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-88pm886.c | 96 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 96 insertions(+) create mode 100644 drivers/rtc/rtc-88pm886.c (limited to 'drivers/rtc/rtc-88pm886.c') diff --git a/drivers/rtc/rtc-88pm886.c b/drivers/rtc/rtc-88pm886.c new file mode 100644 index 000000000..71443ae1b --- /dev/null +++ b/drivers/rtc/rtc-88pm886.c @@ -0,0 +1,96 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include +#include + +#include + +/* + * Time is calculated as the sum of a 32-bit read-only advancing counter and a + * writeable constant offset stored in the chip's spare registers. + */ + +static int pm886_rtc_read_time(struct device *dev, struct rtc_time *tm) +{ + struct regmap *regmap = dev_get_drvdata(dev); + u32 time; + u32 buf; + int ret; + + ret = regmap_bulk_read(regmap, PM886_REG_RTC_SPARE1, &buf, 4); + if (ret) + return ret; + time = buf; + + ret = regmap_bulk_read(regmap, PM886_REG_RTC_CNT1, &buf, 4); + if (ret) + return ret; + time += buf; + + rtc_time64_to_tm(time, tm); + + return 0; +} + +static int pm886_rtc_set_time(struct device *dev, struct rtc_time *tm) +{ + struct regmap *regmap = dev_get_drvdata(dev); + u32 buf; + int ret; + + ret = regmap_bulk_read(regmap, PM886_REG_RTC_CNT1, &buf, 4); + if (ret) + return ret; + + buf = rtc_tm_to_time64(tm) - buf; + + return regmap_bulk_write(regmap, PM886_REG_RTC_SPARE1, &buf, 4); +} + +static const struct rtc_class_ops pm886_rtc_ops = { + .read_time = pm886_rtc_read_time, + .set_time = pm886_rtc_set_time, +}; + +static int pm886_rtc_probe(struct platform_device *pdev) +{ + struct pm886_chip *chip = dev_get_drvdata(pdev->dev.parent); + struct device *dev = &pdev->dev; + struct rtc_device *rtc; + int ret; + + platform_set_drvdata(pdev, chip->regmap); + + rtc = devm_rtc_allocate_device(dev); + if (IS_ERR(rtc)) + return dev_err_probe(dev, PTR_ERR(rtc), + "Failed to allocate RTC device\n"); + + rtc->ops = &pm886_rtc_ops; + rtc->range_max = U32_MAX; + + ret = devm_rtc_register_device(rtc); + if (ret) + return dev_err_probe(dev, ret, "Failed to register RTC device\n"); + + return 0; +} + +static const struct platform_device_id pm886_rtc_id_table[] = { + { .name = "88pm886-rtc" }, + { } +}; +MODULE_DEVICE_TABLE(platform, pm886_rtc_id_table); + +static struct platform_driver pm886_rtc_driver = { + .driver = { + .name = "88pm886-rtc", + }, + .probe = pm886_rtc_probe, + .id_table = pm886_rtc_id_table, +}; +module_platform_driver(pm886_rtc_driver); + +MODULE_DESCRIPTION("Marvell 88PM886 RTC driver"); +MODULE_AUTHOR("Karel Balej "); +MODULE_LICENSE("GPL"); -- cgit v1.3.1