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 --- drivers/firmware/google/memconsole.c | 54 ++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) create mode 100644 drivers/firmware/google/memconsole.c (limited to 'drivers/firmware/google/memconsole.c') diff --git a/drivers/firmware/google/memconsole.c b/drivers/firmware/google/memconsole.c new file mode 100644 index 000000000..6138a1653 --- /dev/null +++ b/drivers/firmware/google/memconsole.c @@ -0,0 +1,54 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * memconsole.c + * + * Architecture-independent parts of the memory based BIOS console. + * + * Copyright 2017 Google Inc. + */ + +#include +#include +#include + +#include "memconsole.h" + +static ssize_t memconsole_read(struct file *filp, struct kobject *kobp, + const struct bin_attribute *bin_attr, char *buf, + loff_t pos, size_t count) +{ + ssize_t (*memconsole_read_func)(char *, loff_t, size_t); + + memconsole_read_func = bin_attr->private; + if (WARN_ON_ONCE(!memconsole_read_func)) + return -EIO; + + return memconsole_read_func(buf, pos, count); +} + +static struct bin_attribute memconsole_bin_attr = { + .attr = {.name = "log", .mode = 0444}, + .read = memconsole_read, +}; + +void memconsole_setup(ssize_t (*read_func)(char *, loff_t, size_t)) +{ + memconsole_bin_attr.private = read_func; +} +EXPORT_SYMBOL(memconsole_setup); + +int memconsole_sysfs_init(void) +{ + return sysfs_create_bin_file(firmware_kobj, &memconsole_bin_attr); +} +EXPORT_SYMBOL(memconsole_sysfs_init); + +void memconsole_exit(void) +{ + sysfs_remove_bin_file(firmware_kobj, &memconsole_bin_attr); +} +EXPORT_SYMBOL(memconsole_exit); + +MODULE_AUTHOR("Google, Inc."); +MODULE_DESCRIPTION("Architecture-independent parts of the memory based BIOS console"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1