MODULE_LICENSE("GPL");