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, 281 insertions, 0 deletions

diff --git a/drivers/clk/at91/clk-programmable.c b/drivers/clk/at91/clk-programmable.c
new file mode 100644
index 000000000..bfd8b03b0
--- /dev/null
+++ b/drivers/clk/at91/clk-programmable.c
@@ -0,0 +1,281 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Copyright (C) 2013 Boris BREZILLON <b.brezillon@overkiz.com>
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/clkdev.h>
+#include <linux/clk/at91_pmc.h>
+#include <linux/of.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
+
+#include "pmc.h"
+
+#define PROG_ID_MAX		7
+
+#define PROG_STATUS_MASK(id)	(1 << ((id) + 8))
+#define PROG_PRES(layout, pckr)	((pckr >> layout->pres_shift) & layout->pres_mask)
+#define PROG_MAX_RM9200_CSS	3
+
+struct clk_programmable {
+	struct clk_hw hw;
+	struct regmap *regmap;
+	u32 *mux_table;
+	u8 id;
+	const struct clk_programmable_layout *layout;
+	struct at91_clk_pms pms;
+};
+
+#define to_clk_programmable(hw) container_of(hw, struct clk_programmable, hw)
+
+static unsigned long clk_programmable_recalc_rate(struct clk_hw *hw,
+						  unsigned long parent_rate)
+{
+	struct clk_programmable *prog = to_clk_programmable(hw);
+	const struct clk_programmable_layout *layout = prog->layout;
+	unsigned int pckr;
+	unsigned long rate;
+
+	regmap_read(prog->regmap, AT91_PMC_PCKR(prog->id), &pckr);
+
+	if (layout->is_pres_direct)
+		rate = parent_rate / (PROG_PRES(layout, pckr) + 1);
+	else
+		rate = parent_rate >> PROG_PRES(layout, pckr);
+
+	return rate;
+}
+
+static int clk_programmable_determine_rate(struct clk_hw *hw,
+					   struct clk_rate_request *req)
+{
+	struct clk_programmable *prog = to_clk_programmable(hw);
+	const struct clk_programmable_layout *layout = prog->layout;
+	struct clk_hw *parent;
+	long best_rate = -EINVAL;
+	unsigned long parent_rate;
+	unsigned long tmp_rate = 0;
+	int shift;
+	int i;
+
+	for (i = 0; i < clk_hw_get_num_parents(hw); i++) {
+		parent = clk_hw_get_parent_by_index(hw, i);
+		if (!parent)
+			continue;
+
+		parent_rate = clk_hw_get_rate(parent);
+		if (layout->is_pres_direct) {
+			for (shift = 0; shift <= layout->pres_mask; shift++) {
+				tmp_rate = parent_rate / (shift + 1);
+				if (tmp_rate <= req->rate)
+					break;
+			}
+		} else {
+			for (shift = 0; shift < layout->pres_mask; shift++) {
+				tmp_rate = parent_rate >> shift;
+				if (tmp_rate <= req->rate)
+					break;
+			}
+		}
+
+		if (tmp_rate > req->rate)
+			continue;
+
+		if (best_rate < 0 ||
+		    (req->rate - tmp_rate) < (req->rate - best_rate)) {
+			best_rate = tmp_rate;
+			req->best_parent_rate = parent_rate;
+			req->best_parent_hw = parent;
+		}
+
+		if (!best_rate)
+			break;
+	}
+
+	if (best_rate < 0)
+		return best_rate;
+
+	req->rate = best_rate;
+	return 0;
+}
+
+static int clk_programmable_set_parent(struct clk_hw *hw, u8 index)
+{
+	struct clk_programmable *prog = to_clk_programmable(hw);
+	const struct clk_programmable_layout *layout = prog->layout;
+	unsigned int mask = layout->css_mask;
+	unsigned int pckr = index;
+
+	if (layout->have_slck_mck)
+		mask |= AT91_PMC_CSSMCK_MCK;
+
+	if (prog->mux_table)
+		pckr = clk_mux_index_to_val(prog->mux_table, 0, index);
+
+	if (index > layout->css_mask) {
+		if (index > PROG_MAX_RM9200_CSS && !layout->have_slck_mck)
+			return -EINVAL;
+
+		pckr |= AT91_PMC_CSSMCK_MCK;
+	}
+
+	regmap_update_bits(prog->regmap, AT91_PMC_PCKR(prog->id), mask, pckr);
+
+	return 0;
+}
+
+static u8 clk_programmable_get_parent(struct clk_hw *hw)
+{
+	struct clk_programmable *prog = to_clk_programmable(hw);
+	const struct clk_programmable_layout *layout = prog->layout;
+	unsigned int pckr;
+	u8 ret;
+
+	regmap_read(prog->regmap, AT91_PMC_PCKR(prog->id), &pckr);
+
+	ret = pckr & layout->css_mask;
+
+	if (layout->have_slck_mck && (pckr & AT91_PMC_CSSMCK_MCK) && !ret)
+		ret = PROG_MAX_RM9200_CSS + 1;
+
+	if (prog->mux_table)
+		ret = clk_mux_val_to_index(&prog->hw, prog->mux_table, 0, ret);
+
+	return ret;
+}
+
+static int clk_programmable_set_rate(struct clk_hw *hw, unsigned long rate,
+				     unsigned long parent_rate)
+{
+	struct clk_programmable *prog = to_clk_programmable(hw);
+	const struct clk_programmable_layout *layout = prog->layout;
+	unsigned long div = parent_rate / rate;
+	int shift = 0;
+
+	if (!div)
+		return -EINVAL;
+
+	if (layout->is_pres_direct) {
+		shift = div - 1;
+
+		if (shift > layout->pres_mask)
+			return -EINVAL;
+	} else {
+		shift = fls(div) - 1;
+
+		if (div != (1 << shift))
+			return -EINVAL;
+
+		if (shift >= layout->pres_mask)
+			return -EINVAL;
+	}
+
+	regmap_update_bits(prog->regmap, AT91_PMC_PCKR(prog->id),
+			   layout->pres_mask << layout->pres_shift,
+			   shift << layout->pres_shift);
+
+	return 0;
+}
+
+static int clk_programmable_save_context(struct clk_hw *hw)
+{
+	struct clk_programmable *prog = to_clk_programmable(hw);
+	struct clk_hw *parent_hw = clk_hw_get_parent(hw);
+
+	prog->pms.parent = clk_programmable_get_parent(hw);
+	prog->pms.parent_rate = clk_hw_get_rate(parent_hw);
+	prog->pms.rate = clk_programmable_recalc_rate(hw, prog->pms.parent_rate);
+
+	return 0;
+}
+
+static void clk_programmable_restore_context(struct clk_hw *hw)
+{
+	struct clk_programmable *prog = to_clk_programmable(hw);
+	int ret;
+
+	ret = clk_programmable_set_parent(hw, prog->pms.parent);
+	if (ret)
+		return;
+
+	clk_programmable_set_rate(hw, prog->pms.rate, prog->pms.parent_rate);
+}
+
+static const struct clk_ops programmable_ops = {
+	.recalc_rate = clk_programmable_recalc_rate,
+	.determine_rate = clk_programmable_determine_rate,
+	.get_parent = clk_programmable_get_parent,
+	.set_parent = clk_programmable_set_parent,
+	.set_rate = clk_programmable_set_rate,
+	.save_context = clk_programmable_save_context,
+	.restore_context = clk_programmable_restore_context,
+};
+
+struct clk_hw * __init
+at91_clk_register_programmable(struct regmap *regmap,
+			       const char *name, const char **parent_names,
+			       struct clk_hw **parent_hws, u8 num_parents, u8 id,
+			       const struct clk_programmable_layout *layout,
+			       u32 *mux_table)
+{
+	struct clk_programmable *prog;
+	struct clk_hw *hw;
+	struct clk_init_data init = {};
+	int ret;
+
+	if (id > PROG_ID_MAX || !(parent_names || parent_hws))
+		return ERR_PTR(-EINVAL);
+
+	prog = kzalloc_obj(*prog);
+	if (!prog)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+	init.ops = &programmable_ops;
+	if (parent_hws)
+		init.parent_hws = (const struct clk_hw **)parent_hws;
+	else
+		init.parent_names = parent_names;
+	init.num_parents = num_parents;
+	init.flags = CLK_SET_RATE_GATE | CLK_SET_PARENT_GATE;
+
+	prog->id = id;
+	prog->layout = layout;
+	prog->hw.init = &init;
+	prog->regmap = regmap;
+	prog->mux_table = mux_table;
+
+	hw = &prog->hw;
+	ret = clk_hw_register(NULL, &prog->hw);
+	if (ret) {
+		kfree(prog);
+		hw = ERR_PTR(ret);
+	}
+
+	return hw;
+}
+
+const struct clk_programmable_layout at91rm9200_programmable_layout = {
+	.pres_mask = 0x7,
+	.pres_shift = 2,
+	.css_mask = 0x3,
+	.have_slck_mck = 0,
+	.is_pres_direct = 0,
+};
+
+const struct clk_programmable_layout at91sam9g45_programmable_layout = {
+	.pres_mask = 0x7,
+	.pres_shift = 2,
+	.css_mask = 0x3,
+	.have_slck_mck = 1,
+	.is_pres_direct = 0,
+};
+
+const struct clk_programmable_layout at91sam9x5_programmable_layout = {
+	.pres_mask = 0x7,
+	.pres_shift = 4,
+	.css_mask = 0x7,
+	.have_slck_mck = 0,
+	.is_pres_direct = 0,
+};