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, 26 insertions, 0 deletions

diff --git a/Documentation/gpu/rfc/index.rst b/Documentation/gpu/rfc/index.rst
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+===============
+GPU RFC Section
+===============
+
+For complex work, especially new uapi, it is often good to nail the high level
+design issues before getting lost in the code details. This section is meant to
+host such documentation:
+
+* Each RFC should be a section in this file, explaining the goal and main design
+  considerations. Especially for uapi make sure you Cc: all relevant project
+  mailing lists and involved people outside of dri-devel.
+
+* For uapi structures add a file to this directory with and then pull the
+  kerneldoc in like with real uapi headers.
+
+* Once the code has landed move all the documentation to the right places in
+  the main core, helper or driver sections.
+
+.. toctree::
+
+   gpusvm
+   i915_gem_lmem
+   i915_scheduler
+   i915_small_bar
+   i915_vm_bind
+   color_pipeline