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/rtc/rtc-efi.c | 224 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 224 insertions(+) create mode 100644 drivers/rtc/rtc-efi.c (limited to 'drivers/rtc/rtc-efi.c') diff --git a/drivers/rtc/rtc-efi.c b/drivers/rtc/rtc-efi.c new file mode 100644 index 000000000..b4f44999e --- /dev/null +++ b/drivers/rtc/rtc-efi.c @@ -0,0 +1,224 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * rtc-efi: RTC Class Driver for EFI-based systems + * + * Copyright (C) 2009 Hewlett-Packard Development Company, L.P. + * + * Author: dann frazier + * Based on efirtc.c by Stephane Eranian + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include +#include +#include +#include +#include + +#define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT) + +/* + * returns day of the year [0-365] + */ +static inline int +compute_yday(efi_time_t *eft) +{ + /* efi_time_t.month is in the [1-12] so, we need -1 */ + return rtc_year_days(eft->day, eft->month - 1, eft->year); +} + +/* + * returns day of the week [0-6] 0=Sunday + */ +static int +compute_wday(efi_time_t *eft, int yday) +{ + int ndays = eft->year * (365 % 7) + + (eft->year - 1) / 4 + - (eft->year - 1) / 100 + + (eft->year - 1) / 400 + + yday; + + /* + * 1/1/0000 may or may not have been a Sunday (if it ever existed at + * all) but assuming it was makes this calculation work correctly. + */ + return ndays % 7; +} + +static void +convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft) +{ + eft->year = wtime->tm_year + 1900; + eft->month = wtime->tm_mon + 1; + eft->day = wtime->tm_mday; + eft->hour = wtime->tm_hour; + eft->minute = wtime->tm_min; + eft->second = wtime->tm_sec; + eft->nanosecond = 0; + eft->daylight = wtime->tm_isdst ? EFI_ISDST : 0; + eft->timezone = EFI_UNSPECIFIED_TIMEZONE; +} + +static bool +convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime) +{ + memset(wtime, 0, sizeof(*wtime)); + + if (eft->second >= 60) + return false; + wtime->tm_sec = eft->second; + + if (eft->minute >= 60) + return false; + wtime->tm_min = eft->minute; + + if (eft->hour >= 24) + return false; + wtime->tm_hour = eft->hour; + + if (!eft->day || eft->day > 31) + return false; + wtime->tm_mday = eft->day; + + if (!eft->month || eft->month > 12) + return false; + wtime->tm_mon = eft->month - 1; + + if (eft->year < 1900 || eft->year > 9999) + return false; + wtime->tm_year = eft->year - 1900; + + /* day in the year [1-365]*/ + wtime->tm_yday = compute_yday(eft); + + /* day of the week [0-6], Sunday=0 */ + wtime->tm_wday = compute_wday(eft, wtime->tm_yday); + + switch (eft->daylight & EFI_ISDST) { + case EFI_ISDST: + wtime->tm_isdst = 1; + break; + case EFI_TIME_ADJUST_DAYLIGHT: + wtime->tm_isdst = 0; + break; + default: + wtime->tm_isdst = -1; + } + + return true; +} + +static int efi_read_time(struct device *dev, struct rtc_time *tm) +{ + efi_status_t status; + efi_time_t eft; + efi_time_cap_t cap; + + status = efi.get_time(&eft, &cap); + + if (status != EFI_SUCCESS) { + /* should never happen */ + dev_err_once(dev, "can't read time\n"); + return -EINVAL; + } + + if (!convert_from_efi_time(&eft, tm)) + return -EIO; + + return 0; +} + +static int efi_set_time(struct device *dev, struct rtc_time *tm) +{ + efi_status_t status; + efi_time_t eft; + + convert_to_efi_time(tm, &eft); + + status = efi.set_time(&eft); + + return status == EFI_SUCCESS ? 0 : -EINVAL; +} + +static int efi_procfs(struct device *dev, struct seq_file *seq) +{ + efi_time_t eft; + efi_time_cap_t cap; + + memset(&eft, 0, sizeof(eft)); + memset(&cap, 0, sizeof(cap)); + + efi.get_time(&eft, &cap); + + seq_printf(seq, + "Time\t\t: %u:%u:%u.%09u\n" + "Date\t\t: %u-%u-%u\n" + "Daylight\t: %u\n", + eft.hour, eft.minute, eft.second, eft.nanosecond, + eft.year, eft.month, eft.day, + eft.daylight); + + if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE) + seq_puts(seq, "Timezone\t: unspecified\n"); + else + /* XXX fixme: convert to string? */ + seq_printf(seq, "Timezone\t: %u\n", eft.timezone); + + /* + * now prints the capabilities + */ + seq_printf(seq, + "Resolution\t: %u\n" + "Accuracy\t: %u\n" + "SetstoZero\t: %u\n", + cap.resolution, cap.accuracy, cap.sets_to_zero); + + return 0; +} + +static const struct rtc_class_ops efi_rtc_ops = { + .read_time = efi_read_time, + .set_time = efi_set_time, + .proc = efi_procfs, +}; + +static int __init efi_rtc_probe(struct platform_device *dev) +{ + struct rtc_device *rtc; + efi_time_t eft; + efi_time_cap_t cap; + + /* First check if the RTC is usable */ + if (efi.get_time(&eft, &cap) != EFI_SUCCESS) + return -ENODEV; + + rtc = devm_rtc_allocate_device(&dev->dev); + if (IS_ERR(rtc)) + return PTR_ERR(rtc); + + platform_set_drvdata(dev, rtc); + + rtc->ops = &efi_rtc_ops; + clear_bit(RTC_FEATURE_ALARM, rtc->features); + + device_init_wakeup(&dev->dev, true); + + return devm_rtc_register_device(rtc); +} + +static struct platform_driver efi_rtc_driver = { + .driver = { + .name = "rtc-efi", + }, +}; + +module_platform_driver_probe(efi_rtc_driver, efi_rtc_probe); + +MODULE_AUTHOR("dann frazier "); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("EFI RTC driver"); +MODULE_ALIAS("platform:rtc-efi"); -- cgit v1.3.1