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, 100 insertions, 0 deletions

diff --git a/drivers/clk/mmp/reset.c b/drivers/clk/mmp/reset.c
new file mode 100644
index 000000000..1e4e105ef
--- /dev/null
+++ b/drivers/clk/mmp/reset.c
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/reset-controller.h>
+
+#include "reset.h"
+
+#define rcdev_to_unit(rcdev) container_of(rcdev, struct mmp_clk_reset_unit, rcdev)
+
+static int mmp_of_reset_xlate(struct reset_controller_dev *rcdev,
+			  const struct of_phandle_args *reset_spec)
+{
+	struct mmp_clk_reset_unit *unit = rcdev_to_unit(rcdev);
+	struct mmp_clk_reset_cell *cell;
+	int i;
+
+	if (WARN_ON(reset_spec->args_count != rcdev->of_reset_n_cells))
+		return -EINVAL;
+
+	for (i = 0; i < rcdev->nr_resets; i++) {
+		cell = &unit->cells[i];
+		if (cell->clk_id == reset_spec->args[0])
+			break;
+	}
+
+	if (i == rcdev->nr_resets)
+		return -EINVAL;
+
+	return i;
+}
+
+static int mmp_clk_reset_assert(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	struct mmp_clk_reset_unit *unit = rcdev_to_unit(rcdev);
+	struct mmp_clk_reset_cell *cell;
+	unsigned long flags = 0;
+	u32 val;
+
+	cell = &unit->cells[id];
+	if (cell->lock)
+		spin_lock_irqsave(cell->lock, flags);
+
+	val = readl(cell->reg);
+	val |= cell->bits;
+	writel(val, cell->reg);
+
+	if (cell->lock)
+		spin_unlock_irqrestore(cell->lock, flags);
+
+	return 0;
+}
+
+static int mmp_clk_reset_deassert(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	struct mmp_clk_reset_unit *unit = rcdev_to_unit(rcdev);
+	struct mmp_clk_reset_cell *cell;
+	unsigned long flags = 0;
+	u32 val;
+
+	cell = &unit->cells[id];
+	if (cell->lock)
+		spin_lock_irqsave(cell->lock, flags);
+
+	val = readl(cell->reg);
+	val &= ~cell->bits;
+	writel(val, cell->reg);
+
+	if (cell->lock)
+		spin_unlock_irqrestore(cell->lock, flags);
+
+	return 0;
+}
+
+static const struct reset_control_ops mmp_clk_reset_ops = {
+	.assert		= mmp_clk_reset_assert,
+	.deassert	= mmp_clk_reset_deassert,
+};
+
+void mmp_clk_reset_register(struct device_node *np,
+			struct mmp_clk_reset_cell *cells, int nr_resets)
+{
+	struct mmp_clk_reset_unit *unit;
+
+	unit = kzalloc_obj(*unit);
+	if (!unit)
+		return;
+
+	unit->cells = cells;
+	unit->rcdev.of_reset_n_cells = 1;
+	unit->rcdev.nr_resets = nr_resets;
+	unit->rcdev.ops = &mmp_clk_reset_ops;
+	unit->rcdev.of_node = np;
+	unit->rcdev.of_xlate = mmp_of_reset_xlate;
+
+	reset_controller_register(&unit->rcdev);
+}