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/acpi/tiny-power-button.c | 87 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 87 insertions(+) create mode 100644 drivers/acpi/tiny-power-button.c (limited to 'drivers/acpi/tiny-power-button.c') diff --git a/drivers/acpi/tiny-power-button.c b/drivers/acpi/tiny-power-button.c new file mode 100644 index 000000000..92516ef84 --- /dev/null +++ b/drivers/acpi/tiny-power-button.c @@ -0,0 +1,87 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +#include +#include +#include +#include +#include + +MODULE_AUTHOR("Josh Triplett"); +MODULE_DESCRIPTION("ACPI Tiny Power Button Driver"); +MODULE_LICENSE("GPL"); + +static int power_signal __read_mostly = CONFIG_ACPI_TINY_POWER_BUTTON_SIGNAL; +module_param(power_signal, int, 0644); +MODULE_PARM_DESC(power_signal, "Power button sends this signal to init"); + +static const struct acpi_device_id tiny_power_button_device_ids[] = { + { ACPI_BUTTON_HID_POWER, 0 }, + { ACPI_BUTTON_HID_POWERF, 0 }, + { "", 0 }, +}; +MODULE_DEVICE_TABLE(acpi, tiny_power_button_device_ids); + +static void acpi_tiny_power_button_notify(acpi_handle handle, u32 event, void *data) +{ + kill_cad_pid(power_signal, 1); +} + +static void acpi_tiny_power_button_notify_run(void *not_used) +{ + acpi_tiny_power_button_notify(NULL, ACPI_FIXED_HARDWARE_EVENT, NULL); +} + +static u32 acpi_tiny_power_button_event(void *not_used) +{ + acpi_os_execute(OSL_NOTIFY_HANDLER, acpi_tiny_power_button_notify_run, NULL); + return ACPI_INTERRUPT_HANDLED; +} + +static int acpi_tiny_power_button_probe(struct platform_device *pdev) +{ + struct acpi_device *device; + acpi_status status; + + device = ACPI_COMPANION(&pdev->dev); + if (!device) + return -ENODEV; + + if (device->device_type == ACPI_BUS_TYPE_POWER_BUTTON) { + status = acpi_install_fixed_event_handler(ACPI_EVENT_POWER_BUTTON, + acpi_tiny_power_button_event, + NULL); + } else { + status = acpi_install_notify_handler(device->handle, + ACPI_DEVICE_NOTIFY, + acpi_tiny_power_button_notify, + NULL); + } + if (ACPI_FAILURE(status)) + return -ENODEV; + + return 0; +} + +static void acpi_tiny_power_button_remove(struct platform_device *pdev) +{ + struct acpi_device *device = ACPI_COMPANION(&pdev->dev); + + if (device->device_type == ACPI_BUS_TYPE_POWER_BUTTON) { + acpi_remove_fixed_event_handler(ACPI_EVENT_POWER_BUTTON, + acpi_tiny_power_button_event); + } else { + acpi_remove_notify_handler(device->handle, ACPI_DEVICE_NOTIFY, + acpi_tiny_power_button_notify); + } + acpi_os_wait_events_complete(); +} + +static struct platform_driver acpi_tiny_power_button_driver = { + .probe = acpi_tiny_power_button_probe, + .remove = acpi_tiny_power_button_remove, + .driver = { + .name = "acpi-tiny-power-button", + .acpi_match_table = tiny_power_button_device_ids, + }, +}; + +module_platform_driver(acpi_tiny_power_button_driver); -- cgit v1.3.1