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 --- scripts/include/hashtable.h | 98 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 98 insertions(+) create mode 100644 scripts/include/hashtable.h (limited to 'scripts/include/hashtable.h') diff --git a/scripts/include/hashtable.h b/scripts/include/hashtable.h new file mode 100644 index 000000000..45abcb12b --- /dev/null +++ b/scripts/include/hashtable.h @@ -0,0 +1,98 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef HASHTABLE_H +#define HASHTABLE_H + +#include "array_size.h" +#include "list.h" + +#define HASH_SIZE(name) (ARRAY_SIZE(name)) + +#define HASHTABLE_DECLARE(name, size) struct hlist_head name[size] + +#define HASHTABLE_DEFINE(name, size) \ + HASHTABLE_DECLARE(name, size) = \ + { [0 ... ((size) - 1)] = HLIST_HEAD_INIT } + +#define hash_head(table, key) (&(table)[(key) % HASH_SIZE(table)]) + +static inline void __hash_init(struct hlist_head *ht, unsigned int sz) +{ + unsigned int i; + + for (i = 0; i < sz; i++) + INIT_HLIST_HEAD(&ht[i]); +} + +/** + * hash_init - initialize a hash table + * @table: hashtable to be initialized + * + * This has to be a macro since HASH_SIZE() will not work on pointers since + * it calculates the size during preprocessing. + */ +#define hash_init(table) __hash_init(table, HASH_SIZE(table)) + +/** + * hash_add - add an object to a hashtable + * @table: hashtable to add to + * @node: the &struct hlist_node of the object to be added + * @key: the key of the object to be added + */ +#define hash_add(table, node, key) \ + hlist_add_head(node, hash_head(table, key)) + +/** + * hash_del - remove an object from a hashtable + * @node: &struct hlist_node of the object to remove + */ +static inline void hash_del(struct hlist_node *node) +{ + hlist_del_init(node); +} + +/** + * hash_for_each - iterate over a hashtable + * @table: hashtable to iterate + * @obj: the type * to use as a loop cursor for each entry + * @member: the name of the hlist_node within the struct + */ +#define hash_for_each(table, obj, member) \ + for (int _bkt = 0; _bkt < HASH_SIZE(table); _bkt++) \ + hlist_for_each_entry(obj, &table[_bkt], member) + +/** + * hash_for_each_safe - iterate over a hashtable safe against removal of + * hash entry + * @table: hashtable to iterate + * @obj: the type * to use as a loop cursor for each entry + * @tmp: a &struct hlist_node used for temporary storage + * @member: the name of the hlist_node within the struct + */ +#define hash_for_each_safe(table, obj, tmp, member) \ + for (int _bkt = 0; _bkt < HASH_SIZE(table); _bkt++) \ + hlist_for_each_entry_safe(obj, tmp, &table[_bkt], member) + +/** + * hash_for_each_possible - iterate over all possible objects hashing to the + * same bucket + * @table: hashtable to iterate + * @obj: the type * to use as a loop cursor for each entry + * @member: the name of the hlist_node within the struct + * @key: the key of the objects to iterate over + */ +#define hash_for_each_possible(table, obj, member, key) \ + hlist_for_each_entry(obj, hash_head(table, key), member) + +/** + * hash_for_each_possible_safe - iterate over all possible objects hashing to the + * same bucket safe against removals + * @table: hashtable to iterate + * @obj: the type * to use as a loop cursor for each entry + * @tmp: a &struct hlist_node used for temporary storage + * @member: the name of the hlist_node within the struct + * @key: the key of the objects to iterate over + */ +#define hash_for_each_possible_safe(table, obj, tmp, member, key) \ + hlist_for_each_entry_safe(obj, tmp, hash_head(table, key), member) + +#endif /* HASHTABLE_H */ -- cgit v1.3.1