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, 259 insertions, 0 deletions

diff --git a/drivers/clk/clk-gate.c b/drivers/clk/clk-gate.c
new file mode 100644
index 000000000..44f5e0c53
--- /dev/null
+++ b/drivers/clk/clk-gate.c
@@ -0,0 +1,259 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
+ * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
+ *
+ * Gated clock implementation
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/err.h>
+#include <linux/string.h>
+
+/**
+ * DOC: basic gateable clock which can gate and ungate its output
+ *
+ * Traits of this clock:
+ * prepare - clk_(un)prepare only ensures parent is (un)prepared
+ * enable - clk_enable and clk_disable are functional & control gating
+ * rate - inherits rate from parent.  No clk_set_rate support
+ * parent - fixed parent.  No clk_set_parent support
+ */
+
+static inline u32 clk_gate_readl(struct clk_gate *gate)
+{
+	if (gate->flags & CLK_GATE_BIG_ENDIAN)
+		return ioread32be(gate->reg);
+
+	return readl(gate->reg);
+}
+
+static inline void clk_gate_writel(struct clk_gate *gate, u32 val)
+{
+	if (gate->flags & CLK_GATE_BIG_ENDIAN)
+		iowrite32be(val, gate->reg);
+	else
+		writel(val, gate->reg);
+}
+
+/*
+ * It works on following logic:
+ *
+ * For enabling clock, enable = 1
+ *	set2dis = 1	-> clear bit	-> set = 0
+ *	set2dis = 0	-> set bit	-> set = 1
+ *
+ * For disabling clock, enable = 0
+ *	set2dis = 1	-> set bit	-> set = 1
+ *	set2dis = 0	-> clear bit	-> set = 0
+ *
+ * So, result is always: enable xor set2dis.
+ */
+static void clk_gate_endisable(struct clk_hw *hw, int enable)
+{
+	struct clk_gate *gate = to_clk_gate(hw);
+	int set = gate->flags & CLK_GATE_SET_TO_DISABLE ? 1 : 0;
+	unsigned long flags;
+	u32 reg;
+
+	set ^= enable;
+
+	if (gate->lock)
+		spin_lock_irqsave(gate->lock, flags);
+	else
+		__acquire(gate->lock);
+
+	if (gate->flags & CLK_GATE_HIWORD_MASK) {
+		reg = BIT(gate->bit_idx + 16);
+		if (set)
+			reg |= BIT(gate->bit_idx);
+	} else {
+		reg = clk_gate_readl(gate);
+
+		if (set)
+			reg |= BIT(gate->bit_idx);
+		else
+			reg &= ~BIT(gate->bit_idx);
+	}
+
+	clk_gate_writel(gate, reg);
+
+	if (gate->lock)
+		spin_unlock_irqrestore(gate->lock, flags);
+	else
+		__release(gate->lock);
+}
+
+static int clk_gate_enable(struct clk_hw *hw)
+{
+	clk_gate_endisable(hw, 1);
+
+	return 0;
+}
+
+static void clk_gate_disable(struct clk_hw *hw)
+{
+	clk_gate_endisable(hw, 0);
+}
+
+int clk_gate_is_enabled(struct clk_hw *hw)
+{
+	u32 reg;
+	struct clk_gate *gate = to_clk_gate(hw);
+
+	reg = clk_gate_readl(gate);
+
+	/* if a set bit disables this clk, flip it before masking */
+	if (gate->flags & CLK_GATE_SET_TO_DISABLE)
+		reg ^= BIT(gate->bit_idx);
+
+	reg &= BIT(gate->bit_idx);
+
+	return reg ? 1 : 0;
+}
+EXPORT_SYMBOL_GPL(clk_gate_is_enabled);
+
+const struct clk_ops clk_gate_ops = {
+	.enable = clk_gate_enable,
+	.disable = clk_gate_disable,
+	.is_enabled = clk_gate_is_enabled,
+};
+EXPORT_SYMBOL_GPL(clk_gate_ops);
+
+struct clk_hw *__clk_hw_register_gate(struct device *dev,
+		struct device_node *np, const char *name,
+		const char *parent_name, const struct clk_hw *parent_hw,
+		const struct clk_parent_data *parent_data,
+		unsigned long flags,
+		void __iomem *reg, u8 bit_idx,
+		u8 clk_gate_flags, spinlock_t *lock)
+{
+	struct clk_gate *gate;
+	struct clk_hw *hw;
+	struct clk_init_data init = {};
+	int ret = -EINVAL;
+
+	if (clk_gate_flags & CLK_GATE_HIWORD_MASK) {
+		if (bit_idx > 15) {
+			pr_err("gate bit exceeds LOWORD field\n");
+			return ERR_PTR(-EINVAL);
+		}
+	}
+
+	/* allocate the gate */
+	gate = kzalloc_obj(*gate);
+	if (!gate)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+	init.ops = &clk_gate_ops;
+	init.flags = flags;
+	init.parent_names = parent_name ? &parent_name : NULL;
+	init.parent_hws = parent_hw ? &parent_hw : NULL;
+	init.parent_data = parent_data;
+	if (parent_name || parent_hw || parent_data)
+		init.num_parents = 1;
+	else
+		init.num_parents = 0;
+
+	/* struct clk_gate assignments */
+	gate->reg = reg;
+	gate->bit_idx = bit_idx;
+	gate->flags = clk_gate_flags;
+	gate->lock = lock;
+	gate->hw.init = &init;
+
+	hw = &gate->hw;
+	if (dev || !np)
+		ret = clk_hw_register(dev, hw);
+	else if (np)
+		ret = of_clk_hw_register(np, hw);
+	if (ret) {
+		kfree(gate);
+		hw = ERR_PTR(ret);
+	}
+
+	return hw;
+
+}
+EXPORT_SYMBOL_GPL(__clk_hw_register_gate);
+
+struct clk *clk_register_gate(struct device *dev, const char *name,
+		const char *parent_name, unsigned long flags,
+		void __iomem *reg, u8 bit_idx,
+		u8 clk_gate_flags, spinlock_t *lock)
+{
+	struct clk_hw *hw;
+
+	hw = clk_hw_register_gate(dev, name, parent_name, flags, reg,
+				  bit_idx, clk_gate_flags, lock);
+	if (IS_ERR(hw))
+		return ERR_CAST(hw);
+	return hw->clk;
+}
+EXPORT_SYMBOL_GPL(clk_register_gate);
+
+void clk_unregister_gate(struct clk *clk)
+{
+	struct clk_gate *gate;
+	struct clk_hw *hw;
+
+	hw = __clk_get_hw(clk);
+	if (!hw)
+		return;
+
+	gate = to_clk_gate(hw);
+
+	clk_unregister(clk);
+	kfree(gate);
+}
+EXPORT_SYMBOL_GPL(clk_unregister_gate);
+
+void clk_hw_unregister_gate(struct clk_hw *hw)
+{
+	struct clk_gate *gate;
+
+	gate = to_clk_gate(hw);
+
+	clk_hw_unregister(hw);
+	kfree(gate);
+}
+EXPORT_SYMBOL_GPL(clk_hw_unregister_gate);
+
+static void devm_clk_hw_release_gate(struct device *dev, void *res)
+{
+	clk_hw_unregister_gate(*(struct clk_hw **)res);
+}
+
+struct clk_hw *__devm_clk_hw_register_gate(struct device *dev,
+		struct device_node *np, const char *name,
+		const char *parent_name, const struct clk_hw *parent_hw,
+		const struct clk_parent_data *parent_data,
+		unsigned long flags,
+		void __iomem *reg, u8 bit_idx,
+		u8 clk_gate_flags, spinlock_t *lock)
+{
+	struct clk_hw **ptr, *hw;
+
+	ptr = devres_alloc(devm_clk_hw_release_gate, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return ERR_PTR(-ENOMEM);
+
+	hw = __clk_hw_register_gate(dev, np, name, parent_name, parent_hw,
+				    parent_data, flags, reg, bit_idx,
+				    clk_gate_flags, lock);
+
+	if (!IS_ERR(hw)) {
+		*ptr = hw;
+		devres_add(dev, ptr);
+	} else {
+		devres_free(ptr);
+	}
+
+	return hw;
+}
+EXPORT_SYMBOL_GPL(__devm_clk_hw_register_gate);