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/tpm.c | 116 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 116 insertions(+) create mode 100644 drivers/firmware/efi/tpm.c (limited to 'drivers/firmware/efi/tpm.c') diff --git a/drivers/firmware/efi/tpm.c b/drivers/firmware/efi/tpm.c new file mode 100644 index 000000000..cdd431027 --- /dev/null +++ b/drivers/firmware/efi/tpm.c @@ -0,0 +1,116 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2017 Google, Inc. + * Thiebaud Weksteen + */ + +#define TPM_MEMREMAP(start, size) early_memremap(start, size) +#define TPM_MEMUNMAP(start, size) early_memunmap(start, size) + +#include +#include +#include +#include +#include + +int efi_tpm_final_log_size; +EXPORT_SYMBOL(efi_tpm_final_log_size); + +static int __init tpm2_calc_event_log_size(void *data, int count, void *size_info) +{ + struct tcg_pcr_event2_head *header; + u32 event_size, size = 0; + + while (count > 0) { + header = data + size; + event_size = __calc_tpm2_event_size(header, size_info, true); + if (event_size == 0) + return -1; + size += event_size; + count--; + } + + return size; +} + +/* + * Reserve the memory associated with the TPM Event Log configuration table. + */ +int __init efi_tpm_eventlog_init(void) +{ + struct linux_efi_tpm_eventlog *log_tbl; + struct efi_tcg2_final_events_table *final_tbl; + unsigned int tbl_size; + int final_tbl_size; + int ret = 0; + + if (efi.tpm_log == EFI_INVALID_TABLE_ADDR) { + /* + * We can't calculate the size of the final events without the + * first entry in the TPM log, so bail here. + */ + return 0; + } + + log_tbl = early_memremap(efi.tpm_log, sizeof(*log_tbl)); + if (!log_tbl) { + pr_err("Failed to map TPM Event Log table @ 0x%lx\n", + efi.tpm_log); + efi.tpm_log = EFI_INVALID_TABLE_ADDR; + return -ENOMEM; + } + + tbl_size = sizeof(*log_tbl) + log_tbl->size; + if (memblock_reserve(efi.tpm_log, tbl_size)) { + pr_err("TPM Event Log memblock reserve fails (0x%lx, 0x%x)\n", + efi.tpm_log, tbl_size); + ret = -ENOMEM; + goto out; + } + + if (efi.tpm_final_log == EFI_INVALID_TABLE_ADDR) { + pr_info("TPM Final Events table not present\n"); + goto out; + } else if (log_tbl->version != EFI_TCG2_EVENT_LOG_FORMAT_TCG_2) { + pr_warn(FW_BUG "TPM Final Events table invalid\n"); + goto out; + } + + final_tbl = early_memremap(efi.tpm_final_log, sizeof(*final_tbl)); + + if (!final_tbl) { + pr_err("Failed to map TPM Final Event Log table @ 0x%lx\n", + efi.tpm_final_log); + efi.tpm_final_log = EFI_INVALID_TABLE_ADDR; + ret = -ENOMEM; + goto out; + } + + final_tbl_size = 0; + if (final_tbl->nr_events != 0) { + void *events = (void *)efi.tpm_final_log + + sizeof(final_tbl->version) + + sizeof(final_tbl->nr_events); + + final_tbl_size = tpm2_calc_event_log_size(events, + final_tbl->nr_events, + log_tbl->log); + } + + if (final_tbl_size < 0) { + pr_err(FW_BUG "Failed to parse event in TPM Final Events Log\n"); + ret = -EINVAL; + goto out_calc; + } + + memblock_reserve(efi.tpm_final_log, + final_tbl_size + sizeof(*final_tbl)); + efi_tpm_final_log_size = final_tbl_size; + +out_calc: + early_memunmap(final_tbl, sizeof(*final_tbl)); +out: + early_memunmap(log_tbl, sizeof(*log_tbl)); + return ret; +} + -- cgit v1.3.1