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/drivers/net/plip/Kconfig b/drivers/net/plip/Kconfig
new file mode 100644
index 000000000..67bfb01de
--- /dev/null
+++ b/drivers/net/plip/Kconfig
@@ -0,0 +1,39 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Parallel Line Internet Protocol (PLIP) network device configuration
+#
+
+config PLIP
+	tristate "PLIP (parallel port) support"
+	depends on PARPORT
+	help
+	  PLIP (Parallel Line Internet Protocol) is used to create a
+	  reasonably fast mini network consisting of two (or, rarely, more)
+	  local machines.  A PLIP link from a Linux box is a popular means to
+	  install a Linux distribution on a machine which doesn't have a
+	  CD-ROM drive (a minimal system has to be transferred with floppies
+	  first). The kernels on both machines need to have this PLIP option
+	  enabled for this to work.
+
+	  The PLIP driver has two modes, mode 0 and mode 1.  The parallel
+	  ports (the connectors at the computers with 25 holes) are connected
+	  with "null printer" or "Turbo Laplink" cables which can transmit 4
+	  bits at a time (mode 0) or with special PLIP cables, to be used on
+	  bidirectional parallel ports only, which can transmit 8 bits at a
+	  time (mode 1); you can find the wiring of these cables in
+	  <file:Documentation/networking/plip.rst>.  The cables can be up to
+	  15m long.  Mode 0 works also if one of the machines runs DOS/Windows
+	  and has some PLIP software installed, e.g. the Crynwr PLIP packet
+	  driver (<http://oak.oakland.edu/simtel.net/msdos/pktdrvr-pre.html>)
+	  and winsock or NCSA's telnet.
+
+	  If you want to use PLIP, say Y and read the PLIP mini-HOWTO as well
+	  as the NET-3-HOWTO, both available from
+	  <http://www.tldp.org/docs.html#howto>.  Note that the PLIP
+	  protocol has been changed and this PLIP driver won't work together
+	  with the PLIP support in Linux versions 1.0.x.  This option enlarges
+	  your kernel by about 8 KB.
+
+	  To compile this driver as a module, choose M here. The module
+	  will be called plip. If unsure, say Y or M, in case you buy
+	  a laptop later.