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/hwmon/surface_fan.c | 83 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 83 insertions(+) create mode 100644 drivers/hwmon/surface_fan.c (limited to 'drivers/hwmon/surface_fan.c') diff --git a/drivers/hwmon/surface_fan.c b/drivers/hwmon/surface_fan.c new file mode 100644 index 000000000..aafb4ac92 --- /dev/null +++ b/drivers/hwmon/surface_fan.c @@ -0,0 +1,83 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Surface Fan driver for Surface System Aggregator Module. It provides access + * to the fan's rpm through the hwmon system. + * + * Copyright (C) 2023 Ivor Wanders + */ + +#include +#include +#include +#include +#include + +// SSAM +SSAM_DEFINE_SYNC_REQUEST_CL_R(__ssam_fan_rpm_get, __le16, { + .target_category = SSAM_SSH_TC_FAN, + .command_id = 0x01, +}); + +static int surface_fan_hwmon_read(struct device *dev, + enum hwmon_sensor_types type, u32 attr, + int channel, long *val) +{ + struct ssam_device *sdev = dev_get_drvdata(dev); + int ret; + __le16 value; + + ret = __ssam_fan_rpm_get(sdev, &value); + if (ret) + return ret; + + *val = le16_to_cpu(value); + + return 0; +} + +static const struct hwmon_channel_info *const surface_fan_info[] = { + HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT), + NULL +}; + +static const struct hwmon_ops surface_fan_hwmon_ops = { + .visible = 0444, + .read = surface_fan_hwmon_read, +}; + +static const struct hwmon_chip_info surface_fan_chip_info = { + .ops = &surface_fan_hwmon_ops, + .info = surface_fan_info, +}; + +static int surface_fan_probe(struct ssam_device *sdev) +{ + struct device *hdev; + + hdev = devm_hwmon_device_register_with_info(&sdev->dev, + "surface_fan", sdev, + &surface_fan_chip_info, + NULL); + + return PTR_ERR_OR_ZERO(hdev); +} + +static const struct ssam_device_id ssam_fan_match[] = { + { SSAM_SDEV(FAN, SAM, 0x01, 0x01) }, + {}, +}; +MODULE_DEVICE_TABLE(ssam, ssam_fan_match); + +static struct ssam_device_driver surface_fan = { + .probe = surface_fan_probe, + .match_table = ssam_fan_match, + .driver = { + .name = "surface_fan", + .probe_type = PROBE_PREFER_ASYNCHRONOUS, + }, +}; +module_ssam_device_driver(surface_fan); + +MODULE_AUTHOR("Ivor Wanders "); +MODULE_DESCRIPTION("Fan Driver for Surface System Aggregator Module"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1