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, 34 insertions, 0 deletions

diff --git a/drivers/crypto/omap-crypto.h b/drivers/crypto/omap-crypto.h
new file mode 100644
index 000000000..506ccde6f
--- /dev/null
+++ b/drivers/crypto/omap-crypto.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * OMAP Crypto driver common support routines.
+ *
+ * Copyright (c) 2017 Texas Instruments Incorporated
+ *   Tero Kristo <t-kristo@ti.com>
+ */
+
+#ifndef __CRYPTO_OMAP_CRYPTO_H
+#define __CRYPTO_OMAP_CRYPTO_H
+
+enum {
+	OMAP_CRYPTO_NOT_ALIGNED = 1,
+	OMAP_CRYPTO_BAD_DATA_LENGTH,
+};
+
+#define OMAP_CRYPTO_DATA_COPIED		BIT(0)
+#define OMAP_CRYPTO_SG_COPIED		BIT(1)
+
+#define OMAP_CRYPTO_COPY_MASK		0x3
+
+#define OMAP_CRYPTO_COPY_DATA		BIT(0)
+#define OMAP_CRYPTO_FORCE_COPY		BIT(1)
+#define OMAP_CRYPTO_ZERO_BUF		BIT(2)
+#define OMAP_CRYPTO_FORCE_SINGLE_ENTRY	BIT(3)
+
+int omap_crypto_align_sg(struct scatterlist **sg, int total, int bs,
+			 struct scatterlist *new_sg, u16 flags,
+			 u8 flags_shift, unsigned long *dd_flags);
+void omap_crypto_cleanup(struct scatterlist *sg, struct scatterlist *orig,
+			 int offset, int len, u8 flags_shift,
+			 unsigned long flags);
+
+#endif