KVM: SEV: Do cache maintenance on the source VM during intra-host migrationgrafted

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 <fane@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260923163721.1584779-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 321 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-mv.c b/drivers/rtc/rtc-mv.c
new file mode 100644
index 000000000..db64c459e
--- /dev/null
+++ b/drivers/rtc/rtc-mv.c
@@ -0,0 +1,321 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for the RTC in Marvell SoCs.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/rtc.h>
+#include <linux/bcd.h>
+#include <linux/bitops.h>
+#include <linux/io.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/delay.h>
+#include <linux/clk.h>
+#include <linux/gfp.h>
+#include <linux/module.h>
+
+
+#define RTC_TIME_REG_OFFS	0
+#define RTC_SECONDS_OFFS	0
+#define RTC_MINUTES_OFFS	8
+#define RTC_HOURS_OFFS		16
+#define RTC_WDAY_OFFS		24
+#define RTC_HOURS_12H_MODE	BIT(22) /* 12 hour mode */
+
+#define RTC_DATE_REG_OFFS	4
+#define RTC_MDAY_OFFS		0
+#define RTC_MONTH_OFFS		8
+#define RTC_YEAR_OFFS		16
+
+#define RTC_ALARM_TIME_REG_OFFS	8
+#define RTC_ALARM_DATE_REG_OFFS	0xc
+#define RTC_ALARM_VALID		BIT(7)
+
+#define RTC_ALARM_INTERRUPT_MASK_REG_OFFS	0x10
+#define RTC_ALARM_INTERRUPT_CASUE_REG_OFFS	0x14
+
+struct rtc_plat_data {
+	struct rtc_device *rtc;
+	void __iomem *ioaddr;
+	int		irq;
+	struct clk	*clk;
+};
+
+static int mv_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+	u32	rtc_reg;
+
+	rtc_reg = (bin2bcd(tm->tm_sec) << RTC_SECONDS_OFFS) |
+		(bin2bcd(tm->tm_min) << RTC_MINUTES_OFFS) |
+		(bin2bcd(tm->tm_hour) << RTC_HOURS_OFFS) |
+		(bin2bcd(tm->tm_wday) << RTC_WDAY_OFFS);
+	writel(rtc_reg, ioaddr + RTC_TIME_REG_OFFS);
+
+	rtc_reg = (bin2bcd(tm->tm_mday) << RTC_MDAY_OFFS) |
+		(bin2bcd(tm->tm_mon + 1) << RTC_MONTH_OFFS) |
+		(bin2bcd(tm->tm_year - 100) << RTC_YEAR_OFFS);
+	writel(rtc_reg, ioaddr + RTC_DATE_REG_OFFS);
+
+	return 0;
+}
+
+static int mv_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+	u32	rtc_time, rtc_date;
+	unsigned int year, month, day, hour, minute, second, wday;
+
+	rtc_time = readl(ioaddr + RTC_TIME_REG_OFFS);
+	rtc_date = readl(ioaddr + RTC_DATE_REG_OFFS);
+
+	second = rtc_time & 0x7f;
+	minute = (rtc_time >> RTC_MINUTES_OFFS) & 0x7f;
+	hour = (rtc_time >> RTC_HOURS_OFFS) & 0x3f; /* assume 24 hour mode */
+	wday = (rtc_time >> RTC_WDAY_OFFS) & 0x7;
+
+	day = rtc_date & 0x3f;
+	month = (rtc_date >> RTC_MONTH_OFFS) & 0x3f;
+	year = (rtc_date >> RTC_YEAR_OFFS) & 0xff;
+
+	tm->tm_sec = bcd2bin(second);
+	tm->tm_min = bcd2bin(minute);
+	tm->tm_hour = bcd2bin(hour);
+	tm->tm_mday = bcd2bin(day);
+	tm->tm_wday = bcd2bin(wday);
+	tm->tm_mon = bcd2bin(month) - 1;
+	/* hw counts from year 2000, but tm_year is relative to 1900 */
+	tm->tm_year = bcd2bin(year) + 100;
+
+	return 0;
+}
+
+static int mv_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
+{
+	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+	u32	rtc_time, rtc_date;
+	unsigned int year, month, day, hour, minute, second, wday;
+
+	rtc_time = readl(ioaddr + RTC_ALARM_TIME_REG_OFFS);
+	rtc_date = readl(ioaddr + RTC_ALARM_DATE_REG_OFFS);
+
+	second = rtc_time & 0x7f;
+	minute = (rtc_time >> RTC_MINUTES_OFFS) & 0x7f;
+	hour = (rtc_time >> RTC_HOURS_OFFS) & 0x3f; /* assume 24 hour mode */
+	wday = (rtc_time >> RTC_WDAY_OFFS) & 0x7;
+
+	day = rtc_date & 0x3f;
+	month = (rtc_date >> RTC_MONTH_OFFS) & 0x3f;
+	year = (rtc_date >> RTC_YEAR_OFFS) & 0xff;
+
+	alm->time.tm_sec = bcd2bin(second);
+	alm->time.tm_min = bcd2bin(minute);
+	alm->time.tm_hour = bcd2bin(hour);
+	alm->time.tm_mday = bcd2bin(day);
+	alm->time.tm_wday = bcd2bin(wday);
+	alm->time.tm_mon = bcd2bin(month) - 1;
+	/* hw counts from year 2000, but tm_year is relative to 1900 */
+	alm->time.tm_year = bcd2bin(year) + 100;
+
+	alm->enabled = !!readl(ioaddr + RTC_ALARM_INTERRUPT_MASK_REG_OFFS);
+
+	return rtc_valid_tm(&alm->time);
+}
+
+static int mv_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
+{
+	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+	u32 rtc_reg = 0;
+
+	if (alm->time.tm_sec >= 0)
+		rtc_reg |= (RTC_ALARM_VALID | bin2bcd(alm->time.tm_sec))
+			<< RTC_SECONDS_OFFS;
+	if (alm->time.tm_min >= 0)
+		rtc_reg |= (RTC_ALARM_VALID | bin2bcd(alm->time.tm_min))
+			<< RTC_MINUTES_OFFS;
+	if (alm->time.tm_hour >= 0)
+		rtc_reg |= (RTC_ALARM_VALID | bin2bcd(alm->time.tm_hour))
+			<< RTC_HOURS_OFFS;
+
+	writel(rtc_reg, ioaddr + RTC_ALARM_TIME_REG_OFFS);
+
+	if (alm->time.tm_mday >= 0)
+		rtc_reg = (RTC_ALARM_VALID | bin2bcd(alm->time.tm_mday))
+			<< RTC_MDAY_OFFS;
+	else
+		rtc_reg = 0;
+
+	if (alm->time.tm_mon >= 0)
+		rtc_reg |= (RTC_ALARM_VALID | bin2bcd(alm->time.tm_mon + 1))
+			<< RTC_MONTH_OFFS;
+
+	if (alm->time.tm_year >= 0)
+		rtc_reg |= (RTC_ALARM_VALID | bin2bcd(alm->time.tm_year - 100))
+			<< RTC_YEAR_OFFS;
+
+	writel(rtc_reg, ioaddr + RTC_ALARM_DATE_REG_OFFS);
+	writel(0, ioaddr + RTC_ALARM_INTERRUPT_CASUE_REG_OFFS);
+	writel(alm->enabled ? 1 : 0,
+	       ioaddr + RTC_ALARM_INTERRUPT_MASK_REG_OFFS);
+
+	return 0;
+}
+
+static int mv_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
+	void __iomem *ioaddr = pdata->ioaddr;
+
+	if (pdata->irq < 0)
+		return -EINVAL; /* fall back into rtc-dev's emulation */
+
+	if (enabled)
+		writel(1, ioaddr + RTC_ALARM_INTERRUPT_MASK_REG_OFFS);
+	else
+		writel(0, ioaddr + RTC_ALARM_INTERRUPT_MASK_REG_OFFS);
+	return 0;
+}
+
+static irqreturn_t mv_rtc_interrupt(int irq, void *data)
+{
+	struct rtc_plat_data *pdata = data;
+	void __iomem *ioaddr = pdata->ioaddr;
+
+	/* alarm irq? */
+	if (!readl(ioaddr + RTC_ALARM_INTERRUPT_CASUE_REG_OFFS))
+		return IRQ_NONE;
+
+	/* clear interrupt */
+	writel(0, ioaddr + RTC_ALARM_INTERRUPT_CASUE_REG_OFFS);
+	rtc_update_irq(pdata->rtc, 1, RTC_IRQF | RTC_AF);
+	return IRQ_HANDLED;
+}
+
+static const struct rtc_class_ops mv_rtc_ops = {
+	.read_time	= mv_rtc_read_time,
+	.set_time	= mv_rtc_set_time,
+	.read_alarm	= mv_rtc_read_alarm,
+	.set_alarm	= mv_rtc_set_alarm,
+	.alarm_irq_enable = mv_rtc_alarm_irq_enable,
+};
+
+static int __init mv_rtc_probe(struct platform_device *pdev)
+{
+	struct rtc_plat_data *pdata;
+	u32 rtc_time;
+	int ret = 0;
+
+	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
+	if (!pdata)
+		return -ENOMEM;
+
+	pdata->ioaddr = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(pdata->ioaddr))
+		return PTR_ERR(pdata->ioaddr);
+
+	pdata->clk = devm_clk_get_optional_prepared(&pdev->dev, NULL);
+	if (IS_ERR(pdata->clk))
+		return PTR_ERR(pdata->clk);
+
+	/* make sure the 24 hour mode is enabled */
+	rtc_time = readl(pdata->ioaddr + RTC_TIME_REG_OFFS);
+	if (rtc_time & RTC_HOURS_12H_MODE) {
+		dev_err(&pdev->dev, "12 Hour mode is enabled but not supported.\n");
+		return  -EINVAL;
+	}
+
+	/* make sure it is actually functional */
+	if (rtc_time == 0x01000000) {
+		ssleep(1);
+		rtc_time = readl(pdata->ioaddr + RTC_TIME_REG_OFFS);
+		if (rtc_time == 0x01000000) {
+			dev_err(&pdev->dev, "internal RTC not ticking\n");
+			return -ENODEV;
+		}
+	}
+
+	pdata->irq = platform_get_irq(pdev, 0);
+
+	platform_set_drvdata(pdev, pdata);
+
+	pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
+	if (IS_ERR(pdata->rtc)) {
+		return PTR_ERR(pdata->rtc);
+	}
+
+	if (pdata->irq >= 0) {
+		writel(0, pdata->ioaddr + RTC_ALARM_INTERRUPT_MASK_REG_OFFS);
+		if (devm_request_irq(&pdev->dev, pdata->irq, mv_rtc_interrupt,
+				     IRQF_SHARED,
+				     pdev->name, pdata) < 0) {
+			dev_warn(&pdev->dev, "interrupt not available.\n");
+			pdata->irq = -1;
+		}
+	}
+
+	if (pdata->irq >= 0)
+		devm_device_init_wakeup(&pdev->dev);
+	else
+		clear_bit(RTC_FEATURE_ALARM, pdata->rtc->features);
+
+	pdata->rtc->ops = &mv_rtc_ops;
+	pdata->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
+	pdata->rtc->range_max = RTC_TIMESTAMP_END_2099;
+
+	ret = devm_rtc_register_device(pdata->rtc);
+	if (!ret)
+		return 0;
+
+	return ret;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id rtc_mv_of_match_table[] = {
+	{ .compatible = "marvell,orion-rtc", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, rtc_mv_of_match_table);
+#endif
+
+#ifdef CONFIG_PM_SLEEP
+static int mv_rtc_suspend(struct device *dev)
+{
+	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
+
+	if (device_may_wakeup(dev) && pdata->irq >= 0)
+		enable_irq_wake(pdata->irq);
+	return 0;
+}
+
+static int mv_rtc_resume(struct device *dev)
+{
+	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
+
+	if (device_may_wakeup(dev) && pdata->irq >= 0)
+		disable_irq_wake(pdata->irq);
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(mv_rtc_pm_ops, mv_rtc_suspend, mv_rtc_resume);
+
+static struct platform_driver mv_rtc_driver = {
+	.driver		= {
+		.name	= "rtc-mv",
+		.of_match_table = of_match_ptr(rtc_mv_of_match_table),
+		.pm	= &mv_rtc_pm_ops,
+	},
+};
+
+module_platform_driver_probe(mv_rtc_driver, mv_rtc_probe);
+
+MODULE_AUTHOR("Saeed Bishara <saeed@marvell.com>");
+MODULE_DESCRIPTION("Marvell RTC driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:rtc-mv");