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/firmware/efi/reboot.c | 78 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 78 insertions(+) create mode 100644 drivers/firmware/efi/reboot.c (limited to 'drivers/firmware/efi/reboot.c') diff --git a/drivers/firmware/efi/reboot.c b/drivers/firmware/efi/reboot.c new file mode 100644 index 000000000..ceae84c19 --- /dev/null +++ b/drivers/firmware/efi/reboot.c @@ -0,0 +1,78 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2014 Intel Corporation; author Matt Fleming + * Copyright (c) 2014 Red Hat, Inc., Mark Salter + */ +#include +#include + +static struct sys_off_handler *efi_sys_off_handler; + +int efi_reboot_quirk_mode = -1; + +void efi_reboot(enum reboot_mode reboot_mode, const char *__unused) +{ + const char *str[] = { "cold", "warm", "shutdown", "platform" }; + int efi_mode, cap_reset_mode; + + if (!efi_rt_services_supported(EFI_RT_SUPPORTED_RESET_SYSTEM)) + return; + + switch (reboot_mode) { + case REBOOT_WARM: + case REBOOT_SOFT: + efi_mode = EFI_RESET_WARM; + break; + default: + efi_mode = EFI_RESET_COLD; + break; + } + + /* + * If a quirk forced an EFI reset mode, always use that. + */ + if (efi_reboot_quirk_mode != -1) + efi_mode = efi_reboot_quirk_mode; + + if (efi_capsule_pending(&cap_reset_mode)) { + if (efi_mode != cap_reset_mode) + printk(KERN_CRIT "efi: %s reset requested but pending " + "capsule update requires %s reset... Performing " + "%s reset.\n", str[efi_mode], str[cap_reset_mode], + str[cap_reset_mode]); + efi_mode = cap_reset_mode; + } + + efi.reset_system(efi_mode, EFI_SUCCESS, 0, NULL); +} + +bool __weak efi_poweroff_required(void) +{ + return false; +} + +static int efi_power_off(struct sys_off_data *data) +{ + efi.reset_system(EFI_RESET_SHUTDOWN, EFI_SUCCESS, 0, NULL); + + return NOTIFY_DONE; +} + +static int __init efi_shutdown_init(void) +{ + if (!efi_rt_services_supported(EFI_RT_SUPPORTED_RESET_SYSTEM)) + return -ENODEV; + + if (efi_poweroff_required()) { + /* SYS_OFF_PRIO_FIRMWARE + 1 so that it runs before acpi_power_off */ + efi_sys_off_handler = + register_sys_off_handler(SYS_OFF_MODE_POWER_OFF, + SYS_OFF_PRIO_FIRMWARE + 1, + efi_power_off, NULL); + if (IS_ERR(efi_sys_off_handler)) + return PTR_ERR(efi_sys_off_handler); + } + + return 0; +} +late_initcall(efi_shutdown_init); -- cgit v1.3.1