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/md/persistent-data/dm-space-map-metadata.h | 45 ++++++++++++++++++++++ 1 file changed, 45 insertions(+) create mode 100644 drivers/md/persistent-data/dm-space-map-metadata.h (limited to 'drivers/md/persistent-data/dm-space-map-metadata.h') diff --git a/drivers/md/persistent-data/dm-space-map-metadata.h b/drivers/md/persistent-data/dm-space-map-metadata.h new file mode 100644 index 000000000..ca5c3e532 --- /dev/null +++ b/drivers/md/persistent-data/dm-space-map-metadata.h @@ -0,0 +1,45 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2011 Red Hat, Inc. + * + * This file is released under the GPL. + */ + +#ifndef DM_SPACE_MAP_METADATA_H +#define DM_SPACE_MAP_METADATA_H + +#include "dm-transaction-manager.h" + +#define DM_SM_METADATA_BLOCK_SIZE (4096 >> SECTOR_SHIFT) + +/* + * The metadata device is currently limited in size. + * + * We have one block of index, which can hold 255 index entries. Each + * index entry contains allocation info about ~16k metadata blocks. + */ +#define DM_SM_METADATA_MAX_BLOCKS (255 * ((1 << 14) - 64)) +#define DM_SM_METADATA_MAX_SECTORS (DM_SM_METADATA_MAX_BLOCKS * DM_SM_METADATA_BLOCK_SIZE) + +/* + * Unfortunately we have to use two-phase construction due to the cycle + * between the tm and sm. + */ +struct dm_space_map *dm_sm_metadata_init(void); + +/* + * Create a fresh space map. + */ +int dm_sm_metadata_create(struct dm_space_map *sm, + struct dm_transaction_manager *tm, + dm_block_t nr_blocks, + dm_block_t superblock); + +/* + * Open from a previously-recorded root. + */ +int dm_sm_metadata_open(struct dm_space_map *sm, + struct dm_transaction_manager *tm, + void *root_le, size_t len); + +#endif /* DM_SPACE_MAP_METADATA_H */ -- cgit v1.3.1