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, 58 insertions, 0 deletions

diff --git a/drivers/crypto/geode-aes.h b/drivers/crypto/geode-aes.h
new file mode 100644
index 000000000..6d0a0cdc7
--- /dev/null
+++ b/drivers/crypto/geode-aes.h
@@ -0,0 +1,58 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Copyright (C) 2003-2006, Advanced Micro Devices, Inc.
+ */
+
+#ifndef _GEODE_AES_H_
+#define _GEODE_AES_H_
+
+/* driver logic flags */
+#define AES_MODE_ECB 0
+#define AES_MODE_CBC 1
+
+#define AES_DIR_DECRYPT 0
+#define AES_DIR_ENCRYPT 1
+
+#define AES_FLAGS_HIDDENKEY (1 << 0)
+
+/* Register definitions */
+
+#define AES_CTRLA_REG  0x0000
+
+#define AES_CTRL_START     0x01
+#define AES_CTRL_DECRYPT   0x00
+#define AES_CTRL_ENCRYPT   0x02
+#define AES_CTRL_WRKEY     0x04
+#define AES_CTRL_DCA       0x08
+#define AES_CTRL_SCA       0x10
+#define AES_CTRL_CBC       0x20
+
+#define AES_INTR_REG  0x0008
+
+#define AES_INTRA_PENDING (1 << 16)
+#define AES_INTRB_PENDING (1 << 17)
+
+#define AES_INTR_PENDING  (AES_INTRA_PENDING | AES_INTRB_PENDING)
+#define AES_INTR_MASK     0x07
+
+#define AES_SOURCEA_REG   0x0010
+#define AES_DSTA_REG      0x0014
+#define AES_LENA_REG      0x0018
+#define AES_WRITEKEY0_REG 0x0030
+#define AES_WRITEIV0_REG  0x0040
+
+/*  A very large counter that is used to gracefully bail out of an
+ *  operation in case of trouble
+ */
+
+#define AES_OP_TIMEOUT    0x50000
+
+struct geode_aes_tfm_ctx {
+	u8 key[AES_KEYSIZE_128];
+	union {
+		struct crypto_skcipher *skcipher;
+		struct crypto_cipher *cip;
+	} fallback;
+	u32 keylen;
+};
+
+#endif