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, 33 insertions, 0 deletions

diff --git a/drivers/scsi/libsas/Kconfig b/drivers/scsi/libsas/Kconfig
new file mode 100644
index 000000000..c640535d1
--- /dev/null
+++ b/drivers/scsi/libsas/Kconfig
@@ -0,0 +1,33 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Kernel configuration file for the SAS Class
+#
+# Copyright (C) 2005 Adaptec, Inc.  All rights reserved.
+# Copyright (C) 2005 Luben Tuikov <luben_tuikov@adaptec.com>
+#
+
+config SCSI_SAS_LIBSAS
+	tristate "SAS Domain Transport Attributes"
+	depends on SCSI
+	select SCSI_SAS_ATTRS
+	help
+	  This provides transport specific helpers for SAS drivers which
+	  use the domain device construct (like the aic94xxx).
+
+config SCSI_SAS_ATA
+	bool "ATA support for libsas (requires libata)"
+	depends on SCSI_SAS_LIBSAS
+	depends on ATA = y || ATA = SCSI_SAS_LIBSAS
+	select SATA_HOST
+	help
+		Builds in ATA support into libsas.  Will necessitate
+		the loading of libata along with libsas.
+
+config SCSI_SAS_HOST_SMP
+	bool "Support for SMP interpretation for SAS hosts"
+	default y
+	depends on SCSI_SAS_LIBSAS
+	help
+		Allows sas hosts to receive SMP frames.  Selecting this
+		option builds an SMP interpreter into libsas.  Say
+		N here if you want to save the few kb this consumes.