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, 143 insertions, 0 deletions

diff --git a/drivers/acpi/proc.c b/drivers/acpi/proc.c
new file mode 100644
index 000000000..c08ead072
--- /dev/null
+++ b/drivers/acpi/proc.c
@@ -0,0 +1,143 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/string_choices.h>
+#include <linux/suspend.h>
+#include <linux/bcd.h>
+#include <linux/acpi.h>
+#include <linux/uaccess.h>
+
+#include "sleep.h"
+#include "internal.h"
+
+/*
+ * this file provides support for:
+ * /proc/acpi/wakeup
+ */
+
+static int
+acpi_system_wakeup_device_seq_show(struct seq_file *seq, void *offset)
+{
+	struct acpi_device *dev, *tmp;
+
+	seq_printf(seq, "Device\tS-state\t  Status   Sysfs node\n");
+
+	mutex_lock(&acpi_device_lock);
+	list_for_each_entry_safe(dev, tmp, &acpi_wakeup_device_list,
+				 wakeup_list) {
+		struct acpi_device_physical_node *entry;
+
+		if (!dev->wakeup.flags.valid)
+			continue;
+
+		seq_printf(seq, "%s\t  S%llu\t",
+			   dev->pnp.bus_id,
+			   dev->wakeup.sleep_state);
+
+		mutex_lock(&dev->physical_node_lock);
+
+		if (!dev->physical_node_count) {
+			seq_printf(seq, "%c%-8s\n",
+				dev->wakeup.flags.valid ? '*' : ' ',
+				str_enabled_disabled(device_may_wakeup(&dev->dev)));
+		} else {
+			struct device *ldev;
+			list_for_each_entry(entry, &dev->physical_node_list,
+					node) {
+				ldev = get_device(entry->dev);
+				if (!ldev)
+					continue;
+
+				if (&entry->node !=
+						dev->physical_node_list.next)
+					seq_printf(seq, "\t\t");
+
+				seq_printf(seq, "%c%-8s  %s:%s\n",
+					dev->wakeup.flags.valid ? '*' : ' ',
+					str_enabled_disabled(device_may_wakeup(ldev) ||
+							     device_may_wakeup(&dev->dev)),
+					ldev->bus ? ldev->bus->name :
+					"no-bus", dev_name(ldev));
+				put_device(ldev);
+			}
+		}
+
+		mutex_unlock(&dev->physical_node_lock);
+	}
+	mutex_unlock(&acpi_device_lock);
+	return 0;
+}
+
+static void physical_device_enable_wakeup(struct acpi_device *adev)
+{
+	struct acpi_device_physical_node *entry;
+
+	mutex_lock(&adev->physical_node_lock);
+
+	list_for_each_entry(entry,
+		&adev->physical_node_list, node)
+		if (entry->dev && device_can_wakeup(entry->dev)) {
+			bool enable = !device_may_wakeup(entry->dev);
+			device_set_wakeup_enable(entry->dev, enable);
+		}
+
+	mutex_unlock(&adev->physical_node_lock);
+}
+
+static ssize_t
+acpi_system_write_wakeup_device(struct file *file,
+				const char __user * buffer,
+				size_t count, loff_t * ppos)
+{
+	struct acpi_device *dev, *tmp;
+	char strbuf[5];
+	char str[5] = "";
+
+	if (count > 4)
+		count = 4;
+
+	if (copy_from_user(strbuf, buffer, count))
+		return -EFAULT;
+	strbuf[count] = '\0';
+	sscanf(strbuf, "%s", str);
+
+	mutex_lock(&acpi_device_lock);
+	list_for_each_entry_safe(dev, tmp, &acpi_wakeup_device_list,
+				 wakeup_list) {
+		if (!dev->wakeup.flags.valid)
+			continue;
+
+		if (!strncmp(dev->pnp.bus_id, str, 4)) {
+			if (device_can_wakeup(&dev->dev)) {
+				bool enable = !device_may_wakeup(&dev->dev);
+				device_set_wakeup_enable(&dev->dev, enable);
+			} else {
+				physical_device_enable_wakeup(dev);
+			}
+			break;
+		}
+	}
+	mutex_unlock(&acpi_device_lock);
+	return count;
+}
+
+static int
+acpi_system_wakeup_device_open_fs(struct inode *inode, struct file *file)
+{
+	return single_open(file, acpi_system_wakeup_device_seq_show,
+			   pde_data(inode));
+}
+
+static const struct proc_ops acpi_system_wakeup_device_proc_ops = {
+	.proc_open	= acpi_system_wakeup_device_open_fs,
+	.proc_read	= seq_read,
+	.proc_write	= acpi_system_write_wakeup_device,
+	.proc_lseek	= seq_lseek,
+	.proc_release	= single_release,
+};
+
+void __init acpi_sleep_proc_init(void)
+{
+	/* 'wakeup device' [R/W] */
+	proc_create("wakeup", 0644, acpi_root_dir, &acpi_system_wakeup_device_proc_ops);
+}