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, 196 insertions, 0 deletions

diff --git a/drivers/input/matrix-keymap.c b/drivers/input/matrix-keymap.c
new file mode 100644
index 000000000..3bea3575a
--- /dev/null
+++ b/drivers/input/matrix-keymap.c
@@ -0,0 +1,196 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Helpers for matrix keyboard bindings
+ *
+ * Copyright (C) 2012 Google, Inc
+ *
+ * Author:
+ *	Olof Johansson <olof@lixom.net>
+ */
+
+#include <linux/device.h>
+#include <linux/export.h>
+#include <linux/gfp.h>
+#include <linux/input.h>
+#include <linux/input/matrix_keypad.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+static bool matrix_keypad_map_key(struct input_dev *input_dev,
+				  unsigned int rows, unsigned int cols,
+				  unsigned int row_shift, unsigned int key)
+{
+	unsigned short *keymap = input_dev->keycode;
+	unsigned int row = KEY_ROW(key);
+	unsigned int col = KEY_COL(key);
+	unsigned short code = KEY_VAL(key);
+
+	if (row >= rows || col >= cols) {
+		dev_err(input_dev->dev.parent,
+			"%s: invalid keymap entry 0x%x (row: %d, col: %d, rows: %d, cols: %d)\n",
+			__func__, key, row, col, rows, cols);
+		return false;
+	}
+
+	keymap[MATRIX_SCAN_CODE(row, col, row_shift)] = code;
+	__set_bit(code, input_dev->keybit);
+
+	return true;
+}
+
+/**
+ * matrix_keypad_parse_properties() - Read properties of matrix keypad
+ *
+ * @dev: Device containing properties
+ * @rows: Returns number of matrix rows
+ * @cols: Returns number of matrix columns
+ * @return 0 if OK, <0 on error
+ */
+int matrix_keypad_parse_properties(struct device *dev,
+				   unsigned int *rows, unsigned int *cols)
+{
+	*rows = *cols = 0;
+
+	device_property_read_u32(dev, "keypad,num-rows", rows);
+	device_property_read_u32(dev, "keypad,num-columns", cols);
+
+	if (!*rows || !*cols) {
+		dev_err(dev, "number of keypad rows/columns not specified\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(matrix_keypad_parse_properties);
+
+static int matrix_keypad_parse_keymap(const char *propname,
+				      unsigned int rows, unsigned int cols,
+				      struct input_dev *input_dev)
+{
+	struct device *dev = input_dev->dev.parent;
+	unsigned int row_shift = get_count_order(cols);
+	unsigned int max_keys = rows << row_shift;
+	int i;
+	int size;
+	int error;
+
+	if (!propname)
+		propname = "linux,keymap";
+
+	size = device_property_count_u32(dev, propname);
+	if (size <= 0) {
+		dev_err(dev, "missing or malformed property %s: %d\n",
+			propname, size);
+		return size < 0 ? size : -EINVAL;
+	}
+
+	if (size > max_keys) {
+		dev_err(dev, "%s size overflow (%d vs max %u)\n",
+			propname, size, max_keys);
+		return -EINVAL;
+	}
+
+	u32 *keys __free(kfree) = kmalloc_array(size, sizeof(*keys), GFP_KERNEL);
+	if (!keys)
+		return -ENOMEM;
+
+	error = device_property_read_u32_array(dev, propname, keys, size);
+	if (error) {
+		dev_err(dev, "failed to read %s property: %d\n",
+			propname, error);
+		return error;
+	}
+
+	for (i = 0; i < size; i++) {
+		if (!matrix_keypad_map_key(input_dev, rows, cols,
+					   row_shift, keys[i]))
+			return -EINVAL;
+	}
+
+	return 0;
+}
+
+/**
+ * matrix_keypad_build_keymap - convert platform keymap into matrix keymap
+ * @keymap_data: keymap supplied by the platform code
+ * @keymap_name: name of device tree property containing keymap (if device
+ *	tree support is enabled).
+ * @rows: number of rows in target keymap array
+ * @cols: number of cols in target keymap array
+ * @keymap: expanded version of keymap that is suitable for use by
+ * matrix keyboard driver
+ * @input_dev: input devices for which we are setting up the keymap
+ *
+ * This function converts platform keymap (encoded with KEY() macro) into
+ * an array of keycodes that is suitable for using in a standard matrix
+ * keyboard driver that uses row and col as indices.
+ *
+ * If @keymap_data is not supplied and device tree support is enabled
+ * it will attempt load the keymap from property specified by @keymap_name
+ * argument (or "linux,keymap" if @keymap_name is %NULL).
+ *
+ * If @keymap is %NULL the function will automatically allocate managed
+ * block of memory to store the keymap. This memory will be associated with
+ * the parent device and automatically freed when device unbinds from the
+ * driver.
+ *
+ * Callers are expected to set up input_dev->dev.parent before calling this
+ * function.
+ */
+int matrix_keypad_build_keymap(const struct matrix_keymap_data *keymap_data,
+			       const char *keymap_name,
+			       unsigned int rows, unsigned int cols,
+			       unsigned short *keymap,
+			       struct input_dev *input_dev)
+{
+	unsigned int row_shift = get_count_order(cols);
+	size_t max_keys = rows << row_shift;
+	int i;
+	int error;
+
+	if (WARN_ON(!input_dev->dev.parent))
+		return -EINVAL;
+
+	if (!keymap) {
+		keymap = devm_kcalloc(input_dev->dev.parent,
+				      max_keys, sizeof(*keymap),
+				      GFP_KERNEL);
+		if (!keymap) {
+			dev_err(input_dev->dev.parent,
+				"Unable to allocate memory for keymap");
+			return -ENOMEM;
+		}
+	}
+
+	input_dev->keycode = keymap;
+	input_dev->keycodesize = sizeof(*keymap);
+	input_dev->keycodemax = max_keys;
+
+	__set_bit(EV_KEY, input_dev->evbit);
+
+	if (keymap_data) {
+		for (i = 0; i < keymap_data->keymap_size; i++) {
+			unsigned int key = keymap_data->keymap[i];
+
+			if (!matrix_keypad_map_key(input_dev, rows, cols,
+						   row_shift, key))
+				return -EINVAL;
+		}
+	} else {
+		error = matrix_keypad_parse_keymap(keymap_name, rows, cols,
+						   input_dev);
+		if (error)
+			return error;
+	}
+
+	__clear_bit(KEY_RESERVED, input_dev->keybit);
+
+	return 0;
+}
+EXPORT_SYMBOL(matrix_keypad_build_keymap);
+
+MODULE_DESCRIPTION("Helpers for matrix keyboard bindings");
+MODULE_LICENSE("GPL");