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, 164 insertions, 0 deletions

diff --git a/drivers/mfd/sun6i-prcm.c b/drivers/mfd/sun6i-prcm.c
new file mode 100644
index 000000000..ee03db0b8
--- /dev/null
+++ b/drivers/mfd/sun6i-prcm.c
@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2014 Free Electrons
+ *
+ * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
+ *
+ * Allwinner PRCM (Power/Reset/Clock Management) driver
+ */
+
+#include <linux/mfd/core.h>
+#include <linux/init.h>
+#include <linux/of.h>
+
+#define SUN8I_CODEC_ANALOG_BASE	0x1c0
+#define SUN8I_CODEC_ANALOG_SIZE	0x4
+
+struct prcm_data {
+	int nsubdevs;
+	const struct mfd_cell *subdevs;
+};
+
+static const struct resource sun6i_a31_ar100_clk_res[] = {
+	DEFINE_RES_MEM(0x0, 4)
+};
+
+static const struct resource sun6i_a31_apb0_clk_res[] = {
+	DEFINE_RES_MEM(0xc, 4)
+};
+
+static const struct resource sun6i_a31_apb0_gates_clk_res[] = {
+	DEFINE_RES_MEM(0x28, 4)
+};
+
+static const struct resource sun6i_a31_ir_clk_res[] = {
+	DEFINE_RES_MEM(0x54, 4)
+};
+
+static const struct resource sun6i_a31_apb0_rstc_res[] = {
+	DEFINE_RES_MEM(0xb0, 4)
+};
+
+static const struct resource sun8i_codec_analog_res[] = {
+	DEFINE_RES_MEM(SUN8I_CODEC_ANALOG_BASE, SUN8I_CODEC_ANALOG_SIZE),
+};
+
+static const struct mfd_cell sun6i_a31_prcm_subdevs[] = {
+	{
+		.name = "sun6i-a31-ar100-clk",
+		.of_compatible = "allwinner,sun6i-a31-ar100-clk",
+		.num_resources = ARRAY_SIZE(sun6i_a31_ar100_clk_res),
+		.resources = sun6i_a31_ar100_clk_res,
+	},
+	{
+		.name = "sun6i-a31-apb0-clk",
+		.of_compatible = "allwinner,sun6i-a31-apb0-clk",
+		.num_resources = ARRAY_SIZE(sun6i_a31_apb0_clk_res),
+		.resources = sun6i_a31_apb0_clk_res,
+	},
+	{
+		.name = "sun6i-a31-apb0-gates-clk",
+		.of_compatible = "allwinner,sun6i-a31-apb0-gates-clk",
+		.num_resources = ARRAY_SIZE(sun6i_a31_apb0_gates_clk_res),
+		.resources = sun6i_a31_apb0_gates_clk_res,
+	},
+	{
+		.name = "sun6i-a31-ir-clk",
+		.of_compatible = "allwinner,sun4i-a10-mod0-clk",
+		.num_resources = ARRAY_SIZE(sun6i_a31_ir_clk_res),
+		.resources = sun6i_a31_ir_clk_res,
+	},
+	{
+		.name = "sun6i-a31-apb0-clock-reset",
+		.of_compatible = "allwinner,sun6i-a31-clock-reset",
+		.num_resources = ARRAY_SIZE(sun6i_a31_apb0_rstc_res),
+		.resources = sun6i_a31_apb0_rstc_res,
+	},
+};
+
+static const struct mfd_cell sun8i_a23_prcm_subdevs[] = {
+	{
+		.name = "sun8i-a23-apb0-clk",
+		.of_compatible = "allwinner,sun8i-a23-apb0-clk",
+		.num_resources = ARRAY_SIZE(sun6i_a31_apb0_clk_res),
+		.resources = sun6i_a31_apb0_clk_res,
+	},
+	{
+		.name = "sun6i-a31-apb0-gates-clk",
+		.of_compatible = "allwinner,sun8i-a23-apb0-gates-clk",
+		.num_resources = ARRAY_SIZE(sun6i_a31_apb0_gates_clk_res),
+		.resources = sun6i_a31_apb0_gates_clk_res,
+	},
+	{
+		.name = "sun6i-a31-apb0-clock-reset",
+		.of_compatible = "allwinner,sun6i-a31-clock-reset",
+		.num_resources = ARRAY_SIZE(sun6i_a31_apb0_rstc_res),
+		.resources = sun6i_a31_apb0_rstc_res,
+	},
+	{
+		.name		= "sun8i-codec-analog",
+		.of_compatible	= "allwinner,sun8i-a23-codec-analog",
+		.num_resources	= ARRAY_SIZE(sun8i_codec_analog_res),
+		.resources	= sun8i_codec_analog_res,
+	},
+};
+
+static const struct prcm_data sun6i_a31_prcm_data = {
+	.nsubdevs = ARRAY_SIZE(sun6i_a31_prcm_subdevs),
+	.subdevs = sun6i_a31_prcm_subdevs,
+};
+
+static const struct prcm_data sun8i_a23_prcm_data = {
+	.nsubdevs = ARRAY_SIZE(sun8i_a23_prcm_subdevs),
+	.subdevs = sun8i_a23_prcm_subdevs,
+};
+
+static const struct of_device_id sun6i_prcm_dt_ids[] = {
+	{
+		.compatible = "allwinner,sun6i-a31-prcm",
+		.data = &sun6i_a31_prcm_data,
+	},
+	{
+		.compatible = "allwinner,sun8i-a23-prcm",
+		.data = &sun8i_a23_prcm_data,
+	},
+	{ /* sentinel */ },
+};
+
+static int sun6i_prcm_probe(struct platform_device *pdev)
+{
+	const struct of_device_id *match;
+	const struct prcm_data *data;
+	struct resource *res;
+	int ret;
+
+	match = of_match_node(sun6i_prcm_dt_ids, pdev->dev.of_node);
+	if (!match)
+		return -EINVAL;
+
+	data = match->data;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "no prcm memory region provided\n");
+		return -ENOENT;
+	}
+
+	ret = mfd_add_devices(&pdev->dev, 0, data->subdevs, data->nsubdevs,
+			      res, -1, NULL);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to add subdevices\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static struct platform_driver sun6i_prcm_driver = {
+	.driver = {
+		.name = "sun6i-prcm",
+		.of_match_table = sun6i_prcm_dt_ids,
+	},
+	.probe = sun6i_prcm_probe,
+};
+builtin_platform_driver(sun6i_prcm_driver);