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, 19 insertions, 0 deletions

diff --git a/sound/soc/sof/sof-utils.h b/sound/soc/sof/sof-utils.h
new file mode 100644
index 000000000..9ac6de9a6
--- /dev/null
+++ b/sound/soc/sof/sof-utils.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause) */
+/*
+ * This file is provided under a dual BSD/GPLv2 license.  When using or
+ * redistributing this file, you may do so under either license.
+ *
+ * Copyright(c) 2022 Intel Corporation
+ */
+
+#ifndef __SOC_SOF_UTILS_H
+#define __SOC_SOF_UTILS_H
+
+struct snd_dma_buffer;
+struct device;
+
+int snd_sof_create_page_table(struct device *dev,
+			      struct snd_dma_buffer *dmab,
+			      unsigned char *page_table, size_t size);
+
+#endif