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 --- tools/testing/radix-tree/test.c | 287 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 287 insertions(+) create mode 100644 tools/testing/radix-tree/test.c (limited to 'tools/testing/radix-tree/test.c') diff --git a/tools/testing/radix-tree/test.c b/tools/testing/radix-tree/test.c new file mode 100644 index 000000000..a15d0512e --- /dev/null +++ b/tools/testing/radix-tree/test.c @@ -0,0 +1,287 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include + +#include "test.h" + +struct item * +item_tag_set(struct radix_tree_root *root, unsigned long index, int tag) +{ + return radix_tree_tag_set(root, index, tag); +} + +struct item * +item_tag_clear(struct radix_tree_root *root, unsigned long index, int tag) +{ + return radix_tree_tag_clear(root, index, tag); +} + +int item_tag_get(struct radix_tree_root *root, unsigned long index, int tag) +{ + return radix_tree_tag_get(root, index, tag); +} + +struct item *item_create(unsigned long index, unsigned int order) +{ + struct item *ret = malloc(sizeof(*ret)); + + ret->index = index; + ret->order = order; + return ret; +} + +int item_insert(struct radix_tree_root *root, unsigned long index) +{ + struct item *item = item_create(index, 0); + int err = radix_tree_insert(root, item->index, item); + if (err) + free(item); + return err; +} + +void item_sanity(struct item *item, unsigned long index) +{ + unsigned long mask; + assert(!radix_tree_is_internal_node(item)); + assert(item->order < BITS_PER_LONG); + mask = (1UL << item->order) - 1; + assert((item->index | mask) == (index | mask)); +} + +void item_free(struct item *item, unsigned long index) +{ + item_sanity(item, index); + free(item); +} + +int item_delete(struct radix_tree_root *root, unsigned long index) +{ + struct item *item = radix_tree_delete(root, index); + + if (!item) + return 0; + + item_free(item, index); + return 1; +} + +static void item_free_rcu(struct rcu_head *head) +{ + struct item *item = container_of(head, struct item, rcu_head); + + free(item); +} + +int item_delete_rcu(struct xarray *xa, unsigned long index) +{ + struct item *item = xa_erase(xa, index); + + if (item) { + item_sanity(item, index); + call_rcu(&item->rcu_head, item_free_rcu); + return 1; + } + return 0; +} + +void item_check_present(struct radix_tree_root *root, unsigned long index) +{ + struct item *item; + + item = radix_tree_lookup(root, index); + assert(item != NULL); + item_sanity(item, index); +} + +struct item *item_lookup(struct radix_tree_root *root, unsigned long index) +{ + return radix_tree_lookup(root, index); +} + +void item_check_absent(struct radix_tree_root *root, unsigned long index) +{ + struct item *item; + + item = radix_tree_lookup(root, index); + assert(item == NULL); +} + +/* + * Scan only the passed (start, start+nr] for present items + */ +void item_gang_check_present(struct radix_tree_root *root, + unsigned long start, unsigned long nr, + int chunk, int hop) +{ + struct item *items[chunk]; + unsigned long into; + + for (into = 0; into < nr; ) { + int nfound; + int nr_to_find = chunk; + int i; + + if (nr_to_find > (nr - into)) + nr_to_find = nr - into; + + nfound = radix_tree_gang_lookup(root, (void **)items, + start + into, nr_to_find); + assert(nfound == nr_to_find); + for (i = 0; i < nfound; i++) + assert(items[i]->index == start + into + i); + into += hop; + } +} + +/* + * Scan the entire tree, only expecting present items (start, start+nr] + */ +void item_full_scan(struct radix_tree_root *root, unsigned long start, + unsigned long nr, int chunk) +{ + struct item *items[chunk]; + unsigned long into = 0; + unsigned long this_index = start; + int nfound; + int i; + +// printf("%s(0x%08lx, 0x%08lx, %d)\n", __FUNCTION__, start, nr, chunk); + + while ((nfound = radix_tree_gang_lookup(root, (void **)items, into, + chunk))) { +// printf("At 0x%08lx, nfound=%d\n", into, nfound); + for (i = 0; i < nfound; i++) { + assert(items[i]->index == this_index); + this_index++; + } +// printf("Found 0x%08lx->0x%08lx\n", +// items[0]->index, items[nfound-1]->index); + into = this_index; + } + if (chunk) + assert(this_index == start + nr); + nfound = radix_tree_gang_lookup(root, (void **)items, + this_index, chunk); + assert(nfound == 0); +} + +/* Use the same pattern as tag_pages_for_writeback() in mm/page-writeback.c */ +int tag_tagged_items(struct xarray *xa, unsigned long start, unsigned long end, + unsigned batch, xa_mark_t iftag, xa_mark_t thentag) +{ + XA_STATE(xas, xa, start); + unsigned int tagged = 0; + struct item *item; + + if (batch == 0) + batch = 1; + + xas_lock_irq(&xas); + xas_for_each_marked(&xas, item, end, iftag) { + xas_set_mark(&xas, thentag); + if (++tagged % batch) + continue; + + xas_pause(&xas); + xas_unlock_irq(&xas); + rcu_barrier(); + xas_lock_irq(&xas); + } + xas_unlock_irq(&xas); + + return tagged; +} + +static int verify_node(struct radix_tree_node *slot, unsigned int tag, + int tagged) +{ + int anyset = 0; + int i; + int j; + + slot = entry_to_node(slot); + + /* Verify consistency at this level */ + for (i = 0; i < RADIX_TREE_TAG_LONGS; i++) { + if (slot->tags[tag][i]) { + anyset = 1; + break; + } + } + if (tagged != anyset) { + printf("tag: %u, shift %u, tagged: %d, anyset: %d\n", + tag, slot->shift, tagged, anyset); + for (j = 0; j < RADIX_TREE_MAX_TAGS; j++) { + printf("tag %d: ", j); + for (i = 0; i < RADIX_TREE_TAG_LONGS; i++) + printf("%016lx ", slot->tags[j][i]); + printf("\n"); + } + return 1; + } + assert(tagged == anyset); + + /* Go for next level */ + if (slot->shift > 0) { + for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) + if (slot->slots[i]) + if (verify_node(slot->slots[i], tag, + !!test_bit(i, slot->tags[tag]))) { + printf("Failure at off %d\n", i); + for (j = 0; j < RADIX_TREE_MAX_TAGS; j++) { + printf("tag %d: ", j); + for (i = 0; i < RADIX_TREE_TAG_LONGS; i++) + printf("%016lx ", slot->tags[j][i]); + printf("\n"); + } + return 1; + } + } + return 0; +} + +void verify_tag_consistency(struct radix_tree_root *root, unsigned int tag) +{ + struct radix_tree_node *node = root->xa_head; + if (!radix_tree_is_internal_node(node)) + return; + verify_node(node, tag, !!root_tag_get(root, tag)); +} + +void item_kill_tree(struct xarray *xa) +{ + XA_STATE(xas, xa, 0); + void *entry; + + xas_for_each(&xas, entry, ULONG_MAX) { + if (!xa_is_value(entry)) { + item_free(entry, xas.xa_index); + } + xas_store(&xas, NULL); + } + + assert(xa_empty(xa)); +} + +void tree_verify_min_height(struct radix_tree_root *root, int maxindex) +{ + unsigned shift; + struct radix_tree_node *node = root->xa_head; + if (!radix_tree_is_internal_node(node)) { + assert(maxindex == 0); + return; + } + + node = entry_to_node(node); + assert(maxindex <= node_maxindex(node)); + + shift = node->shift; + if (shift > 0) + assert(maxindex > shift_maxindex(shift - RADIX_TREE_MAP_SHIFT)); + else + assert(maxindex > 0); +} -- cgit v1.3.1