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, 45 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-block-aoe b/Documentation/ABI/testing/sysfs-block-aoe
new file mode 100644
index 000000000..b5837765b
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-block-aoe
@@ -0,0 +1,45 @@
+What:		/sys/block/etherd*/mac
+Date:		Apr, 2005
+KernelVersion:	v2.6.12
+Contact:	Ed L. Cashin <ed.cashin@acm.org>
+Description:
+		(RO) The ethernet address of the remote Ata over Ethernet (AoE)
+		device.
+
+What:		/sys/block/etherd*/netif
+Date:		Apr, 2005
+KernelVersion:	v2.6.12
+Contact:	Ed L. Cashin <ed.cashin@acm.org>
+Description:
+		(RO) The names of the network interfaces on the localhost (comma
+		separated) through which we are communicating with the remote
+		AoE device.
+
+What:		/sys/block/etherd*/state
+Date:		Apr, 2005
+KernelVersion:	v2.6.12
+Contact:	Ed L. Cashin <ed.cashin@acm.org>
+Description:
+		(RO) Device status. The state attribute is "up" when the device
+		is ready for I/O and "down" if detected but unusable. The
+		"down,closewait" state shows that the device is still open and
+		cannot come up again until it has been closed.  The "up,kickme"
+		state means that the driver wants to send more commands to the
+		target but found out there were already the max number of
+		commands waiting for a response. It will retry again after being
+		kicked by the periodic timer handler routine.
+
+What:		/sys/block/etherd*/firmware-version
+Date:		Apr, 2005
+KernelVersion:	v2.6.12
+Contact:	Ed L. Cashin <ed.cashin@acm.org>
+Description:
+		(RO) Version of the firmware in the target.
+
+What:		/sys/block/etherd*/payload
+Date:		Dec, 2012
+KernelVersion:	v3.10
+Contact:	Ed L. Cashin <ed.cashin@acm.org>
+Description:
+		(RO) The amount of user data transferred (in bytes) inside each AoE
+		command on the network, network headers excluded.