From 93de2a6a4b91b72607136dd656edf03fb399d27f Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 23 Sep 2026 09:37:21 -0700 Subject: KVM: SEV: Do cache maintenance on the source VM during intra-host migration Manually perform cache maintenance on the source VM during intra-host migration to ensure no stale data is left in CPU caches after the VM is destroyed. Because the source VM is "converted" to a non-SEV VM, KVM's memory reclaim flows won't trigger cache maintenance, e.g. when all guest memory is reclaimed in response to detaching from the mmu_notifier. Note, relying on the destination VM to do cache maintenance isn't an option as KVM doesn't require identical guest memory configurations, i.e. the source VM may have access to memory that the destination VM does not. Enforcing equivalent memory configurations is infeasible, as it would require a *deep* comparison of memslots, e.g. to verify that not only are the memslot identical, but what the memslots point at is also identical. Fixes: b56639318bb2 ("KVM: SEV: Add support for SEV intra host migration") Cc: stable@vger.kernel.org Reported-by: Stefan Teodorescu Signed-off-by: Sean Christopherson Message-ID: <20260923163721.1584779-3-seanjc@google.com> Signed-off-by: Paolo Bonzini --- drivers/rtc/rtc-rx4581.c | 292 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 292 insertions(+) create mode 100644 drivers/rtc/rtc-rx4581.c (limited to 'drivers/rtc/rtc-rx4581.c') diff --git a/drivers/rtc/rtc-rx4581.c b/drivers/rtc/rtc-rx4581.c new file mode 100644 index 000000000..c092e0452 --- /dev/null +++ b/drivers/rtc/rtc-rx4581.c @@ -0,0 +1,292 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* drivers/rtc/rtc-rx4581.c + * + * written by Torben Hohn + * + * Based on: + * drivers/rtc/rtc-max6902.c + * + * Copyright (C) 2006 8D Technologies inc. + * Copyright (C) 2004 Compulab Ltd. + * + * Driver for MAX6902 spi RTC + * + * and based on: + * drivers/rtc/rtc-rx8581.c + * + * An I2C driver for the Epson RX8581 RTC + * + * Author: Martyn Welch + * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc. + * + * Based on: rtc-pcf8563.c (An I2C driver for the Philips PCF8563 RTC) + * Copyright 2005-06 Tower Technologies + */ + +#include +#include +#include +#include +#include +#include +#include + +#define RX4581_REG_SC 0x00 /* Second in BCD */ +#define RX4581_REG_MN 0x01 /* Minute in BCD */ +#define RX4581_REG_HR 0x02 /* Hour in BCD */ +#define RX4581_REG_DW 0x03 /* Day of Week */ +#define RX4581_REG_DM 0x04 /* Day of Month in BCD */ +#define RX4581_REG_MO 0x05 /* Month in BCD */ +#define RX4581_REG_YR 0x06 /* Year in BCD */ +#define RX4581_REG_RAM 0x07 /* RAM */ +#define RX4581_REG_AMN 0x08 /* Alarm Min in BCD*/ +#define RX4581_REG_AHR 0x09 /* Alarm Hour in BCD */ +#define RX4581_REG_ADM 0x0A +#define RX4581_REG_ADW 0x0A +#define RX4581_REG_TMR0 0x0B +#define RX4581_REG_TMR1 0x0C +#define RX4581_REG_EXT 0x0D /* Extension Register */ +#define RX4581_REG_FLAG 0x0E /* Flag Register */ +#define RX4581_REG_CTRL 0x0F /* Control Register */ + + +/* Flag Register bit definitions */ +#define RX4581_FLAG_UF 0x20 /* Update */ +#define RX4581_FLAG_TF 0x10 /* Timer */ +#define RX4581_FLAG_AF 0x08 /* Alarm */ +#define RX4581_FLAG_VLF 0x02 /* Voltage Low */ + +/* Control Register bit definitions */ +#define RX4581_CTRL_UIE 0x20 /* Update Interrupt Enable */ +#define RX4581_CTRL_TIE 0x10 /* Timer Interrupt Enable */ +#define RX4581_CTRL_AIE 0x08 /* Alarm Interrupt Enable */ +#define RX4581_CTRL_STOP 0x02 /* STOP bit */ +#define RX4581_CTRL_RESET 0x01 /* RESET bit */ + +static int rx4581_set_reg(struct device *dev, unsigned char address, + unsigned char data) +{ + struct spi_device *spi = to_spi_device(dev); + unsigned char buf[2]; + + /* high nibble must be '0' to write */ + buf[0] = address & 0x0f; + buf[1] = data; + + return spi_write_then_read(spi, buf, 2, NULL, 0); +} + +static int rx4581_get_reg(struct device *dev, unsigned char address, + unsigned char *data) +{ + struct spi_device *spi = to_spi_device(dev); + + /* Set MSB to indicate read */ + *data = address | 0x80; + + return spi_write_then_read(spi, data, 1, data, 1); +} + +/* + * In the routines that deal directly with the rx8581 hardware, we use + * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch. + */ +static int rx4581_get_datetime(struct device *dev, struct rtc_time *tm) +{ + struct spi_device *spi = to_spi_device(dev); + unsigned char date[7]; + unsigned char data; + int err; + + /* First we ensure that the "update flag" is not set, we read the + * time and date then re-read the "update flag". If the update flag + * has been set, we know that the time has changed during the read so + * we repeat the whole process again. + */ + err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data); + if (err != 0) { + dev_err(dev, "Unable to read device flags\n"); + return -EIO; + } + + do { + /* If update flag set, clear it */ + if (data & RX4581_FLAG_UF) { + err = rx4581_set_reg(dev, + RX4581_REG_FLAG, (data & ~RX4581_FLAG_UF)); + if (err != 0) { + dev_err(dev, "Unable to write device " + "flags\n"); + return -EIO; + } + } + + /* Now read time and date */ + date[0] = 0x80; + err = spi_write_then_read(spi, date, 1, date, 7); + if (err < 0) { + dev_err(dev, "Unable to read date\n"); + return -EIO; + } + + /* Check flag register */ + err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data); + if (err != 0) { + dev_err(dev, "Unable to read device flags\n"); + return -EIO; + } + } while (data & RX4581_FLAG_UF); + + if (data & RX4581_FLAG_VLF) + dev_info(dev, + "low voltage detected, date/time is not reliable.\n"); + + dev_dbg(dev, + "%s: raw data is sec=%02x, min=%02x, hr=%02x, " + "wday=%02x, mday=%02x, mon=%02x, year=%02x\n", + __func__, + date[0], date[1], date[2], date[3], date[4], date[5], date[6]); + + tm->tm_sec = bcd2bin(date[RX4581_REG_SC] & 0x7F); + tm->tm_min = bcd2bin(date[RX4581_REG_MN] & 0x7F); + tm->tm_hour = bcd2bin(date[RX4581_REG_HR] & 0x3F); /* rtc hr 0-23 */ + tm->tm_wday = ilog2(date[RX4581_REG_DW] & 0x7F); + tm->tm_mday = bcd2bin(date[RX4581_REG_DM] & 0x3F); + tm->tm_mon = bcd2bin(date[RX4581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */ + tm->tm_year = bcd2bin(date[RX4581_REG_YR]); + if (tm->tm_year < 70) + tm->tm_year += 100; /* assume we are in 1970...2069 */ + + + dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, " + "mday=%d, mon=%d, year=%d, wday=%d\n", + __func__, + tm->tm_sec, tm->tm_min, tm->tm_hour, + tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); + + return 0; +} + +static int rx4581_set_datetime(struct device *dev, struct rtc_time *tm) +{ + struct spi_device *spi = to_spi_device(dev); + int err; + unsigned char buf[8], data; + + dev_dbg(dev, "%s: secs=%d, mins=%d, hours=%d, " + "mday=%d, mon=%d, year=%d, wday=%d\n", + __func__, + tm->tm_sec, tm->tm_min, tm->tm_hour, + tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); + + buf[0] = 0x00; + /* hours, minutes and seconds */ + buf[RX4581_REG_SC+1] = bin2bcd(tm->tm_sec); + buf[RX4581_REG_MN+1] = bin2bcd(tm->tm_min); + buf[RX4581_REG_HR+1] = bin2bcd(tm->tm_hour); + + buf[RX4581_REG_DM+1] = bin2bcd(tm->tm_mday); + + /* month, 1 - 12 */ + buf[RX4581_REG_MO+1] = bin2bcd(tm->tm_mon + 1); + + /* year and century */ + buf[RX4581_REG_YR+1] = bin2bcd(tm->tm_year % 100); + buf[RX4581_REG_DW+1] = (0x1 << tm->tm_wday); + + /* Stop the clock */ + err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data); + if (err != 0) { + dev_err(dev, "Unable to read control register\n"); + return -EIO; + } + + err = rx4581_set_reg(dev, RX4581_REG_CTRL, + (data | RX4581_CTRL_STOP)); + if (err != 0) { + dev_err(dev, "Unable to write control register\n"); + return -EIO; + } + + /* write register's data */ + err = spi_write_then_read(spi, buf, 8, NULL, 0); + if (err != 0) { + dev_err(dev, "Unable to write to date registers\n"); + return -EIO; + } + + /* get VLF and clear it */ + err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data); + if (err != 0) { + dev_err(dev, "Unable to read flag register\n"); + return -EIO; + } + + err = rx4581_set_reg(dev, RX4581_REG_FLAG, + (data & ~(RX4581_FLAG_VLF))); + if (err != 0) { + dev_err(dev, "Unable to write flag register\n"); + return -EIO; + } + + /* Restart the clock */ + err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data); + if (err != 0) { + dev_err(dev, "Unable to read control register\n"); + return -EIO; + } + + err = rx4581_set_reg(dev, RX4581_REG_CTRL, + (data & ~(RX4581_CTRL_STOP))); + if (err != 0) { + dev_err(dev, "Unable to write control register\n"); + return -EIO; + } + + return 0; +} + +static const struct rtc_class_ops rx4581_rtc_ops = { + .read_time = rx4581_get_datetime, + .set_time = rx4581_set_datetime, +}; + +static int rx4581_probe(struct spi_device *spi) +{ + struct rtc_device *rtc; + unsigned char tmp; + int res; + + res = rx4581_get_reg(&spi->dev, RX4581_REG_SC, &tmp); + if (res != 0) + return res; + + rtc = devm_rtc_device_register(&spi->dev, "rx4581", + &rx4581_rtc_ops, THIS_MODULE); + if (IS_ERR(rtc)) + return PTR_ERR(rtc); + + spi_set_drvdata(spi, rtc); + return 0; +} + +static const struct spi_device_id rx4581_id[] = { + { "rx4581", 0 }, + { } +}; +MODULE_DEVICE_TABLE(spi, rx4581_id); + +static struct spi_driver rx4581_driver = { + .driver = { + .name = "rtc-rx4581", + }, + .probe = rx4581_probe, + .id_table = rx4581_id, +}; + +module_spi_driver(rx4581_driver); + +MODULE_DESCRIPTION("rx4581 spi RTC driver"); +MODULE_AUTHOR("Torben Hohn"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("spi:rtc-rx4581"); -- cgit v1.3.1