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-opal.c | 301 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 301 insertions(+) create mode 100644 drivers/rtc/rtc-opal.c (limited to 'drivers/rtc/rtc-opal.c') diff --git a/drivers/rtc/rtc-opal.c b/drivers/rtc/rtc-opal.c new file mode 100644 index 000000000..ad41aaf8a --- /dev/null +++ b/drivers/rtc/rtc-opal.c @@ -0,0 +1,301 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * IBM OPAL RTC driver + * Copyright (C) 2014 IBM + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#define DRVNAME "rtc-opal" + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static void opal_to_tm(u32 y_m_d, u64 h_m_s_ms, struct rtc_time *tm) +{ + tm->tm_year = ((bcd2bin(y_m_d >> 24) * 100) + + bcd2bin((y_m_d >> 16) & 0xff)) - 1900; + tm->tm_mon = bcd2bin((y_m_d >> 8) & 0xff) - 1; + tm->tm_mday = bcd2bin(y_m_d & 0xff); + tm->tm_hour = bcd2bin((h_m_s_ms >> 56) & 0xff); + tm->tm_min = bcd2bin((h_m_s_ms >> 48) & 0xff); + tm->tm_sec = bcd2bin((h_m_s_ms >> 40) & 0xff); + + tm->tm_wday = -1; +} + +static void tm_to_opal(struct rtc_time *tm, u32 *y_m_d, u64 *h_m_s_ms) +{ + *y_m_d |= ((u32)bin2bcd((tm->tm_year + 1900) / 100)) << 24; + *y_m_d |= ((u32)bin2bcd((tm->tm_year + 1900) % 100)) << 16; + *y_m_d |= ((u32)bin2bcd((tm->tm_mon + 1))) << 8; + *y_m_d |= ((u32)bin2bcd(tm->tm_mday)); + + *h_m_s_ms |= ((u64)bin2bcd(tm->tm_hour)) << 56; + *h_m_s_ms |= ((u64)bin2bcd(tm->tm_min)) << 48; + *h_m_s_ms |= ((u64)bin2bcd(tm->tm_sec)) << 40; +} + +static int opal_get_rtc_time(struct device *dev, struct rtc_time *tm) +{ + s64 rc = OPAL_BUSY; + int retries = 10; + u32 y_m_d; + u64 h_m_s_ms; + __be32 __y_m_d; + __be64 __h_m_s_ms; + + while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) { + rc = opal_rtc_read(&__y_m_d, &__h_m_s_ms); + if (rc == OPAL_BUSY_EVENT) { + msleep(OPAL_BUSY_DELAY_MS); + opal_poll_events(NULL); + } else if (rc == OPAL_BUSY) { + msleep(OPAL_BUSY_DELAY_MS); + } else if (rc == OPAL_HARDWARE || rc == OPAL_INTERNAL_ERROR) { + if (retries--) { + msleep(10); /* Wait 10ms before retry */ + rc = OPAL_BUSY; /* go around again */ + } + } + } + + if (rc != OPAL_SUCCESS) + return -EIO; + + y_m_d = be32_to_cpu(__y_m_d); + h_m_s_ms = be64_to_cpu(__h_m_s_ms); + opal_to_tm(y_m_d, h_m_s_ms, tm); + + return 0; +} + +static int opal_set_rtc_time(struct device *dev, struct rtc_time *tm) +{ + s64 rc = OPAL_BUSY; + int retries = 10; + u32 y_m_d = 0; + u64 h_m_s_ms = 0; + + tm_to_opal(tm, &y_m_d, &h_m_s_ms); + + while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) { + rc = opal_rtc_write(y_m_d, h_m_s_ms); + if (rc == OPAL_BUSY_EVENT) { + msleep(OPAL_BUSY_DELAY_MS); + opal_poll_events(NULL); + } else if (rc == OPAL_BUSY) { + msleep(OPAL_BUSY_DELAY_MS); + } else if (rc == OPAL_HARDWARE || rc == OPAL_INTERNAL_ERROR) { + if (retries--) { + msleep(10); /* Wait 10ms before retry */ + rc = OPAL_BUSY; /* go around again */ + } + } + } + + return rc == OPAL_SUCCESS ? 0 : -EIO; +} + +/* + * TPO Timed Power-On + * + * TPO get/set OPAL calls care about the hour and min and to make it consistent + * with the rtc utility time conversion functions, we use the 'u64' to store + * its value and perform bit shift by 32 before use.. + */ +static int opal_get_tpo_time(struct device *dev, struct rtc_wkalrm *alarm) +{ + __be32 __y_m_d, __h_m; + struct opal_msg msg; + int rc, token; + u64 h_m_s_ms; + u32 y_m_d; + + token = opal_async_get_token_interruptible(); + if (token < 0) { + if (token != -ERESTARTSYS) + pr_err("Failed to get the async token\n"); + + return token; + } + + rc = opal_tpo_read(token, &__y_m_d, &__h_m); + if (rc != OPAL_ASYNC_COMPLETION) { + rc = -EIO; + goto exit; + } + + rc = opal_async_wait_response(token, &msg); + if (rc) { + rc = -EIO; + goto exit; + } + + rc = opal_get_async_rc(msg); + if (rc != OPAL_SUCCESS) { + rc = -EIO; + goto exit; + } + + y_m_d = be32_to_cpu(__y_m_d); + h_m_s_ms = ((u64)be32_to_cpu(__h_m) << 32); + + /* check if no alarm is set */ + if (y_m_d == 0 && h_m_s_ms == 0) { + pr_debug("No alarm is set\n"); + rc = -ENOENT; + goto exit; + } else { + pr_debug("Alarm set to %x %llx\n", y_m_d, h_m_s_ms); + } + + opal_to_tm(y_m_d, h_m_s_ms, &alarm->time); + +exit: + opal_async_release_token(token); + return rc; +} + +/* Set Timed Power-On */ +static int opal_set_tpo_time(struct device *dev, struct rtc_wkalrm *alarm) +{ + u64 h_m_s_ms = 0; + struct opal_msg msg; + u32 y_m_d = 0; + int token, rc; + + /* if alarm is enabled */ + if (alarm->enabled) { + tm_to_opal(&alarm->time, &y_m_d, &h_m_s_ms); + pr_debug("Alarm set to %x %llx\n", y_m_d, h_m_s_ms); + + } else { + pr_debug("Alarm getting disabled\n"); + } + + token = opal_async_get_token_interruptible(); + if (token < 0) { + if (token != -ERESTARTSYS) + pr_err("Failed to get the async token\n"); + + return token; + } + + /* TPO, we care about hour and minute */ + rc = opal_tpo_write(token, y_m_d, + (u32)((h_m_s_ms >> 32) & 0xffff0000)); + if (rc != OPAL_ASYNC_COMPLETION) { + rc = -EIO; + goto exit; + } + + rc = opal_async_wait_response(token, &msg); + if (rc) { + rc = -EIO; + goto exit; + } + + rc = opal_get_async_rc(msg); + if (rc != OPAL_SUCCESS) + rc = -EIO; + +exit: + opal_async_release_token(token); + return rc; +} + +static int opal_tpo_alarm_irq_enable(struct device *dev, unsigned int enabled) +{ + struct rtc_wkalrm alarm = { .enabled = 0 }; + + /* + * TPO is automatically enabled when opal_set_tpo_time() is called with + * non-zero rtc-time. We only handle disable case which needs to be + * explicitly told to opal. + */ + return enabled ? 0 : opal_set_tpo_time(dev, &alarm); +} + +static const struct rtc_class_ops opal_rtc_ops = { + .read_time = opal_get_rtc_time, + .set_time = opal_set_rtc_time, + .read_alarm = opal_get_tpo_time, + .set_alarm = opal_set_tpo_time, + .alarm_irq_enable = opal_tpo_alarm_irq_enable, +}; + +static int opal_rtc_probe(struct platform_device *pdev) +{ + struct rtc_device *rtc; + + rtc = devm_rtc_allocate_device(&pdev->dev); + if (IS_ERR(rtc)) + return PTR_ERR(rtc); + + if (pdev->dev.of_node && + (of_property_read_bool(pdev->dev.of_node, "wakeup-source") || + of_property_read_bool(pdev->dev.of_node, "has-tpo")/* legacy */)) + device_set_wakeup_capable(&pdev->dev, true); + else + clear_bit(RTC_FEATURE_ALARM, rtc->features); + + rtc->ops = &opal_rtc_ops; + rtc->range_min = RTC_TIMESTAMP_BEGIN_0000; + rtc->range_max = RTC_TIMESTAMP_END_9999; + clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features); + + return devm_rtc_register_device(rtc); +} + +static const struct of_device_id opal_rtc_match[] = { + { + .compatible = "ibm,opal-rtc", + }, + { } +}; +MODULE_DEVICE_TABLE(of, opal_rtc_match); + +static const struct platform_device_id opal_rtc_driver_ids[] = { + { + .name = "opal-rtc", + }, + { } +}; +MODULE_DEVICE_TABLE(platform, opal_rtc_driver_ids); + +static struct platform_driver opal_rtc_driver = { + .probe = opal_rtc_probe, + .id_table = opal_rtc_driver_ids, + .driver = { + .name = DRVNAME, + .of_match_table = opal_rtc_match, + }, +}; + +static int __init opal_rtc_init(void) +{ + if (!firmware_has_feature(FW_FEATURE_OPAL)) + return -ENODEV; + + return platform_driver_register(&opal_rtc_driver); +} + +static void __exit opal_rtc_exit(void) +{ + platform_driver_unregister(&opal_rtc_driver); +} + +MODULE_AUTHOR("Neelesh Gupta "); +MODULE_DESCRIPTION("IBM OPAL RTC driver"); +MODULE_LICENSE("GPL"); + +module_init(opal_rtc_init); +module_exit(opal_rtc_exit); -- cgit v1.3.1