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, 52 insertions, 0 deletions

diff --git a/Documentation/admin-guide/LSM/tomoyo.rst b/Documentation/admin-guide/LSM/tomoyo.rst
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+======
+TOMOYO
+======
+
+What is TOMOYO?
+===============
+
+TOMOYO is a name-based MAC extension (LSM module) for the Linux kernel.
+
+LiveCD-based tutorials are available at
+
+https://tomoyo.sourceforge.net/1.8/ubuntu12.04-live.html
+https://tomoyo.sourceforge.net/1.8/centos6-live.html
+
+Though these tutorials use non-LSM version of TOMOYO, they are useful for you
+to know what TOMOYO is.
+
+How to enable TOMOYO?
+=====================
+
+Build the kernel with ``CONFIG_SECURITY_TOMOYO=y`` and pass ``security=tomoyo`` on
+kernel's command line.
+
+Please see https://tomoyo.sourceforge.net/2.6/ for details.
+
+Where is documentation?
+=======================
+
+User <-> Kernel interface documentation is available at
+https://tomoyo.sourceforge.net/2.6/policy-specification/index.html .
+
+Materials we prepared for seminars and symposiums are available at
+https://sourceforge.net/projects/tomoyo/files/docs/ .
+Below lists are chosen from three aspects.
+
+What is TOMOYO?
+  TOMOYO Linux Overview
+    https://sourceforge.net/projects/tomoyo/files/docs/lca2009-takeda.pdf
+  TOMOYO Linux: pragmatic and manageable security for Linux
+    https://sourceforge.net/projects/tomoyo/files/docs/freedomhectaipei-tomoyo.pdf
+  TOMOYO Linux: A Practical Method to Understand and Protect Your Own Linux Box
+    https://sourceforge.net/projects/tomoyo/files/docs/PacSec2007-en-no-demo.pdf
+
+What can TOMOYO do?
+  Deep inside TOMOYO Linux
+    https://sourceforge.net/projects/tomoyo/files/docs/lca2009-kumaneko.pdf
+  The role of "pathname based access control" in security.
+    https://sourceforge.net/projects/tomoyo/files/docs/lfj2008-bof.pdf
+
+History of TOMOYO?
+  Realities of Mainlining
+    https://sourceforge.net/projects/tomoyo/files/docs/lfj2008.pdf