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, 25 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-tee b/Documentation/ABI/testing/sysfs-class-tee
new file mode 100644
index 000000000..1a0a3050a
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-tee
@@ -0,0 +1,25 @@
+What:		/sys/class/tee/tee{,priv}X/rpmb_routing_model
+Date:		May 2024
+KernelVersion:	6.10
+Contact:        op-tee@lists.trustedfirmware.org
+Description:
+		RPMB frames can be routed to the RPMB device via the
+		user-space daemon tee-supplicant or the RPMB subsystem
+		in the kernel. The value "user" means that the driver
+		will route the RPMB frames via user space. Conversely,
+		"kernel" means that the frames are routed via the RPMB
+		subsystem without assistance from tee-supplicant. It
+		should be assumed that RPMB frames are routed via user
+		space if the variable is absent. The primary purpose
+		of this variable is to let systemd know whether
+		tee-supplicant is needed in the early boot with initramfs.
+
+What:		/sys/class/tee/tee{,priv}X/revision
+Date:		Jan 2026
+KernelVersion:	6.19
+Contact:	op-tee@lists.trustedfirmware.org
+Description:
+		Read-only revision string reported by the TEE driver. This is
+		for diagnostics only and must not be used to infer feature
+		support. Use TEE_IOC_VERSION for capability and compatibility
+		checks.