From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes 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 Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- arch/mips/mm/sc-debugfs.c | 61 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 61 insertions(+) create mode 100644 arch/mips/mm/sc-debugfs.c (limited to 'arch/mips/mm/sc-debugfs.c') diff --git a/arch/mips/mm/sc-debugfs.c b/arch/mips/mm/sc-debugfs.c new file mode 100644 index 000000000..80ff39471 --- /dev/null +++ b/arch/mips/mm/sc-debugfs.c @@ -0,0 +1,61 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2015 Imagination Technologies + * Author: Paul Burton + */ + +#include +#include +#include +#include +#include + +static ssize_t sc_prefetch_read(struct file *file, char __user *user_buf, + size_t count, loff_t *ppos) +{ + bool enabled = bc_prefetch_is_enabled(); + char buf[3]; + + buf[0] = enabled ? 'Y' : 'N'; + buf[1] = '\n'; + buf[2] = 0; + + return simple_read_from_buffer(user_buf, count, ppos, buf, 2); +} + +static ssize_t sc_prefetch_write(struct file *file, + const char __user *user_buf, + size_t count, loff_t *ppos) +{ + bool enabled; + int err; + + err = kstrtobool_from_user(user_buf, count, &enabled); + if (err) + return err; + + if (enabled) + bc_prefetch_enable(); + else + bc_prefetch_disable(); + + return count; +} + +static const struct file_operations sc_prefetch_fops = { + .open = simple_open, + .llseek = default_llseek, + .read = sc_prefetch_read, + .write = sc_prefetch_write, +}; + +static int __init sc_debugfs_init(void) +{ + struct dentry *dir; + + dir = debugfs_create_dir("l2cache", mips_debugfs_dir); + debugfs_create_file("prefetch", S_IRUGO | S_IWUSR, dir, NULL, + &sc_prefetch_fops); + return 0; +} +late_initcall(sc_debugfs_init); -- cgit v1.3.1