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 --- crypto/cipher.c | 91 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 91 insertions(+) create mode 100644 crypto/cipher.c (limited to 'crypto/cipher.c') diff --git a/crypto/cipher.c b/crypto/cipher.c new file mode 100644 index 000000000..c9dab656a --- /dev/null +++ b/crypto/cipher.c @@ -0,0 +1,91 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Cryptographic API. + * + * Single-block cipher operations. + * + * Copyright (c) 2002 James Morris + * Copyright (c) 2005 Herbert Xu + */ + +#include +#include +#include +#include +#include +#include +#include +#include "internal.h" + +static int setkey_unaligned(struct crypto_cipher *tfm, const u8 *key, + unsigned int keylen) +{ + struct cipher_alg *cia = crypto_cipher_alg(tfm); + unsigned long alignmask = crypto_cipher_alignmask(tfm); + int ret; + u8 *buffer, *alignbuffer; + unsigned long absize; + + absize = keylen + alignmask; + buffer = kmalloc(absize, GFP_ATOMIC); + if (!buffer) + return -ENOMEM; + + alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1); + memcpy(alignbuffer, key, keylen); + ret = cia->cia_setkey(crypto_cipher_tfm(tfm), alignbuffer, keylen); + kfree_sensitive(buffer); + return ret; + +} + +int crypto_cipher_setkey(struct crypto_cipher *tfm, + const u8 *key, unsigned int keylen) +{ + struct cipher_alg *cia = crypto_cipher_alg(tfm); + unsigned long alignmask = crypto_cipher_alignmask(tfm); + + if (keylen < cia->cia_min_keysize || keylen > cia->cia_max_keysize) + return -EINVAL; + + if ((unsigned long)key & alignmask) + return setkey_unaligned(tfm, key, keylen); + + return cia->cia_setkey(crypto_cipher_tfm(tfm), key, keylen); +} +EXPORT_SYMBOL_NS_GPL(crypto_cipher_setkey, "CRYPTO_INTERNAL"); + +static inline void cipher_crypt_one(struct crypto_cipher *tfm, + u8 *dst, const u8 *src, bool enc) +{ + unsigned long alignmask = crypto_cipher_alignmask(tfm); + struct cipher_alg *cia = crypto_cipher_alg(tfm); + void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = + enc ? cia->cia_encrypt : cia->cia_decrypt; + + if (unlikely(((unsigned long)dst | (unsigned long)src) & alignmask)) { + unsigned int bs = crypto_cipher_blocksize(tfm); + u8 buffer[MAX_CIPHER_BLOCKSIZE + MAX_CIPHER_ALIGNMASK]; + u8 *tmp = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1); + + memcpy(tmp, src, bs); + fn(crypto_cipher_tfm(tfm), tmp, tmp); + memcpy(dst, tmp, bs); + } else { + fn(crypto_cipher_tfm(tfm), dst, src); + } +} + +void crypto_cipher_encrypt_one(struct crypto_cipher *tfm, + u8 *dst, const u8 *src) +{ + cipher_crypt_one(tfm, dst, src, true); +} +EXPORT_SYMBOL_NS_GPL(crypto_cipher_encrypt_one, "CRYPTO_INTERNAL"); + +void crypto_cipher_decrypt_one(struct crypto_cipher *tfm, + u8 *dst, const u8 *src) +{ + cipher_crypt_one(tfm, dst, src, false); +} +EXPORT_SYMBOL_NS_GPL(crypto_cipher_decrypt_one, "CRYPTO_INTERNAL"); -- cgit v1.3.1