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/nvmem/u-boot-env.c | 99 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 99 insertions(+) create mode 100644 drivers/nvmem/u-boot-env.c (limited to 'drivers/nvmem/u-boot-env.c') diff --git a/drivers/nvmem/u-boot-env.c b/drivers/nvmem/u-boot-env.c new file mode 100644 index 000000000..467b28891 --- /dev/null +++ b/drivers/nvmem/u-boot-env.c @@ -0,0 +1,99 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2022 Rafał Miłecki + */ + +#include +#include +#include +#include +#include +#include + +#include "layouts/u-boot-env.h" + +struct u_boot_env { + struct device *dev; + struct nvmem_device *nvmem; + enum u_boot_env_format format; + + struct mtd_info *mtd; +}; + +static int u_boot_env_read(void *context, unsigned int offset, void *val, + size_t bytes) +{ + struct u_boot_env *priv = context; + struct device *dev = priv->dev; + size_t bytes_read; + int err; + + err = mtd_read(priv->mtd, offset, bytes, &bytes_read, val); + if (err && !mtd_is_bitflip(err)) { + dev_err(dev, "Failed to read from mtd: %d\n", err); + return err; + } + + if (bytes_read != bytes) { + dev_err(dev, "Failed to read %zu bytes\n", bytes); + return -EIO; + } + + return 0; +} + +static int u_boot_env_probe(struct platform_device *pdev) +{ + struct nvmem_config config = { + .name = "u-boot-env", + .reg_read = u_boot_env_read, + }; + struct device *dev = &pdev->dev; + struct device_node *np = dev->of_node; + struct u_boot_env *priv; + + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + priv->dev = dev; + + priv->format = (uintptr_t)of_device_get_match_data(dev); + + priv->mtd = of_get_mtd_device_by_node(np); + if (IS_ERR(priv->mtd)) { + dev_err_probe(dev, PTR_ERR(priv->mtd), "Failed to get %pOF MTD\n", np); + return PTR_ERR(priv->mtd); + } + + config.dev = dev; + config.priv = priv; + config.size = priv->mtd->size; + + priv->nvmem = devm_nvmem_register(dev, &config); + if (IS_ERR(priv->nvmem)) + return PTR_ERR(priv->nvmem); + + return u_boot_env_parse(dev, priv->nvmem, priv->format); +} + +static const struct of_device_id u_boot_env_of_match_table[] = { + { .compatible = "u-boot,env", .data = (void *)U_BOOT_FORMAT_SINGLE, }, + { .compatible = "u-boot,env-redundant-bool", .data = (void *)U_BOOT_FORMAT_REDUNDANT, }, + { .compatible = "u-boot,env-redundant-count", .data = (void *)U_BOOT_FORMAT_REDUNDANT, }, + { .compatible = "brcm,env", .data = (void *)U_BOOT_FORMAT_BROADCOM, }, + {}, +}; + +static struct platform_driver u_boot_env_driver = { + .probe = u_boot_env_probe, + .driver = { + .name = "u_boot_env", + .of_match_table = u_boot_env_of_match_table, + }, +}; +module_platform_driver(u_boot_env_driver); + +MODULE_AUTHOR("Rafał Miłecki"); +MODULE_DESCRIPTION("U-Boot environment variables support module"); +MODULE_LICENSE("GPL"); +MODULE_DEVICE_TABLE(of, u_boot_env_of_match_table); -- cgit v1.3.1