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, 135 insertions, 0 deletions

diff --git a/drivers/reset/reset-hsdk.c b/drivers/reset/reset-hsdk.c
new file mode 100644
index 000000000..98460e087
--- /dev/null
+++ b/drivers/reset/reset-hsdk.c
@@ -0,0 +1,135 @@
+/*
+ * Copyright (C) 2017 Synopsys.
+ *
+ * Synopsys HSDK Development platform reset driver.
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#define to_hsdk_rst(p)	container_of((p), struct hsdk_rst, rcdev)
+
+struct hsdk_rst {
+	void __iomem			*regs_ctl;
+	void __iomem			*regs_rst;
+	spinlock_t			lock;
+	struct reset_controller_dev	rcdev;
+};
+
+static const u32 rst_map[] = {
+	BIT(16), /* APB_RST  */
+	BIT(17), /* AXI_RST  */
+	BIT(18), /* ETH_RST  */
+	BIT(19), /* USB_RST  */
+	BIT(20), /* SDIO_RST */
+	BIT(21), /* HDMI_RST */
+	BIT(22), /* GFX_RST  */
+	BIT(25), /* DMAC_RST */
+	BIT(31), /* EBI_RST  */
+};
+
+#define HSDK_MAX_RESETS			ARRAY_SIZE(rst_map)
+
+#define CGU_SYS_RST_CTRL		0x0
+#define CGU_IP_SW_RESET			0x0
+#define CGU_IP_SW_RESET_DELAY_SHIFT	16
+#define CGU_IP_SW_RESET_DELAY_MASK	GENMASK(31, CGU_IP_SW_RESET_DELAY_SHIFT)
+#define CGU_IP_SW_RESET_DELAY		0
+#define CGU_IP_SW_RESET_RESET		BIT(0)
+#define SW_RESET_TIMEOUT		10000
+
+static void hsdk_reset_config(struct hsdk_rst *rst, unsigned long id)
+{
+	writel(rst_map[id], rst->regs_ctl + CGU_SYS_RST_CTRL);
+}
+
+static int hsdk_reset_do(struct hsdk_rst *rst)
+{
+	u32 reg;
+
+	reg = readl(rst->regs_rst + CGU_IP_SW_RESET);
+	reg &= ~CGU_IP_SW_RESET_DELAY_MASK;
+	reg |= CGU_IP_SW_RESET_DELAY << CGU_IP_SW_RESET_DELAY_SHIFT;
+	reg |= CGU_IP_SW_RESET_RESET;
+	writel(reg, rst->regs_rst + CGU_IP_SW_RESET);
+
+	/* wait till reset bit is back to 0 */
+	return readl_poll_timeout_atomic(rst->regs_rst + CGU_IP_SW_RESET, reg,
+		!(reg & CGU_IP_SW_RESET_RESET), 5, SW_RESET_TIMEOUT);
+}
+
+static int hsdk_reset_reset(struct reset_controller_dev *rcdev,
+			      unsigned long id)
+{
+	struct hsdk_rst *rst = to_hsdk_rst(rcdev);
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&rst->lock, flags);
+	hsdk_reset_config(rst, id);
+	ret = hsdk_reset_do(rst);
+	spin_unlock_irqrestore(&rst->lock, flags);
+
+	return ret;
+}
+
+static const struct reset_control_ops hsdk_reset_ops = {
+	.reset	= hsdk_reset_reset,
+	.deassert = hsdk_reset_reset,
+};
+
+static int hsdk_reset_probe(struct platform_device *pdev)
+{
+	struct hsdk_rst *rst;
+
+	rst = devm_kzalloc(&pdev->dev, sizeof(*rst), GFP_KERNEL);
+	if (!rst)
+		return -ENOMEM;
+
+	rst->regs_ctl = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(rst->regs_ctl))
+		return PTR_ERR(rst->regs_ctl);
+
+	rst->regs_rst = devm_platform_ioremap_resource(pdev, 1);
+	if (IS_ERR(rst->regs_rst))
+		return PTR_ERR(rst->regs_rst);
+
+	spin_lock_init(&rst->lock);
+
+	rst->rcdev.owner = THIS_MODULE;
+	rst->rcdev.ops = &hsdk_reset_ops;
+	rst->rcdev.of_node = pdev->dev.of_node;
+	rst->rcdev.nr_resets = HSDK_MAX_RESETS;
+	rst->rcdev.of_reset_n_cells = 1;
+
+	return reset_controller_register(&rst->rcdev);
+}
+
+static const struct of_device_id hsdk_reset_dt_match[] = {
+	{ .compatible = "snps,hsdk-reset" },
+	{ },
+};
+
+static struct platform_driver hsdk_reset_driver = {
+	.probe	= hsdk_reset_probe,
+	.driver	= {
+		.name = "hsdk-reset",
+		.of_match_table = hsdk_reset_dt_match,
+	},
+};
+builtin_platform_driver(hsdk_reset_driver);
+
+MODULE_AUTHOR("Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>");
+MODULE_DESCRIPTION("Synopsys HSDK SDP reset driver");
+MODULE_LICENSE("GPL v2");