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, 39 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/openrisc/opencores/or1ksim.txt b/Documentation/devicetree/bindings/openrisc/opencores/or1ksim.txt
new file mode 100644
index 000000000..4950c794e
--- /dev/null
+++ b/Documentation/devicetree/bindings/openrisc/opencores/or1ksim.txt
@@ -0,0 +1,39 @@
+OpenRISC Generic SoC
+====================
+
+Boards and FPGA SoC's which support the OpenRISC standard platform.  The
+platform essentially follows the conventions of the OpenRISC architecture
+specification, however some aspects, such as the boot protocol have been defined
+by the Linux port.
+
+Required properties
+-------------------
+ - compatible: Must include "opencores,or1ksim"
+
+CPU nodes:
+----------
+A "cpus" node is required.  Required properties:
+ - #address-cells: Must be 1.
+ - #size-cells: Must be 0.
+A CPU sub-node is also required for at least CPU 0.  Since the topology may
+be probed via CPS, it is not necessary to specify secondary CPUs.  Required
+properties:
+ - compatible: Must be "opencores,or1200-rtlsvn481".
+ - reg: CPU number.
+ - clock-frequency: The CPU clock frequency in Hz.
+Example:
+	cpus {
+		#address-cells = <1>;
+		#size-cells = <0>;
+		cpu@0 {
+			compatible = "opencores,or1200-rtlsvn481";
+			reg = <0>;
+			clock-frequency = <20000000>;
+		};
+	};
+
+
+Boot protocol
+-------------
+The bootloader may pass the following arguments to the kernel:
+ - r3:  address of a flattened device-tree blob or 0x0.