KVM: SEV: Do cache maintenance on the source VM during intra-host migrationgrafted

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 <fane@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260923163721.1584779-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 56 insertions, 0 deletions

diff --git a/drivers/crypto/qce/aead.h b/drivers/crypto/qce/aead.h
new file mode 100644
index 000000000..efb8477cc
--- /dev/null
+++ b/drivers/crypto/qce/aead.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2021, Linaro Limited. All rights reserved.
+ */
+
+#ifndef _AEAD_H_
+#define _AEAD_H_
+
+#include "common.h"
+#include "core.h"
+
+#define QCE_MAX_KEY_SIZE		64
+#define QCE_CCM4309_SALT_SIZE		3
+
+struct qce_aead_ctx {
+	u8 enc_key[QCE_MAX_KEY_SIZE];
+	u8 auth_key[QCE_MAX_KEY_SIZE];
+	u8 ccm4309_salt[QCE_CCM4309_SALT_SIZE];
+	unsigned int enc_keylen;
+	unsigned int auth_keylen;
+	unsigned int authsize;
+	bool need_fallback;
+	struct crypto_aead *fallback;
+};
+
+struct qce_aead_reqctx {
+	unsigned long flags;
+	u8 *iv;
+	unsigned int ivsize;
+	int src_nents;
+	int dst_nents;
+	struct scatterlist result_sg;
+	struct scatterlist adata_sg;
+	struct sg_table dst_tbl;
+	struct sg_table src_tbl;
+	struct scatterlist *dst_sg;
+	struct scatterlist *src_sg;
+	unsigned int cryptlen;
+	unsigned int assoclen;
+	unsigned char *adata;
+	u8 ccm_nonce[QCE_MAX_NONCE];
+	u8 ccmresult_buf[QCE_BAM_BURST_SIZE];
+	u8 ccm_rfc4309_iv[QCE_MAX_IV_SIZE];
+	struct aead_request fallback_req;
+};
+
+static inline struct qce_alg_template *to_aead_tmpl(struct crypto_aead *tfm)
+{
+	struct aead_alg *alg = crypto_aead_alg(tfm);
+
+	return container_of(alg, struct qce_alg_template, alg.aead);
+}
+
+extern const struct qce_algo_ops aead_ops;
+
+#endif /* _AEAD_H_ */