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 --- include/net/libeth/cache.h | 66 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 66 insertions(+) create mode 100644 include/net/libeth/cache.h (limited to 'include/net/libeth/cache.h') diff --git a/include/net/libeth/cache.h b/include/net/libeth/cache.h new file mode 100644 index 000000000..bdb0c043c --- /dev/null +++ b/include/net/libeth/cache.h @@ -0,0 +1,66 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* Copyright (C) 2024 Intel Corporation */ + +#ifndef __LIBETH_CACHE_H +#define __LIBETH_CACHE_H + +#include + +/** + * libeth_cacheline_group_assert - make sure cacheline group size is expected + * @type: type of the structure containing the group + * @grp: group name inside the struct + * @sz: expected group size + */ +#if defined(CONFIG_64BIT) && SMP_CACHE_BYTES == 64 +#define libeth_cacheline_group_assert(type, grp, sz) \ + static_assert(offsetof(type, __cacheline_group_end__##grp) - \ + offsetofend(type, __cacheline_group_begin__##grp) == \ + (sz)) +#define __libeth_cacheline_struct_assert(type, sz) \ + static_assert(sizeof(type) == (sz)) +#else /* !CONFIG_64BIT || SMP_CACHE_BYTES != 64 */ +#define libeth_cacheline_group_assert(type, grp, sz) \ + static_assert(offsetof(type, __cacheline_group_end__##grp) - \ + offsetofend(type, __cacheline_group_begin__##grp) <= \ + (sz)) +#define __libeth_cacheline_struct_assert(type, sz) \ + static_assert(sizeof(type) <= (sz)) +#endif /* !CONFIG_64BIT || SMP_CACHE_BYTES != 64 */ + +#define __libeth_cls1(sz1) SMP_CACHE_ALIGN(sz1) +#define __libeth_cls2(sz1, sz2) (SMP_CACHE_ALIGN(sz1) + SMP_CACHE_ALIGN(sz2)) +#define __libeth_cls3(sz1, sz2, sz3) \ + (SMP_CACHE_ALIGN(sz1) + SMP_CACHE_ALIGN(sz2) + SMP_CACHE_ALIGN(sz3)) +#define __libeth_cls(...) \ + CONCATENATE(__libeth_cls, COUNT_ARGS(__VA_ARGS__))(__VA_ARGS__) + +/** + * libeth_cacheline_struct_assert - make sure CL-based struct size is expected + * @type: type of the struct + * @...: from 1 to 3 CL group sizes (read-mostly, read-write, cold) + * + * When a struct contains several CL groups, it's difficult to predict its size + * on different architectures. The macro instead takes sizes of all of the + * groups the structure contains and generates the final struct size. + */ +#define libeth_cacheline_struct_assert(type, ...) \ + __libeth_cacheline_struct_assert(type, __libeth_cls(__VA_ARGS__)); \ + static_assert(__alignof(type) >= SMP_CACHE_BYTES) + +/** + * libeth_cacheline_set_assert - make sure CL-based struct layout is expected + * @type: type of the struct + * @ro: expected size of the read-mostly group + * @rw: expected size of the read-write group + * @c: expected size of the cold group + * + * Check that each group size is expected and then do final struct size check. + */ +#define libeth_cacheline_set_assert(type, ro, rw, c) \ + libeth_cacheline_group_assert(type, read_mostly, ro); \ + libeth_cacheline_group_assert(type, read_write, rw); \ + libeth_cacheline_group_assert(type, cold, c); \ + libeth_cacheline_struct_assert(type, ro, rw, c) + +#endif /* __LIBETH_CACHE_H */ -- cgit v1.3.1