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, 137 insertions, 0 deletions

diff --git a/drivers/net/phy/ste10Xp.c b/drivers/net/phy/ste10Xp.c
new file mode 100644
index 000000000..d4835d4c5
--- /dev/null
+++ b/drivers/net/phy/ste10Xp.c
@@ -0,0 +1,137 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * drivers/net/phy/ste10Xp.c
+ *
+ * Driver for STMicroelectronics STe10Xp PHYs
+ *
+ * Author: Giuseppe Cavallaro <peppe.cavallaro@st.com>
+ *
+ * Copyright (c) 2008 STMicroelectronics Limited
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/moduleparam.h>
+#include <linux/interrupt.h>
+#include <linux/netdevice.h>
+#include <linux/ethtool.h>
+#include <linux/mii.h>
+#include <linux/phy.h>
+
+#define MII_XCIIS	0x11	/* Configuration Info IRQ & Status Reg */
+#define MII_XIE		0x12	/* Interrupt Enable Register */
+#define MII_XIE_DEFAULT_MASK 0x0070 /* ANE complete, Remote Fault, Link Down */
+
+#define STE101P_PHY_ID		0x00061c50
+#define STE100P_PHY_ID		0x1c040011
+
+static int ste10Xp_config_init(struct phy_device *phydev)
+{
+	int value, err;
+
+	/* Software Reset PHY */
+	value = phy_read(phydev, MII_BMCR);
+	if (value < 0)
+		return value;
+
+	value |= BMCR_RESET;
+	err = phy_write(phydev, MII_BMCR, value);
+	if (err < 0)
+		return err;
+
+	do {
+		value = phy_read(phydev, MII_BMCR);
+	} while (value & BMCR_RESET);
+
+	return 0;
+}
+
+static int ste10Xp_ack_interrupt(struct phy_device *phydev)
+{
+	int err = phy_read(phydev, MII_XCIIS);
+
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
+static int ste10Xp_config_intr(struct phy_device *phydev)
+{
+	int err;
+
+	if (phydev->interrupts == PHY_INTERRUPT_ENABLED) {
+		/* clear any pending interrupts */
+		err = ste10Xp_ack_interrupt(phydev);
+		if (err)
+			return err;
+
+		/* Enable all STe101P interrupts (PR12) */
+		err = phy_write(phydev, MII_XIE, MII_XIE_DEFAULT_MASK);
+	} else {
+		err = phy_write(phydev, MII_XIE, 0);
+		if (err)
+			return err;
+
+		err = ste10Xp_ack_interrupt(phydev);
+	}
+
+	return err;
+}
+
+static irqreturn_t ste10Xp_handle_interrupt(struct phy_device *phydev)
+{
+	int irq_status;
+
+	irq_status = phy_read(phydev, MII_XCIIS);
+	if (irq_status < 0) {
+		phy_error(phydev);
+		return IRQ_NONE;
+	}
+
+	if (!(irq_status & MII_XIE_DEFAULT_MASK))
+		return IRQ_NONE;
+
+	phy_trigger_machine(phydev);
+
+	return IRQ_HANDLED;
+}
+
+static struct phy_driver ste10xp_pdriver[] = {
+{
+	.phy_id = STE101P_PHY_ID,
+	.phy_id_mask = 0xfffffff0,
+	.name = "STe101p",
+	/* PHY_BASIC_FEATURES */
+	.config_init = ste10Xp_config_init,
+	.config_intr = ste10Xp_config_intr,
+	.handle_interrupt = ste10Xp_handle_interrupt,
+	.suspend = genphy_suspend,
+	.resume = genphy_resume,
+}, {
+	.phy_id = STE100P_PHY_ID,
+	.phy_id_mask = 0xffffffff,
+	.name = "STe100p",
+	/* PHY_BASIC_FEATURES */
+	.config_init = ste10Xp_config_init,
+	.config_intr = ste10Xp_config_intr,
+	.handle_interrupt = ste10Xp_handle_interrupt,
+	.suspend = genphy_suspend,
+	.resume = genphy_resume,
+} };
+
+module_phy_driver(ste10xp_pdriver);
+
+static const struct mdio_device_id __maybe_unused ste10Xp_tbl[] = {
+	{ STE101P_PHY_ID, 0xfffffff0 },
+	{ STE100P_PHY_ID, 0xffffffff },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(mdio, ste10Xp_tbl);
+
+MODULE_DESCRIPTION("STMicroelectronics STe10Xp PHY driver");
+MODULE_AUTHOR("Giuseppe Cavallaro <peppe.cavallaro@st.com>");
+MODULE_LICENSE("GPL");